Temporal and Spatial Variations of Vegetation Cover in Hulun Buir Grassland of Inner Mongolia, China

Abstract

We map temporal-spatial variation of vegetation cover in the grassland of Hulun Buir in northern China by analyzing remotely sensed data from MODIS. Results from our study indicate that vegetation cover in the grassland steadily decreased during 2000–09, with relatively high variations in both spatial and temporal dimensions. Average vegetation fractional cover (PV) was 0.56 for this period, with a maximum of 0.64 in 2002 and a minimum of 0.43 in 2007 when a massive drought occurred. In the early 2000s, the cover was approximately ∼0.60, dropping to ∼0.52 in 2007–09. The percentage of both dense (0.50 ≤ PV < 0.70) and very dense (PV ≥ 0.70) categories of grass gradually decreased by 6.58% during 2000–09, while the area of grasslands following into the bare surface (PV < 0.15) and very sparse (0.15 ≤ PV < 0.25) categories expanded up to 3.84 × 106 square kilometers over these ten years. The western part of the grassland where temperate steppe prevails had lower vegetation cover than the eastern part where lowland meadow and mountain meadow dominate. This variation of vegetation helps to understand ecosystem degradation on the grassland discussed in several studies though precipitation shortage and intensive grazing activities are the driving forces for the vegetation variation. Therefore, monitoring of vegetation change on the grassland is imperative for making sound environmental policies.