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1 April 2007 Relationships among forest age, composition and elemental dynamics of Adirondack northern hardwood forests
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We conducted a biogeochemical analysis of four Adirondack northern hardwood forests (two old-growth and two maturing second-growth) to elucidate correlations among stand age, site conditions and several nutrient cycling processes. One each of the old-growth and maturing forests were located on base-rich sites, while the other two were on base-poor sites. At each site we analyzed soil solution chemistry and estimated nutrient flux rates; measured annual litter production, and nutrient and lignin content; measured annual N mineralization and nitrification rates; and characterized herb- and canopy-layer vegetation, and coarse woody debris volumes. Vascular plant communities of the two base-rich sites were dominated by several rich-site indicator species, while such indicators were lacking at the base-poor sites. Tree basal areas and annual litter production did not differ among the study sites, but the old-growth stands contained 3-fold more coarse woody debris than the maturing stands. Foliar litter N concentrations did not differ among the study sites, but foliar litter from the base-rich sites had higher Ca2 and lower lignin concentrations than the base-poor sites. Differences in foliar litter quality among the sites were due, in part, to intraspecific variation in litter chemistry. There were no consistent differences between the old-growth and maturing stands in soil solution nutrient concentrations or fluxes. Soil solution H concentrations were higher and Ca:Al ratios lower at the two base-poor sites. Annual, net N mineralization rates did not differ among the sites, but net nitrification rates in the organic soil horizons at the rich old-growth site were more than twice those at the other sites. High levels of net nitrification and N leaching were observed only in the base-rich old-growth site. Our data suggest that net forest nutrient retention may be a function of interacting mechanisms associated with forest developmental stage, community composition and site conditions.

Gregory G. McGee, Myron J. Mitchell, Donald J. Leopold, Dudley J. Raynal, and Monday Mbila "Relationships among forest age, composition and elemental dynamics of Adirondack northern hardwood forests," The Journal of the Torrey Botanical Society 134(2), 253-268, (1 April 2007).[253:RAFACA]2.0.CO;2
Received: 8 January 2005; Published: 1 April 2007

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