Land-use history impacts spatial patterns and composition of woody plant species across a 35-hectare temperate forest plot

Land-use history is the template upon which contemporary plant and tree populations establish and interact with one another and exerts a legacy on the structure and dynamics of species assemblages and ecosystems. We use the first census (2010-2014) of a 35-ha forest-dynamics plot at the Harvard Forest in central Massachusetts to explore such legacies. The plot includes 108,632 live stems [≥] 1 cm in diameter (2215 individuals/ha) and 7,595 dead stems [≥] 5 cm in diameter. Fifty-one woody plant species were recorded in the plot, but two tree species - Tsuga canadensis (eastern hemlock) and Acer rubrum (red maple) - and one shrub - Ilex verticillata (winterberry) -comprised 56% of all stems. Live tree basal area averaged 42.25 m2/ha, of which 84% was represented by T. canadensis (14.0 m2/ha), Quercus rubra (northern red oak; 9.6 m2/ha), A. rubrum (7.2 m2/ha) and Pinus strobus (eastern white pine; 4.4 m2/ha). These same four species also comprised 78% of the live aboveground biomass, which averaged 245.2 Mg/ha, and were significantly clumped at distances up to 50 m within the plot. Spatial distributions of A. rubrum and Q. rubra showed negative intraspecific correlations in diameters up to at least a 150-m spatial lag, likely indicative of competition for light in dense forest patches. Bivariate marked point-pattern analysis showed that T. canadensis and Q. rubra diameters were negatively associated with one another, indicating resource competition for light. Distribution and abundance of the common overstory species are predicted best by soil type, tree neighborhood effects, and two aspects of land-use history: when fields were abandoned in the late 19th century and the succeeding forest types recorded in 1908. In contrast, a history of intensive logging prior to 1950 and a damaging hurricane in 1938 appear to have had little effect on the distribution and abundance of present-day tree species.