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Mesophication and xerophication of temperate forests in western New York State

Authors: Chris Larsen*, University At Buffalo, David Robertson, SUNY Geneseo, Stephen Tulowiecki, SUNY Geneseo
Topics: Biogeography, Land Use and Land Cover Change, Indigenous Peoples
Keywords: drought, forest, Indigenous
Session Type: Paper
Presentation File: No File Uploaded

Mesophication, replacement of sun-loving fire-tolerant tree species with shade-tolerant fire-intolerant tree species, has been much observed across eastern USA. Xerophication, the opposite of mesophication, has been noted but little studied. There are two main hypotheses for mesophication: loss of Native American burning upon Euro-American settlement, and reduction of drought incidence since the late-1700s. There are two main hypotheses for xerophication: increased drought incidence, and increased browsing. We evaluate those hypotheses using tree-data collected from 160 forest plots in 6000 km2 of New York State. Plots were selected to vary soil drainage, precipitation, temperature, slope aspect, and distance from Native American villages ca. 1700 CE. In each plot, 16 trees were recorded, four in each of four DBH classes. Species were categorized by 6 traits related to mesophication: tolerance for fire, drought, shade, temperature, browsing, and food source for Native Americans. Plot age was estimated using a cross-dated increment-core from the largest tree. Degree of mesophyticness/xerophyticness in each plot was calculated using the 8 larger-DBH trees (the canopy), and the 8 smaller-DBH trees (advance regeneration). Mesophication/xerophication was calculated for the 6 individual traits by subtracting degree of mesophyticness/xerophyticness of advance regeneration from that of the canopy. For all 6 traits, the degree of mesophication was negatively correlated with plot mesophyticness, such that mesophytic sites were xerophied and xerophytic plots were mesophied. Preliminary multiple regression analyses indicate that the most important variables explaining mesophication/xerophication were, in descending order of importance: plot age, soil conditions, climate conditions, and distance to Native American villages.

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