Biology

Pesticides

Sewage

Industrial wastes

Fertilizers

Crude oil.

Well developed tap root system

Small leaves with thick Epidermis

Stems with spike-like leaves

Metabolic waste in the form of uric acid in some animals

Broad leaves for storage

a stable composition of plant and animal species

rapid changes in the composition of species

constant changes in appearance of the habitat

different species occurring at different times

gradual change in animal population

Population outstripping available space

Population exceeding available food

Competition within the population

increase in primary production

Population increasing at the same rate as the birth rate

predator control

chemical control

biological control

animal control

parasitic control