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Succession

The succession pattern of tropical lowland forests. Adapted from Miyawaki (1991)

Succession is the process in which the plant community changes over time. A forest goes through several stages where different plants become established and in turn change the environment of the forest. Note that this isn’t straightforward process, each stage can have many different species of plants and a very high number of possible combinations of species. Sometimes it can even move in reverse due to disease, fire or human disturbance. However, understanding the succession process can help in choosing the planting strategies.

Fig 2: Early succession annual herb dominated community

From bare ground, small herbs and shrubs are the first to establish themselves. These plants help to build up organic material in the soil and change the soil from a bacterial dominated community to a fungal one. Shade intolerant trees and plants that can survive in areas with high heat and unstable microclimates begin to take over in the following stage of succession. Once these trees become large enough to produce shady environments, forest species start to establish themselves.

Fig 4: Young shade-intolerant trees.

Old agricultural trees like rubber can create shade and allow shade tolerant forest trees to grow. This allows some of these areas to skip the shrubby community and shade intolerant stages of succession, but generally these agroforests have less diversity than natural forests due to isolation (native tree seeds cannot reach these forests) and competition from the existing population of agricultural trees. Replanting these areas with forest trees may help to restore the plant diversity while taking advantage of the more stable shaded environments created by existing trees.