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| Relationship between stand structure and hydrological functions of typical water conservation forests in Liupan Mountains of Ningxia |
| Sun Hao1, Yang Minyi2, Yu Yangchun3, Xiong Wei1, Wang Yanhui1, Cao Gongxiang1,Du Min4, Wang Yunni1, Yu Pengtao1, Xu Lihong1, Zuo Haijun1 |
1.The Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, 100091, Beijing, China;
2.The Forestry Administration of Yuanzhou District, 756000, Guyuan, Ningxia, China;
3.Liupanshan Forestry Bureau of Ningxia, 756401, Guyuan, Ningxia, China;
4.College of Forestry, Central South University of Forestry and Technology, 410002, Changsha, China |
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Abstract To quantify the relationship between stand structure and hydrological functions of water conservation forests, the characteristics of forest structure, interception of canopy and litterfall, and evapotranspiration from understory layer were studied in four forest stands with different structures (i. e. ,mixed forest of Larix principis-rupprechtii and shrub, pure L. principis-rupprechtii forest, mixed shrubs with sparse arbor trees, natural shrubs) during the growing season, which were located at a small catchment of Xiangshuihe of Liupan Mountains of Ningxia. The results showed that there were significant differences in hydrological functions between forest stands. The order of canopy interception percentage was natural shrubs (25.92%) > pure Larix forest (23.38%) > mixed Larix forest and shrubs (22.81%) > mixed shrubs (22.07%). The water holding capability of litter followed the order of mixed Larix forest (26.49 t/ hm2) > pure Larix forest (23.06 t/ hm2) > mixed shrubs (16.89 t/ hm2) > natural shrubs (14.45 t/ hm2), which might be the result of the depth and composition of litterfall. The daily mean evapotranspiration of understory layer of mixed shrubs was the highest (1.09 mm/ d) among the four stands, followed by mixed Larix forest (0.96 mm/ d), while pure Larix forest (0.88 mm/ d) and natural shrubs (0.69 mm/ d) were lower, and it was possibly attributed by the difference in light distribution in the forest floor among stands due to different canopy structures. Regression analysis showed that canopy interception increased with increasing leaf area index (LAI), and the relationships can be well-described in an exponential function (P < 0.01) at different rainfall intensities (except for heavy rain). Excluding the interference of meteorological factors outside the stands to the forest microenvironment, evapotranspiration of understory layer decreased with increasing LAI following a logarithm function (R2 =0.639, P <0.01). It suggests that the changes in light and temperature caused by canopy structure are main reasons for soil water loss.
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Received: 20 March 2013
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