内蒙古西部草原地上生物量的遥感估算

利用2005-2011年内蒙古西部草原756个地面调查样方与2001-2011年MODIS NDVI数据集,建立统计模型,估算了内蒙古西部草原地上生物量,并探索了地上生物量与气候因子的关系.结论如下:①内蒙古西部草原地上生物量2001-2011年均值为5.27 Tg(1 Tg=1012g).2001-2011年间,内蒙古西部草原地上生物量呈波动状态且略有下降趋势.②内蒙古西部草原地上生物量的空间差异显著,总体自东南向西北逐步降低.③内蒙古西部草原地上生物量年际波动的主要驱动因子是1-7月的降水量,而与同期气温无显著关系；降水量同样是决定地上生物量空间分布的重要因素,而气温的影响较弱.本研究的估值仍存在一定的不确定性,主要来源于样方的采集标准差异、样方生物量的折算偏差、灌木生物量的低估与遥感数据集误差.

Estimation of Aboveground Biomass by Remote Sensing in the Western Inner Mongolia Grassland

Using 756 field aboveground biomass (AGB) samples from the western Inner Mongolia grassland during 2005-2011, and MODIS-NDVI 16-day tiled product with a spatial resolution of 500 m×500 m during 2001-2011, we identified the size and distribution of aboveground biomass with statistic model and explored possible relationships between spatio-temporal pattern of AGB and climatic factors for the studied area. Results are summarized as follows: (1) AGB averaged 5.27 Tg in the western Inner Mongolia grassland during 2001-2011, experiencing a slight decrease trend. (2) AGB density exhibited a large spatial heterogeneity in the western Inner Mongolia grassland, and decreased from the southeast to the northwest. (3) AGB variation was in good accordance with inter-annual precipitation from January to July, but did not show a robust relationship with the temperature changes at the corresponding time. Precipitation was also a primarily determinant of the spatial pattern of AGB in the studied area, and the temperature might be a minor factor. However, the estimation has limitations due to uncertainties in the standards of field measurement, the uniform conversion factors that fresh grass yield converted to AGB (dry weight mass), underestimate of shrub biomass and satellite time series data sets.