Effects of postsettlement human activities on forest composition in the north‐eastern United States: a comparative approach

Abstract

Aim This study compares human impacts and forest ecosystem response across geographical regions. Such a comparison allows us to evaluate the relationship between regional changes in forest composition and regional patterns of human activity.Location Four study areas in the north-eastern USA were investigated, two of which were dominated by oak-pine forests at the time of European settlement (Central Massachusetts, MA; Pike County, PA), and two of which were dominated by beech and hemlock (South Berkshire, MA; Wayne County, PA).Methods Trees recorded in early land survey records were compiled and compared with data on modern forest composition obtained from recent forest inventories. To assess the similarity of the four regions with regard to species composition, Euclidean Distances (ED) were calculated between the colonial and modern forest composition for each of the four regions. Information about the history of human impacts in the four study regions was used to interpret the changes in forest composition. ResultsGeneral changes in forest composition through the historical period include a decline in beech, hemlock and chestnut, and an increase in maple and birch. Changes in pine and oak were minor by comparison. Supraregional human impacts are generally linked with supraregional trends in species composition, whereas regional patterns of land use caused regional patterns of change in species composition. Main conclusionsThese results suggest that human activities do not necessarily lead to more similar species composition between regions, especially if these activities show clear spatial patterns at about the same resolution that species composition is evaluated. Comparing species-specific changes in forest composition with species-specific human activities on the same spatial scale is crucial in order to evaluate human impacts on ecosystems and to make more robust generalizations about the temporal dynamics of landscapes.

Disassociating tree species associations in the eastern United States

“…There appears to be evidence from historical records that sugar maple-beech was a more representative association than oak-hickory because both sugar maple and beech were dominant and longlived species with similar traits that represent forests after long periods without disturbance, perhaps a true "climax" association (Seischab 1990, Fuller et al 1998, Bürgi et al 2000, Lorimer 2001, Cogbill et al 2002, Whitney & DeCant 2003, Wang et al 2010, Thomas-Van Gundy & Strager 2012. Additionally, in the northern lower peninsula of Michigan, historical rank-order correlation was 0.87 (B. Hanberry, unpublished data).…”

“…In the northeast, eastern hemlock may have had greater correlation with beech whereas sugar maple gained other tree associates such as American basswood in western regions outside of current beech distribution (Bürgi et al 2000, Cogbill et al 2002, Whitney & Decant 2003. Because long periods without disturbance by current land use (i.e., tree removals occur more frequently than the lifespan of most tree species) are not present in the landscape, sugar maple and beech were not likely to continue as a dominant association; indeed, current correlation between the two species was not particularly strong and American beech currently is a minor species.…”

Land-use and climate change effects in forest compositional trajectories in a dry Central-Alpine valley

“…There is no standard procedure how to deal with this problem and it is therefore essential to carefully evaluate and remove systematic bias resulting from such comparison (Bürgi et al, 2000;Egan and Howell, 2001). In our study, we apply a conversion key to make this comparison possible (Tab.…”

Kulturlandschaft verstehen

“…Zweitens verwenden den Begriff Ökologinnen und Ökologen, die anthropogene Einflüsse auf Ökosysteme und Landschaften untersuchen (z.B. Östlund et al 1997;Bürgi et al 2000;Hellberg et al 2003;Foster und Motzkin 2003). Dearing et al (2006) forderten, dass dabei der menschliche Einfluss nicht lediglich als "Stressor" mit einer gewissen Wirkung auf ein Ökosys-tem oder auf eine Landschaft betrachtet werden sollte, sondern dass die Menschen als Akteure verstanden und analysiert werden müssten.…”