Plant ecology is a subdiscipline of ecology. There are three main parts: (1) the distribution and abundance of plants, the effects of environmental factors upon the abundance of plants, and (3) the interactions among and between members of plant species in particular and other organisms in general. An example of the first might be the study of the distribution of temperate deciduous forests in North America. An example of the second might be the effects of drought or flooding upon plant survivial. Examples of the third might included competition among desert plants for water, or effects of herds of grazing animals upon the composition of grasslands.

A global overview of the Earth's major vegetation types is provided by O.W. Archibold He recognizes 11 major vegetation types: tropical forests, tropical savnnas, arid regions (deserts), Mediterranean ecosystems, temperate forest ecosystems, temperate grasslands, coniferous forests, tundra (both polar and high mountain), terrestrial wetlands, freshwater ecosystems and coastal/marine systems. This breadth of topics shows the complexity of plant ecology, since it includes plants from floating single-celled algae up to large canopy forming trees.