Papers Published

1. Palmroth, Sari and Oren, Ram and McCarthy, Heather R. and Johnsen, Kurt H. and Finzi, Adrien C. and Butnor, John R. and Ryan, Michael G. and Schlesinger, William H., Aboveground sink strength in forests controls the allocation of carbon below ground and its {[}CO(2)] - induced enhancement, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, vol. 103 no. 51 (December, 2006), pp. 19362-19367 [doi] .
   (last updated on 2012/01/03)

   Abstract:
   The partitioning among carbon (C) pools of the extra C captured under elevated atmospheric CO(2) concentration {[}CO(2)] determines the enhancement in C sequestration, yet no clear partitioning rules exist. Here, we used first principles and published data from four free-air CO(2) enrichment (FACE) experiments on forest tree species to conceptualize the total allocation of C to below ground (TBCA) under current {[}CO(2)] and to predict the likely effect of elevated {[}CO(2)]. We show that at a FACE site where leaf area index (L) of Pinus taeda L. was altered through nitrogen fertilization, ice-storm damage, and droughts, changes in L, reflecting the aboveground sink for net primary productivity, were accompanied by opposite changes in TBCA. A similar pattern emerged when data were combined from the four FACE experiments, using leaf area duration (L(D)) to account for differences in growing-season length. Moreover, elevated {[}CO(2)]-induced enhancement of TBCA in the combined data decreased from approximate to 50\% (700 gCm(-2) y(-1)) at the lowest LD to approximate to 30\% (200 g C m(-2) y(-1)) at the highest L(D). The consistency of the trend in TIBCA with L and its response to {[}CO(2)] across the sites provides a norm for predictions of ecosystem C cycling, and is particularly useful for models that use L to estimate components of the terrestrial C balance.