|Forests, Climate, and Hydrology: Regional Impacts (UNU, 1988, 217 pages)|
It is evident that there is a tendency to resort to overstatement and unbalanced reporting when presenting scientific theories and findings to the public through the media. The same can be true even of the scientist eager to impress the holders of the purse strings of research funds. The objective is to grasp the attention of the audience and make it so concerned about the matter that action is taken. Sooner or later the balance has to be restored by painstaking research and dissemination of the facts. Unfortunately, the earlier misinformation is often very difficult to dislodge.
This is the case with our subject. The informed public and the influential politician are convinced that felling or planting trees has a significant effect on the climate over a large area, if not globally Consequently, decisions to increase or decrease forest cover are supposed to implicate continental, or even world-wide, changes of climate. Indeed, it is only a small step to suppose that afforestation can be employed to ameliorate regional climate or that extensive deforestation will reduce rainfall at places far removed from the felling axe.
Claims that the global climate can be protected by a policy of forest conservation have become wedded to legitimate cases for conservation of the forest fauna and flora and the control of erosion and flooding by maintaining forest areas. Proper conservation arguments are pertinent to the world's remaining tropical rain forests and the scene for this is presented in chapter 2. In terms of climatic effects, through evaporation or fixation of atmospheric carbon dioxide, any tall woody vegetation might serve in place of the tropical rain forest. Thus, to distinguish between the effects on climate and other aspects of forest conservation it is important at this stage to establish what constitutes deforestation. An extensive but transient interference with the tree cover can have enormous and permanent effects on such factors as the flora, fauna, and the soil. In contrast, at current rates of forest clearance, unless there is no regrowth of shrubs and trees, the actual area without forest cover at any one time can hardly be expected to cause any climatic change even on a regional scale. The aim of this book is to approach the influence on the regional climate of vegetation change as quantitatively as possible. We hope that it will contribute an awareness of the magnitude of likely regional climatic changes resulting from land use policies.