Effects of over-deforestation

Forests can provide a natural barrier to disasters such as over-flowing rivers. In China, authorities have admitted that excessive felling could have led to the worst case of flooding seen there in 1998. This has resulted in a ban on logging in eastern Tibet and an emphasis placed on re-forestation. Bangladesh has seen similar loss of forests and resulting floods too, for example.
The huge forest fires in the Amazon earlier in March, 1998 had already added a lot of Carbon Dioxide to the atmosphere, months before the "burning season".
The massive fires in Indonesia that caused enormous pollution and breathing-related illnesses even as far away as Singapore in 1998 and had still been causing problems at least into the middle of 1999. In East Kalimantan (formerly Borneo) the Dayak people who have had to endure these burning forests, believed to be started by large timber businesses, have seen an ecological disaster that has led to starvation and deaths, as reported by a documentary on the politics involved that were related to the environmental issues in that region. This shorter report from the International Development Research Center in Canada has some additional information as well.
Forests are vital parts of many ecosystems. Ensuring a healthy ecosystem that includes forests also means sustainable preservation of other species that dwell in forests. As part of a living system, forests rely on these various species, and the various species rely on forests. For more about the importance of such biodiversity, go to this web site's section on Biodiversity.