ecology and human influences

population

number of organisms of one species living in same habitat

community

all organisms belonging to different species living in same habitat

habitat

place where an organism lives

ecosystem

a self supporting system that includes all living organisms

abiotic factors

non living

temperature or rainfall

biotic factor

living

competition for food/light

biodiversity

measure of the variety of living organisms in an area

transects

used to look at how distribution changes across habitat

ecology

study of the interaction of the organisms in an ecosystem with their environment

decomposers

organisms that break down dead or decaying material

nitrogen fixing bacteria

nitrogen gas - nitrogen compounds

nitrifying bacteria

ammonium ions - nitrates

denitrifying bacteria

nitrates - nitrogen gas

decomposers

proteins/urea - ammonium ions

lightning

so much energy it can make nitrogen react with oxygen to form nitrates

greenhouse gas effect

short wave radiation from sun strikes planet

some is absorbed and some re-emitted as long wave radiation

greenhouse gases absorb then trap some long wave radiation.

pesticides

fast acting

kills pests

less crops eaten

not specific

need to reapply

affects food chains

bioaccumulation

pests might become resistant

biological control

long lasting

specific

no bioaccumulation

might become pests itself

unknown consequences on food chain