Part 5, p. 319 - Organization of Communities

Chapter 15, p. 321 - Ecological Concept of Communiites

Originated with studies of plant communities during which time many plants were being classifed and scientifically named; therefore, taxonomy is an important aspect of community ecological studies. These studies provided the foundation of plant taxonomy, plant ecological studies, and community ecological studies.

Parts of a community

• Trophic levels (feeding levels) - complex, inclusive levels of orgainiation with in communities and ecosystems which include:
1. Nutrient cycling (material or nutrient cycles) - recycling of material components of communiites and ecosystems
2. Energy flows - pathways of energy exchange from one trophic level to another with loss of energy in the form of heat; therefore, the amount of available energy for each successive trophic level is less than the amount available to the previous one; results in a food pyramid (over-simplified model of illustrating this loss of energy from one level to the next); examples of specific trophic levels include:
1. Primary producers - autotrophs - organisms that use an inorganic, abiotic, and sometimes, non-chemical form of energy as their primary source.
• Photoautotrophs - photosynthetic organisms; unicellular and multicellular algae of the protist kingdom and chlorophyll-containing plants; derive energy from light; convert light energy into chemical bond energy.
• Lithoautotrophs - lithotrophic organisms (lithos - stone) - derive energy from the oxidation of reduced inorganic compounds, such as NH4.
2. Primary consumers - herbivores
3. Secondary consumers - predators of herbivores
4. Tertiary consumers - predators of secondary consumers
5. Decomposers - end of the food chain - organisms that live by feeding on non-living organic mater (waste and or dead organisms); sometimes called detritus feeders or scavengers; include microorganisms such as bacteria, protozoa, fungi, and certain animals.
• Guild - a group of spp. with in a communitiy which have the same, or very similar, niches (i.e. make a living in the same way; obtain and utilize resources in the same way); less inclusive than trophic levels; examples include:
1. birds that feed on insects from leaves and branches vs.
2. those that catch insects in while in flight vs.
3. seed-eating birds.

Chapter 16, p. 326 - Food-limited guilds: coexistence and niches

1. Niche - the role that an organism plays with in its community or ecosystem; how it utilizes resources, especially with regard to limited resources.
2. Food-limited guild - part of a community that is composed of collections of spp. that compete with one another for food (usually a limited amount or type of food).
3. Coexistence - use of either different resources with in a community by 2 different organisms or use of the same resource in a different way.
4. Resource partitioning - specific mechanisms for using different types of limited resources by tow or more spp. with in a given community; such mechanisms result in complex a pattern of trophism (food web) due to the interaction of several specialized, adapted groups of organisms with in communities.

Chapter 18, p. 360 - Aquatic and terrestrial communities

1. Aquatic:
1. Marine - sea water, salt water, oceanic communities
1. coral reefs - occur in all tropical oceans; have an abundance of life and are the most complex of all ecosystems in the entire biosphere; examples include:
1. The Great Barrier Reef on the northeast coast of Australia - many spp. of marine invertebrates and various types of fish communities in coexistence.
2. Caribbean reefs - have a lower degree of diversity consisting of only a few spp. of invertebrates and fish among the stony corals.
2. Guilds with in coral reef communities:
1. Size-structured guilds - resource partitioning forms the basis for coexistence; depends upon the amount of available resources. The size of the organisms (specifically the reef fish) varies greatly with in each given spp. resulting in many diverse subspp. with in each sp..
2. Space-limited guilds - determined by the amount of substrates (places to live) available; characterized by small amount of limited space, thus resulting in less diversity with in given spp. and fewer numbers of subspp..
3. Tide pools - collections of marine populations due to the activities of tides; consist of many sessile invertebrates suited to changing conditions as well as other associated marine organisms.
4. Marine infaunal communities - most widespread of marine community types; classified by type of substrate and / or type of organisms making up the communities; consist of organisms living in the soft sediments (sand and mud) of benthic (bottom) habitats, coastal soft sediment habitats, sandy beaches, salt marshes, and river deltas. Types of organisms include:
1. suspension feeders - extract particles of food from the water; also called filter feeders; e.g. clams
2. Deposit feeders - eat particles of sediment and assimilate the bacterial and other microorganisms that coat the particles; e.g. snails
3. sessile - immoble; attached to substrate; e.g. hydra, sponges, corals, and many other invertebrates
4. sedentary - build and live in tubes of sediment; e.g. certain types of worms
5. burrowers - live in sediments, but do not build tubes to live in; e.g. certain clams, crabs and other crustacea, sea cucumbers, and various worms
5. Plankton guilds - microscopic uni- and multicellular pro- and eukaryotic organisms of various types:
1. phytoplankton - unicellular algae - include the free-living members of the genus Euglena, colonial Volvox spp., and the unicellular green algae Chlamydomonas spp.; also certain spp. of small multicellular red, brown, and green algae are included.
2. zooplankton - unicellular, animal-like eukaryotes - protozoa, such as Paramecium caudatum and Ameoba spp.; also certain spp. of small invertebrates, such as the crustacean water flea, Daphnia spp..
6. Amphibian communities - occupy the interface between terrestrial and aquatic communities; include permenant and temporary bodies of water; usually fresh water, but some marine ones exist.
2. Freshwater communities - include some of the same types of communities and guilds as marine systems except no coral reefs
1. Freshwater infaunal communities
2. Freshwater plankton guilds - consist of same general types of organisms as for marine communities except for certain spp. differences regarding certain algae and invertebrates.
3. Freshwater amphibian communities - more abundant than marine ones.
3. Terrestrial plant communities