Multiple scale composition and spatial distribution patterns of the north-eastern Minnesota presettlement forest
S.K. Friedman, Forestry Department 126 Natural Resouces, Michigan State University, East Lansing, Michigan 48823-1312, USA. Tel.: +1 517-355-0092. Fax: +1 517-432-1143.
- 1Bearing tree data were used to characterize the composition and spatial structure of the southern boreal presettlement forest in north-eastern Minnesota, United States of America. Data collected during the General Land Office Survey (GLO) between 1853 and 1917, represents 35 324 samples (each with 1–4 trees) in a 3.2 million-hectare landscape. Nine tree species contributed at least 1% to the overall composition. Individuals of white pine and red pine were larger than all other species and represented 9% of the tree population, while accounting for 27% of the standing basal area. Black spruce, paper birch and larch, the three most abundant species, collectively accounted for 51% of the population and 38% of the basal area.
- 2Eight physiographic zones were characterized by differences in glacial histories, geological surfaces, soil complexes and topographic properties, and supported different compositional mixes of the nine important species.
- 3Fifty-six per cent of all four-tree plots had three or four individuals of a single species. This level of conspecific aggregation is an order of magnitude greater than would be expected based on a random distribution of the same population of trees and species. Jack pine had the greatest plot-scale aggregation, with 45% of all plots containing jack pine trees having three or four jack pine individuals. Jaccard association of similarity values of species co-occurrence ranged from less than 0.05 to 0.24, indicating limited plot–scale interspecific associations.
- 4Landscape spatial patterns of the species were measured at two spatial scales, 1–10 km and from 5 to 50 km. Conspecific autocorrelation patterns were positive while interspecific autocorrelation patterns tended to be either neutral or negative. Hence, plots dominated by any given species tended to spatially aggregate near other such plots, out to substantial distances.
- 5Forest tree spatial patterns reflect complex fine to landscape-scale relationships involving environmental factors, disturbance events and regeneration strategies. Management and long-term conservation of forest landscapes should consider multiscale patterns in order to re-establish forest structural properties eliminated following the disruption of natural disturbance processes.