For 232 1st Edition Lecture 15Outline of Last Lecture I. Stable populations II. Competition III. Lotka-Volterra ModelIV. Competition for different resources V. Availability affects behaviorVI. NicheOutline of Current Lecture: Community Structure and DynamicsI. CommunityII. Horizontal structural diversityIII. SuccessionCurrent LectureI. Communitya. The combination of species present and interacting at a place (directly and indirectly)b. The collection of plants and animals present at a place and that affect each otherc. Guild: species using habitat and food resources in a similar manner. A term usually applied to animal life (often bird species)d. Association: a plant community having a specific mix of species. Giving them a particular biologic and physical structuree. A stand in ecology: a contiguous group of similar plantsi. In forestry: a contiguous group of trees (and other plants) sufficiently similar in age arrangement, species composition, community structure and location to distinguish it from adjacent communitiesii. And in silviculture we recognize three different kinds of standsf. Consider an even-aged stand with all trees of the same age. Aging with a clear pattern of development through time within a single standi. But with many trees in each stand, the stand-wide aging will look like steps (older = bigger, younger= smaller)ii. With different stands across a forest developing similarly but not all stands necessarily the same ageThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.iii. Uneven-aged (trees with at least three distinct ages, multiple cohorts growing together) multiple ages together, intermixed at the same place. Eventually the oldest ones will die and be replaced by new ones.g. Structure: physical structure based on abiotic features (precipitation, temperature, seasons, etc. soil, objects like rocks, hoes, surface water)h. Biologic structure: based largely on plant community characteristics (density, size, and height of plants, dead materials like snags, fallen trees, forest floor organic layer)i. Two basic kinds of stand-level structure:i. Vertical Structural Diversity (VSD); the dispersion of living ranches from the round to the top of the tallest treesii. Diversity along a vertical plane (foliage and primary production at multiple layers)iii. Primary production (energy fixation) in the green leaves and regenerationand decomposition at or near the forest flooriv. Macro-scale vertical structure and micro-scale vertical structurej. In general, the greater the vertical stratification in the plant community the morediverse the animal life in it. The more stratifies the abiotic structure the more habitats for additional creatures. Different species feed and operate in different canopy layer but some plant communities have limited vertical structure.k. That difference affects the diversity of avian species using a site, as well as the herbivores that require short plants for feeding and cover.II. Horizontal structural diversitya. The spatial distribution and degree of interspersion of stands having different VSD across space and usually at the multi-stand levelb. Largely based on differences in plant associations from one place to another across the landscape c. Providing structural diversity on a horizontal planed. Commonly associated with an interspersion of even-aged stands at different stages of development and intermixed across the landscape e. With different species benefiting from each unique habitat but likely arranged in different patterns across space f. We can have a high degree of HSD with a mix of even- and uneven-aged communities. Induced patchiness based on a pattern that satisfies the management objectives. Several factors affect unmanaged patchiness in a “natural” landscape not altered by management. Other factors also influence community composition and structure:i. Competitionii. Predationiii. Parasitism and diseaseiv. Mutualismg. Habitat Quality (HQ)i. HQ= f(FOOD+ cover+water+space)*ii. Food-webs: resulting in an energy flow through different trophic levels with a loss/reduction at each step in the food chainiii. All dependent on the amount of energy fixed into biomass by the plant community and limited by that available. With a dramatic reduction in energy passed from on trophic level to the next.iv. So the character of a community and abundance of different component species ultimately tied to primary net production in the associated plant community.v. Consider plant associations and the linkage to gradients of the physical environment (moisture, temp, and light) often aligned along a topographic gradient.vi. Overall vegetation patterns reflect variations of the physical environmentvii. Mountain tops with an environment of key limiting factors may lack treesh. Zonation: the spatial variation in community structure and composition along an environmental gradientIII. Successiona. The change in community structure and composition through time at a specific place on Earthb. Due to a shift of environmental conditions as a result of changing effects by an existing plant community as it matures and develops and though largely attributed to the plant community. As plant community changes so does the associated animal association. Longevity of component species or due to different growth patterns and life spans. c. In any landscape, areas may have vegetation at early, middle or late seral stage:i. a stage in the progression of plant community succession, conceptually from primary through secondary and eventually to a climax stage. Assuming that no natural or induced disturbance resets development to an earlier or later seral stage.d. With landscape ecology concepts suggesting that in dynamic landscapes, the vegetation should include multiple seral stages, insuring diversity at multiple scales.i. With variation in the animal community related to the vegetation structure at different places.e. Succession also occurred at ecologic time scales as with paleosuccession:i. Triggered by major events like glaciation, earthquakes, drought, floods and just time as seen in the pollen