重庆铁山坪马尾松天然次生林降雨截持与贮水特征

马尾松林是三峡库区防护林体系中最重要的森林类型，然而以往对结构更为复杂的马尾松天然次生林的生态水文效应研究还很不足，限制着全面了解和准确评价库区森林发挥的涵养水源服务功能。以重庆铁山坪的马尾松天然次生林为对象，采用定位监测结合室内测定的实验方法，系统研究了林冠层、林下草本层、枯落物层、土壤层的水文特征。结果表明：（1）2010-2011年马尾林穿透雨量、干流量、林冠截留量分别占总降雨量（1972.39 mm）的84.66%、0.26%和15.07%，且均与次降雨量呈显著正相关（P<0.01），其中干流在次降雨量达到5 mm时产生；林冠截留量随次降雨量增大而逐渐达到饱和（6 mm左右）。（2）林下草本植物的地上生物量达1.32 t/hm²，其持水率随浸水时间呈对数函数增加（P<0.01），最大持水量为0.61 mm。（3）枯落物贮存量达10.74 t/hm²，未分解、半分解、未分解与半分解混合枯落物的最大持水率为183.76%、206.31%和197.62%，未分解与半分解层枯落物的最大持水能力达1.44 mm。（4）0-80 cm土层的饱和贮水量达334.75 mm，其中滞留贮水量达49.08 mm，占饱和贮水量14.66%。马尾松天然次生林各作用层的降雨截持及贮水作用明显，其中尤以土壤层贮水能力最强。研究结果可为三峡库区森林涵养水源服务功能模拟与评价提供重要参考依据。

The characteristics of rainfall interception and water storage of the natural secondary forests of Masson pine at Tieshanping of Chongqing

The Three Gorges Reservoir area is the largest strategic reserve of fresh water resources in China, and its ecological location is extremely important in the Yangtze River region. Therefore, it is very necessary and crucial to build the protection forest system with water conservation as the main function in the Three Gorges Reservoir area. Masson pine forest is the most important forest type in the protection forest system of the Three Gorges Reservoir area. However, the eco-hydrological effects of natural secondary forest of Masson pine with more complex structure was not studied enough in the past, which led to a limitation to the complete understanding and the accurate evaluation of the water conservation service of the forests of the Three Gorges Reservoir area. Therefore, the hydrological effects of all functional layers (forest canopy layer, undergrowth herbaceous layer, humus layer and soil layer) of the natural secondary forests of Masson pine were systematically studied at Tieshanping of Chongqing, based on the field positioning observation and laboratory measurement. The results showed that:(1) the throughfall, stemflow and interception of Masson pine forests accounted for 84.66%, 0.26% and 15.07% of total precipitation (1972.39 mm) in 2010 and 2011, respectively, and all presented a significantly positive relation (P< 0.01) with the rainfall depth of individual rainfall events. The stemflow began to appear only when rainfall was more than 5 mm. The rainfall interception increased gradually with rising rainfall depth to its maximum value of about 6 mm. (2) The aboveground biomass of the undergrowth herbaceous was 1.32 t/hm². The water amount absorbed by the herbaceous increased logarithmically with soaking time (P<0.01) until to its maximum value of 0.61 mm. (3) The humus layer amounted to 10.74 t/hm². The ratios of the maximum water-holding capacity of the un-decomposed humus, half-decomposed humus, and mixture of un-decomposed and half-decomposed humus were 183.76%, 206.31% and 197.62%, respectively. The maximum water-holding capacity of both the un-decomposed and half-decomposed humus layer was 1.44 mm. (4) The saturated water-holding capacity of the soil layer (0-80 cm) was 334.75 mm, in which the non-capillary water-holding capacity was 49.08 mm (14.66%). In summary, all functional layers of the natural secondary forests of Masson pine in the studied site present an obvious service of rainfall interception and water storage, and especially the service of the soil layer is the highest. The result of this study can provide an important basis for the simulation and evaluation of the water conservation service of the forests in the Three Gorges Reservoir area.