BIODIVERSITY AND THE NEED FOR HABITAT RENEWAL

The conservation of species requires preservation of natural habitats. Where the integrity of natural habitats has been upset, species go ex tinct. All natural habitats are continuing to decline, both inside and outside of reserves. Habitat change is partly a natural process (e.g. , succession), but human activities have accelerated the process of de cay so that natural rates of renewal are insufficient to maintain natu ral habitats. We argue that our only recourse, in light of these scena rios, is to adopt a new conservation strategy that considers the impor tance of habitat renewal in addition to habitat preservation. Accordin gly, in our management decisions we must not only choose the size of a rea to preserve but also the size of area that balances habitat loss w ith habitat renewal. We also suggest that this habitat equilibrium poi nt, H, needs to be decided upon urgently, otherwise many species will become extinct in the next 50 yr according to numerous predictions. T here are two ways to achieve H. The first is to set habitats aside in protected areas in perpetuity. There are two reasons why this protect ion alone is insufficient: (1) protected areas continue to decline, al beit at a slower rate than outside of their boundaries, and (2) achiev ing H simply by setting aside protected areas is no longer an option in many areas where severe habitat degradation or fragmentation has al ready occurred. The other way to achieve H is to promote the restabli shment of natural habitats, or ''habitat renewal.'' This concept is il lustrated using a simple trade-off model that balances habitat decay a nd habitat renewal. We then provide examples of habitat loss outside a nd inside of protected areas and discuss the potential for habitat ren ewal to offset these losses. We conclude that continued emphasis needs to be placed on setting aside natural habitat in protected areas. How ever, our examples of habitat loss show that this policy alone is most likely doomed to failure, so a policy of habitat renewal is also requ ired.