Natural vegetation varies from place to place. Why do evergreen trees grow…

Natural vegetation type in a region is governed chiefly by climate — the combination of temperature and rainfall pattern through the year. Evergreen (tropical rainforest) vegetation needs consistently high temperature and abundant, well-distributed rainfall throughout the year, so trees never face a dry or cold season that would force them to shed their leaves.

Equatorial regions lie close to the equator, so they receive almost vertical sun rays all year, keeping temperatures high with little seasonal variation. Convectional rainfall occurs on most days of the year, giving very heavy annual rainfall spread evenly across the year rather than concentrated in one short season.

Because there is no dry season, the trees retain their leaves throughout the year and stay green — this is why evergreen tropical forests are found near the equator. The climate pairing that produces this is heavy rainfall together with high temperature.

• Moderate temperature and moderate rainfall describes temperate or monsoon climates with a distinct dry spell, which forces seasonal leaf shedding — not year-round evergreen growth.

• Low rainfall and high temperature describes hot desert or semi-arid climates, which support thorny scrub and drought-resistant plants, not lush evergreen forest.

• Moderate rainfall and low temperature describes cooler temperate or highland climates, which support deciduous or coniferous vegetation, not equatorial evergreen forest.