InteRnAtIOnAl ReSeARCh tO MOnItOR SUStAInABle FOReSt SPAtIAl PAtteRnS

“Fragmentation of forest types” is an indicator of biological diversity in the Montréal Process. In the 2003 U.S. National Assessment, the indicator was interpreted as the extent to which forests are distributed as large blocks of habitat. It was assessed by measuring patch size, amount of edge, interpatch distance, and patch contrast on land-cover maps derived from satellite imagery. Although the available data permitted a good characterization of the four metrics at continental scale, it is too early to prove the relationships between those metrics and actual biological diversity. Instead, attention should be focused on improving the conceptual model that links forest spatial patterns to biological diversity and on testing alternate metrics in that framework. IntROdUCtIOn The Montréal Process is a framework for reporting forest sustainability indicators for 12 countries comprising 90 percent of the world’s temperate and boreal forest area (MPLO 1995). The framework includes nine criteria addressing a variety of concerns that society has about forests and 67 indicators that measure specific aspects of those criteria. Nine indicators of genetic, species, and ecosystem diversity address the biodiversity criterion, and fragmentation of forest types is one of the indicators of ecosystem diversity. The United States is committed to periodic reporting of these indicators for the Montréal Process, and the U.S. 2003 National Report on Sustainable Forests (Darr 2004, USDA Forest Service 2004) is the first full report. The implementation of the fragmentation indicator for the U.S. 2003 report is reviewed in this paper with a view towards discussion of alternatives and recommendations to improve future reports. Together with the Sustainable Forest Data Working Group of the Federal Geographic Data Committee, the Roundtable on Sustainable Forests convened public and expert workshops to reach agreement on how to evaluate sustainability (USDA Forest Service 2004). The Roundtable evaluated the data and information requirements for assessing forest fragmentation and made recommendations that were the point of departure for the research described in this paper. The group recommended data sources, metrics of fragmentation, and a reporting framework (table 1). The conceptual model focused on the characteristics of unbroken or intact forest land and viewed fragmentation as a measure of habitat quality and, thus, as an indirect measure of biodiversity. The Roundtable recognized many limitations to the recommended approach including: • The approach describes forest fragmentation, not forest-type fragmentation. • The metrics do not recognize movement corridors. • The approach does not distinguish natural from anthropogenic fragmentation. • The interpretation depends on the context to understand the implication of observed fragmentation. • There are no standards or baselines for comparisons. 1 USDA Forest Service, Southern Research Station, Research Triangle Park, NC 27709.