Wetenschap - 22 februari 1996

Monkeys help with forestation

Monkeys help with forestation

In the Amazonian rainforest 76% of the commercially interesting tree species is reproduced through seed dispersal by animals. It turns out that primates, especially the black spider monkey, are the most important animal forest rangers; birds come off second best. Monday 12 February, David Koning and Miriam Spierings presented the results of their thesis research at the Department of Forestry. Both students studied the importance of seed dispersal by animals for the sustainable production of timber in the Brazilian province of Amazonas. A Swiss-Brazilian company working in that region uses the Celos silvicultural system for the management and domestication of tropical rainforest. Essential to this system is that, after felling, reforestation occurs in a natural way, and not by planting new trees. The Celos system consists of a set of management measures and criteria for prospecting, selection and felling of commercial tree species. The distribution and density of commercial and
non-commercial trees is mapped and put in a computer. Deciding which trees to fell is a very selective procedure. Not only size and species matter, it also is important that the density of the remaining forest does not fall below a minimum level. Since animals play an important role in seed dispersal, and consequently in sustaining the forest, the environment must also be kept suitable for them to be able to live there.

Koning and Spierings composed a fruiting calendar based on both literature and a pilot study, in order to determine whether enough food would be available all year round. A change in composition of tree species will inevitably change the primate's diet. Future research will indicate whether the animals can appreciate new menus.

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