Aboveground biomass and their changes in the eastern Inner Mongolia grasslands during 2001–2011

摘要

In this study, we evaluated the precision of different regression models correlating grasslands aboveground biomass (AGB) and its corresponding vegetable index (VI). We further identified changes in the size and distribution of AGB and explored the relationships between interannual AGB pattern and climatic factors in the eastern Inner Mongolia grasslands by integrating AGB data collected from 520 sites and vegetation index (VI) derived from MODIS data sets during 2001–2011. Our results are summarized as follows: (1) the exponential model of mean NDVI in peak season for estimation AGB showed the highest precise. (2) During 2001∼2011, grassland AGB averaged 18.78Tg (1Tg=10¹²g) over a total area of 16.3×10⁴ km², showing a slight decrease trend in the study area (R²=0.15, p=0.22). The higher AGB density appeared north and northeast (>200 g/m²), and the lower AGB density appeared south and west (<200g/m²). (3) Interannual AGB variation was coupled well with interannual precipitation pattern, and the relationship between AGB and precipitation is positive (R²=0.28, p=0.10). However, we did not find a robust relationship between AGB and the same temporary temperature (R²=0.009, p=0.79). It suggested that the interannual AGB variation was mainly derived by precipitation fluctuation (January–July), and the temperature changes at the corresponding time might be a minor factor.