Thursday, August 6, 2009 - 2:30 PMOOS 40-4: Spatial structure and dynamics of a temperate deciduous forest in northern Wisconsin, USA
Robert W. Howe, University of Wisconsin-Green Bay, Amy T. Wolf, University of Wisconsin-Green Bay, and Richard Condit, Smithsonian Tropical Research Institute.
Background/Question/Methods Despite great interest in the differences between tropical and temperate biotas, few studies have directly compared tropical and temperate forest sites using standard methods. The objective of this paper is to describe spatial patterns of woody plants ≥ 1 cm dbh at a 25 ha temperate forest study area and to present some of the first quantitative comparisons between standardized temperate and tropical forest dynamics plots. The Wabikon Forest Dynamics Plot is part of an extensive forested landscape on glacially-derived topography in northeastern Wisconsin, USA. Total species richness (29 woody species ≥ 1 cm dbh) and mean stem density (2363/ha) are low, representing an ecologically simplified community that contrasts markedly with species-rich and structurally complex tropical forests. We compare findings from the first census of this temperate forest plot with comparable published data from tropical forest dynamics plots.
Results/Conclusions Species richness at the Wabikon Plot does not vary significantly among tree diameter classes, but the relative importance of many tree species varies dramatically between the canopy and understory. The dominant species, sugar maple (Acer saccharum), is an important exception to this pattern, occurring widely in both large and small diameter classes. Two other common species, American basswood (Tilia americana) and yellow birch (Betula alleghaniensis), are prominent in the canopy but are poorly represented among small trees. Several other tree species, especially ironwood (Ostrya virginiana), are more abundant in the understory than in the canopy. Spatial patterns of woody species at the Wabikon Forest Dynamics Plot reflect historical disturbances, topography, and species interactions. Like tropical forests, virtually all woody species in this temperate forest are aggregated at local scales, but older trees tend to be less aggregated than younger trees of the same species. Comparative data from standardized temperate and tropical forest plots provide unique opportunities for exploring these and other spatial patterns, revealing novel insights into the dynamics of forest communities in general.
Results/Conclusions Species richness at the Wabikon Plot does not vary significantly among tree diameter classes, but the relative importance of many tree species varies dramatically between the canopy and understory. The dominant species, sugar maple (Acer saccharum), is an important exception to this pattern, occurring widely in both large and small diameter classes. Two other common species, American basswood (Tilia americana) and yellow birch (Betula alleghaniensis), are prominent in the canopy but are poorly represented among small trees. Several other tree species, especially ironwood (Ostrya virginiana), are more abundant in the understory than in the canopy. Spatial patterns of woody species at the Wabikon Forest Dynamics Plot reflect historical disturbances, topography, and species interactions. Like tropical forests, virtually all woody species in this temperate forest are aggregated at local scales, but older trees tend to be less aggregated than younger trees of the same species. Comparative data from standardized temperate and tropical forest plots provide unique opportunities for exploring these and other spatial patterns, revealing novel insights into the dynamics of forest communities in general.