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| Implication of various growth characteristics of slope forests of Larix principisrupprechtii for indicating the water-carrying capacity of forest/vegetation in Diediegou of Liupan Mountains of China |
| Han Xinsheng1,2,3, Wang Yanhui2, Deng Lilan3, Xiong Wei2, Yu Pengtao2, Li Zhenhua2,Wang Yanbing2, Liu Qian2 |
| 1. Institute of Desertification Control, Ningxia Academy of Agriculture and Forestry Sciences, 750002, Yinchuan, China; 2. Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Key Laboratory of Forestry Ecology and Environment of State Forestry Administration, 100091, Beijing, China; 3. Forestry College of Southwest Forestry University, 650224, Kunming, China |
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Abstract Water shortage is often the key limitation for the vegetation distribution and forest growth in arid and semi-arid regions. It is necessary to select rational vegetation growth parameters to indicate the water-carrying capacity of forest/vegetation, for guiding the vegetation restoration, the conversion of slope farmland to forests and the forest/ vegetation management taking hydrological impacts into account. Two representative slopes (a shady and a half-shady slope) covered by 27-year-old Larix principis-rupprechtii plantation in the small watershed of Diediegou within the semi-arid region of Liupan Mountains, northwestern China, were chosen for this study. Along the slope position downwards, six forest plots were established on each slope, the variation of growth characteristics of these plots were investigated, and the potential use of these growth characteristics as indicator of water-carrying capacity of forest/ vegetation was analyzed. It showed: 1) The tree growth on the half-shady slope is inferior to those on the shady slope, in terms of mean tree height, height of dominant trees, forest canopy Leaf Area Index, and total aboveground biomass of stands, indicating a lower water-carrying capacity on the half-shady slope than on the shady slope. 2) The forest canopy Leaf Area Index measured at the middle growing season for both slopes increases gradually from the upper to the lower slope position, reaches their maximum at the middle-down position, and thereafter decreases till to the slope foot. The overall tendency of variation along slope position for mean tree height, height of dominant trees, and total aboveground vegetation biomass is the same as that of forest canopy Leaf Area Index, but their maximum values mostly move downwards to the lower position of slope, and the decreasing tendency for tree height is accompanied with some fluctuation. 3) Based on a correlation analysis, the forest canopy Leaf Area Index is very significantly, positively related with the total aboveground vegetation biomass and the aboveground tree layer biomass, significantly positively related with the height of dominant trees, but not significantly related with the mean height of all trees, shrub and herb layer biomass. In addition, the density of existing trees has a very significantly positive correlation with the vegetation biomass. The integrated analysis of this study showed that the relatively easy-to-measure aboveground biomass of tree layer (and the total aboveground vegetation biomass) can be used to replace the Leaf Area Index as a parameter expressing the water-carrying apacity of forest/ vegetation, when the initial planting density and planting time are the same. In case of lack of biomass data, the height of dominant trees can be used as a parameter indicating the water-carrying capacity of forest/vegetation.
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Received: 21 November 2014
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