Infodoc : Sciences, Techniques et Culture

It is not simple to predict how environmental changes may impact tropical forest species diversity. Published hypotheses are almost invariably too incomplete, too poorly specified and too dependent upon unrealistic assumptions to be useful. Ecologists have sought theoretical simplicity, and whiel this has provided many elegant abstract concept, it has hindered the attainment of more practical goals. The problem is not how to judge the individual hypotheses and arguments, but rather how to build upon and combine the many hard-won facts and principales into an integrated science. Controversy is inevitable when the assumption, definitions and applications of a given hypothesis are unclear. Elegance, as an end in itself, has too often been used to justify abstract simplication ans a lack [...]

It is not simple to predict how environmental changes may impact tropical forest species diversity. Published hypotheses are almost invariably too incomplete, too poorly specified and too dependent upon unrealistic assumptions to be useful. Ecologists have sought theoretical simplicity, and whiel this has provided many elegant abstract concept, it has hindered the attainment of more practical goals. The problem is not how to judge the individual hypotheses and arguments, but rather how to build upon and combine the many hard-won facts and principales into an integrated science. Controversy is inevitable when the assumption, definitions and applications of a given hypothesis are unclear. Elegance, as an end in itself, has too often been used to justify abstract simplication ans a lack of operational definition. Clarifying and combining hypotheses while avoiding assumption provides a potentially more useful, if less elegant, stand-point. An appraisal of
Connell's intermediate disturbance hypothesis, and its application to long-term observation from a Ugandan forest illustrates these concerns. Current emphases encourage ecologists to exclude consideration of environmental instability and non pristine ecosystems. In reality, many environmental changes and ecological processes contribute to both the accumulation and erosion of diversity, at all spatial and temporal scales. Site histories, contexts, long-term processes, species pool dynamics, and the role of people require greater emphasis. These consideratiion reveal that many environmental changes, even those associated with degradation, can lead to a transient rise in species densites. Drawing on related studies, such as forest yield prediction, suggests that the formulation and calibration of simulation models provides the most tractable means to address the complexity of real vegetation. Simulation based approaches will become increasingly useful both in
unifying the study of vegetation dynamics and in providing improved predictive capacity. Quantification of the processes, scales and sensitivities of the dynamics of tropical forest communities remains a major challenge.