模拟外源性氮磷对尾叶桉和马占相思混合凋落叶分解的影响

Effects of Nitrogen and Phosphorus Additions on the Decomposition of Mixed Leaf Litter in Eucalyptusurophyllaand Acacia mangium Plantations

以广东省云勇林场尾叶桉(Eucalyptus urophylla)和马占相思(Acacia mangium)的混合凋落叶为材料,采用尼龙网袋分解法,设置对照(CK)、施N(N 10g·m^(-2))、施P(P 5g·m^(-2))、施N+P(N 10g·m^(-2)+P 5g·m^(-2))4种处理,研究了外源性氮、磷对凋落叶分解和凋落叶分解残留物中N、P、K含量动态的影响。结果表明,施N处理对尾叶桉和马占相思林下混合凋落叶分解多为抑制作用,施P和N+P处理能起到加快凋落叶分解的作用。尾叶桉和马占相思林下各处理的凋落叶分解残留物的N含量、施P和N+P处理的凋落叶分解残留物的P含量在分解过程中总体呈现波动上升的趋势,而各处理的凋落叶分解残留物的K含量变化规律不明显。建议该地区适当施用P肥,促进凋落物的分解和养分释放,以达到增加土壤肥力,促进林分生长的目的。

Taking the mixed leaf litters collected from Eucalyptus urophylla and Acacia rnangium planta- tions in Yunyong Forest Farm of Guangdong Province as materials, effects of exogenous nitrogen and phos- phorus on the decomposition the leaf litters were examined by the decomposition in plastic bag method. Four treatments with different N and P levels were designed, control （no addition of N or P）,N addition （N 10 g·m^-2）,P addition （P 5 g·m^-2）,and Nq-P addition （N 10 g·m^-2 P 5 g·m^-2）.The results showed that N addition inhibited the litter decomposition,whereas P and N＋P additions improved the lit- ter decomposition. Generally, the N contents in the litters of four treatments,P contents in the treatments in which P or N＋P were added tended to increase and were greater than their initial value during litter de- composition process,respectively. The K content in the leaf litters of four treatments changed irregularly. The results suggested that appropriate amount of P fertilizer could be used in acidic soil regions, to promote litter decomposition and nutrient release, which would increase soil fertility and promote stand growth.