Geoscience Reference
In-Depth Information
Figure 4.7 Dense understory can be common in tropical deciduous forests where the
canopy opens seasonally, as shown here in Guanacaste, Costa Rica.
(Photo by author.)
pollinated by insects, or are located on drier sites, where moisture stress may in-
hibit flower initiation.
Seasonal forests are distinctive in the number of conspicuous flowers that have
specialized pollinators such as hawk moths, bats, birds, and large- and medium-
size bees. Although many of the plants in the seasonal forest are pollinated by ani-
mals, about one-third of all trees and 80 percent of lianas seeds are wind dispersed.
In the rainforest, the majority of seeds are dispersed by animals.
Cauliflory is seen in trees of tropical seasonal forests. Cauliflory is the production
of flowers and fruits on leafless trunks, rather than on twigs or smaller branches.
Many trees in the seasonal forest flower (and later fruit) on very short leafless stems,
or they develop flowers directly on the trunk or large branches. The flowers of cau-
liflorous trees are often pollinated by birds and bats. Their fruits are consumed by
larger animals that may be unable to reach fruit in the canopy. These trees need these
animals for the dispersal and germination of their seeds. Fig trees are an example of
a common cauliflorous tree found throughout the Tropical Seasonal Forest Biome.
With increasing duration of the dry season and increasing latitude, seasonal for-
ests move from deciduous to dry evergreen forests. With this change, the number
of plants using a crassulacean acid metabolism (CAM) photosynthesis as a strategy
for photosynthesis increases.
Underground biomass is higher in seasonal forests than rainforests. Roots are
thought to be more extensive and deeper as an adaptation for storing and retrieving
