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4.4: Community Ecology - Biology

4.4: Community Ecology - Biology


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Populations typically do not live in isolation from other species. Populations that interact within a given habitat form a community. The number of species occupying the same habitat and their relative abundance is known as the diversity of the community. Areas with low species diversity, such as the glaciers of Antarctica, still contain a wide variety of living organisms, whereas the diversity of tropical rainforests is so great that it cannot be accurately assessed. Scientists study ecology at the community level to understand how species interact with each other and compete for the same resources.

Predation and Herbivory

Perhaps the classical example of species interaction is the predator-prey relationship. The narrowest definition of predation describes individuals of one population that kill and then consume the individuals of another population. Population sizes of predators and prey in a community are not constant over time, and they may vary in cycles that appear to be related. The most often cited example of predator-prey population dynamics is seen in the cycling of the lynx (predator) and the snowshoe hare (prey), using 100 years of trapping data from North America (Figure (PageIndex{1})). This cycling of predator and prey population sizes has a period of approximately ten years, with the predator population lagging one to two years behind the prey population. An apparent explanation for this pattern is that as the hare numbers increase, there is more food available for the lynx, allowing the lynx population to increase as well. When the lynx population grows to a threshold level, however, they kill so many hares that hare numbers begin to decline, followed by a decline in the lynx population because of scarcity of food. When the lynx population is low, the hare population size begins to increase due, in part, to low predation pressure, starting the cycle anew.

Defense Mechanisms against Predation and Herbivory

Predation and predator avoidance are strong influenced by natural selection. Any heritable character that allows an individual of a prey population to better evade its predators will be represented in greater numbers in later generations. Likewise, traits that allow a predator to more efficiently locate and capture its prey will lead to a greater number of offspring and an increase in the commonness of the trait within the population. Such ecological relationships between specific populations lead to adaptations that are driven by reciprocal evolutionary responses in those populations. Species have evolved numerous mechanisms to escape predation (including herbivory, the consumption of plants for food). Defenses may be mechanical, chemical, physical, or behavioral.

Mechanical defenses, such as the presence of armor in animals or thorns in plants, discourage predation and herbivory by discouraging physical contact (Figure (PageIndex{2})a). Many animals produce or obtain chemical defenses from plants and store them to prevent predation. Many plant species produce secondary plant compounds that serve no function for the plant except that they are toxic to animals and discourage consumption. For example, the foxglove produces several compounds, including digitalis, that are extremely toxic when eaten (Figure (PageIndex{2})b). (Biomedical scientists have repurposed the chemical produced by foxglove as a heart medication, which has saved lives for many decades.)

Many species use their body shape and coloration to avoid being detected by predators. The tropical walking stick is an insect with the coloration and body shape of a twig, which makes it very hard to see when it is stationary against a background of real twigs (Figure (PageIndex{3})a). In another example, the chameleon can change its color to match its surroundings (Figure (PageIndex{3})b).

Some species use coloration as a way of warning predators that they are distasteful or poisonous. For example, the monarch butterfly caterpillar sequesters poisons from its food (plants and milkweeds) to make itself poisonous or distasteful to potential predators. The caterpillar is bright yellow and black to advertise its toxicity. The caterpillar is also able to pass the sequestered toxins on to the adult monarch, which is also dramatically colored black and red as a warning to potential predators. Fire-bellied toads produce toxins that make them distasteful to their potential predators (Figure (PageIndex{4})). They have bright red or orange coloration on their bellies, which they display to a potential predator to advertise their poisonous nature and discourage an attack. Warning coloration only works if a predator uses eyesight to locate prey and can learn—a naïve predator must experience the negative consequences of eating one before it will avoid other similarly colored individuals.

While some predators learn to avoid eating certain potential prey because of their coloration, other species have evolved mechanisms to mimic this coloration to avoid being eaten, even though they themselves may not be unpleasant to eat or contain toxic chemicals. In some cases of mimicry, a harmless species imitates the warning coloration of a harmful species. Assuming they share the same predators, this coloration then protects the harmless ones. Many insect species mimic the coloration of wasps, which are stinging, venomous insects, thereby discouraging predation (Figure (PageIndex{5})).

In other cases of mimicry, multiple species share the same warning coloration, but all of them actually have defenses. The commonness of the signal improves the compliance of all the potential predators. Figure (PageIndex{6}) shows a variety of foul-tasting butterflies with similar coloration.

Competitive Exclusion Principle

Resources are often limited within a habitat and multiple species may compete to obtain them. Ecologists have come to understand that all species have an ecological niche: the unique set of resources used by a species, which includes its interactions with other species. The competitive exclusion principle states that two species cannot occupy the exact same niche in a habitat. In other words, different species cannot coexist in a community if they are competing for all the same resources. It is important to note that competition is bad for both competitors because it wastes energy. The competitive exclusion principle works because if there is competition between two species for the same resources, then natural selection will favor traits that lessen reliance on the shared resource, thus reducing competition. If either species is unable to evolve to reduce competition, then the species that most efficiently exploits the resource will drive the other species to extinction. An experimental example of this principle is shown in Figure (PageIndex{7}) with two protozoan species: Paramecium aurelia and Paramecium caudatum. When grown individually in the laboratory, they both thrive. But when they are placed together in the same test tube (habitat), P. aurelia outcompetes P. caudatum for food, leading to the latter’s eventual extinction.

Symbiosis

Symbiotic relationships are close, long-term interactions between individuals of different species. Symbioses may be commensal, in which one species benefits while the other is neither harmed nor benefited; mutualistic, in which both species benefit; or parasitic, in which the interaction harms one species and benefits the other.

Commensalism occurs when one species benefits from a close prolonged interaction, while the other neither benefits or is harmed. Birds nesting in trees provide an example of a commensal relationship (Figure (PageIndex{8})). The tree is not harmed by the presence of the nest among its branches. The nests are light and produce little strain on the structural integrity of the branch, and most of the leaves, which the tree uses to get energy by photosynthesis, are above the nest so they are unaffected. The bird, on the other hand, benefits greatly. If the bird had to nest in the open, its eggs and young would be vulnerable to predators. Many potential commensal relationships are difficult to identify because it is difficult to prove that one partner does not derive some benefit from the presence of the other.

A second type of symbiotic relationship is called mutualism, in which two species benefit from their interaction. For example, termites have a mutualistic relationship with protists that live in the insect’s gut (Figure (PageIndex{9})a). The termite benefits from the ability of the protists to digest cellulose. However, the protists are able to digest cellulose only because of the presence of symbiotic bacteria within their cells that produce the cellulase enzyme. The termite itself cannot do this; without the protozoa, it would not be able to obtain energy from its food (cellulose from the wood it chews and eats). The protozoa benefit by having a protective environment and a constant supply of food from the wood chewing actions of the termite. In turn, the protists benefit from the enzymes provided by their bacterial endosymbionts, while the bacteria benefit from a doubly protective environment and a constant source of nutrients from two hosts. Lichen are a mutualistic relationship between a fungus and photosynthetic algae or cyanobacteria (Figure (PageIndex{9})b). The glucose produced by the algae provides nourishment for both organisms, whereas the physical structure of the lichen protects the algae from the elements and makes certain nutrients in the atmosphere more available to the algae. The algae of lichens can live independently given the right environment, but many of the fungal partners are unable to live on their own.

A parasite is an organism that feeds off another without immediately killing the organism it is feeding on. In parasitism, the parasite benefits, but the organism being fed upon, the host, is harmed. The host is usually weakened by the parasite as it siphons resources the host would normally use to maintain itself. Parasites may kill their hosts, but there is usually selection to slow down this process to allow the parasite time to complete its reproductive cycle before it or its offspring are able to spread to another host. Parasitism is a form of predation.

The reproductive cycles of parasites are often very complex, sometimes requiring more than one host species. A tapeworm causes disease in humans when contaminated and under-cooked meat such as pork, fish, or beef is consumed (Figure (PageIndex{10})). The tapeworm can live inside the intestine of the host for several years, benefiting from the host’s food, and it may grow to be over 50 feet long by adding segments. The parasite moves from one host species to a second host species in order to complete its life cycle.

Characteristics of Communities

Communities are complex systems that can be characterized by their structure (the number and size of populations and their interactions) and dynamics (how the members and their interactions change over time). Understanding community structure and dynamics allows us to minimize impacts on ecosystems and manage ecological communities we benefit from.

Ecologists have extensively studied one of the fundamental characteristics of communities: biodiversity. One measure of biodiversity used by ecologists is the number of different species in a particular area and their relative abundance. The area in question could be a habitat, a biome, or the entire biosphere. Species richness is the term used to describe the number of species living in a habitat or other unit. Species richness varies across the globe (Figure (PageIndex{11})). Species richness is related to latitude: the greatest species richness occurs near the equator and the lowest richness occurs near the poles. The exact reasons for this are not clearly understood. Other factors besides latitude influence species richness as well. For example, ecologists studying islands found that biodiversity varies with island size and distance from the mainland.

Relative abundance is the number individuals in a species relative to the total number of individuals in all species within a system. Foundation species, described below, often have the highest relative abundance of species.

Foundation species are considered the “base” or “bedrock” of a community, having the greatest influence on its overall structure. They are often primary producers, and they are typically an abundant organism. For example, kelp, a species of brown algae, is a foundation species that forms the basis of the kelp forests off the coast of California.

Foundation species may physically modify the environment to produce and maintain habitats that benefit the other organisms that use them. Examples include the kelp described above or tree species found in a forest. The photosynthetic corals of the coral reef also provide structure by physically modifying the environment (Figure (PageIndex{12})). The exoskeletons of living and dead coral make up most of the reef structure, which protects many other species from waves and ocean currents.

A keystone species is one whose presence has inordinate influence in maintaining the prevalence of various species in an ecosystem, the ecological community’s structure, and sometimes its biodiversity. Pisaster ochraceus, the intertidal sea star, is a keystone species in the northwestern portion of the United States (Figure (PageIndex{13})). Studies have shown that when this organism is removed from communities, mussel populations (their natural prey) increase, which completely alters the species composition and reduces biodiversity. Another keystone species is the banded tetra, a fish in tropical streams, which supplies nearly all of the phosphorus, a necessary inorganic nutrient, to the rest of the community. The banded tetra feeds largely on insects from the terrestrial ecosystem and then excretes phosphorus into the aquatic ecosystem. The relationships between populations in the community, and possibly the biodiversity, would change dramatically if these fish were to become extinct.

BIOLOGY IN ACTION

Invasive species are non-native organisms that, when introduced to an area out of its native range, alter the community they invade. In the United States, invasive species like the purple loosestrife (Lythrum salicaria) and the zebra mussel (Dreissena polymorpha) have drastically altered the ecosystems they invaded. Some well-known invasive animals include the emerald ash borer (Agrilus planipennis) and the European starling (Sturnus vulgaris). Whether enjoying a forest hike, taking a summer boat trip, or simply walking down an urban street, you have likely encountered an invasive species.

One of the many recent proliferations of an invasive species concerns the Asian carp in the United States. Asian carp were introduced to the United States in the 1970s by fisheries (commercial catfish ponds) and by sewage treatment facilities that used the fish’s excellent filter feeding abilities to clean their ponds of excess plankton. Some of the fish escaped, and by the 1980s they had colonized many waterways of the Mississippi River basin, including the Illinois and Missouri Rivers.

Voracious feeders and rapid reproducers, Asian carp may outcompete native species for food and could lead to their extinction. One species, the grass carp, feeds on phytoplankton and aquatic plants. It competes with native species for these resources and alters nursery habitats for other fish by removing aquatic plants. In some parts of the Illinois River, Asian carp constitute 95 percent of the community’s biomass. Although edible, the fish is bony and not desired in the United States.

The Great Lakes and their prized salmon and lake trout fisheries are being threatened by Asian carp. The carp are not yet present in the Great Lakes, and attempts are being made to prevent its access to the lakes through the Chicago Ship and Sanitary Canal, which is the only connection between the Mississippi River and Great Lakes basins. To prevent the Asian carp from leaving the canal, a series of electric barriers have been used to discourage their migration; however, the threat is significant enough that several states and Canada have sued to have the Chicago channel permanently cut off from Lake Michigan. Local and national politicians have weighed in on how to solve the problem. In general, governments have been ineffective in preventing or slowing the introduction of invasive species.

Community Dynamics

Community dynamics are the changes in community structure and composition over time, often following environmental disturbances such as volcanoes, earthquakes, storms, fires, and climate change. Communities with a relatively constant number of species are said to be at equilibrium. The equilibrium is dynamic with species identities and relationships changing over time, but maintaining relatively constant numbers. Following a disturbance, the community may or may not return to the equilibrium state.

Succession describes the sequential appearance and disappearance of species in a community over time after a severe disturbance. In primary succession, newly exposed or newly formed rock is colonized by living organisms. In secondary succession, a part of an ecosystem is disturbed and remnants of the previous community remain. In both cases, there is a sequential change in species until a more or less permanent community develops.

Primary Succession and Pioneer Species

Primary succession occurs when new land is formed, or when the soil and all life is removed from pre-existing land. An example of the former is the eruption of volcanoes on the Big Island of Hawaii, which results in lava that flows into the ocean and continually forms new land. From this process, approximately 32 acres of land are added to the Big Island each year. An example of pre-existing soil being removed is through the activity of glaciers. The massive weight of the glacier scours the landscape down to the bedrock as the glacier moves. This removes any original soil and leaves exposed rock once the glacier melts and retreats.

In both cases, the ecosystem starts with bare rock that is devoid of life. New soil is slowly formed as weathering and other natural forces break down the rock and lead to the establishment of hearty organisms, such as lichens and some plants, which are collectively known as pioneer species (Figure (PageIndex{14})) because they are the first to appear. These species help to further break down the mineral-rich rock into soil where other, less hardy but more competitive species, such as grasses, shrubs, and trees, will grow and eventually replace the pioneer species. Over time the area will reach an equilibrium state, with a set of organisms quite different from the pioneer species.

Secondary succession

A classic example of secondary succession occurs in forests cleared by wildfire, or by clearcut logging (Figure (PageIndex{15})). Wildfires will burn most vegetation, and unless the animals can flee the area, they are killed. Their nutrients, however, are returned to the ground in the form of ash. Thus, although the community has been dramatically altered, there is a soil ecosystem present that provides a foundation for rapid recolonization.

Before the fire, the vegetation was dominated by tall trees with access to the major plant energy resource: sunlight. Their height gave them access to sunlight while also shading the ground and other low-lying species. After the fire, though, these trees are no longer dominant. Thus, the first plants to grow back are usually annual plants followed within a few years by quickly growing and spreading grasses and other pioneer species. Due, at least in part, to changes in the environment brought on by the growth of grasses and forbs, over many years, shrubs emerge along with small trees. These organisms are called intermediate species. Eventually, over 150 years or more, the forest will reach its equilibrium point and resemble the community before the fire. This equilibrium state is referred to as the climax community, which will remain until the next disturbance. The climax community is typically characteristic of a given climate and geology. Although the community in equilibrium looks the same once it is attained, the equilibrium is a dynamic one with constant changes in abundance and sometimes species identities.


Experiments on Ecology | Biology

Are you researching on experiments on ecology ? You are in the right place. The below mentioned article includes a collection of nineteen experiments on ecology: 1. Community Structure Study 2. Biomass Study 3. Soil Science 4. Aquatic Ecosystem 5. Physico-Chemical Analysis of Water.

  1. Experiments on Community Structure Study
  2. Experiments on Biomass Study
  3. Experiments on Soil Science
  4. Experiments on Aquatic Ecosystem
  5. Experiments on Physico-Chemical Analysis of Water

1. Experiment on Community Structure Study: (8 Experiments)

1. Aim of the Experiment:

To determine the minimum size of the quadrat by species area-curve method.

Requirements:

Nails, cord or string, metre scale, hammer, pencil, notebook.

i. Prepare a L-shaped structure of 1 × 1 metre size in the given area by using 3 nails and tying them with a cord or string.

ii. Measure 10 cm on one side of the arm L and the same on the other side of L, and prepare 10 x 10 sq. cm area using another set of nails and string. Note the number of species in this area of 10 x 10 sq. cm.

iii. Increase this area to 20 × 20 sq. cm and note the additional species growing in this area.

iv. Repeat the same procedure for 30 × 30 sq. cm, 40 × 40 sq. cm and so on till 1 × 1 sq. metre area is covered (Fig. 67) and note the number of additional species every time.

Record your data in the following table:

v. Prepare a graph using the data recorded in the above table. Size of the quadrats is plotted on X- axis and the number of species on Y-axis (Fig. 67 B).

The curve starts flattening or shows only a steady increase (Fig. 67 B) at one point in the graph.

The point of the graph, at which the curve starts flattening or shows only a steady or gradual increase, indicates the minimum size or minimum area of the quadrat suitable for study.

2. Aim of the Experiment:

To study communities by quadrat method and to determine % Frequency, Density and Abundance.

Metre scale, string, four nails or quadrat, notebook.

Frequency is the number of sampling units or quadrats in which a given species occurs.

Percentage frequency (%F) can be estimated by the following formula:

Density is the number of individuals per unit area and can be calculated by the following formula:

Abundance is described as the number of individuals per quadrat of occurrence.

Abundance for each species can be calculated by the following formula:

Lay a quadrat (Fig. 68) in the field or specific area to be studied. Note carefully the plants occurring there. Write the names and number of individuals of plant species in the note-book, which are present in the limits of your quadrat. Lay at random at least 10 quadrats (Fig. 69) in the same way and record your data in the form of Table 4.1.

In Table 4.1, % frequency, density and abundance of Cyperus have been determined. Readings of the other six plants, occurred in the quadrats studied, are also filled in the table. Calculate the frequency, density and abundance of these six plants for practice. (For the practical class take your own readings. The readings in Table 4.1 are only to give an explanation of the matter).

Calculate the frequency, density and abundance of all the plant species with the help of the formulae given earlier and note the following results:

(i) In terms of % Frequency (F), the field is being dominated by…

(ii) In terms of Density (D), the field is being dominated by…

(iii) In terms of Abundance (A), the field is being dominated by…

Table 4.1: Size of quadrat: 50cm × 50cm = 2500 cm 2

3. Aim of the Experiment:

To determine minimum number of quadrats required for reliable estimate of biomass in grasslands.

Metre scale, string, four nails (or quadrat), note book, graph paper, herbarium sheet, cello tape.

i. Lay down 20-50 quadrats of definite size at random in the grassland to be studied, make a list of different plant species (e.g., A-J) present in each quadrat and note down their botanical names or hypothetic numbers (e.g., A, B, C,…, J) as shown in Table 42. u

ii. With the help of the data available in Table 4.2, find out the accumulating total of the number of species for each quadrat.

iii. Now take a graph paper sheet and plot the number of quadrats on X-axis and the accumulating total number of species on Y-axis of the graph paper.

Observations and results:

A curve would be obtained. Note carefully that this curve also starts flattening. The point at which this curve starts flattening up would give us the minimum number of quadrats required to be laid down in the grassland.

4. Aim of the Experiment:

To study frequency of herbaceous species in grassland and to compare the frequency distribution with Raunkiaer’s standard frequency diagram.

Quadrat, pencil, note-book, graph paper.

i. Lay 10 quadrats in the given area and calculate the percentage frequency of different plant species by the method and formula given above in Exercise No. 2.

ii. Arrange your data in the form of following Table 4.3:

Raunkiaer (1934) classified the species in a community into following five classes as shown in Table 4.4:

Arrange percentage frequency of different species of the above Table 4.3 in the five frequency classes (A-E) as formulated by Raunkiaer (1934) in Table 4.4.

Draw a histogram (Fig. 70) with the percentage of total number of species plotted on Y-axis and the frequency classes (A-E) on X-axis.

This is the frequency diagram (Fig. 70):

Observations and results:

The histogram takes a “J- shaped” curve as suggested by Raunkiaer (1934), and this shows the normal distribution of frequency percentage. If the vegetation in the area is uniform, class ‘E’ is always larger than class ‘D’. And in case class ‘E’ is smaller than class ‘D, the community or vegetation in the area shows considerable disturbance.

5. Aim of the Experiment:

To estimate Importance Value Index for grassland species on the basis of relative frequency, relative density and relative dominance in protected and grazed grassland.

Wooden quadrat of 1ࡧ metre, pencil, notebook.

What is Importance Value Index?

The Importance Value Index (IVI) shows the complete or overall picture of ecological importance of the species in a community. Community structure study is made by studying frequency, density, abundance and basal cover of species. But these data do not provide an overall picture of importance of a species, e.g., frequency gives us an idea about dispersion of a species in the area but does not give any idea about its number or the area covered.

Density gives the numerical strength and nothing about the spread or cover. A total picture of the ecological importance of a species in a community is obtained by IVI. For finding IVI, the percentage values of relative frequency, relative density and relative dominance are added together, and this value out of 300 is called Importance Value Index or IVI of a species.

Relative frequency (RF) of a species is calculated by the following formula:

Relative density (RD) of a species is calculated by the following formula:

Relative dominance of a species is calculated by the following formula:

Basal area of a plant species is calculated by the following formula:

Basals area of a species = p r 2

where p = 3.142, and r = radius of the stem

i. Find out the values of relative frequency, relative density and relative dominance by the above-mentioned formulae.

ii. Calculate the IVI by adding these three values:

IVI = relative frequency + relative density + relative dominance.

Arrange the species in order of decreasing importance, i.e., the species having highest IVI is of most ecological importance and the one having the lowest IVI is of least ecological importance.

6. Aim of the Experiment:

To determine the basal cover, or vegetational cover of one herbaceous community by quadrat method.

Wooden quadrat of 1×1 m, Verniercalliper, pencil, notebook.

i. Lay a wooden-framed quadrat of 1 x 1 metre randomly in a selected plot of vegetation and count the total number of individuals of the selected species inside the quadrat.

ii. Cut a few stems of some plants of this individual species and measure the diameter of the stem with the help of Verniercalliper.

iii. Calculate the basal area of the individuals by the formula:

Average basal area = π r 2 where r is the radius of the stem.

iv. Take 5 readings, arrange them in tabular form and find out the average basal area by the above formula.

v. Lay the quadrat again randomly at another place and note the same observations in the table.

vi. Lay about 10 quadrats in the same fashion and each time note the total number of the species and average basal area of the single individual.

Observations and results:

(a) For finding the average basal area, divide the sum of average basal area in all quadrats with the total number of quadrats studied.

(b) For finding the total basal cover of a particular species multiply the average basal area of all observations with the density of that particular species as under:

Basal cover of a particular species = Average basal area x Density (D) of that species.

The basal cover of a particular species is expressed in… sq. cm/sq. metre.

7. Aim of the Experiment:

To measure the vegetation cover of grassland through point-frame method.

Point-frame apparatus, graph paper sheet, herbarium sheet, cello tape, note-book.

A point-frame apparatus is a simple wooden frame of about 50 cm long and 50 cm high in which 10 movable pins are inserted at 45° angle. Each movable pin is about 50 cm long.

i. Put the point-frame apparatus (with 10 pins) at a place in the vegetation of grassland (Fig. 71) and note down various plant species hit by one or more of 10 pins of the apparatus. Treat this as one sampling unit.

ii. Now put the apparatus at random at 10-25 or more places and note down each time the various plants species in a similar fashion. In case three plants of any species touch three pins in one sampling unit put at a place, the numerical strength of that particular species in this sampling unit will be three individuals. Write this value against the species below this sampling unit.

Observations and results:

Note down the details in the form of following Table 4.5:

Now calculate the percentage frequency of each species as already done in Exercise No. 2. Allocate the various species among five frequency classes (A, B, C, D, E) mentioned in Exercise No. 4, find out the percentage value of each frequency class and prepare a frequency diagram as done in Exercise No. 4. Compare the thus-developed frequency diagram with normal frequency diagram.

Find out the three most frequently occurring species in the area studied. Also find out whether the vegetation is homogeneous or heterogeneous. Also try to determine the density values of individual species. Also find out at each place the total number of individuals of each species being hit by 10 pins of the point-frame apparatus.

8. Aim of the Experiment:

To prepare a list of plants occurring in a grassland and also to prepare chart along the line transect.

i. Prepare a 25 feet long line transect in a selected grassland by tying each end of a 25 feet cord to the upper knobs of two nails.

ii. Note down the names of the plant species whose projection touches one edge of the cord along the line transect, and assign all of them a definite number (e.g., 1,2,3,4, …etc.).

iii. Take several such samples at regular or irregular intervals in the grassland along the line transect.

iv. Also record the plant species from different grassland types in the similar fashion.

Record your data in the following Table 4.6 in the form of the following manner:

Table 4.6 gives the complete list of plants occurring in the selected grassland. Also find out the name of the species represented in maximum number in each locality.

These data will also provide a clear picture of the dominant species of the grassland in a particular area.

2. Experiment on Biomass Study: (2 Experiments)

It is usually expressed as dry weight of all the living materials (plants as w ell as animals) in an area. Under biomass we include plants (their aboveground and underground parts) as well as animals. Fallen leaves and twigs of the plants are also taken in consideration at the time of studying biomass.

In the forests, the humus is in different stages of decomposition. The floor of the forest remains covered by organic matter which is slightly or not at all decomposed. This is called litter. A partially decomposed matter is present below this layer. It is called duff. Further decomposed matter, which has lost its original form, is present below duff and called leaf mould.

9. Aim of the Experiment:

To measure the above-ground plant biomass in a grassland.

To determine the biomass of a particular area.

Nails (4), metre scale, string, khurpa (a weeding instrument), polythene bags, oven.

i. Make a quadrat of the size of 50 cm × 50 cm in the field by digging the nails and connecting them with the string. Weed out all the above-ground parts of the plants growing in that limit with the help of weeding instrument. Collect all of them in a polythene bag.

ii. Collect the fallen leaves and other parts of the plants in the second polythene bag.

iii. Collect all the animals such as ants, larvae, earthworms, insects, etc., in the third polythene bag.

iv. By digging the soil to about 20 to 25 cm., take out all the underground parts of the plants and collect them in a separate bag after washing.

In the same way lay some more quadrats in the area under study and collect all the materials in polythene bags.

Dry weight of aboveground parts = 15 gm.

Dry weight of underground parts = 4 gm.

Dry weight of animals = 1 gm.

. . . Total dry weight = 20 gm.

50 × 50 cm field area contains = 20 gm. total dry biomass

. . .100 × 100 cm field area will contain

80 gm. is the biomass of 100 × 100 cm. field area.

Results of Different Parts:

(i) 50 x 50 cm. field area contains 15 gm. of aboveground parts.

100 × 100 cm. field area will contain

= 15×100×100/50×50 = 60 gm. biomass.

(ii) 50 x 50 cm. field area contains 4 gm. of underground parts.

100 × 100 cm. field area will contain

= 4×100×100/50×50 = 16 gm. biomass

(iii) 50 × 50 cm. field area contains 1 gm. of animals

100 × 100 cm. field area will contain

1×100×100/50×50 = 4 gm. biomass.

One square metre (100×100 cm.) field area contains 80 gm. biomass in terms of dry weight of the total plant and animal parts.

10. Aim of the Experiment:

To determine diversity indices (richness, Simpson, Shannon-Wiener) in grazed and protected grassland.

To study species diversity (richness and evenness), Index of dominance, Similarity index, Dissimilarity index and Species diversity index in grazed and protected grassland.

Species diversity is a statistical abstraction with two components.

These two components are:

(i) Richness (or number of species), and

(ii) Evenness or equitability.

In any grassland, to be studied, if there are seventy species in a stand, then its richness is seventy. Pick out individual plants of different species with the help of khurpa, count the number of species in a stand of the area provided, and calculate the richness. On the other hand, if all the species in the grassland have equal number of individuals, then its evenness or equitability is high and if some species have only a few individuals then the evenness is low.

The species which have strongest control over energy flow and environment in given habitat are called ecological dominant. According to Simpson (1949), the Index of dominance (C) is calculated by the formula

where∑ (sigma) refers to summation, ni refers to the importance value of the species in terms of number of individuals or biomass or productivity of each species over a unit area, and N refers to the total of corresponding importance values of all the component species in the same unit area and period. Count the Index of Dominance by the above-mentioned formula.

Similarity Index between two stands of vegetation can be worked out by the formula S = 2 C/(A+B), where S is the Similarity Index, C is the number of species common to both the stands, and A and B are number of species on stand A and stand B. For example, if there are 20 species on site A and 20 on site B and 14 species are common in both sites, the Similarity Index (S) will be

(d) Dissimilarity index:

The Dissimilarity Index is counted by the formula D = 1 – S, where D is the dissimilarity index and S is the similarity index. For example, if there are 20 species on site A and 20 species on site B and 14 species are common in both sites the similarity index (S) comes to 0.7 as calculated above in case of similarity index. Therefore, dissimilarity index (D) can be counted, as

Species diversity index (d) is calculated by the following formula given by Menhinick (1964):

where d = diversity index, S = number of species, and N= number of individuals of that particular species.

3. Experiment on Soil Science: (1 Experiment)

11. Aim of the Experiment:

To study the characteristics of different types of soils.

Samples of different types of soils (e.g., clay soil, sand or alluvial soil, humus, black soil, yellow soil, red soil, laterite or lateritic soil).

Method and observations:

Different soil samples are taken and studied individually.

Some of their major characteristics are under mentioned:

i. It is a compact and heavy-textured soil.

ii. The size of its particles is less than 0.002 mm.

iii. It has very minute spaces in between its particles.

iv. It is quite sticky when wet but becomes hard and develops cracks on drying.

v. It has higher water-holding capacity and poor aeration.

vi. It gets waterlogged easily.

vii. Its particles are negatively charged and have the ability to absorb cations of Mg, Ca, K, P, Fe and Na.

viii. This soil is made up of hydrated alumino silicate.

ix. It is quite rich in calcium carbonate and magnesium carbonate.

x. The pore space between its particles is greater than sand.

xi. This soil has high degree of fertility.

On the basis of above characteristics, the given sample belongs to clay soil.

II. Fine sand or alluvial soil:

i. This soil is loose, light-textured and silver-grey in colour.

ii. The size of its particles is between 0.02 mm to 0.2 mm.

iii. It has poor water-holding capacity.

iv. This soil shows quite rapid rate of water infiltration.

vi. The carbonate content of this soil is very low.

vii. It does not get waterlogged easily.

viii. It shows good aeration.

ix. It is non-sticky and non-plastic when wet.

x. It has very low contents of phosphate, nitrogen and organic matter.

xi. It has shiny particles of aluminium silicate or mica.

xii. Some amounts of iron, magnesium, sodium, aluminium, silicon and calcium are present in this soil.

xiii. Its particles become warm on long exposure to the sun.

The above characteristics show that the given soil sample belongs to fine sand or alluvial soil.

i. It is decomposed matter of plant and animal remains.

ii. This organic matter is amorphous and dark brown to black in colour.

iii. It is soluble in dilute alkali solution like KOH and NaOH but insoluble in water.

iv. It is actually a layer of organic matter at the top of a soil profile. It is the habitat of most decomposers. The main decomposers are bacteria and fungi.

v. It is made up of nitrogen-rich proteins, lignin and polysaccharides.

vi. A large amount of carbon and small amounts of sulphur, phosphorus and some other elements are also present.

vii. It is colloidal in nature.

On the basis of the above characteristics, it can be concluded that the given material is humus.

i. This is black-coloured soil. The black colour is due to the presence of iron in this soil.

ii. High percentage of iron oxides, calcium carbonates, magnesium carbonates and alumina are present in this soil.

iii. It also contains large amount of nitrogen and organic matter. It, however, contains very low amount of phosphorus.

iv. If made wet by adding some water, this soil is sticky. On drying, it contracts and shows cracks.

v. It has high water-retaining capacity.

vi. It is highly productive and suits most for the crops like cotton.

Based on the above-mentioned characteristics, it can be concluded that the given sample belongs to black soil.

i. The yellow colour of this soil is due to the enhanced hydration of ferric oxide.

ii. It is a porous soil with nearly neutral pH.

iii. Size of the particles of this soil is between 0.002 mm to 0.02 mm.

iv. It is a granite-derived soil with moderately rich humus.

v. It contains very low amount of oxides of phosphorus, nitrogen and potassium.

vi. It contains large amount of silicon oxide and alminosilicate.

The above characteristics show that this is a sample of yellow soil.

i. This is the sample of red-coloured soil.

ii. The red colour is due to the diffusion of large amount of iron compounds such as ferrous oxide and ferric oxide.

iii. It is a slightly acidic type of soil. Its pH varies between 5 and 8.

iv. Some amount of silicon oxide and aluminium oxide are also present in this soil.

v. This soil is not good for agriculture because it is poor in nitrogen, phosphorus and humus.

Because of the above characteristics, the given sample is of red soil.

VII. Laterite soil:

i. This is yellowish or red-coloured soil. On exposure to sun it turns black.

ii. It is produced from aluminium-rich rocks.

iii. It is quite compact type of soil made up of hydrated oxides of iron and aluminium.

iv. It also contains small amounts of compounds like magnesium oxide and titanium oxide.

v. Small amounts of nitrogen, phosphorus, magnesium, potash and lime are also present in this soil.

vi. It is also quite rich in humus.

vii. Because of the above characteristics, this soil is good for the purpose of agriculture.

Above-mentioned characteristics show that the given sample is of laterite or lateritic soil.

4. Experiment on Aquatic Ecosystem: (1 Experiment)

Living organisms are structurally and functionally inter-related with the external world or the environment, and this functional and structural relationship of communities and the environment is called ecological system or ecosystem.

Ecosystem normally contains:

Taking in view the organisms and their habitat conditions, the ecosystem can be classified as follows:

Pond ecosystem can be studied as follows:

12. Aim of the Experiment:

To study the biotic components of a pond. Make diagram of a pond ecosystem.

Hand lens, collection net, meshes of different sizes, collection tubes, iron hook, scissor, forceps, and centrifuge.

Biotic components of a pond can be studied exactly according to the classification of a pond ecosystem given above. Hydrophytes can be picked by hand and collected in polythene bags. Other submerged plants may also be taken out by iron hooks (Fig. 74).

Phytoplankton and zooplankton can be collected in plankton bottles.

With the help of plankton nets, microorganisms can be collected in tubes.

Macro-producers and macro-consumers can be estimated in gm./cubic metre by the quadrat method used in the exercise of biomass.

Micro-producers and micro-consumers can be estimated in gm./litre of water collected as sample from an undisturbed part of the pond. They can be separated by centrifuging a little amount of pond water (containing micro-producers and micro-consumers) in test tube.

On the basis of their trophic position in the ecosystem different organisms may be grouped as follows:

Vallisneria, Ceratophyllum, Hydrilla, Potamogeton, Chara, etc.

(ii) Free-floating:

Azolla, Eichhornia, Lemna, Pistia, Spirodella, Salvinia, etc.

(iii) Rooted floating:

Trapa, Jussiaea, Nymphaea, Potamogeton, Nelumbium, etc.

Marsilea, Typha, Ranunculus, Polygonum, Cyperus, etc.

Agal members of Chlorophyceae, Xanthophyceae, Bacillariophyceae, Myxophyceae, etc.

(i) Consumers of the 1st order (Primary consumers):

e.g., Zooplankton, some insects.

(ii) Consumers of the 2nd order (Secondary consumers):

e.g., Fishes, frogs and some insects.

(iii) Consumers of the 3rd order (Tertiary consumers):

5. Experiment on Physico-Chemical Analysis of Water: (7 Experiments)

13. Aim of the Experiment:

To measure temperature and pH of different water bodies.

Maximum-minimum thermometer or thermometer or thermo flask.

The temperature of the pond can be determined by any of the following apparatuses:

(a) Maximum-minimum thermometer:

It contains two indicators (Fig. 73). With the help of a magnet these indicators are set to the present atmospheric temperature. Quickly lower down the thermometer to the desired depth in the pond. Keep it there for 10 minutes.

Bring out the thermometer quickly and note the readings of both the indicators. Out of the two indicators, one remains at the point and other moves to some extent giving the reading of temperature at that particular depth of the pond.

It is an instrument which gives correct reading of temperature in centigrade. It contains a long cable. At the end of the cable is attached a thermocouple (Fig. 75).

A milliammeter is present which is calibrated in C° and gives direct reading. Quickly lower the thermocouple upto a desired depth and note the temperature.

It is also one of the good apparatuses for measuring the temperature of a pond. After lowering to the desired depth, bring it out when it is filled completely with water. With the help of a good sensitive thermometer, note the temperature of the water.

pH of the pond water can be tested by pH meter, pH paper or B.D.H. Universal Indicator.

14. Aim of the Experiment:

To determine transparency or turbidity of different water bodies.

Transparency (clarity of pond):

It is directly related to and mainly depends upon the presence of microorganisms and microscopic soil particles in the pond water. If the quantity of soil particles and microscopic organisms will be more, the pond water will be less transparent. It also depends upon the depth of the pond water. The turbidity value will be very low in the deep water.

The instrument for knowing the turbidity value is called Secchi disc (Fig. 76). It is a circular disc with black and white or other contrasting colours. The disc is lowered down in the water. Note the depth of the water where there is no colour contrast on the disc.

15. Aim of the Experiment:

To find out the light intensity available to pond.

Light intensity available to the pond is measured with the help of ‘photometer’ (Fig. 77).

A ‘photometer’ consists of a photoelectric cell and a micro-ammeter. Photometer for pond is specially sealed in water-tight containers fitted with a glass window. Photoelectric cell is sensitive to light and generates current when light falls on it. Light intensity is proportional to the current generated in the photoelectric cell by the light falling on it. Readings can be noted in micro-ammeter.

Calculate the light intensity by the following formula:

Light Intensity = r × 100 / a

where r – Reading of lux-meter or photometer

a = Reflected light from the cardboard.

16. Aim of the Experiment:

To measure amount of dissolved oxygen content in polluted and unpolluted water bodies.

To measure amount of dissolved oxygen in pond water.

Water sample, glass stoppered conical flask, manganous-sulphate, potassium iodide solution (alkaline), pipettes, sulphuric acid (conc.), sodium thiosulphate solution, starch solution, reagent bottles.

Preparation of reagents:

(a) Starch solution:

Add 1 gm. starch in 100 ml distilled water, warm and dissolve it.

(b) Potassium iodide solution (alkaline):

Heat 200 ml of distilled water and dissolve in it 100 gm. KOH and 50 gm. KI.

(c) Manganous sulphate solution:

Add 200 gmMnSO4 . 4H2O in 200 ml distilled water. Heat it to dissolve maximum salt. Cool it and then filter it.

(d) Sodium shiosulphate solution:

Dissolve 24.82 gmNa2SO4 . 5H2O in some amount of distilled water and make up the volume to 1 litre by adding more distilled water. To stabilize the solution add a small pellet of sodium hydroxide. Thus prepared solution is 0.1N stock solution. In 250 ml of this stock solution add 750 ml of distilled water to dilute the solution of sodium thiosulphate.

i. Take 100 ml of water sample in a 250 ml glass-stoppered conical flask and add 1 ml of manganous sulphate solution and 1 ml alkaline potassium iodide solution by separate pipettes. Appearance of brown precipitate indicates the presence of oxygen in the water sample.

ii. Shake it well and then allow the precipitate to settle down.

iii. Add 2 ml sulphuric acid (conc.) and again shake it well. The precipitate will be dissolved.

iv. Decant the liquid and titrate it with sodium thiosulphate solution. Starch solution is used as an indicator. The blue black colour disappears when the end point is reached.

Calculations and results:

Dissolved oxygen in mg/ liter is calculated by the following formula:

= (ml × N of sodium thiosulphate) × 8 ×1000/V1 – V2

where V1 = Volume of water sample titrated,

V2 = Volume of MnSO4 and KI solution added.

17. Aim of the Experiment:

To determine the total dissolved solids (TDS) in water.

Water, sample, evaporating dish, Whatman filter paper, oven, desiccator, balance, beakers.

i. Weigh a dry and clean evaporating dish of200 ml capacity.

ii. Shake the water sample well and filter it through Whatman filter paper.

iii. Take 100 ml of filtrate in a pre-weighed evaporating dish and keep it in an oven at 180°C for some time. The water will be evaporated and the sample will become dry.

iv. Cool it in a desiccator and weigh. Calculate the total dissolved solids using following formula:

Total Dissolved Solids (mg/1) = (a-b) × 10/V

a = Weight of dish and dried filtered sample (in gm.)

b = Weight of empty evaporating dish (in gm).

V= Volume of sample evaporated (in ml).

18. Aim of the Experiment:

To count phytoplankton by haemocytometer method.

Haemocytometer, water sample, cover slip, microscope, dropper.

Haemocytometer is a special type of glass slide having more than 500 small grooved chambers or counting chambers (1 × 1 × 0.5 mm) in the middle portion. This specially designed slide is used for counting the microorganisms or plankton present in a water drop.

i. Take a haemocytometer and put a drop of concentrated water sample on its counting chambers.

ii. Put a cover slip, wait for about 2-5 minutes and examine under the high power of microscope. Count the plankton present in each chamber.

19. Aim of the Experiment:

To determine plankton biomass of a pond.

Pond water, shallow water bottle, chemical balance, oven, beaker, funnel, Whatman filter paper.

i. Collect 1000 ml of surface water of pond with the help of a shallow water bottle. This water contains phytoplankton and zooplankton.

ii. Weigh a dry filter paper. Suppose it is A1 gm.

iii. Take another filter paper. Make it wet and weigh it. Suppose it is A2 gm.

iv. Filter the water sample through a Whatman filter paper and weigh this filter paper containing plankton. Suppose it is A3 gm.

v. Now put this plankton-containing filter paper in oven for 24 hours at 85°C. Weigh this dry filter paper with plankton. Suppose it is A4 gm.

Calculations and result:

Calculate the biomass (fresh weight or dry weight of organisms) in mg/litre as follows:

(i) Fresh weight of plankton/1000 ml = A3– A2gm.

(ii) Fresh weight of plankton/ml = A3 – A2gm/1000


Process of Community Analysis: 4 Categories | Ecology

This article throws light upon the four categories of processes of Community Analysis. The categories of processes are: 1. Biological Spectrum or Life Form Analysis 2. Stratification 3. Quantitative Structures of Plant Community 4. Synthetic Characters of Plant Community.

Category # 1. Biological Spectrum or Life Form Analysis:

Danish Botanist Christen Raunkiaer (1903) at­tempted to describe the communities (higher plants) into five major life form classes viz.,

These are trees, shrubs and climbers where the growing buds are located on the upright shoot much above the ground surface and they are the least protected.

There are four subgroups of phanerophytes depend­ing on the height of the plants:

(i) Mega-phanerophytes (for trees over 30 meters tall)

(ii) Meso-phanerophytes (for trees between 8 meters and 30 meters height)

(iii) Micro-phanerophytes (for trees between 2 and 8 meters height) and

(iv) Nano-phanerophytes (for shrubs smaller than 2 meters).

These are the herbs or creep­ers whose buds are located close to the ground surface or up to a maximum height of 25 cm.

These are mostly bien­nial or perennial herbs whose perennating buds are present just under the surface soil and remain protected there.

D. Cryptophytes or Geophytes:

These are plants having bulbs or rhizomatous stem lies under­neath the soil.

These are annual herbs which only survive by seeds. According to Raunkiaer (1934), in general in normal vegetation of different habitats showed distinctive life-form pattern. Though there are some limitation in application of life-form classification, yet it is indicative of climatic condition of an area. The different life-form classes were depicted in Fig. 3.1.

Category # 2. Stratification:

All the plants in a community are not of the same size and do not occupy the same strata in multistoried structure. Thus the distribution of plants in vertical space is known as stratification. Depending on the vegetation types and climatic condition, the stratification may vary widely how­ever, in general the following strata could be recognised in a plant community (Fig. 3.2).

Category # 3. Quantitative Structures of Plant Community:

In the plant community different species are rep­resented by few or a large number of individuals aggregating in different vegetation units. It is es­sential to know the quantitative structure of the community, specially the numerical distribution and the space occupied by the individuals of different species.

Category # 4. Synthetic Characters of Plant Community:

Synthetic characters express the make-up of a community.

The chief synthetic characters are described below:

The faithfulness of a species to its community is referred to as fidelity. While plants of low fidelity grow in several types of communities, a high fidelity plant occurs in only one kind in community. So, the charac­teristic species of a community has high fi­delity value but a low ecological amplitude. In other words, the species is tolerant to a nar­row range of environmental conditions.

The degrees of fidelity are usually expressed in the following manner:

Species belonging to F3, F4 and F5 classes are called characteristic or key species of a community.

ii. Presence and Constancy:

The uniformity of species over a number of sample plots or stands of the same type of community is ex­pressed in terms of presence or constancy. The term Constancy is used if the sample ar­eas are of equal size and Presence is used when the sample areas are of variable sizes.

Physiognomy refers to the general appearance of plant community. Ma­jor plant communities of large area are classi­fied into component communities on the ba­sis of physiognomy. Component communi­ties recognized on the basis of physiognomy are named after the dominant forms of life, as for example forest grassland, desert com­munity, etc.


Department of Ecology and Conservation Biology

The Department of Ecology and Conservation Biology (ECCB) offers graduate programs leading to the MS and PhD degrees in Ecology and Conservation Biology. The MS and PhD degrees are intended to educate scientists and professionals in research and management in natural resources and related fields. The MS offers a thesis option for those who desire a serious research experience and a non-thesis option for those who seek a professional career outside of research.

Fields of study are available in:

  1. Ecosystem Science: biogeochemistry, ecohydrology, global change ecology, landscape ecology, ecological restoration, ecophysiology
  2. Ecosystem Management: forest management, rangeland management, watershed management, natural resource economics and policy, human dimensions of ecosystem management
  3. Genetics, Systematics, Evolution: genetics, molecular biology, genomics, population genetics, tree improvement, plant systematics, and evolution
  4. Spatial Sciences: geographic information systems, remote sensing, spatial analysis, and statistics.

Facilities within the department include modern teaching classrooms and laboratories. There are fifteen state-of-the-art research laboratories in the department, including the Stable Isotopes for Biosphere Sciences Laboratory, the Spatial Sciences Laboratory, and the S.M. Tracy Herbarium. Field sites and facilities are available throughout Texas and many of them are associated with research and extension centers connected with the department. The ECCB faculty acquire external competitive research grants and contracts that provide funding for additional research avenues and graduate student support.

Graduate courses are designed to develop the academic skills of individuals and to advance their knowledge in the professional fields related to Ecology and Conservation Biology. Departmental seminars facilitate graduate student development and serve to relate the most recent research findings applicable to the discipline. The department welcomes applications from students with diverse educational backgrounds, experiences, and interests. Individually planned graduate programs assure a focused education that meets the needs of each candidate.

Additional information on academic programs and faculty may be found at eccb.tamu.edu.

ESSM 600 Principles of Ecosystem Science and Management

Credits 3. 3 Lecture Hours.

Ecological foundations for sustained use of natural resources climatic, edaphic, biotic and cultural factors in land resource allocation land and cover viewed with respect to population dynamics, succession and climax, gradients and graduation, equilibria and imbalance.
Prerequisite: Graduate classification in agriculture or in allied subject.

ESSM 601 Ecosystem Stewardship

Credits 3. 3 Lecture Hours.

Integrates ecological concepts of resilience, sustainability, transformation and vulnerability within a framework of cosystem stewardship to support human well-being in a rapidly changing world emphasizes social-ecological systems. adaptive management, and valuation of ecosystem services as mechanisms to strengthen management and policy recommendations supporting ecosystem stewardship.
Prerequisite: Graduate classification.

ESSM 604 Changing Natural Resource Policy

Credits 3. 3 Lecture Hours.

Process through which environmental policies are changed theories of social and political change using these theories along with original research on environmental policy problems to create and implement plans for changing environmental policies in communities.
Prerequisite: Graduate classification.

ESSM 605 The Research Process

Credits 2. 2 Lecture Hours.

Nature and objectives of graduate work, the scientific method and basic and applied research. Introduction to design of experiments and analysis of data principles of organization of project proposals, theses and scientific reports.

ESSM 610 Rangeland Resource Management

Credits 3. 3 Lecture Hours.

Basic concepts and theories of rangeland resource management trends in range classification, grazing management and improvement practices.
Prerequisite: Graduate classification in agriculture or related subject matter areas.

ESSM 611 Grazing Management and Range Nutrition

Credits 3. 3 Lecture Hours.

Nutritional ecology of domestic and wild herbivores on rangelands vegetation and animal response to various grazing management practices diet selection, quality, intake and supplementation of herbivores.

ESSM 612 Rangeland Vegetation Management

Credits 3. 3 Lecture Hours.

Principles of rangeland brush and weed control with mechanical, chemical, burning and biological methods interrelationships of brush management with grazing, wildlife and watershed management planning and economic analysis of range improvement practices.

ESSM 620 Plant and Range Ecology

Credits 3. 3 Lecture Hours.

Investigation of community/ecosystem/landscape distribution patterns, structure, spatial/temporal organization and function, paleoecology, ecological succession, disturbance regimes, ecological diversity and classification schemes. North American rangelands (grasslands, shrublands, deserts, wetlands, etc.) stressed but world ecosystems reviewed.
Prerequisites: RENR 205 RENR 215 or equivalent graduate classification.

ESSM 621 Physiological Plant Ecology

Credits 3. 3 Lecture Hours.

Investigation of physiological mechanisms influencing ecological patterns and processes, including plant acclimation and adaptation in contrasting habitats, abiotic controls on species productivity and distribution, relevant conceptual and experimental approaches, and integration among ecological scales.
Prerequisites: RENR 205 or MEPS 313 or equivalent graduate classification.

ESSM 622 Biogeochemistry of Terrestrial Ecosystems

Credits 3. 3 Lecture Hours.

Biogeochemical cycles of carbon, nitrogen, sulfur and phosphorus and their interaction with biotic and abiotic processes biogeochemical processes investigated at the global level and in several types of terrestrial ecosystems addressing global climate change, deforestation, acid precipitation, ozone depletion.
Prerequisites: RENR 205 or equivalent graduate classification.

ESSM 624 Terrestrial Ecosystems and Global Change

Credits 3. 3 Lecture Hours.

Identify the physical and biological principles governing the structure and function of terrestrial ecosystems in an earth-system context analyze how plants and microorganisms respond to environmental change and affect global carbon, nutrient, and water cycles evaluate ecosystem response to global change, including rising carbon dioxide, climate warming, and human impacts.
Prerequisite: Graduate classification.

ESSM 626 Fire and Natural Resources Management

Credits 3. 2 Lecture Hours. 3 Lab Hours.

Behavior and use of fire in the management of natural resources principles underlying the role of weather, fuel characteristics and physical features of the environment related to development and implementation of fire plans.
Prerequisites: Graduate classification and approval of instructor.

ESSM 628 Wetland Delineation

Credits 3. 2 Lecture Hours. 2 Lab Hours.

Application of the 1987 Wetland Delineation Manual in use by the Army Corps of Engineers field indicators of hydrophytic vegetation, hydric soils, wetland hydrology, methods for making jurisdictional determination in non-disturbed and disturbed areas, recognition of problem wetlands and technical guidelines for wetlands.
Prerequisite: Graduate classification or approval of instructor.

ESSM 630 Restoration Ecology

Credits 3. 3 Lecture Hours.

Review and discuss fundamental concepts, current literature, and contemporary topics relating to ecological restoration. This includes the theoretical development of restoration ecology and its application. The relationship with conservation biology will be explored. The goal is to inform, exchange views, and develop critical thinking skills through case studies.
Prerequisite: Graduate classification.

ESSM 631 Ecological Restoration of Wetland and Riparian Systems

Credits 3. 2 Lecture Hours. 2 Lab Hours.

How wetland and riparian areas link terrestrial and aquatic systems and function hydrologically and ecologically within watersheds integrated approaches for restoration of degraded wetland and riparian systems improving water resources through vegetation management with a special interest in rangelands.
Prerequisites: RENR 205 or equivalent and WFSC 428 or equivalent.

ESSM 633 Coastal Processes and Ecosystem Management

Credits 3. 3 Lecture Hours.

Exploration of current state of knowledge in coastal ecosystem science with integrated view across sub-fields of coastal ecology, geomorphology, biology, law, policy, economics and engineering focus on techniques to manage, construct and restore ecosystems.
Prerequisite: Graduate classification.

ESSM 635 Ecohydrology

Credits 3. 3 Lecture Hours.

Framework for understanding how plants and animals affect the water cycle examine and explore the water cycle in all of its aspects with the idea of understanding how changes in land cover may influence the water cycle implications for both upland and riparian systems.
Prerequisite: Graduate classification.

ESSM 636 Wildland Watershed Management

Credits 3. 3 Lecture Hours.

Elements of watershed management and principles and practices of wildland management for protection, maintenance and improvement of water resources values current literature and research advances.

ESSM 646 Unmanned Aerial Systems (UAS) for Remote Sensing

Credits 3. 2 Lecture Hours. 2 Lab Hours.

Fundamental components of small unmanned aerial systems (sUAS), sensors and platforms, UAS operational concepts, the principles of UAS data collection, legal framework within which UAS should be operated and applied, data processing software and the generation of orthomosaics and 3D point clouds, emphasizes the use of UAS in a broad spatial sciences, technology and applications context, including vegetated ecosystems.

ESSM 647 Range Grasses and Grasslands

Credits 3. 2 Lecture Hours. 3 Lab Hours.

Basic concepts of grass structure and classification, recent advances in agrostological research, genetic and ecological basis for patterns of variation and evolution in grasses. Offered Spring Semester of even numbered years.

ESSM 648 Wetland Plant Taxonomy

Credits 3. 1 Lecture Hour. 4 Lab Hours.

Interpretation of plant morphologies for keying and the identification of wetland plants from prime habitats plant communities including the plant's adaptation to variation in salinity and soils identification of inconspicuous flowered plant species including sedges, rushes and grasses.
Prerequisite: RLEM 304 or approval of instructor. Offered Fall Semester of even numbered years.

ESSM 651 Geographic Information System for Resource Management

Credits 3. 2 Lecture Hours. 2 Lab Hours.

Geographic Information System (GIS) approach to the integration of spatial and attribute data to study the capture, analysis, manipulation and portrayal of natural resource data examination of data types/formats, as well as the integration of GIS with remote sensing and Global Positioning System laboratory includes extensive use of GIS applications to conduct analyses of topics in natural resources.
Prerequisites: Graduate classification.
Cross Listing: BAEN 651 and RENR 651.

ESSM 652 Advanced Topics in Geographic Information Systems

Credits 3. 2 Lecture Hours. 2 Lab Hours.

Advanced GIS topics with a focus on modeling actual GIS applications including relational and database theory, design and implementation and its connection to GIS surface analysis with digital terrain models and an introduction to spatial statistics.
Prerequisite: ESSM 651 or BAEN 651.

ESSM 655 Remote Sensing of the Environment

Credits 3. 2 Lecture Hours. 1 Lab Hour.

Remote sensing for the management of renewable natural resources use of aerial photography and satellite imagery to detect, identify and monitor forest, range and agricultural resources utilize remotely sensed data as input to computerized information management systems.
Prerequisite: Graduate classification.

ESSM 656 Advanced Remote Sensing

Credits 3. 2 Lecture Hours. 1 Lab Hour.

Advanced techniques for information extraction using airborne and satellite imagery active and passive sensors characteristics customizing and developing image processing tools for remote sensing applications for a broad range of sensors and applications.
Prerequisites: ESSM 655, RENR 444, GEOG 651, GEOG 661.

ESSM 660 Landscape Analysis and Modeling

Credits 3. 2 Lecture Hours. 2 Lab Hours.

Introduction to quantitative methods of landscape analysis and modeling for applications in natural resource conservation and management quantification of landscape composition and configuration spatial statistical methods for characterizing landscape pattern methods for hypothesis testing with spatial data landscape modeling approaches and applications current literature and software.
Prerequisite: Approval of instructor.

ESSM 663/SCSC 663 Applied Spatial Statistics

Credits 4. 3 Lecture Hours. 2 Lab Hours.

An introduction to the theory and practice of spatial statistics as applied to the natural resources. Spatial analyses focusing primarily on ordinary kriging, point processes, and lattice data.
Prerequisites: MATH 168, MATH 142 STAT 651 or equivalents ESSM 651 preferred.
Cross Listing: SCSC 663/ESSM 663.

ESSM 665 Computer Programming for Natural Resources Applications

Credits 3. 2 Lecture Hours. 2 Lab Hours.

An introduction to programming concepts and applications elements of Visual Basic programming including data types, control and program structure introduction to objects and object-oriented programming macro and applications development automation of GIS programming through the use of macros.
Prerequisites: Approval of instructor.

ESSM 671 Ecological Economics

Credits 3. 3 Lecture Hours.

Study of the relationships between ecosystems and economic systems understanding the effects of human economic endeavors on ecological systems and how the ecological benefits and costs of such activities can be quantified and internalized.
Prerequisite: Graduate Classification.
Cross Listing: AGEC 659 and RENR 659.

ESSM 672/RENR 660 Environmental Impact Analysis for Renewable Natural Resources

Credits 3. 3 Lecture Hours.

Analysis and critique of contemporary environmental analysis methods in current use environmental impact statements national policies political, social and legal ramifications as related to development and use of renewable natural resources.
Prerequisite: Graduate Classification.
Cross Listing: RENR 660/ESSM 672.

ESSM 676/RENR 650 Leadership, Development and Management of Environmental NGOs

Credits 3. 3 Lecture Hours.

Trends and increasing power of NGOs in environment and sustainable development understanding of the organizational structures, functions, planning and management processes of environmental NGOs technical skills and leadership qualities for careers with environmental NGOs.
Prerequisite: Graduate classification.
Cross Listing: RENR 650/ESSM 676.

ESSM 681 Seminar

Credit 1. 1 Lecture Hour.

Reviews and discussions of current topics and advances in Ecosystem Science and Management.
Prerequisite: Graduate classification.

ESSM 684 Professional Internship

Credits 1 to 16. 1 to 16 Lecture Hours.

On-the-job training in fields of ecosystem science and management.
Prerequisite: Graduate classification in an ecosystem science and management major.

ESSM 685 Directed Studies

Credits 1 to 9. 1 to 9 Lecture Hours.

Investigations not included in student's research for thesis or dissertation.
Prerequisite: Graduate majors or minors in Ecosystem Science and Management.

ESSM 689 Special Topics in.

Credits 1 to 4. 1 to 4 Lecture Hours. 0 to 4 Lab Hours.

Selected topics in an identified area of ecosystem science and management. May be repeated for credit.
Prerequisite: Graduate classification.

ESSM 691 Research

Credits 1 to 23. 1 to 23 Lecture Hours.

Research for thesis or dissertation.
Prerequisite: Graduate majors in Ecosystem Science and Management.

RENR 650/ESSM 676 Leadership, Development and Management of Environmental NGOs

Credits 3. 3 Lecture Hours.

Trends and increasing power of NGOs in environment and sustainable development understanding of the organizational structures, functions, planning and management processes of environmental NGOs technical skills and leadership qualities for careers with environmental NGOs.
Prerequisite: Graduate classification.
Cross Listing: ESSM 676/RENR 650.

RENR 651 Geographic Information System for Resource Management

Credits 3. 2 Lecture Hours. 2 Lab Hours.

Geographic Information System (GIS) approach to the integration of spatial and attribute data to study the capture, analysis, manipulation and portrayal of natural resource data examination of data types/formats, as well as the integration of GIS with remote sensing and Global Positioning System laboratory includes extensive use of GIS applications to conduct analyses of topics in natural resources.
Prerequisite: Graduate classification.
Cross Listing: BAEN 651 and ESSM 651.

RENR 653/RPTS 653 Conservation Psychology

Credits 3. 3 Lecture Hours.

Theories and methods of psychology applied to conservation behavior for the improvement of relationships between people and natural systems understand challenges and generate solutions related to the human psyche and wilderness, children and nature, role of culture.
Cross Listing: RPTS 653/RENR 653.

RENR 659 Ecological Economics

Credits 3. 3 Lecture Hours.

Study of the relationships between ecosystems and economic systems understanding the effects of human economic endeavors on ecological systems and how the ecological benefits and costs of such activities can be quantified and internalized.
Prerequisite: Graduate classification.
Cross Listing: AGEC 659 and ESSM 671.

RENR 660/ESSM 672 Environmental Impact Analysis for Renewable Natural Resources

Credits 3. 3 Lecture Hours.

Analysis and critique of contemporary environmental analysis methods in current use environmental impact statements national policies political, social and legal ramifications as related to development and use of renewable natural resources.
Cross Listing: ESSM 672/RENR 660.

RENR 662 Environmental Law and Policy

Credits 3. 3 Lecture Hours.

Analysis of the legal theories used to allocate and protect environmental resources common law, federal and state statutes, and international treaties dealing with the environment policies and laws for controlling air, water, solid waste, toxic waste and water pollution species protection and natural resource use.

RENR 678/RPTS 678 Latent Variable Model Applications in the Leisure Sciences

Credits 3. 3 Lecture Hours.

Introduction to structural equation modeling (SEM) background on conceptual issues, application of the method, and insight on SEM software measurement theory, missing data analysis, non-normal data, confirmatory factor analysis, path analysis, multi-group models.
Prerequisites: STAT 636 or approval of instructor.
Cross Listing: RPTS 678/RENR 678.

WFSC 602 Field Herpetology

Credit 1. 3 Lab Hours.

Field work involving collection and preservation of herpetological specimens natural history, ecological relations.
Prerequisites: Graduate classification.

WFSC 604 Ecological Modeling

Credits 3. 3 Lecture Hours.

Philosophical basis, theoretical framework, and practical application of systems analysis and simulation within the context of ecology and natural resource management emphasis placed on development, evaluation and use of simulation models by students.
Prerequisite: Approval of instructor.

WFSC 605 Community Ecology

Credits 3. 3 Lecture Hours.

Overview and in-depth knowledge of community ecology historical development current issues, methodologies, and practical applications in natural resource management, biological conservation, agriculture, and human health practice critical thinking, communication skills, and professionalism.
Prerequisite: Graduate classification.

WFSC 613 Animal Ecology

Credits 3. 2 Lecture Hours. 3 Lab Hours.

Concepts of animal ecology which emerge at various levels or organization the ecosystem, the community, the population and the individual laboratories emphasis on the quantitative analysis of field data and the simulation of population dynamics.
Prerequisite: Graduate classification or approval of instructor.

WFSC 614 Down River: Biology of Gulf Coastal Fishes

Credit 1. 3 Lab Hours.

Understanding the biological complexity of Gulf Coast river systems while gaining hands-on experience in field and museum ichthyological techniques sampling of the Guadalupe and San Antonio rivers participation in lectures, museum preparation and archiving specimens at the Biodiversity Research and Teaching Collections (BRTC).
Prerequisite: Graduate classification.

WFSC 618 Wildlife Study Design and Analysis

Credits 3. 3 Lecture Hours.

Fundamental and advanced aspects of study design applicable to terrestrial animals analysis and review of the scientific literature related to study design and the development of study design for written and oral presentations.
Prerequisite: Graduate classification or approval of instructor.

WFSC 619 Wildlife Restoration

Credits 3. 2 Lecture Hours. 3 Lab Hours.

Study of the fundamentals of the restoration of animal populations and the resources they require factors that control the distribution and abundances of animals in relation to restoration and how restoration plans for wildlife are developed.
Prerequisite: Graduate classification or approval of instructor.

WFSC 623 Aquaculture

Credits 4. 3 Lecture Hours. 3 Lab Hours.

Principle of fish production for stock enhancement and human food. Species of fish used for production, cross-breeding and selection feeds and feeding of fish and nutritional and environmental requirements for optimum productivity effects of fish production on land and water uses as related to conservation.
Prerequisite: Graduate classification or approval of instructor.

WFSC 624 Dynamics of Populations

Credits 4. 3 Lecture Hours. 2 Lab Hours.

Principles, models and methods for analysis of population dynamics analysis of contemporary research emphasizing theory and its uses in evaluation and management of animal populations. Laboratory emphasizes mathematical, statistical and computer modeling of population phenomena.

WFSC 627 Ecological Risk Assessment

Credits 3. 3 Lecture Hours.

Approaches used to identify, evaluate and manage ecological risks of chemicals on aquatic and terrestrial environments emphasis on methods useful to assess effects of contaminants on ecosystems testing techniques, site assessment and monitoring procedures, regulatory requirements and field and laboratory techniques. Only one of the following will satisfy the requirements for a degree: WFSC 627 or WFSC 639.

WFSC 628 Wetland Ecology and Pollution

Credits 3. 3 Lecture Hours.

Wetlands as ecological systems that are prime habitats for wildlife and fish geomorphology, hydrology, limnology, plant and animal communities, and humans use and management wetlands as ultimate reservoirs of environmental pollutants distribution, fate and effects of environmental pollutants on aquatic and terrestrial wildlife.
Prerequisite: Graduate classification or approval of instructor.

WFSC 630 Ecology and Society

Credits 3. 3 Lecture Hours.

Study and compare human and natural ecosystems using diversity, interrelations, cycles, and energy as the conceptional organization central themes of the course are sustainability, stewardship and science.
Prerequisite: Graduate classification or approval of instructor.

WFSC 631 Ecological Applications in R

Credits 3. 3 Lecture Hours.

Introduction to R and diversity of statistical packages available data summary and manipulation univariate and multivariate statistics populations and community ecology time-series and spatial analysis.

WFSC 633 Conservation Genetics

Credits 3. 3 Lecture Hours.

Genetic concepts and techniques relevant to management and conservation of biological diversity research and conservation strategies within a conservation genetics framework.
Prerequisite: Introductory courses in genetics and ecology or biological conservation.

WFSC 636 Wildlife Habitat Management

Credits 3. 3 Lecture Hours.

Designed to acquaint with major land use practices on lands that produce wildlife, how these influences wildlife production and alterations or manipulations of habitat used to achieve specific wildlife management goals.
Prerequisite: Graduate classification or approval of instructor.

WFSC 637/VTMI 631 Wildlife Diseases

Credits 3. 3 Lecture Hours.

Overview of diseases that affect populations of wild mammals, birds, amphibians and reptiles emphasis on diseases that are transmissible to humans or domestic animals and those found in Texas.
Cross Listing: VTMI 631/WFSC 637.

WFSC 638 Techniques of Wildlife Management

Credits 3. 2 Lecture Hours. 3 Lab Hours.

Techniques available to directly and indirectly manipulate wild animal populations to achieve balance between socioeconomic and aesthetic values.
Prerequisite: Graduate classification or approval of instructor.

WFSC 639 Wildlife Ecotoxicology

Credits 3. 3 Lecture Hours.

Distribution, fate, and effects of environmental pollutants on wildlife behavior and reproduction. Global distribution of pollutants and effects on near and remote ecosystems. Field studies, biomarkers, stable isotope and various techniques for evaluating pollutant hazards on wildlife. Only one of the following will satisfy the requirements for a degree: WFSC 627 or WFSC 639.
Prerequisites: Courses in CHEM and BICH and graduate classification or approval of instructor.

WFSC 641 Sustainable Military Land Management

Credits 3. 3 Lecture Hours.

Overview of the Department of Defense (DOD) lands within a temporal, geographic, and environmental context and perspective major policies/laws impacting military land use and areas critical to mission sustainment management strategies important to sustaining installations and ranges.
Prerequisite: Graduate classification or approval of instructor.

WFSC 642 Field Military Land Management

Credit 1. 0 Lecture Hours. 2 Lab Hours.

Review of land management practices and challenges on military and adjacent private lands through field visits of select military installations. Field trips required. Previous or concurrent registration in WFSC 636 is strongly encouraged.
Prerequisite: Graduate classification or approval of instructor.

WFSC 644 Wildlife and Natural Resource Policy

Credits 3. 3 Lecture Hours.

Review formation and implementation of major natural resource laws and policies that impact land uses overview of natural resource laws/policies followed by presentations of a selected case study current natural resource management (including forestry, air, water, wildlife, climate change and energy) programs and institutions analyzed and related to current natural resource policy challenges.

WFSC 646 Quantitative Phylogenetics

Credits 3. 2 Lecture Hours. 1 Lab Hour.

Designed to provide the theory and tools required for inference of phylogenetic (evolutionary) relationships among biological taxa using various types of comparative data including morphological characters, biochemical and molecular characters, and DNA sequences hands-on analysis of data using contemporary tools.
Prerequisites: ENTO 601 or approval of instructor.
Cross Listing: ENTO 606 and GENE 606.

WFSC 647/NUTR 651 Nutritional Biochemistry of Fishes

Credits 3. 3 Lecture Hours.

Principles of nutritional biochemistry including nutrient metabolism and biochemical energetics with special emphasis on finfish and shell fish.
Prerequisite: BICH 410 or equivalent.
Cross Listing: NUTR 651/WFSC 647.

WFSC 648/GENE 648 Molecular Evolution

Credits 3. 2 Lecture Hours. 1 Lab Hour.

Theory and tools used in the analysis of molecular evolutionary patterns of DNA and protein sequences format combines lecture presentations by instructor discussion of relevant scientific literature, computer exercises, preparation of research proposal or independent research project, and practice in peer-review process.
Prerequisite: Basic courses in general Genetics and Evolution.
Cross Listing: GENE 648/WFSC 648.

WFSC 654 Amazon Field School

Credits 4. 4 Lecture Hours.

Investigation of social and ecological complexities of biodiversity conservation in tropical ecosystems biological and social science approaches to evaluate causes, consequences and solutions to biodiversity loss through ecology, culture and governance.
Cross Listing: RPTS 654 and VTMI 604.

WFSC 655/RPTS 655 Applied Biodiversity Science I

Credits 3. 3 Lecture Hours.

Applied Biodiversity Science. Students will study in the areas of Conservation genetics, metapopulations, landscape ecology, and ecosystem management.
Prerequisite(s): Graduate classification.
Cross Listing: RPTS 655/WFSC 655.

WFSC 670 Excel Biometry

Credits 3. 3 Lecture Hours.

Rational and mathematics behind upper level biometrical methods construct spreadsheets and analyze a common data set topics include multiple regressions, principle components analysis, multivariate analysis of variance and others.
Prerequisites: Graduate classification STAT 651 or equivalent.

WFSC 681 Seminar

Credit 1. 1 Lecture Hour.

Important current developments in wildlife or fisheries fields with special reference to literature. Students may register up to but no more than two sections of this course in the same semester.

WFSC 684 Professional Internship

Credits 1 to 16. 1 to 16 Other Hours.

On-the-job training in fields of wildlife and fisheries sciences.
Prerequisite: Graduate classification in Wildlife and Fisheries Sciences.

WFSC 685 Directed Studies

Credits 1 to 6. 1 to 6 Other Hours.

Individual study and research on selected problem approved by instructor and graduate advisor. Credit adjusted in accordance with requirements of each individual case.
Prerequisite: Approved proposal.

WFSC 689 Special Topics in.

Credits 1 to 4. 1 to 4 Lecture Hours. 0 to 4 Lab Hours.

Special topics in wildlife ecology, fisheries ecology, vertebrate systematics, evolutionary biology of vertebrates and conservation education. May be repeated for credit.

WFSC 691 Research

Credits 1 to 23. 1 to 23 Other Hours.

Original research on selected wildlife and/or fisheries problem to be used in thesis or dissertation.

Barboza, Peregrine, Professor
Ecology and Conservation Biology
PHD, University of New England, 1991

Boutton, Thomas, Professor
Ecology and Conservation Biology
PHD, Brigham Young University, 1979

Briske, David, Regents Professor
Ecology and Conservation Biology
PHD, Colorado State University, 1978

Casola, Claudio, Associate Professor
Ecology and Conservation Biology
PHD, University of Pisa, Italy, 2006

Conway, Kevin, Associate Professor
Ecology and Conservation Biology
PHD, San Louis University, 2010

Dewitt, Thomas, Associate Professor
Ecology and Conservation Biology
PHD, State University of New York - Binghamton, 1996

Feagin, Russell, Professor
Ecology and Conservation Biology
PHD, Texas A&M University, 2003

Fitzgerald, Lee, Professor
Ecology and Conservation Biology
PHD, University of New Mexico, 1993

Fujiwara, Masami, Associate Professor
Ecology and Conservation Biology
PHD, Massachusetts Inst of Technology, 2002

Gan, Jianbang, Professor
Ecology and Conservation Biology
PHD, Iowa State University, 1990

Gatlin, Delbert, Regents Professor
Ecology and Conservation Biology
PHD, Mississippi State University, 1983

Grace, Jacquelyn, Assistant Professor
Ecology and Conservation Biology
PHD, Wake Forest University, 2014

Grant, William, Professor
Ecology and Conservation Biology
PHD, Colorado State University, 1974

Hurtado Clavijo, Luis, Associate Professor
Ecology and Conservation Biology
PHD, Rutgers, 2002

Kreuter, Urs, Professor
Ecology and Conservation Biology
PHD, Utah State University, 1992

Lacher, Thomas, Professor
Ecology and Conservation Biology
PHD, University of Pittsburgh, 1980

Lawing, Anna, Associate Professor
Ecology and Conservation Biology
PHD, Indiana University, 2012

Light, Jessica, Associate Professor
Ecology and Conservation Biology
PHD, Louisiana State University, 2005

Loopstra, Carol, Associate Professor
Ecology and Conservation Biology
PHD, North Carolina State University, 1992

Mateos, Mariana, Associate Professor
Ecology and Conservation Biology
PHD, Rutgers, 2002

Moore, Georgianne, Professor
Ecology and Conservation Biology
PHD, Oregon State University, 2004

Mora-Zacarias, Miguel, Professor
Ecology and Conservation Biology
PHD, University of California at Davis, 1990

Noormets, Asko, Professor
Ecology and Conservation Biology
PHD, Michigan Technological University, 2001

Osorio Leyton, Javier, Visiting Lecturer
Ecology and Conservation Biology
PHD, Virginia Polytechnic Institute and State University, 2012

Perkin, Joshuah, Assistant Professor
Ecology and Conservation Biology
PHD, Kansas State University, 2012

Popescu, Sorin, Professor
Ecology and Conservation Biology
PHD, Virginia Tech, 2002

Rogers, William, Professor
Ecology and Conservation Biology
PHD, Kansas State University, 1998

Spalink, Daniel, Assistant Professor
Ecology and Conservation Biology
PHD, University of Wisconsin, Madison, 2015

Srinivasan, Raghavan, Professor
Ecology and Conservation Biology
PHD, Purdue University, 1992

Stronza, Amanda, Professor
Ecology and Conservation Biology
PHD, University of Florida, 2000

Struminger, Rhonda, Assistant Professor of the Practice
Ecology and Conservation Biology
PHD, Texas A&M University, 2013

Veldman, Joseph, Assistant Professor
Ecology and Conservation Biology
PHD, University of Florida, 2010

Voelker, Gary, Professor
Ecology and Conservation Biology
PHD, University of Washington, 1998

West, Jason, Associate Professor
Ecology and Conservation Biology
PHD, University of Georgia, 2002

Wilcox, Bradford, Professor
Ecology and Conservation Biology
PHD, Texas A&M University, 1986

Winemiller, Kirk, University Distinguished Professor
Ecology and Conservation Biology
PHD, The University of Texas at Austin, 1987

Wu, Xinyuan, Professor
Ecology and Conservation Biology
PHD, University of Tennessee, Knoxville, 1991

Yorzinski, Jessica, Assistant Professor
Ecology and Conservation Biology
PHD, University of California at Davis, 2012

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College Station, Texas 77843


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Community Ecology and Population Biology

Community ecology and population biology are particular areas of strength, covering the nature of species interactions, the composition of species assemblages over space and time, evolutionary ecology (including trait-mediated interactions), and population dynamics. We integrate well to other conceptual areas including behavioral ecology, climate change, ecosystem ecology, evolutionary genetics, and phylogenetics.

One area that has captured the attention of several labs is how rapid evolutionary change can shape population and community dynamics. Our vibrant group frequently hosts graduate seminars and recent topics have included eco-evolutionary feedbacks, biodiversity-ecosystem function, community ecology and phylogenetics, and specialism and generalism in ecology. Community ecology and population biology interfaces with Organismal Biology, which concentrates on the ecology and life-history evolution of single species. Applied research in community ecology and population biology includes work on conservation biology, invasions, biodiversity, disease dynamics, and agroecology in systems that range from the coral reefs to local corn fields.


The merging of community ecology and phylogenetic biology

The increasing availability of phylogenetic data, computing power and informatics tools has facilitated a rapid expansion of studies that apply phylogenetic data and methods to community ecology. Several key areas are reviewed in which phylogenetic information helps to resolve long-standing controversies in community ecology, challenges previous assumptions, and opens new areas of investigation. In particular, studies in phylogenetic community ecology have helped to reveal the multitude of processes driving community assembly and have demonstrated the importance of evolution in the assembly process. Phylogenetic approaches have also increased understanding of the consequences of community interactions for speciation, adaptation and extinction. Finally, phylogenetic community structure and composition holds promise for predicting ecosystem processes and impacts of global change. Major challenges to advancing these areas remain. In particular, determining the extent to which ecologically relevant traits are phylogenetically conserved or convergent, and over what temporal scale, is critical to understanding the causes of community phylogenetic structure and its evolutionary and ecosystem consequences. Harnessing phylogenetic information to understand and forecast changes in diversity and dynamics of communities is a critical step in managing and restoring the Earth's biota in a time of rapid global change.


Publications

Liu, W., Liu, L., Yang, X., Deng, M., Wang, Z., Wang, P., Yang, S., Li, P., Peng, Z., Yang, L. and Jiang, L. 2021. Long-term nitrogen input alters plant and soil bacterial, but not fungal beta diversity in a semiarid grassland. Glob Change Biol. Accepted Author Manuscript. https://doi.org/10.1111/gcb.15681

Xu, Q., X. Yang, Y. Yan, S. Wang, M. Loreau, and L. Jiang. 2021. Consistently positive effect of species diversity on ecosystem, but not population, temporal stability. Ecology Letters. https://doi.org/10.1111/ele.13777

Yang, X., Y. Wang, Q. Xu, W. Liu, L. Liu, Y. Wu, L. Jiang, and J. Lu. 2021. Soil fertility underlies the positive relationship between island area and litter decomposition in a fragmented subtropical forest landscape. CATENA 204:105414.

Hu, Z., C. Chen, X. Chen, J. Yao, L. Jiang, and M. Liu. 2021. Home-field advantage in soil respiration and its resilience to drying and rewetting cycles. Science of The Total Environment 750:141736.

Zhu, J., Y. Zhang, X. Yang, N. Chen, and L. Jiang. 2020. Synergistic effects of nitrogen and CO2 enrichment on alpine grassland biomass and community structure. New Phytologist 228:1283–1294.

Yang, X., J. Tan, K. H. Sun, and L. Jiang. 2020. Experimental demonstration of the importance of keystone communities for maintaining metacommunity biodiversity and ecosystem functioning. Oecologia. https://doi.org/10.1007/s00442-020-04693-x

Zhu, J., Y. Zhang, X. Yang, N. Chen, S. Li, P. Wang, and L. Jiang. 2020. Warming alters plant phylogenetic and functional community structure. Journal of Ecology 108:2406–2415.

Tan, J., X. Yang, Q. He, X. Hua, and L. Jiang. 2020. Earlier parasite arrival reduces the repeatability of host adaptive radiation. The ISME Journal. https://doi.org/10.1038/s41396-020-0681-8

Li, S., Wang, P., Chen, Y., … Jiang, L. 2020. Island biogeography of soil bacteria and fungi: similar patterns, but different mechanisms. The ISME Journal. doi: 10.1038/s41396-020-0657-8

Zhu, J., Y. Zhang, W. Wang, X. Yang, N. Chen, R. Shen, L. Wang, and L. Jiang. 2020. Species turnover drives grassland community to phylogenetic clustering over long-term grazing disturbance. Journal of Plant Ecology 13:157–164.

Wang, P., S.-P. Li, X. Yang, J. Zhou, W. Shu, and L. Jiang. 2020. Mechanisms of soil bacterial and fungal community assembly differ among and within islands. Environmental Microbiology 22:1559–1571. doi:10.1111/1462-2920.14864

Yang, X. , Li, G. , Li, S. , Xu, Q. , Wang, P. , Song, H. , … Jiang, L. 2019 . Resource addition drives taxonomic divergence and phylogenetic convergence of plant communities . Journal of Ecology 107 : 2121 – 2132 .

Zhang, Y., J. Feng, M. Loreau, N. He, X. Han, and L. Jiang. 2019. Nitrogen addition does not reduce the role of spatial asynchrony in stabilizing grassland communities. Ecology Letters 22 : 563–571 .

Tan, J., Q. He, J.T. Pentz, C. Peng, X. Yang, M. Tsai, Y. Chen, W.C. Ratcliff, and L. Jiang. 2019. Copper oxide nanoparticles promote the evolution of multicellularity in yeast. Nanotoxicology. doi : 10.1080/17435390.2018.1553253

Li, S., J. Tan, X. Yang, C. Ma, and L. Jiang. 2019. Niche and fitness differences determine invasion success and impact in laboratory bacterial communities. The ISME Journal 13:402–412. doi: 10.1038/s41396-018-0283-x

Deng, M., L. Liu, L. Jiang, W. Liu, X. Wang, S. Li, S. Yang, and B. Wang. 2018. Ecosystem scale trade-off in nitrogen acquisition pathways. Nature Ecology & Evolution 2: 1724–1734.

Zhao, N., S. Gao, H. Ren, X. Yang, Z. Sun, J. Wang, L. Jiang, and Y. Gao. 2018. Competition alters plant-soil feedbacks of two species in the Inner Mongolia Steppe, China. Plant and Soil:1–12.

Lu, J., S. Li, Y. Wu, and L. Jiang. 2018. Are Hong Kong and Taiwan stepping‐stones for invasive species to the mainland of China? Ecology and Evolution 8:1966–1973.

Yang, X., Z. Yang, J. Tan, G. Li, S. Wan, and L. Jiang. 2018. Nitrogen fertilization, not water addition, alters plant phylogenetic community structure in a semi‐arid steppe. Journal of Ecology 106:991–1000.

Xu, Z., M. Li, N. E. Zimmermann, S. Li, H. Li, H. Ren, H. Sun, X. Han, Y. Jiang, and L. Jiang. 2018. Plant functional diversity modulates global environmental change effects on grassland productivity. Journal of Ecology 106: 1941–1951.

Zhu, J., Y. Zhang, and L. Jiang. 2017. Experimental warming drives a seasonal shift of ecosystem carbon exchange in Tibetan alpine meadow. Agricultural and forest meteorology 233:242–249.

Ma, Z., H. Liu, Z. Mi, Z. Zhang, Y. Wang, W. Xu, L. Jiang, and J.-S. He. 2017. Climate warming reduces the temporal stability of plant community biomass production. Nature Communications 8:15378.

Peng, C., Y. Chen, Z. C. Pu, Q. Zhao, X. Tong, Y. S. Chen, and L. Jiang. 2017. CeO2 nanoparticles alter the outcome of species interactions. Nanotoxicology 11:625-636.

Zhang, Q., A. Buyantuev, F. Y. Li, L. Jiang, J. Niu, Y. Ding, S. Kang, and W. Ma. 2017. Functional dominance rather than taxonomic diversity and functional diversity mainly affects community aboveground biomass in the Inner Mongolia grassland. Ecology and Evolution 7:1605–1615.

Tan, J., X. Yang, and L. Jiang. 2017. Species ecological similarity modulates the importance of colonization history for adaptive radiation. Evolution 71:1719–1727.

Tan, J., J. B. Rattray, X. Yang, and L. Jiang. 2017. Spatial storage effect promotes biodiversity during adaptive radiation. Proc. R. Soc. B 284:20170841.

Miao, Y., H. Han, Y. Du, Q. Zhang, L. Jiang, D. Hui, and S. Wan. 2017. Nonlinear responses of soil respiration to precipitation changes in a semiarid temperate steppe. Scientific Reports 7:45782.

Gibbs, D. A., and L. Jiang. 2017. Environmental warming accelerates extinctions but does not alter extinction debt. Basic and Applied Ecology 24:30–40.

Pu Z, MH Cortez and L Jiang. 2017 Predator-prey coevolution drives productivity-diversity relationships in planktonic systems. American Naturalist 189: 28-42

Ojima MN and L Jiang. 2017 Interactive effects of disturbance and dispersal on community assembly. Oikos 126: 682-691

Yang Z, F Su, Z Pu, C Zhang, Q Zhang, J Xia, S Wan and L Jiang. 2017 Daytime warming lowers community temporal stability by reducing the abundance of dominant, stable species. Global Change Biology 23: 154-163.

Ma C, SP Li, Z Pu, J Tan, M Liu, J Zhou, H Li, and L Jiang. 2016.Different effects of invader-native phylogenetic relatedness on invasion success and impact: a meta-analysis of Darwin’s naturalization hypothesis. Proceedings of the Royal Society B 283: 20160663.

Li SP, MW Cadotte, SJ Meiners, Z Pu, T Fukami, and L Jiang. 2016. Convergence and divergence in a long-term old-field succession: the importance of spatial scale and species abundance. Ecology Letters 19: 1101-1109.

Tan J, MR Slattery, X Yang and L Jiang. 2016. Phylogenetic context determines the role of competition in adaptive radiation. Proceedings of the Royal Society B 283: 20160241.

Johnston N, Z Pu, and L Jiang. 2016. Predator identity influences metacommunity assembly. Journal of Animal Ecology 85: 1161-1170.

Zhang W, Z Pu, S Du, Y Chen, and L Jiang. 2016. Fate of engineered cerium oxide nanoparticles in an aquatic environment and their toxicity toward 14 ciliated protist species. Environmental Pollution 212: 584-591.

Yang Z, L Jiang, F Su, Q Zhang, J Xia, and S Wan. 2016. Nighttime warming enhances drought resistance of plant communities in a temperate steppe. Scientific Reports 6: 23267

Zhao C, Y Miao, C Yu, L Zhu, F Wang, L Jiang, D Hui and S Wan. 2016. Soil microbial community composition and respiration along an experimental precipitation gradient in a semiarid steppe. Scientific Reports 6: 24317

Nemergut DR, JE Knelman, S Ferrenberg, T Bilinski, B Melbourne, L Jiang, C Violle, JL Darcy, T Prest, SK Schmidt and AR Townsend. 2016. Decreases in average bacterial community rRNA operon copy number during succession. The ISME Journal 10: 1147-1156.

Wilson, MC, XY Chen, RT Corlett, RK Didham, P Ding, RD Holt, M Holyoak, G Hu, AC Hughes, L Jiang, WF Laurance, J Liu, SL Pimm, SK Robinson, SE Russo, X Si, DS Wilcove, J. Wu and M Yu. 2016. Habitat fragmentation and biodiversity conservation: key findings and future challenges. Landscape Ecology 31: 219-227.

Xu Z, H Ren, MH Li, J van Ruijven, X Han, S Wan, H Li, Q Yu, Y Jiang and L Jiang. 2015 Environmental changes drive the temporal stability of semi-arid natural grasslands through altering species asynchrony. Journal of Ecology 103: 1308-1316.

Li SP, MW Cadotte, SJ Meiners, Z Shuang, L Jiang and W Shu. 2015. Species colonization, not competitive exclusion, drives community overdispersion over long-term succession. Ecology Letters 18: 964-973.

Zhang X, W Lu, G Zhang, L Jiang and X Han. 2015. Mechanisms of soil acidification reducing bacterial diversity. Soil Biology & Biochemistry, 81: 275-281.

Pu Z, and L Jiang. 2015. Dispersal among local communities does not reduce historical contingencies during metacommunity assembly. Oikos 124: 1327-1336.

Tan J, Z Pu, WA Ryberg and L Jiang. 2015. Resident-invader phylogenetic relatedness, not resident phylogenetic diversity, controls community invasibility. American Naturalist 186: 59-71.

Zhu J, L Jiang, Y Zhang, Y Jiang, J Tao, T Zhang and Y Xi. 2015. Belowground competition drives the self-thinning process of populations in the Northern Tibet. Journal of Vegetation Science 26: 166-174.

Qian H, and L Jiang. 2014. Phylogenetic community ecology: integrating community ecology and evolutionary biology. Journal of Plant Ecology 7: 97-100

Zhang X, W Lu, G Zhang, L Jiang and X Han. 2015. Mechanisms of soil acidification reducing bacterial diversity. Soil Biology & Biochemistry 81: 275-281.

Pu, Z and L Jiang. 2015. Dispersal among local communities does not reduce historical contingencies during metacommunity assembly. Oikos 124: 1327-1336.

Zhu J, L Jiang, Y Zhang, Y Jiang, J Tao, T Zhang and Y Xi. 2015. Belowground competition drives the self-thinning process of populations in the Northern Tibet. Journal of Vegetation Science 26: 166-174.

Qian, H and L Jiang. 2014. Phylogenetic community ecology: integrating community ecology and evolutionary biology. Journal of Plant Ecology 7: 97-100

Pu, Z., P Daya, J Tan and L Jiang. 2014. Phylogenetic diversity stabilizes community biomass. Journal of Plant Ecology 7: 176-187

Liu, W., L Jiang, S Hu, L Li, L Liu and S Wan. 2014. Decoupling of soil microbes and plants with increasing anthropogenic nitrogen inputs in a temperate steppe. Soil Biology & Biochemistry 72: 116-122.

Ren, H., Z Xu, W Zhang, L Jiang, J Huang, S Chen, L Wang and X Han. 2013. Linking ethylene to nitrogen-dependent leaf longevity of grass species in a temperate steppe. Annals of Botany 112: 1879-1885.

Tan, J., CK Kelly, and L Jiang. 2013. Temporal niche promotes biodiversity during adaptive radiation. Nature Communications 4: 2102.

Ferrenberg, S., S O’Neill, J Knelman, B Todd, S Duggan, D Bradley, T Robinson, SK Schmidt, AR Townsend, M Williams, CC Cleveland, B Melbourne, L Jiang and DR Nemergut. 2013. Changes in assembly processes in soil microbial communities following a wildfire disturbance. The ISME Journal 7: 1102-1011.

Li, K. G., Y Chen, W Zhang, Z Pu, L Jiang, and YS Chen. 2012. Surface interactions affect the toxicity of engineered metal oxide nanoparticles toward Paramecium. Chemical Research in Toxicology 25:1675-1681.

Violle, C., BJ Enquist, BJ McGill, L Jiang, CH Albert, C Hulshof, V Jung, and J Messier. 2012. Viva la variance! A reply to Nakagawa & Schielzeth. Trends in Ecology & Evolution 27:475-476.

Yang H., L. Jiang, L. Li, A. Li, M. Wu and S. Wan. 2012. Diversity-dependent stability under mowing and nutrient addition: evidence from a seven-year grassland experiment. Ecology Letters, 15: 619-626.

Tan J, Z Pu, WA Ryberg and L Jiang. 2012. Species phylogenetic relatedness, priority effects, and ecosystem functioning. Ecology, 93: 1164-1172. Faculty of 1000 Biology recommended paper.

Violle C, BJ Enquist, BJ McGill, L Jiang, CH Albert, C Hulshof, V Jung and J Messier. 2012. The return of the variance: intraspecific variability in community ecology. Trends in Ecology and Evolution, 27: 244-252.

Jiang L, L Brady and J Tan. 2011. Species diversity, invasion, and alternative community states in sequentially assembled communities. American Naturalist, 178: 411-418.

Violle C, DR Nemergut, Z Pu and L Jiang. 2011. Phylogenetic limiting similarity and competitive exclusion. Ecology Letters, 14:782-787. Faculty of 1000 Biology recommended paper.

Jiang L, H Joshi, SK Flakes and Y Jung. 2011. Alternative community compositional and dynamical states: the dual consequences of assembly history. Journal of Animal Ecology 80: 577-585.

Lu J, L Jiang, L Yu and Q Sun. 2011. Local factors determine community structure on closely neighbored islands. PLoS ONE 6(5): e19762.

Nemergut DR, EK Costello, M Hamady, C Lozupone, L Jiang, SK Schmidt, N Fierer, AR Townsend, CC Cleveland, L Stanish, and R Knight. 2011. Global patterns in the biogeography of bacterial taxa. Environmental Microbiology 13:135-144.

Violle C, Z Pu, and L Jiang. 2010. Experimental demonstration of the importance of competition under disturbance. Proceedings of the National Academy of Sciences USA 107:12925-12929.

Jiang L, J Tan and Z Pu. 2010. An experimental test of Darwin’s naturalization hypothesis. American Naturalist 175: 415-423. Faculty of 1000 Biology recommended paper.

Jiang L and Z Pu. 2009. Different effects of species diversity on temporal stability in single-trophic and multi-trophic communities. American Naturalist 174: 651-659.

Wang H, L Jiang and JS Weitz. 2009. Bacterivorous grazers facilitate organic matter decomposition: a stoichiometric modeling approach. FEMS Microbiology Ecology 69: 170-179.

Violle C and L Jiang. 2009. Towards a trait-based quantification of species niche. Journal of Plant Ecology 2: 87-93.

Jiang L, S Wan and L Li. 2009. Species diversity and productivity: why do results of diversity-manipulation experiments differ from natural patterns? Journal of Ecology 97: 603-608.

Jiang L. 2009. Biodiversity and ecosystem functioning: beyond complementarity and positive selection effects. Pages 38-57 in Wu J and J Yang (eds), Lectures in Modern Ecology (IV): Theory and Applications. Higher Education Press, Beijing.

Jiang L, H Joshi and SN Patel. 2009. Predation alters relationships between biodiversity and temporal stability. American Naturalist 173: 389-399.

Jiang L and SN Patel. 2008. Community assembly in the presence of disturbance: a microcosm experiment. Ecology 89: 1931-1940.

Jiang L, Z Pu, and DR Nemergut. 2008. On the importance of the negative selection effect for the relationship between biodiversity and ecosystem functioning. Oikos 117: 488-493.

2007 and earlier

Jiang L and PJ Morin. 2007. Temperature fluctuation facilitates coexistence of competing species in experimental microbial communities. Journal of Animal Ecology 76: 660-668.

Jiang L. 2007. Negative selection effects suppress relationships between bacterial diversity and ecosystem functioning in experimental bacterial communities. Ecology 88: 1075-1085.

Jiang L. 2007. Density compensation can cause no effect of biodiversity on ecosystem functioning. Oikos 126: 324-334.

Jiang L and JA Krumins 2006. Consumer versus environmental productivity control of bacterial diversity and bacteria-mediated organic matter decomposition. Oikos 114: 441-450.

Jiang L and JA Krumins 2006. Emergent multiple predator effects in an experimental microbial community. Ecological Research 21: 723-731.

Jiang L, O Schofield, and PG Falkowski 2005. Adaptive evolution of phytoplankton cell size. American Naturalist 166: 496-505.

Shi T, TS Bibby, L Jiang, AJ Irwin and PG Falkowski 2005. Protein interactions limit the rate of evolution of photosynthetic genes in cyanobacteria. Molecular Biology and Evolution 22: 2179-2189.

Jiang L and PJ Morin. 2005. Predator diet breadth influences the relative importance of bottom-up and top-down control of prey biomass and diversity. American Naturalist 165: 350-363. Faculty of 1000 Biology recommended paper.

Jiang L and PJ Morin. 2004. Productivity gradients cause positive diversity-invasibility relationships in microbial communities. Ecology Letters 7: 1047-1057.

Jiang L and N Shao. 2004. Red environmental noise and the appearance of delayed density dependence in age-structured populations. Proceedings of the Royal Society of London, series B 271: 1059-1064.

Jiang L and PJ Morin. 2004. Temperature-dependent interaction explains unexpected responses to environmental warming in communities of competitors. Journal of Animal Ecology 73: 569-576.

Jiang L and A Kulczycki. 2004. Competition, predation, and responses to environmental change. Oikos 106: 217-224.

Jiang L and N Shao. 2003. Autocorrelated exogenous factors and the detection of delayed density dependence. Ecology 84: 2208-2213.

Petchey OL, TM Casey, L Jiang, PT McPhearson, and J Price. 2002. Species richness, environmental fluctuations, and temporal change in total community biomass. Oikos 99: 231-240.


DateMay 2013Marks available1Reference code13M.1.HL.TZ1.17
LevelHigher levelPaperPaper 1Time zoneTime zone 1
Command term Question number17Adapted fromN/A

Global warming caused by the enhanced greenhouse effect is likely to have major consequences for arctic ecosystems. Which of the following are likely to occur in the arctic if the Earth’s surface temperature rises?

I. Decreased rates of decomposition of detritus

II. Increased range of predators from temperate regions

III. Increase in numbers of pest species and pathogens

A. I and II only
B. I and III only
C. II and III only
D. I, II and III


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