Community Ecology

G.1.1 Outline the factors that affect the distribution of plant species, including temperature, water, light, soil pH, salinity, and mineral nutrients  High temperature denatures enzymes and slows growth of plants; the rate of transpiration is also increased.  Low temperatures decrease enzyme activity and freezing temperatures inactivate enzymes.  Water is needed for enzyme activity, transport, photosynthesis, support, and many other things. There is a low diversity of plants in deserts and polar regions.

 Light is important for photosynthesis and flowering. Because of this, dark areas have small numbers of plants.  Soil pH is important for absorption of nutrients. If soil is acidic, desertification can occur; the use of limestone can neutralize the soil.

 Salinity has an affect on the absorption through osmosis. High salinity causes plants to lose water through osmosis. Halophytes live in high salinity.  Mineral nutrients are needed for many important functions. Nitrogen is needed to make proteins, enzymes, nucleotides, vitamins, and other compounds. Phosphorous is used in the formation of phospholipids and other structures.

G.1.2 Explain the factors that affect the distribution of animal species, including temperature, water, breeding sites, food supply and territory  Temperatures affect the concentration of animals. Only especially adapted organisms can live in extreme temperatures.  Water is needed for important functions, so only animals that can conserve water are found in deserts, like snakes.

 Breeding sites are needed for growth and protection of young. High animal diversity is found in areas with varied topographical nature.  Food supply is important for survival since animals are heterotrophs. High animal diversity is once again found in the rain forest.

Some animals are territorial and need large areas for feeding, mating, and protecting their young. Some are territorial during breeding season and occupy areas to prevents others from approaching them. There is high animal distribution where there is room to occupy territory and defend against other members of the species.

G.1.3 Describe one method of random sampling, based on quadrate methods, that is used to compare the population size of two plants or two animal species  Create a plot and make a grid on a map.  Number the grids and measure population size in those quadrates  Calculate average population density and multiply to get total population

G.1.4 Outline the use of a transect to correlate the distribution of plant or animal species with an a biotic variable  Stretch a rope down the area that you want to investigate. At predetermined intervals, measure the population size for the organism you are interested in. These measurements can be at the point on the rope or (point transect), in a belt transect, in a band going on both sides of the rope. You may see changes in the species present as abiotic factors change along the length of your transect.  You use a transect to correlate the distribution of a plant or animal species with an abiotic variable

G.1.5 Explain what is meant by the niche concept, including an organism’s spatial habitat, its feeding activities and its interactions with other species  A niche is all the characteristics, biotic and abiotic, specific to a species. It includes the habitat, nutrition, and relationships. For example, the place that the species sleeps, lives, breeds, its food source and relationship with other species.

G.1.6 Outline the following interactions between species, giving two examples of each: competition, herbivore, predation, parasitism, and mutualism  Competition is when two species need the same resource such as a breeding site or food. Usually one of the species will out- compete the other. The European starlings and American Robins are birds that compete in part of their niches.

 Herbivory is the relation between an animal and a plant. Different animals feed on different plants. Deer feed on tree leaves, rabbit feed on grass, giraffes on trees.  Predation is the relation between the predator, which is usually bigger, and the prey, which is usually smaller. An example would be a fox and a rabbit, or bonitos on anchovies.

 Parasitism is the relation between the host and the parasite. The parasite causes harm to the host to get food and other resources. Examples of parasites are the malaria protist and tapeworm in humans.  Mutualism is where two members of different species benefit and neither suffers.

G.1.7 Explain the principle of competitive exclusion  No two species can live in the same niche, because there is competition for the resources of the land and only one species will survive.

G.1.8 Distinguish between fundamental and realized niches  The fundamental niche is the potential mode of existence, given the adaptations of the species.  The realized niche is the actual mode of existence, which results from its adaptations and competition with other species

G.1.9 Define biomass  The total organic matter comprising a group of organisms in a particular habitat  The weight of all the organisms in the same trophic level

G.1.10 Describe one method for the measurement of biomass of different trophic levels in an ecosystem  Biomass: Measure total area of ecosystem.  Divide ecosystem into small areas (grid/plot).  Sample from one/few grids/plots.  Measure and remove all plant materials from that  Dry  Create a calculation to convert your estimate of total wet weight to total dry weight