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

摘要

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 (R _S) in a 70-year-old natural Pinus densiflora S. et Z. forest in central Korea. Concurrent with R _S 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 R _S (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, R _S was correlated with ST (R 2 = 0.77–0.80, P < 0.001) and SWC (R 2 = 0.31–0.35, P < 0.001). It appeared that stand density influenced R _S via changes in leaf litterfall, LAI and SWC. Leaf litterfall (R 2 = 0.71), TBCA (R 2 = 0.64–0.87), and total soil N contents in 2007 (R 2 = 0.94) explained a significant amount of the variance in R _S (P < 0.01). The current study showed that stand density is one of the key factors influencing R _S due to the changing biophysical and environmental factors in P. densiflora.