Legacy of forest composition and changes over the long-term on tree radial growth

Forests of North America have undergone important changes since European settlement, especially in terms of stand composition and associated changes in soil properties, and the causes and consequences of such variations through time remains poorly understood. This study investigates the effects of long-term changes in forest composition and soil properties on the radial growth of sugar maple and balsam fir, two important species of northeastern North America’s forests. Using data from 130 plots measured in 1930 and in 2012-14 and a mixed-effects modelling approach, we studied the links between radial growth, soil nutrient availability, current stand composition and shifts in vegetation. Balsam fir radial growth was found to vary with soil available nitrogen and present-day relative basal area of yellow birch, while that of sugar maple was found to be invariant to soil characteristics, but proportional to spruce relative basal area. However, no direct effects of vegetation change on radial growth were detected. Our results suggest that prior stand composition had no influence on radial growth of both studied species, yet vegetation change could influence balsam fir growth through an improvement of litter quality from other species. Moreover, we conclude that maintaining a certain proportion of compositional diversity may enhance radial growth of both balsam fir and sugar maple.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author