Comparing spatial pattern in unaltered old-growth and disturbed forest landscapes

Used geographic information systems to analyze the structure of a second-growth forest landscape (9600 ha) in Michigan and Wisconsin, that contains scattered old-growth patches, and compared this landscape to a nearby, unaltered old-growth landscape on comparable landforms and soils to assess the effects of human activity on forest spatial pattern. The natural old-growth landscape is dominated by the original forest cover of eastern hemlock Tsuga canadensis, sugar maple Acer saccharum and yellow birch Betula alleghaniensis. The disturbed landscape has only scattered, remnant patches of old-growth ecosystems among a greater number of early successional hardwood and conifer forest types. 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 significantly simpler in shape (lower fractal dimension, D) than in the intact old-growth landscape. Change in fractal dimension with patch size, a relationship that may be characteristics of differing processes of patch formation at different scales, is present within the intact landscape but has been obscured by human activity in the disturbed landscape. Important ecosystem juxtapositions of the old-growth landscape, such as hemlock with lowland conifers, have been lost in the disturbed landscape. Significant landscape heterogeneity in this glaciated region is produced by landforms alone, without natural or human disturbances. -from Authors