The forests of presettlement New England, USA: spatial and compositional patterns based on town proprietor surveys

Aim This study uses the combination of presettlement tree surveys and spatial analysis to produce an empirical reconstruction of tree species abundance and vegetation units at different scales in the original landscape. Location The New England study area extends across eight physiographic sections, from the Appalachian Mountains to the Atlantic Coastal Plain. The data are drawn from 389 original towns in what are now seven states in the north-eastern United States. These towns have early land division records which document the witness trees growing in the town before European settlement (c. seventeenth to eighteenth century AD). Methods Records of witness trees from presettlement surveys were collated from towns throughout the study area (1.3 x 10(5) km(2)). Tree abundance was averaged over town-wide samples of multiple forest types, integrating proportions of taxa at a local scale (10(2) km(2)). These data were summarized into genus groups over the sample towns, which were then mapped [geographical information system (GIS)], classified (Cluster Analysis) and ordinated [detrended correspondence analysis (DCA)]. Modern climatic and topographic variables were also derived from GIS analyses for each town and all town attributes were quantitatively compared. Distributions of both individual species and vegetation units were analysed and displayed for spatial analysis of vegetation structure. Results The tally of 153,932 individual tree citations show a dominant latitudinal trend in the vegetation. Spatial patterns are concisely displayed as pie charts of genus composition arrayed on sampled towns. Detailed interpolated frequency surfaces show spatial patterns of range and abundance of the dominant taxa. Oak, spruce, hickory and chestnut reach distinctive range limits within the study area. Eight vegetation clusters are distinguished. The northern vegetation is a continuous geographical sequence typified by beech while the southern vegetation is an amorphous group typified by oak. Main conclusions The wealth of information recorded in the New England town presettlement surveys is an ideal data base to elucidate the natural patterns of vegetation over an extensive spatial area. The timing, town-wide scale, expansive coverage, quantitative enumeration and unbiased estimates are critical advantages of proprietor lotting surveys in determining original tree distributions. This historical-geographical approach produces a vivid reconstruction of the natural vegetation and species distributions as portrayed on maps. The spatial, vegetational and environmental patterns all demonstrate a distinct 'tension zone' separating 'northern hardwood' and 'central hardwood' towns. The presettlement northern hardwood forests, absolutely dominated by beech, forms a continuum responding to a complex climatic gradient of altitude and latitude. The oak forests to the south are distinguished by non-zonal units, probably affected by fire. Although at the continental scale, the forests seem to be a broad transition, at a finer scale they respond to topography such as the major valleys or the northern mountains. This study resets some preconceptions about the original forest, such as the overestimation of the role of pine, hemlock and chestnut and the underestimation of the distinctiveness of the tension zone. Most importantly, the forests of the past and their empirical description provide a basis for many ecological, educational and management applications today.