不同落叶林林下凋落物的分解与养分归还

用分解袋法研究胡桃楸、落叶松纯林及其混交林下叶凋落物的分解及养分归还速率。结果表明：在1个生长季内，3种林分叶凋落物分解速率从大到小依次为：胡桃楸纯林、混交林、落叶松纯林。胡桃楸纯林叶凋落物归还氮的速率最快，落叶松纯林叶凋落物归还磷、钾的速率最快。二组成混交林后，混交林叶凋落物归还氮的速率较落叶松纯林明显提高，而归还磷、钾的速率较胡桃楸纯林明显提高。胡桃楸与落叶松混交后叶凋落物养分归还速率较其各自纯林的有所提高，可能是混交林增产机理之一。

Decomposition and Nutrient Return of the Leaf Litter under the Pure and Mixed Plantations of Juglans mandshrica and Larix gmelinii

The characteristics of the decomposition and the nutrient return of the leaf litters under the pure and mixed plantations of Juglans mandshurica and Larix gmelinii were studied by decomposing-bag method.The result showed that in one growth season the decomposing rates were as follows:the J.mandshurica pure plantation>mixed plantation>the L.gmelinii pure plantation.The return rate of the nitrogen element was the fastest in the pure plantation of J.mandshurica and on the other hand the return rates of the phosphorus and potassium were the fastest in the pure plantation of L.gmelinii.The return rate of the nitrogen in the mixed plantation was obviously faster than it was in the L.gmelinii pure plantation and those of the phosphorus and potassium were obviously faster than they were in the J.mandshurica pure plantation.In contrast with the pure plantations,the improvement of the return rates of the nutrient elements in the mixed plantation may be one of the machenisms for the growth improvement of the mixed plantation.