Influence of stand density on soil CO2 efflux for a Pinus densiflora forest in Korea

Abstract

We investigated the influence of stand density [938 tree ha-1 for high stand density (HD), 600 tree ha-1 for medium stand density (MD), and 375 tree ha-1 for low stand density (LD)] on soil CO2 efflux (RS) in a 70-year-old natural Pinus densiflora S. et Z. forest in central Korea. Concurrent with RS measurements, we measured litterfall, total belowground carbon allocation (TBCA), leaf area index (LAI), soil temperature (ST), soil water content (SWC), and soil nitrogen (N) concentration over a 2-year period. The RS (t C ha-1 year-1) and leaf litterfall (t C ha-1 year-1) values varied with stand density: 6.21 and 2.03 for HD, 7.45 and 2.37 for MD, and 6.96 and 2.23 for LD, respectively. In addition, RS was correlated with ST (R2 = 0.77-0.80, P < 0.001) and SWC (R2 = 0.31-0. 35, P < 0.001). It appeared that stand density influenced RS via changes in leaf litterfall, LAI and SWC. Leaf litterfall (R2 = 0.71), TBCA (R2 = 0.64-0.87), and total soil N contents in 2007 (R2 = 0.94) explained a significant amount of the variance in RS (P < 0.01). The current study showed that stand density is one of the key factors influencing RS due to the changing biophysical and environmental factors in P. densiflora. ? 2010 The Botanical Society of Japan and Springer.