Monday, March 23, 2015

Vegetation

-Mostly deciduous tree species. Many evergreen tree species of the rain forest become deciduous in this zone. 
-Growing conditions are not so optimal, so the tree canopy is lower (10-30m) than in the tropical rain forest and the trees less dense where drought is more extreme. 
-The undergrowth is dense and tangled because of greater light penetration. 
-Lianas (woody vines) are much less common than in the rain forest, not such an important growth form where light is less limiting and also perhaps highly susceptible to desiccation. 
-Drought-resistant epiphytes (orchids, bromeliads and cacti) may be abundant. 
-The trees have thicker, more ridged, bark; deeper roots without buttresses; much more variable leaves, including many compound-leaved legumes; and more species with thorns.


Climate

Temperatures are high all year, but there is a better-developed dry season than in the tropical rain forest. Evapotranspiration exceeds precipitation for enough of the year to have a significant effect on the vegetation. Edaphic conditions (dryer, better-drained soil) may produce this vegetation type in this biome.