Most projects combined aquatic and terrestrial systems in a single category, thus the high rankings are somewhat reflective of a fairly broad issue. But specific rationales indicate a strong tendency for project participants to surmise significantly high impacts to terrestrial ecosystems even in the absence of supporting information. Typically, comparative ecological risk assessments focus on describing a set of ecosystem types and identifying major sources of stressors for each. A discussion of the potential effects of various stressors upon each ecosystem type along with some sense of the resiliency of that ecosystem provides the bulk of the information. For each zone, relevant stressors such as grazing, agriculture, highways, timber management, and urbanization were discussed in terms of effects on these specific ecosystem types.
Quantitative information describing the extent of habitat alteration is scarce.
Trends in forest acreage, type, and wood sales are typically available. In Maine, total acres harvested for pulp and timber had increased from 260,562 in the mid-80s to 437,292 in 1992. Data describing development pressures is reported less often. Vermont's sandplain ecosystem has lost all but less than 400 acres to lakeshore development. Total miles of roads or roads per square mile are sometimes provided as an index of habitat fragmentation, but data describing other agents of fragmentation such as utility corridors or vacation home development are not reported.