Canopy exchanges of H^+ and N (NH4^+-N, NO3^--N) and other major ions were evaluated and quantified In twolayer canopies based on throughfall measurements in Shaoshan Forest during the period 2000-2002, central-so...Canopy exchanges of H^+ and N (NH4^+-N, NO3^--N) and other major ions were evaluated and quantified In twolayer canopies based on throughfall measurements in Shaoshan Forest during the period 2000-2002, central-south China, The collected annual rainfall, throughfall, and sub-throughfall were 1 401, 1 191, and 1 084 mm/year, respectively. Fifteen percent and 8% of rainfall (or 9% of throughfall) were intercepted by the top canopy and sub-canopy layers, respectively, The foliar leaching of base cations from the top canopy was significantly higher than that from the sub-canopy, and the latter accounted for 25% of the former. The uptake of H^+ and NH4^+ was significantly higher in the top canopy than in the sub-canopy, indicating that the canopy buffering capacity in the top canopy was stronger than the sub-canopy; Mg^2+ can be absorbed from water flux on the sub-canopy foliar surfaces to compensate for the Mg deficit in the forest soil during the growing season,展开更多
文摘Canopy exchanges of H^+ and N (NH4^+-N, NO3^--N) and other major ions were evaluated and quantified In twolayer canopies based on throughfall measurements in Shaoshan Forest during the period 2000-2002, central-south China, The collected annual rainfall, throughfall, and sub-throughfall were 1 401, 1 191, and 1 084 mm/year, respectively. Fifteen percent and 8% of rainfall (or 9% of throughfall) were intercepted by the top canopy and sub-canopy layers, respectively, The foliar leaching of base cations from the top canopy was significantly higher than that from the sub-canopy, and the latter accounted for 25% of the former. The uptake of H^+ and NH4^+ was significantly higher in the top canopy than in the sub-canopy, indicating that the canopy buffering capacity in the top canopy was stronger than the sub-canopy; Mg^2+ can be absorbed from water flux on the sub-canopy foliar surfaces to compensate for the Mg deficit in the forest soil during the growing season,