模拟酸沉降对桉树纯林和混交林土壤化学性质的影响

Effects of Simulated Acid Deposition on Soil Chemical Properties of Pure Eucalyptus and Mixed Forest

【目的】研究在不同酸度的模拟酸雨下,桉树纯林和桉树+红椎混交林土壤化学性质的变化。【方法】通过严格的土柱淋洗试验,模拟酸雨pH分别为3.0、4.0、5.6、6.0。【结果】酸雨处理下两种林分土壤和土壤淋洗液pH值均随酸雨pH的降低而降低,桉树纯林土壤pH的平均下降幅度为1.41,桉树+红椎混交林为1.66;土壤淋洗液养分含量随酸雨pH的降低而增加;两种林分土壤全氮、铵态氮、硝态氮含量均随酸雨pH的降低先增加后降低;土壤全磷和速效磷含量在桉树纯林中随酸雨pH的降低而显著降低,在桉树+红椎混交林中无显著变化;同一pH(pH3.0)条件下,与CK对比,桉树纯林土壤全氮、硝态氮和铵态氮的下降率分别为28.7%、46.6%、12.4%,桉树+红椎混交林下降率分别为18.9%、23.5%、11.3%。【结论】两种林分对比可知,桉树+红椎混交林对酸雨的缓冲能力强于桉树纯林。

【Objective】The changes of soil chemical properties of pure eucalyptus forest and mixed forest(eucalyptus+Castanopsis hystrix)under different simulated acid rains were studied.【Method】The pH of the acid rain was simulated to be 3.0,4.0,5.6 and 6.0 by a strict soil column leaching test.【Result】The pH values of soil and soil leaching solution decreased with the decrease of acid rain pH under acid rain treatment.The average pH of pure eucalyptus forest soil decreased by 1.41,and that of mixed forest(eucalyptus+C.hystrix)decreased by 1.66.The nutrient contents of the leaching solution increased with the decrease of acid rain pH;the contents of soil total N,ammonium N and nitrate N in the two forests increased first and then decreased with the decrease of acid rain pH,and soil P and available P in the pure eucalyptus forest decreased significantly with the decrease of acid rain pH while there was no significant change in soil P and available P in the mixe d forest(eucalyptus+C.hystrix).Under same pH(pH=3.0),compared with CK,the decline rates of total N,nitrate N and ammonium N in the pure eucalyptus forest soil were 28.7%,46.6%and 12.4%,respectively,and those of the mixed forest(eucalyptus+Castanopsis hystrix)were 18.9%,23.5%and 11.3%,respectively.【Conclusion】The comparison of the two forest stands shows that the buffering capacity of mixed forest of eucalyptus and C.hystrix to acid rain is stronger than that of pure eucalyptus forest.