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为了解马尾松(Pinus massoniana)人工林不同面积林窗边缘凋落叶分解的养分释放规律,采用凋落袋分解实验,以长江上游低山丘陵区人为采伐形成的马尾松人工林7种不同大小林窗(G1:100 m~2;G2:225 m~2;G3:400 m~2;G4:625 m~2;G5:900 m~2;G6:1 225 m~2;G7:1 600 m~2)为研究对象,以林下为对照,探讨马尾松和香樟(Cinnamomum camphora)凋落叶的质量损失率和养分释放率.结果表明:除钾释放率外,林窗边缘两种凋落叶的质量损失率和养分释放率均显著高于林下.在1.5年分解过程中,两种凋落叶的质量损失率和碳释放率呈持续上升趋势.分解前90 d,两种凋落叶的质量损失速率和养分释放速率最快;分解90-360 d后,部分林窗出现氮和磷的富集现象;180-270 d和1.5年后,部分林窗出现钾的富集现象.随林窗面积增大,除钾释放率外,两种凋落叶在中型林窗边缘(400、600和900 m~2)具有较高的质量损失率和养分释放率.在凋落叶分解过程中,质量损失率和碳、氮释放率与土壤含水率均呈显著正相关.中型林窗(400-900 m~2)对凋落物的分解具有更显著的边缘效应,而这种边缘效应与物种有一定关联.因此,在马尾松低效林改造过程中,可利用中型林窗(400-900 m~2)边缘这一显著作用,引入乡土阔叶树种加速马尾松人工林的物质循环,维持林分地力.
In order to understand the rule of nutrient release in leaf litter decomposition of Pinus massoniana plantation with different area, using the litter bag decomposition experiment, seven different size gaps of Pinus massoniana plantation were planted in the upper reaches of the Yangtze River, G4: 625 m ~ 2; G5: 900 m ~ 2; G6: 1 225 m ~ 2; G7: 1 600 m ~ 2), the quality loss rate and nutrient release rate of the litter of Pinus massoniana and Cinnamomum camphora were compared under the forest understory.The results showed that except for the release rate of potassium, the quality of two litters Loss rate and nutrient release rate were significantly higher than under the forest in the decomposition process of 1.5 years, the two kinds of litter leaf mass loss rate and carbon release rate showed a rising trend.Diet 90 d before decomposition, the mass loss rate of two litterfall And the release rate of nutrient was the fastest. After 90-360 days of decomposition, nitrogen and phosphorus enrichment occurred in some gaps; after 180-270 days and 1.5 years, potassium accumulation was observed in some gaps; The results showed that both litter and leaf litter had higher mass loss rate and nutrient release rate at the edges of medium size gaps (400, 600 and 900 m ~ 2) During the decomposition process, mass loss rate, carbon and nitrogen release rate were significantly and positively correlated with soil moisture content.The middle margin of 400-900 m 2 had more significant edge effect on litter decomposition, Therefore, in the transformation process of Pinus massoniana inefficient forests, the significant role of the margin of 400-900 m ~ 2 can be utilized to introduce native broad-leaved species to accelerate the material circulation of Pinus massoniana plantation , To maintain the woody soil.