Ecology Final

community

a group of actually or potentially interacting populations living in the same location

taxonomic affinity

method of subdividing communities, describes closely related species (ex. birds, fish, etc.)

guild

way to subdivide communities, a group of species, regardless of their taxonomic position, that exploit the same class of environmental resources in a similar way (ex. obtaining food with a beak); often implies competition for the same resource

functional group

way to subdivide communities, a collection of species that share similar, specific roles, behaviors, or ecological traits within an ecosystem, regardless of their evolutionary relationships (role, ex. filter feeders, nitrogen fixers, herbivores); often don’t share resources but use similar strategies

species richness

total number of species in a particular area

species evenness

the relative abundance of different species, not even = high dominance

species diversity

combines aspects of both species richness and evenness, measured by Shannon-Wiener diversity (H)

Species accumulation curves

help us determine when most or all of the species in a community have

been observed

keystone species

organisms that have a disproportionately large, critical impact on their ecosystem relative to their low abundance or biomass

foundation species

dominant, highly abundant organisms that define, build, and maintain ecosystems by creating habitats that support diverse communities (ex. trees, coral)

ecosystem engineers

any

organism that creates, significantly modifies, maintains or destroys a habitat; they can have a large impact on species richness and landscape-level heterogeneity

of an area (ex. beavers, termites)

biogeography

the study of patterns of species composition and diversity across geographic locations

what does membership in a community depend on?

1. regional species pools and dispersal ability

2. environmental conditions

3. species interactions

what does the regional species pool provide?

an upper limit on the number and types of species that can be present in a community

disturbance

any abiotic physical force that causes mortality or loss of biomass in a community

what does disturbance impact depend on?

• severity

• frequency

• spatial scale

• community resistance and resilience

resistance

the ability of a community or ecosystem to maintain its structure and/or function in the face of disturbance

resilience

the ability and rate of an ecosystem to recover from a disturbance and return to its pre-disturbed state

succession

the non-seasonal, directional and continuous pattern of change in the species found at a site, following a disturbance or biotic agent or the formation of new habitat

pioneer

early community that colonizes new land

climax community

late successional community that remains stable until disrupted by disturbance

hysteresis

an inability to shift back to the original community type, even when original conditions

are restored

alternative stable states

when different communities develop in the same area under similar environmental conditions after disturbance

what is the currency used to measure primary production?

carbon

primary production

the generation of chemical energy by autotrophs

gross primary production (GPP)

total carbon produced by primary producers (total energy fixed by autotrophs)

net primary production (NPP)

carbon accumulated (in stored form) by primary producers (also can be expressed as GPP – RP). Usually ~25-50% of GPP

how is primary production controlled by climate?

through its influence on photosynthetic rate, nutrients, light, mixing (if in water)

net ecosystem exchange (NEE)

exchange of CO2 with the atmosphere

photosynthesis (GPP) - (autotroph respiration (AR) + heterotrophic respiration(HR))

how do plants respond to environmental conditions?

by allocating carbon to the growth of different tissues in effort to maximize primary production and, through that, their fitness.

how is primary production controlled by leaf area index (LAI)?

it regulates light interception and photosynthetic capacity