亚热带地区3种喀斯特林分凋落物组成对其持水性能的影响

Effect of Litter Composition on Its Water Holding Capacity for Three Typical Karst Forest Types in Subtropical Region

[目的]揭示亚热带不同喀斯特林分凋落物组成对其持水性能的影响,为丰富森林生态水文研究和加深凋落物层与水文功能关系的认识提供科学依据。[方法]收集亚热带喀斯特区的青冈林、青冈+光蜡树林、化香树+密花树林3种代表性林分的凋落物层,将其分为半分解、未分解枝、未分解叶和其他未分解凋落物4种成分,选择每种林分前3种主要成分分别按0%,20%,40%,60%,80%和100%比例混合成21组质量相同、组成比例不同的处理(3种林分共63组处理)。采用浸水法研究其持水性能。[结果]①3种林分类型不同组成凋落物的持水率和吸水速率分别与浸水时间呈对数函数关系(R^(2)≥0.718)和幂函数关系(R^(2)≥0.998);在各浸水时段的持水率和吸水速率以化香树+密花树林纯未分解叶凋落物最大,青冈+光蜡树林纯未分解枝凋落物最小;②凋落物的持水率和吸水速率均与未分解叶比例呈极显著正相关关系(p<0.01),与未分解枝的比例呈极显著负相关关系(p<0.01),与半分解凋落物的比例无明显关系;③3种林分类型凋落物层的总蓄积量及其最大持水量无显著差异,但青冈林凋落物层的最大吸水速率显著高于化香树+密花树林。[结论]凋落物组成显著影响其持水性能。在凋落物生态水文效应研究中应综合考虑凋落物蓄积量及其组成的影响。

[Objective]The effect of litter composition on its water holding capacity for three different karst forest types in subtropical region was determined in order to provide a scientific basis for enriching forest ecohydrological research and deepening the understanding of the relationship between litter and hydrological functions.[Methods]Litters were collected from three representative karst forest types,i.e.,Cyclobalanopsis glauca forest,Cyclobalanopsis glauca+Fraxinus griffithii forest,and Platycarya strobilacea+Myrsine seguinii forest in subtropical region.The litters were sorted into four components:semi-decomposed litter,undecomposed branches,undecomposed leaves,and undecomposed other litter forms.The first three main litter components of each forest type were mixed at the ratios of 0%,20%,40%,60%,80%,and 100%with the same total weight,resulting in 21 groups for each forest type.The water holding capacities of the 63 litter groups were compared based on laboratory soaking experiments.[Results]①The relationships of the water holding rate and the water absorption rate with soaking time were determined by logarithmic function(R^(2)≥0.718)and power function(R^(2)≥0.998).The highest value was observed in the group of undecomposed leaf litter of P.strobilacea+M.seguinii forest,while the lowest value was observed in the group of undecomposed branch litter of C.glauca+F.griffithii forest.②The water holding rate and water absorption rate of litters had significant positive correlations with the proportion of undecomposed leaves(p<0.01),significant negative correlations with the proportion of undecomposed branches(p<0.01),and no significant relationship with the proportion of half-decomposed litters.③No significant differences in the total accumulation of litters and their maximum water holding capacity were found among the three forest types,whereas the maximum water absorption rate of litter was significantly higher in C.glauca forest than in P.strobilacea+M.seguinii forest.[Conclusion]The water holding capacity of litter is significantly affected by its composition,and this factor should be taken into account in studies of the hydrological effects of litters.