Chapter 26: Community Ecology
Concepts:
community
same place/time
must have boundaries in both^
some change
some remain the same
studying comm. ecology
decreases damage during habitat loss
we want low impact on other organisms
comm. restoration projects
Diversity:
mult. species in a comm.
some more than others
checklist to count species
comm.eco. focuses on certain species
so full checklist not required
diversity of growth forms may be the focus:
presence
relative abundance of:
absence
shrubs
herbs
trees
or of:
annuals
ephemerals
perennials
Diversity of Scale:
scale matters
large areas=more diversity
species-area relationship
S=cAz
S=number of species
A=area
c and z are constants
discovered by studying indiv. spec.
Robert Whittaker
proposed studying diversity @ diff scales
Beta diversity
Gamma diversity
Alpha diversity
spec. abundance distribution
plots abundance of spec. in each class
diversity varies w/latitude
geological and geographical diff. also contribute
evolutionary history also contributes
until 50 mya, most of earth was tropics
Predator-Prey Interactions
simplest system:
2pops can cycle up/dowb
pred's functional response:
prey-dependent
Lotka-Volterra model:
dN/dt=rN-aNP
constant conds. are straight lines
both zero growth isoclines on graph
important relationship
Rosenzeig MacArthur model
more factors than LV model
paradox of enrichment
fixed effort harvesting
or fixed quota harvesting
Competition
several species compete for same resources
exploitation competition
interference competition
invasive competition
Metapopulations
crucial in conservation bio
has 4 assumptions
quality of patches differ