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Article

Temporal and Spatial Variations in the Leaf Area Index and Its Response to Topography in the Three-River Source Region, China from 2000 to 2017

1
College of Earth Science, Chengdu University of Technology, Chengdu 610059, China
2
Research Center for Digital Mountain and Remote Sensing Application, Institute of Mountain Hazards and Environment, CAS, Chengdu 610041, China
3
School of Surveying and Land Information Engineering, Henan Polytechnic University, Jiaozuo 454000, China
4
Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions (Henan University), Ministry of Education, Kaifeng 475004, China
*
Author to whom correspondence should be addressed.
ISPRS Int. J. Geo-Inf. 2021, 10(1), 33; https://0-doi-org.brum.beds.ac.uk/10.3390/ijgi10010033
Received: 26 October 2020 / Revised: 4 January 2021 / Accepted: 11 January 2021 / Published: 13 January 2021
The Three-River Source Region (TRSR) is an important area for the ecological security of China. Vegetation growth has been affected by the climate change, topography, and human activities in this area. However, few studies have focused on analyzing time series tendencies of vegetation change in various terrain conditions. To address this issue in the TRSR, this study explored vegetation stability, tendency, and sustainability with multiple methods (e.g., coefficient of variation, Theil-Sen median trend analysis, Mann-Kendall test, and Hurst index) based on the 2000–2017 Global LAnd Surface Satellite Leaf Area Index (GLASS LAI) product. The differentiation patterns of LAI variations and multiyear mean LAI value under different topographic factors were also investigated in combination with digital elevation model (DEM). The results showed that (1) the mean LAI value in the study area increased, with a linear tendency of 0.013·10 a−1; (2) LAI values decreased from southeast to northwest in terms of spatial distribution and the CV indicated LAI variations were relatively stable; (3) the trend analysis revealed that the improved area of LAI accounted for 62.72% which was larger than the degraded area (37.28%), and hurst index revealed a weak anti-sustaining effect of the current tendencies; and (4) the increasing trend was found in multiyear mean LAI value as relief amplitude and slope increased, while LAI stability improved with increasing slope. They exhibited a clear regular pattern. Moreover, significant improvement in LAI generally occurred in low-altitude and flat areas. Finally, the overall improvement and sustainability of LAI improved when moving from sunny aspects to shady aspects, but the LAI stability decreased. Note that vegetation degradation was observed in some high slope areas and was further aggravated. This study is beneficial for revealing the spatial and temporal changes of LAI and their changing rules as a function of different topographic factors in the TRSR. Meanwhile, the results of this study provide theoretical support for sustainable development of this area. View Full-Text
Keywords: Three-River Source Region; leaf area index; vegetation changes; topographic effect Three-River Source Region; leaf area index; vegetation changes; topographic effect
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MDPI and ACS Style

Zhang, W.; Jin, H.; Shao, H.; Li, A.; Li, S.; Fan, W. Temporal and Spatial Variations in the Leaf Area Index and Its Response to Topography in the Three-River Source Region, China from 2000 to 2017. ISPRS Int. J. Geo-Inf. 2021, 10, 33. https://0-doi-org.brum.beds.ac.uk/10.3390/ijgi10010033

AMA Style

Zhang W, Jin H, Shao H, Li A, Li S, Fan W. Temporal and Spatial Variations in the Leaf Area Index and Its Response to Topography in the Three-River Source Region, China from 2000 to 2017. ISPRS International Journal of Geo-Information. 2021; 10(1):33. https://0-doi-org.brum.beds.ac.uk/10.3390/ijgi10010033

Chicago/Turabian Style

Zhang, Wenqi, Huaan Jin, Huaiyong Shao, Ainong Li, Shangzhi Li, and Wenjie Fan. 2021. "Temporal and Spatial Variations in the Leaf Area Index and Its Response to Topography in the Three-River Source Region, China from 2000 to 2017" ISPRS International Journal of Geo-Information 10, no. 1: 33. https://0-doi-org.brum.beds.ac.uk/10.3390/ijgi10010033

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