Indicators for Monitoring Biodiversity: A Hierarchical Approach

Biodiversity is presently a minor consideration in environmental policy. It has been regarded as too broad and vague a concept to be applied to real-world regulatoy and managernentproblems. This problem can be corrected ifbio- diversity is recognized as an end in itsea and if measurable indicators can be selected to assess the status of biodiversity over time. Biodiversity, as presently understood, encom- passes multiple levels of biological organization. In thispa- per, I expand the three primay attributes of biodiversity recognized by Jerry Franklin - composition, structure, and function - into a nested hierarcby that incorporates ele- ments of each attribute at four levels of organization: re- gional landscape, community-ecosystem, population- species, andgenetic. Indicators of each attribute in terrestrial ecosystems, at the four levels of organization, are identified for environmental monitoring purposes. Projects to monitor biodiversity will benefit from a direct linkage to long-term ecological research and a commitment to test hypotheses relevant to biodiversity conservation. A general guideline is to proceed from the top down, beginning with a coarse-scale invent0 y of landscape pattern, vegetation, habitat structure, and species distributions, then overlaying data on stress lev- els to identiD biologically significant areas at high risk of impoverishment. Intensive research and monitoring can be directed to high-risk ecosystems and elements of biodiversity, while less intensive monitoring is directed to the total land- scape (or samples thereon. In any monitoringprogram, par- ticular attention should be paid to specifying the questions that monitoring is intended to answer and validating the relationships between indicators and the components of bio- diversity they represent