蒙古高原草地退化程度时空分布定量研究

为了实现大面积遥感定量评估蒙古高原草地退化状况,利用NDVI数据反演1982-2013年草地植被覆盖度,并以1982-1985年覆盖度作为基准数据,计算1986-1999年和2000-2013年草地退化指数。结果表明,1986-1999年和2000-2013年,蒙古高原草地覆盖度分别达到14.60%和18.43%,呈上升趋势;1986-1999年显著(P0.05)和极显著(P0.01)增加的面积分别为298.86和189.67 km2,2000-2013年增加面积分别为443.32和92.46 km2;相对1986年,2007年的草地覆盖度最差,2001和1995年也较差,而2013年草地覆盖度最好,表现为初期一般、中期变差、后期变好且好于初期;草地退化程度方面,1986-1999年重度退化草地面积所占百分比最大,达50.35%;2000-2013年中度和重度退化草地面积百分比分别是39.42%和30.34%,总和接近70%,草地退化状况有由极重度、重度向中度和轻度转变的趋势,草地趋于好转。

Research on the quantitative evaluation of grassland degradation and spatial and temporal distribution on the Mongolia Plateau

In this study,we used remote sensing technology to obtain a quantitative evaluation of the present situation of grassland degradation on the Mongolia Plateau.The time scale investigated was 1982 to 2013.We used NDVI data inversion vegetation coverage,and took vegetation coverage in the period 1982-1985 as the main indicator of ecosystem health.Furthermore,we calculated the grassland degradation index(GDI) and evaluated grassland degradation in the Mongolia Plateau during the period 1986-2013 to gain a quantitative estimate of the Mongolia Plateau grassland degradation time and space distribution characteristics.The results showed that the grassland vegetation coverage reached 14.60％ and 18.43％,respectively,in the periods 1986-2000 and 2001-2013,with both showing an increase trend.The areas of significant(P＜0.05) and highly significant (P＜0.01) increase were 298.86 and 189.67 km2 in the period 1986-1999,respectively,and the areas of significant (P＜0.05) and highly significant (P＜0.01) increase were 443.32 and 92.46 km2 in the period 2001-2013,respectively.Compared with 1986,the worst grassland coverage was in 2007,whereas it was poor in 2001 and 1995.The best grassland coverage was recorded in 2013.In terms of the GDI,in the period 1986-1999,severely degraded grassland area had the largest area percentage(50.35 ％),whereas in the period 2000-2013,the percentage areas of moderately and seriously degraded grassland were 39.42 ％ and 30.34％,respectively.Collectively,the results showed that grassland degradation conditions are improving on the Mongolia Plateau,from extremely serious and serious degradation to moderate and light grassland degradation.