The lower timberline is a special eco-geographic phenomenon in the dry valley background. Research on the positioning and comparison of lower timberline could reveal the relationship between mountain environmental changes and environmental influence from anthropic activities. Based on remote sensing data and cluster analysis of Geographic Information System (GIS), the research took the lower timberline in the upper reaches of Minjiang River as an investigated object. By comparing the lower timberline in 1999 and 2009, this paper analyzed the lower timberlines of the settlement area and non-settlement area, respectively, and revealed the spatially distributed characters and moving rules of the lower timberline were revealed. The results show that: 1) The lower timberline is characterized by cluster distribution and mainly concentrates in the upper part of V-shaped valley ranged from 1400 m to 3800 m. This character is consistent with distribution of precipitation along altitude. 2) The peak values of lower timberline were observed on the slopes of 6°~15°. Furthermore, the lower timberline values clearly decrease as the increase of slope. 3) The distribution of lower timberline varies significantly with slope. The lower timberline on the southern slope is obviously higher than that on the northern slope, and that in the eastern part is higher than that in the western. The lowest altitude of lower timberline is found in the northwest. The altitude distribution of lower timberline is related to shady slope, which is more suitable for growth of vegetation than sunny slope owing to more moisture. 4) The spatial variation of the lower timberline in the settlement area is different from that in the non-settlement area. The lower timberline in the settlement area spatially moves downward by 108.6 m from 1999 to 2009, but in the non-settlement area by 38 m. The spatially moving downward degree of lower timberline caused by human activities such as the Grain-for-Green Project is larger than that caused by natural factors in the non-settlement area. This result could provide scientific basis for evaluating the effect of the Grain-for-Green Project on mountain environmental change.
翟真, 王青. 岷江上游林树下线地理分布格局及其空间移动特征[J]. 地理研究, 2015, 34(11): 2105-2112.
ZHAI Zhen, WANG Qing. The geography distribution pattern and spatial move of the lower timberline in the upper reaches of Minjiang River. GEOGRAPHICAL RESEARCH, 2015, 34(11): 2105-2112.
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