凋落物处理对南亚热带枫香人工林土壤碳氮矿化耦合的影响

Influences of litter management on soil carbon and nitrogen mineralization coupling in the south subtropical Liquidambar formosana plantation

【目的】通过探索添加、去除凋落物处理对南亚热带枫香人工林土壤呼吸、氮矿化速率的影响,为枫香人工林培育、经营和生态管理实践提供理论依据。【方法】选取广西壮族自治区德保县红叶森林公园枫香人工林进行为期1年的凋落物管理试验,设置3个凋落物水平:对照(CK,自然凋落物)、添加凋落物(LA,加倍凋落物)、去除凋落物(LE,无凋落物)。测量土壤呼吸速率、土壤温湿度、土壤净氨化、净硝化及净氮矿化速率,分析其变化规律。【结果】1)LA使土壤呼吸速率增加了39.1%~65.3%,年均值显著增加53.4%(P<0.05);LE使土壤呼吸速率降低了6.1%~20.7%,年均值降低12.4%但并不显著(P> 0.05);凋落物处理后,净氨化、净硝化、净氮矿化速率均表现为LA> CK> LE,而处理间并无显著差异(P> 0.05)。2)所有处理的土壤呼吸、氮矿化速率均显示出与土壤温度的显著相关,而与土壤湿度的关联性则主要表现在LA处理中。3)不同处理土壤呼吸与氮矿化速率间(净氨化、净硝化、净氮矿化)均显示出显著正相关,且LA处理提升了土壤碳、氮矿化速率间(尤其是土壤呼吸与净氨化速率间)的关联性。【结论】添加凋落物处理能够增强枫香人工林的土壤碳、氮矿化速率,提升土壤碳氮矿化耦合的正相关性,研究结果对深入认识森林土壤养分循环过程具有重要意义。

【Objective】The aim of this study was to investigate the effects of litter addition and removal on soil respiration and nitrogen mineralization rate of the south subtropical Liquidambar formosana plantation,to provide a theoretical basis for the cultivation,management and ecological methods of L.formosana plantation.【Method】A litter management experiment was conducted on the L.formosana plantation in Debao,Guangxi for about one year.Three litter treatments were established as natural litter input(CK),double litter input(LA)and non-litter input(LE).The soil respiration rate(Rs),soil temperature(ST)and moisture(SWC),soil net ammonium(Ramm),nitrification(Rnit)and N mineralization(Rmin)rate were measured and analyzed.【Result】1)Rs was increased under LA treatment(39.1%-65.3%with an annual mean value of 53.4%,P<0.05)and decreased under LE treatment(6.1%-20.7%with an annual mean value of 12.4%,P>0.05).Ramm,Rnit and Rmin under different litter treatments were in the order of LA>CK>LE,but the difference was not significant(P>0.05).2)The regression model between Rs,Ramm,Rnit and Rmin and ST all showed significant correlations,while their profound relationships with SWC were mainly presented under LA treatment.3)Rs showed a linear correlation with Ramm,Rnit and Rmin in all litter levels,and the correlation coefficients were increased under LA treatment.【Conclusion】Leaf litter addition elevates soil C and N mineralization rates in L.formosana plantation,and further promotes the coupling of C and N.The results are significant for understanding the nutrient cycling process of forest soils.