地表覆盖栽培对雷竹林凋落物养分及其化学计量特征的影响

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为了解不同覆盖栽培年限雷竹林凋落物养分及其化学计量特征,分析了换叶期雷竹林凋落物的凋落量,C、N、P、K养分含量,养分季节归还量以及养分元素生态化学计量比值在不同覆盖年限之间的差异。结果表明:(1)雷竹林在连续覆盖3a后,叶凋落量极显著性提高(<em>P</em>＜0.01),在总凋落量中比例增加,但枝凋落量变化不明显。(2)连续3a覆盖对雷竹林凋落物中的养分含量影响极显著(<em>P</em>＜0.01),C、N养分含量极显著降低,P含量极显著升高,而K养分含量在覆盖2a时就出现了显著增加的变化响应;林地凋落物的养分归还量同时还受凋落量的影响,其伴随覆盖年限增长的变化趋势与养分含量并不一致。(3)覆盖2a内的雷竹林地凋落物表现出稳定的高N∶P以及低P含量,表明凋落物分解速率较低;连续覆盖3a的林地凋落物P含量极显著升高,N∶P极显著下降(<em>P</em>＜0.01),表明此时凋落物分解速率加快。(4)线性回归分析表明,凋落物中K元素随覆盖年限增长而消耗的规律与N、P元素无显著相关关系。;Litter plays an important part of the nutrient circle involving plants and soil in forest ecosystems, with its nutrient return determining the productivity of forestlands. The quality factors and relative decomposability of litter are internal factors that restrict nutrient contribution. Ecological stoichiometry, which is a theory applied in the nutrient elements' response to ecological environment interaction, has been widely incorporated into nutrient cycling research. Several analyses have indicated that nutrient contents and their stoichiometric ratio influence the litter decomposition rate and nutrient cycling. In the present work, we determined whether or not litter nutrients and the stoichiometric characteristics of these nutrients could be applicable in <em>Phyllostachys praecox</em>. Litter production, nutrient content, nutrient return, and nutrient mass ratios of carbon (C), nitrogen (N), phosphorus (P), and potassium (K) were investigated to understand litter nutrient differentiation and the ecological stoichiometry of <em>P. praecox</em> over several years of mulching during refoliation. The results of the present study showed that: (1) Leaf litter production, which accounts for the majority of the total litter produced, increased by extremely significant levels (<em>P</em><0.01) over three years of mulching. In contrast, no significant changes were observed for twig litter production. (2) The nutrient contents of litter reflected highly significant differences (<em>P</em><0.01) over three years of mulching. The C and N contents significantly decreased, while the opposite trend was found in P. The K content increased significantly over two years of mulching. The litter nutrient return showed variations in change trends with nutrient contents and increasing number of mulching years. (3) Constantly high N∶P ratios and low P concentrations were observed over the first two years of mulching, indicating a low litter decomposition rate. However, the N∶P ratio decreased significantly (<em>P</em><0.01) on the third year of continuous mulching, exhibiting a higher litter decomposition rate in contrast to previous years. (4) Linear regression analysis showed that the consumption of K in litter was independent of elemental N and P.