Enhanced woody biomass production in a mature temperate forest under elevated CO2
Richard J. Norby, Neil J. Loader, Carolina Mayoral, Sami Ullah, Giulio Curioni, Andy R. Smith, Michaela K. Reay, Klaske van Wijngaarden, Muhammad Shoaib Amjad, Deanne Brettle, Martha E. Crockatt, Gael Denny, Robert T. Grzesik, R. Liz Hamilton, Kris M. Hart, Iain P. Hartley, Alan G. Jones, Angeliki Kourmouli, Joshua Larsen, Zongbo Shi, Rick Thomas, A. R. MacKenzie
Abstract
Abstract Enhanced CO 2 assimilation by forests as atmospheric CO 2 concentration rises could slow the rate of CO 2 increase if the assimilated carbon is allocated to long-lived biomass. Experiments in young tree plantations support a CO 2 fertilization effect as atmospheric CO 2 continues to increase. Uncertainty exists, however, as to whether older, more mature forests retain the capacity to respond to elevated CO 2. Here, aided by tree-ring analysis and canopy laser scanning, we show that a 180-year-old Quercus robur L. woodland in central England increased the production of woody biomass when exposed to free-air CO 2 enrichment (FACE) for 7 years. Further, elevated CO 2 increased exudation of carbon from fine roots into the soil with likely effects on nutrient cycles. The increase in tree growth and allocation to long-lived woody biomass demonstrated here substantiates the major role for mature temperate forests in climate change mitigation.