hrsb
APES Notes – Chapter 8
Community Ecology: Structure, Species Interactions, Succession, and Sustainability
I. Appearance and Species Diversity
A. The structure or spatial distribution of a community or ecosystem can be described by:
a. Physical Appearance : relative sizes, stratification, and distribution of its population and species
b. Species Diversity or Richness : the number of different species
c. Species Abundance : the number of individuals of each species
d. Niche Structure : the number of ecological niches, how they resemble or differ from each other from each other, and how they interact (species interactions)
B. The types, relative sizes, and stratification of plants and animals vary in different terrestrial communities
a. The differences are apparent in the physical structures on oceans, rocky shores and sandy beaches, lakes, river systems, and inland wetlands.
b. Large terrestrial communities, ecosystems, and biomes consist of vegetation patches of differing size, which leads to a combination of fairly sharp edges or boundaries and wider and more diffuse ecotones, or transition zones, between one patch or community and another.
c. Differences in the physical structure and physical properties such as sunlight, temperature, wind, and humidity at boundaries and ecotones are called edge effects.
i. Increased edge area from habitat fragmentation makes many species more vulnerable to stresses such as predators and fire and creates barriers that can prevent some species from colonizing new areas and finding food and mates.
C. Studies show that the most species-rich environments are tropical rain forests, coral reefs, the deep sea, and large tropical lakes.
a. Communities with a large number of species (high species diversity) generally have only a few members of each species (low species abundance)
b. Three major factors affect species diversity:
i. Latitude: Distance from the equator.
1. For most groups of plants and animals,
Community Ecology: Structure, Species Interactions, Succession, and Sustainability
I. Appearance and Species Diversity
A. The structure or spatial distribution of a community or ecosystem can be described by:
a. Physical Appearance : relative sizes, stratification, and distribution of its population and species
b. Species Diversity or Richness : the number of different species
c. Species Abundance : the number of individuals of each species
d. Niche Structure : the number of ecological niches, how they resemble or differ from each other from each other, and how they interact (species interactions)
B. The types, relative sizes, and stratification of plants and animals vary in different terrestrial communities
a. The differences are apparent in the physical structures on oceans, rocky shores and sandy beaches, lakes, river systems, and inland wetlands.
b. Large terrestrial communities, ecosystems, and biomes consist of vegetation patches of differing size, which leads to a combination of fairly sharp edges or boundaries and wider and more diffuse ecotones, or transition zones, between one patch or community and another.
c. Differences in the physical structure and physical properties such as sunlight, temperature, wind, and humidity at boundaries and ecotones are called edge effects.
i. Increased edge area from habitat fragmentation makes many species more vulnerable to stresses such as predators and fire and creates barriers that can prevent some species from colonizing new areas and finding food and mates.
C. Studies show that the most species-rich environments are tropical rain forests, coral reefs, the deep sea, and large tropical lakes.
a. Communities with a large number of species (high species diversity) generally have only a few members of each species (low species abundance)
b. Three major factors affect species diversity:
i. Latitude: Distance from the equator.
1. For most groups of plants and animals,