采用网袋法,对 0 ~ 360 d 内杉木[ Cunninghamia lanceolata ( Lamb.) Hook.]、楠木[ Phoebe bournei ( Hemsl.)Yang]和木荷(Schima superba Gardn. et Champ.)叶凋落物在杉木人工林下的分解特征及营养元素( N、P、K 和 C)含量的变化动态进行了比较分析。 结果显示,经过 360 d 的分解,杉木、楠木和木荷叶凋落物的干质量损失率分别为40. 6% 、42. 0% 和 51. 6% ,平均腐解率分别为 0. 001 3、0. 001 6 和 0. 002 0 d^-1 ,叶凋落物的分解半衰期分别为 537、482 和372 d。 在整个分解过程中,3 个树种叶凋落物中 P 含量总体上均呈波动且缓慢的上升趋势;K 含量在分解过程前期均急剧下降,然后随分解时间的延长变化趋缓;N 含量变化差异较大,随分解时间的延长,杉木叶凋落物中 N含量呈缓慢上升趋势,另外 2 个树种叶凋落物中 N 含量总体上呈先下降后上升的变化趋势;C 含量基本上呈前期上升、中期下降、后期又略有上升的趋势,而 C / N 比则呈前期略上升而后期逐渐下降的趋势。 3 个树种叶凋落物分解过程中 N、P、K 和 C 的释放率及其动态变化也存在一定差异。 3 个树种叶凋落物中 K 的释放率均较高、变化趋势较接近,且均处于净释放状态;杉木叶凋落物中 N、P 和 C 的释放率总体上低于另 2 个树种,且木荷叶凋落物中 N、P和 C 基本均处于单调净释放状态,而杉木叶凋落物中 N、P 和 C 以及楠木叶凋落物中 P 和 C 在分解过程前期均略呈净富集状态,之后 N 和 C 基本上呈净释放状态、P 则呈波动式净释放状态。 结果表明,在杉木人工林下,阔叶树种(楠木和木荷)叶凋落物比针叶树种(杉木)叶凋落物易分解,且阔叶树种叶凋落物中的营养元素也较易释放。

Using mesh nylon bag method, decomposition characteristics and change dynamics of nutrient element ( N, P, K and C) content of leaf litter of Cunninghamia lanceolata ( Lamb.) Hook., Phoebe bournei (Hemsl.) Yang and Schima superba Gardn. et Champ. were comparatively analyzed under C. lanceolata artificial forest during 0-360 d decomposition process. The results show that, by decomposing for 360 d, the loss rate of dry weight of leaf litter of C. lanceolata, P. bournei and S. superba is 40. 6% ,42. 0% and 51. 6% , the average decomposition rate is 0. 001 3, 0. 001 6 and 0. 002 0 d^-1, and the half-time ( t0. 5 ) for leaf litter decomposition is 537, 482 and 372 d, respectively. During the whole decomposition process, P content in leaf litter of three tree species appears generally a fluctuant and slow ascending trend; K content descends sharply in the early phase and then changes gently with decomposition time prolonging. Among leaf litters of three tree species, there is an obvious difference in N content change, in which N content in C. lanceolata leaf litter appears a slow ascending trend, and that in other two tree species generally appears increasing firstly and then decreasing with decomposition time prolonging. C content in leaf litters of three tree species basically shows an increasing trend in the early phase, a decreasing trend in the middle phase and a slight increasing trend in the later phase, and C / N ratio increases slightly in the early phase and decreases gradually in the later phase. The release rates and  dynamic changes of nutrient elements (N, P, K and C) in leaf litters exist some differences among three tree species during decomposition process. In leaf litters of three tree species, the K release rate is higher with a similar change trend and a net release. The release rate of N, P and C in C. lanceolata leaf litter is generally lower than that of other two tree species. The leaf litter of S. superba exhibits a monotonously net release of N, P and C, but N, P and C in C. lanceolata leaf litter and P, C in P. bournei leaf litter are in slightly net enrichment in the early stage of decomposition, and then, N and C are generally in net release and P is in a wavy net release. It means that the decomposition of leaf litters of broad-leaved tree species ( P. bournei and S. superba) is easier than that of coniferous tree species (C. lanceolata), and also the nutrient elements release more easily in the formers than in the latter under C. lanceolata artificial forest.