Terrestrial biomes are categorized by their major plant growth forms. Ecologists use the dominant plant forms to categorize ecosystems into terrestrial biomes because many plants have evolved convergent forms in response to similar climate conditions. Climate and dominant plant forms are similar within biomes.
There are nine categories of terrestrial biomes. The coldest biomes are the tundra and boreal forests. In temperate regions, we can find temperate rainforests, temperate seasonal forests, woodlands/shrublands, and temperate grasslands/cold deserts. In tropical latitudes, the biomes can be categorized as tropical rainforests, tropical seasonal forests/savannas, and subtropical deserts.
Aquatic biomes are categorized by their flow, depth, and salinity. Freshwater biomes include streams and rivers, ponds and lakes, and freshwater wetlands. Saltwater biomes include salt marshes/estuaries, mangrove swamps, intertidal zones, coral reefs, and the open ocean.