30 terms

Chapter 8: Community Ecology: Structure, Species Interactions, Succession, and Sustainability

edge effects
differences in the physical structure and physical properties at boundaries and in transition zones between two ecosystems
species equilibrium model (theory of island biogeography)
explains the differences in species diversity with island size
native species
species that normally live and thrive in a particular ecosystem
nonnative species (exotic species or alien species)
species that migrate into an ecosystem or are deliberately or accidentally introduced into an ecosystem by humans
indicator species
species that serve as early warnings of damage to a community or an ecosystem
keystone species
species whose roles in an ecosystem are much more important than their abundance or biomass suggests
intraspecific competition
competition between members of the same species for the same resources
process in which organisms patrol or mark an area around their home, nesting, or major feeding site and defend it against members of their own species
interspecific competition
competition between members of two or more different species for food, space, or any other limited resource
interference competition
one species may limit another's access to some resource, regardless or abundance, using the same type of methods found in intraspecific competition
exploitation competition
competing species have roughly equal access to a specific resource but differ in how fast or efficiently they exploit it
resource partitioning
the dividing up of scarce resources so that species with similar needs use them at different times, in different ways, or in different places
members of one species feed directly on all or part of a living organism of another species
predator-prey relationship
interaction between two organisms of different species in which one organism (predator) captures and feeds on parts or all of another organism (prey)
a relationship in which species live together in an intimate association
occurs when one species feeds on part of another organism by living on or in the host (symbiotic relationship where the host is harmed)
two species involved in a symbiotic relationship interact in ways that benefit both
a symbiotic interaction that benefits one species but neither harms nor helps the other species much, if at all
ecological succession
gradual change in species composition of a given area
primary succession
involves the gradual establishment of biotic communities on nearly lifeless ground
secondary succession
involves the reestablishment of biotic communities in an area where some type of biotic community is already present
pioneer species
first hardy species that begin colonizing a site as the first stage of ecological successtion
early successional plant species
plant species found in the early stages of succession that grow close to the ground, can establish large populations quickly under harsh conditions, and have short lives
midsuccessional plant species
grasses and low shrubs that are less hardy than early successional plant species
late successional plant species
mostly trees that can tolerate shade and form a fairly stable complex forest community
a change in environmental conditions that disrupts an ecosystem or community
inertia (persistence)
ability of a living system to resist being disturbed or altered
ability of a living system such as a population to keep its numbers within the limits imposed by available resources
ability of a living system to bounce back after an external disturbance that is not too drastic
precautionary principle
when evidence indicates that an activity can harm human health or the environment, we should take precautionary measures to prevent harm even if some of the cause-and-effect relationships have not been fully established significantly