Leaves become smaller and thorns or spines more frequent. At the drier extremes of this gradient, succulents become common. Tropical Semi-evergreen Forests. These are broadleaf forests, some species of which are evergreen and some of which are deciduous. There are many fewer tree species than in the rainforests, but still many lianas.
Epiphytes are infrequent.
The seasonal leaf fall produces abundant nutrients and more fertile soils than found under tropical broadleaf evergreen forests but also creates fuel for fires. The fire factor in the environment may explain the thicker bark of tree species in this formation compared to those of the rainforest. Some researchers consider teak woodlands to be a fire subclimax. Tropical Deciduous Broadleaf Forests or Dry Forests. This forest type occurs where two of the dry season months receive less than 1 inch of rain.