The Natural Imperative for Biological Conservation

To contribute significantly to environmnentalpolicy of the next century, conservationists wi.ll need to reach a consensus on their fundamental values and goals and to persuade society to adopt tbem. Resolu- tion of the debate over the continued role of naturalness as a guiding concept bas imnportant implications for how conservation is practiced and the future of the discipline. I examine five aspects of naturalness in the context of biological conservation: (1) its utility, (2) its assessment, (3) its relation to values and ethics, (4) al- ternative imperatives,, and (5) implications of adopting it as a guiding concept. Naturalness can be viewed as a continuous gradient with comnpletely natural and completely artificial extremes. Human actions are unnat- ural to the extent that they rely on technology to transform natural ecosystems. The ecological consequences of technological transformnation often overwhelm the capacity of other biota to adapt and are a root cause of biodiversity loss. The naturalness of most ecosystems or ecosystem alterations can be assessed objectively de- spite imperfect knowledge if evolutionary limits and natural ranges of variability are carefaully considered. Most conservationists value naturally evolved biotic elements such as genomes and communities over artifi- cial elements. This judgment, which is not shared by society at large, is based on intrinsic and instrumental