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	The spatial pattern of grassland aboveground biomass on Xizang Plateau and its climatic controls
	Jiang Y. B.; Tao, J.; Huang, Y. Q.; Zhu, J. T.; Tian, L.; Zhang, Y. J.
	2015
关键词	aboveground biomass grassland vegetation index Xizang Plateau grain size precipitation adjusted vegetation index species-richness patterns net primary productivity remote-sensing approach temperate grassland epiphyllous liverworts precipitation gradient hyperspectral data tibetan plateau inner-mongolia
英文摘要	Aims Grassland is the most widely distributed vegetation type on the Xizang Plateau. Accurate remote sensing estimation of the grassland aboveground biomass (AGB) in this region is influenced by the types of vegetation indexes (VIs) used, the grain size (resolution) of the remote sensing data and the targeted ecosystem features. This study attempts to answer the following questions: (i) Which VI can most accurately reflect the grassland AGB distribution on the Xizang Plateau? (ii) How does the grain size of remote sensing imagery affect AGB reflection? (iii) What is the spatial distribution pattern of the grassland AGB on the plateau and its relationship with the climate? Methods We investigated 90 sample sites and measured site-specific AGBs using the harvest method for three grassland types (alpine meadow, alpine steppe and desert steppe). For each sample site, four VIs, namely, Normalized Difference VI (NDVI), Enhanced VI, Normalized Difference Water Index (NDWI) and Modified Soil-Adjusted VI (MSAVI) were extracted from the Moderate Resolution Imaging Spectroradiometer (MODIS) products with grain sizes of 250 m and 1 km. Linear regression models were employed to identify the best estimator of the AGB for the entire grassland and the three individual grassland types. Paired Wilcoxon tests were applied to assess the grain size effect on the AGB estimation. General linear models were used to quantify the relationships between the spatial distribution of the grassland AGB and climatic factors. Important Findings The results showed that the best estimator for the entire grassland AGB on the Xizang Plateau was MSAVI at a 250 m grain size (MSAVI(250) (m)). For each individual grassland type, the best estimator was MSAVI at a grain size of 250 m for alpine meadow, NDWI at a grain size of 1 km for alpine steppe and NDVI at a grain size of 1 km for desert steppe. The explanation ability of each VI for the grassland AGB did not significantly differ for the two grain sizes. Based on the best fit model (AGB = -10.80 + 139.13 MSAVI(250 m)), the spatial pattern of the grassland AGB on the plateau was characterized. The AGB varied from 1 to 136 g m(-2). Approximately 59% of total spatial variation in the AGB for the entire grassland was explained by the combination of the mean annual precipitation (MAP) and mean annual temperature. The explanatory power of MAP was weaker for each individual grassland type than that for the entire grassland. This study illustrated the high efficiency of the VIs derived from MODIS data in the grassland AGB estimation on the Xizang Plateau due to the vegetation homogeneity within a 1 x 1 km pixel in this region. Furthermore, MAP is a primary driver on the spatial variation of AGB at a regional scale.
出处	Journal of Plant Ecology
卷	8
期	1
页	30-40
收录类别	SCI
语种	英语
ISSN号	1752-9921
内容类型	SCI/SSCI论文
源URL	[http://ir.igsnrr.ac.cn/handle/311030/38674]
专题	地理科学与资源研究所_历年回溯文献
推荐引用方式 GB/T 7714	Jiang Y. B.,Tao, J.,Huang, Y. Q.,et al. The spatial pattern of grassland aboveground biomass on Xizang Plateau and its climatic controls. 2015.

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