Effect of Slash Burning on Nutrient Removal and Soil Fertility in Chinese Fir and Evergreen Broadleaved Forests of Mid-Subtropical China

摘要

A Chinese fir forest (Cunninghamia lanceolata, CF) and an evergreen broadleaved forest (EB) located in Fujian Province, southeastern China, were examined following slash burning to compare nutrient capital and topsoil properties with pre-burn levels. After fire, nutrient (N, P and K) removal from burning residues was estimated at 302.5 kg ha~(-1) in the CF and 644.8 kg ha~(-1) in the EB. Fire reduced the topsoil capitals of total N and P by about 20% and 10%, respectively, in both forests, while K capital was increased in the topsoils of both forests following fire. Total site nutrient loss through surface erosion was 28.4 kg (N) ha~(-1), 8.4 kg (P) ha~(-1) and 328.7 kg (K) ha~(-1) in the CF. In the EB, the losses of total N, P and K were 58.5, 10.5 and 396.3 kg ha~(-1), respectively. Improvement of soil structure and increase in mineralization of nutrients associated with increased microbe number and enzyme activities and elevated soil respiration occurred 5 days after fire. However, organic matter and available nutrient contents and most of other soil parameters declined one year after fire on the burned CF and EB topsoils. These results suggest that short-term site productivity can be stimulated immediately, but reduced subsequently by soil and water losses, especially in South China, where high-intensity precipitation, steep slopes and fragile soil can be expected. Therefore, the silvicultural measurements should be developed in plantation management.