凋落物分解是维持生态系统养分循环和能量流动的关键过程，但在雨热同期的黄土丘陵区，不同降雨时期凋落物基质质
量动态对该区不同树种凋落物分解速率的影响还不清楚。采用凋落物分解袋法，基于野外原位分解实验分析黄土丘陵区主要
人工林刺槐(Ｒobinia pseudoacacia Linn．)和油松(Pinus tabulaeformis Carr．)凋落叶在不同降雨时期的分解特征和分解过程中凋落
叶基质质量的变化与分解速率之间的关系。研究结果发现:(1)经过 391 d 的分解，刺槐凋落叶的平均质量损失速率为(51．0±
8．44) mg/d，显著地高于油松凋落叶(36．7±4．83) mg/d;雨季期间两树种凋落叶的质量损失速率均显著地高于旱季，其中夏季
多雨期间凋落叶的质量损失速率最高，冬季微量降雨期间质量损失速率最低。(2)在整个分解过程中两树种凋落叶 C 和 N 含
量都表现为净释放且主要发生在雨季，P 含量表现为释放与富集交替进行;刺槐凋落叶 C/N 比、C/P 比和 N/P 比呈波动的趋
势，油松凋落叶 C/N 比则显著地增加且在夏季多雨期出现峰值，C/P 比呈波动的状态，N/P 比变化较小。(3)不同降雨时期刺
槐凋落叶的质量损失速率与凋落叶 P 含量动态显著正相关，与 C 含量、C/P 比和 N/P 比动态显著负相关。油松凋落叶质量损
失速率与 C/N 比动态显著正相关，与 C、N 含量动态显著负相关，与 N/P 比动态呈负二次函数的关系。这些结果说明黄土丘陵
区刺槐和油松凋落叶在不同降雨时期分解速率之间的差异显著且两树种凋落叶的分解都集中在雨季期间;此外凋落叶分解主
要受到凋落叶 N 含量和 N/P 比动态变化的制约，与刺槐凋落叶相比，N 含量与 N/P 比对油松凋落叶的限制作用更强。
其他摘要
Litter decomposition is a key process to maintain nutrient circulation and energy flow in the ecosystem． However，
in the loess hilly region where rain and heat happen in the same period，it remains unclear how the litter quality during
different rainfall periods affects litter decomposition rate． In order to better understand the leaf-litter decomposition
characteristics during different rainfall periods and the relationships between the dynamic in substrate mass anddecomposition rate during decomposition，a field litter bag experiment was conducted in two types of planted forest of
Ｒobinia pseudoacacia and Pinus tabulaeformis in the loess hilly region． The results revealed that: (1) after 391 days of
decomposition，the average leaf-litter mass loss rate of Ｒ． pseudoacacia was (51．0±8．44) mg/d，significantly higher than
that of P． tabulaeformis (36． 7 ± 4． 83) mg/d． The leaf-litter mass loss rate of both species during rainy season was
significantly higher than those during dry season． (2) During decomposition，C and N content in the leaf-litter of two
studied species showed a net release，mainly occurring in the summer rainy season． The dynamic of P content showed a
release and enrichment alternately． The leaf-litter C/N，C/P and N/P ratios of Ｒ． pseudoacacia showed a fluctuant trend，
while the C/N ratio of P． tabulaeformis increased significantly over time and peaked in summer rainy season，the C/P ratio
had a trend of fluctuation but the N/P ratio did not significantly change． ( 3) The leaf-litter mass loss rate of
Ｒ． pseudoacacia was significantly and positively correlated with leaf-litter P content dynamic，negatively correlated with C
content，C/P ratio and N/P ratio． However，the leaf-litter mass loss rate of P． tabulaeformis was positively correlated with
C/N ratio and negatively with C and N content and N/P ratio，and showed negative quadratic function with N/P ratio．
These results indicated that the leaf-litter decomposition of Ｒ． pseudoacacia and P． tabulaeformis in loess hilly region tended
to significantly differ in different rainfall periods and mainly occur in rainy season． And the leaf-litter decomposition was
mainly restricted by leaf-litter N content and N/P ratio，the leaf-litter decomposition of P． tabulaeformi was more restricted
by N content and N/P ratio than that of Ｒ． pseudoacacia．
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