Exploring the black box: coupling above- and belowground plant traits to understand disturbance effects on soil carbon storage in a temperature plantation

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The recent IPCC science meetings clearly underline the need for fundamental science to support understanding of ecosystem feedback to climate change and consequent important policy decisions in the next decades. A key element of this fundamental science program relates to understanding biogeochemical cycles of carbon and nitrogen, as well as how changes in land use and vegetation response may modify these cycles. The current proposal continues 20 years of fundamental research on nutrient cycles in temperate plantation ecosystems, with an emphasis on feedbacks of vegetation changes to these cycles, and the resulting forms and relative stability of carbon in the soil. The present five-year program will integrate the approach of functional plant traits in order to interpret the effects of different plant communities created by intensive silviculture on nutrient cycling and specifically, carbon accumulation and stability in the soil. Specific objectives include: 1) characterize age-related change in plant traits (both green foliage and litter) of dominant tree species (specific leaf area, foliar C and N) ; 2) characterize above- and belowground traits (roots) of dominant tree and understory species to interpret differences in soil carbon accumulation and stability in humus and mineral soil ; 3) further investigate potential soil carbon losses (potential priming effect) in deeper mineral horizons associated with plantation establishment and intensive soil disturbance. Newly accessible methods of mid- and near infrared spectroscopy will be applied to investigate their potential to evaluate both plant tissue chemistry and soil carbon stability more efficiently than current techniques. These next five years of a long term program will simultaneously probe deeper questions of plant feedback on carbon sequestration while synthesizing what will be a 25-year program (in 2011) of research on the same site. To culminate this program I will write a major synthesis paper with previous collaborators and students. These studies are important in order to understand and manage soil carbon accrual in forests, and will also contribute important information to improve current models for predicting carbon dynamics in ecosystems.