COMPARING SPATIAL PATTERN IN UNALTERED OLD-GROWTH AND DISTURBED FOREST LANDSCAPES

We used geographic information systems (GIS) to analyze the structure of a second-growth forest landscape (9600 ha) that contains scattered old-growth patches. We compared this landscape to a nearby, unaltered old-growth landscape on comparable land forms and soils to assess the effects of human activity on forest spatial pattern. Our objective is to determine if characteristic landscape structural patterns distingui sh the primary old-growth forest landscape from the disturbed landscap e. Characteristic patterns of old-growth landscape structure would be useful in enhancing and restoring old-growth ecosystem functioning in managed landscapes. Our natural old-growth landscape is still dominate d by the original forest cover of eastern hemlock (Tsuga canadensis), sugar maple (Acer saccharum), and yellow birch (Betula allegheniensis) . The disturbed landscape has only scattered, remnant patches of old-g rowth ecosystems among a greater number of early successional hardwood and conifer forest types. Human disturbances can either increase or d ecrease landscape heterogeneity depending on the parameter and spatial scale examined. In this study, we found that a number of important st ructural features of the intact old-growth landscape do not occur in t he disturbed landscape. The disturbed landscape has significantly more small forest patches and fewer large, matrix patches than the intact landscape. Forest patches in the fragmented landscape are significantl y simpler in shape (lower fractal dimension, D) than in the intact old -growth landscape. Change in fractal dimension with patch size, a rela tionship that may be characteristic of differing processes of patch fo rmation at different scales, is present within the intact landscape bu t has been obscured by human activity in the disturbed landscape. Impo rtant ecosystem juxtapositions of the old-growth landscape, such as he mlock with lowland conifers, have been lost in the disturbed landscape . In addition, significant landscape heterogeneity in this glaciated r egion is produced by landforms alone, without natural or human disturb ances. The features that distinguish disturbed and old-growth forest l andscape structure that we have described need to be examined elsewher e to determine if such features are characteristic of other landscapes and regions. Such forest landscape structural differences that exist more broadly could form the basis of landscape principles to be applie d both to the restoration of old-growth forest landscapes and the modi fication of general forest management for enhancing biodiversity. Thes e principles may be particularly useful for constructing integrated la ndscapes managed for both commodity production and biodiversity protec tion.