4.3.1. Microclimatic conditions and forest fires

Rainforests continually transpire large amounts of water which then, in turn precipitate as rain. Both the evaporation process and the produced clouds reduce the temperature on the surface. Once the forest is logged, both the rainfall and evaporation are reduced, leading to a drier and hotter local climate (Houghton, 1995; Hurst, 1990). The humidity of the plantations is not comparable to that of the natural rainforests. They are less able to retain moisture, and the local microclimate often dries and heats up once a natural forest is replaced by a plantation. This phenomenon has also been observed in Riau as the pulp and oil palm plantations have expanded. The previously wooded and practically constantly clouded central part of Riau is nowadays largely forest- and cloud-free (interviews in Riau, WALHI et al., 1992).

As the microclimate changes, the risk of forest fires grows. APRIL has according to its own statements not been burning any forests to make way for its plantations since 1994 (SGS, 1998). Despite this, forest fires have been raging in its plantations, precisely because of the greater risk of fires in and in the vicinity of the dry plantations (Helsingin Sanomat, Oct. 24, 1997). The drying of swamps to make way for the plantations increases the likelihood of peat fires, which are very difficult to extinguish.