2000-2013年浑善达克沙地植被净初级生产力变化研究

Variation of vegetation net primary productivity in Hunshandak Sandyland during 2000-2013

利用卫星遥感资料和地面气象观测资料,基于CASA模型及其他数理方法估算了浑善达克沙地2000-2013年生长季(4-10月)植被净初级生产力(NPP),并对其时空变化特征进行了分析,讨论了气候因子和人类活动对植被净初级生产力的影响。结果表明:14年间,研究区生长季的植被净初级生产力呈波动中增加趋势,多年平均NPP为239.8 gC·m^(-2)·a^(-1)。整个研究区表现为高NPP值(大于150 gC·m^(-2)·a^(-1))的植被面积在增加,低NPP值(小于150 gC·m^(-2)·a^(-1))的植被面积在减少。在空间分布上,研究区的北部、中部和南部边缘区域的植被NPP增加趋势较明显,而东部和西部部分区域未发生明显的趋势性变化。总体而言,研究区植被净初级生产力变化趋势与降水量的关系更密切,其相关系数达到0.86,是驱动植被NPP年际波动的最直接因素。而与温度呈负相关,相关系数为-0.42。综合考虑气候因素和人类活动对沙地NPP的影响发现,温度降低、种饲料面积、年末牲畜存栏头数和羊的数量的减少是NPP值提高的关键因素。

Using remote sensing data and ground meteorological station data, sand land net primary productivity （NPP） during the growing season from 2000 to 2013 in Hunshandak Sandyland were estimated using CASA model, and the spatial-temporal characteristics of NPP were analyzed. Impacts of climatic factors and human activities on the sand land NPP were primarily revealed by statistical analysis. The results showed that the sand land NPP had increased by fluctuation during growing season in Hunshandak Sandyland from 2000 to 2013, with an average annual NPP of 239.8 gC·m-2·a-1 in the study area. The area of high NPP （NPP〉150 gC·m-2·a-1） had increased while that of low NPP （NPP〈150 gC·m-2·a-1） had decreased. In spatial pattern, the NPP in northern, central and southern fringe regions of the study area had increased, but no obvious trends had been observed in eastern and some of the western parts. As a whole, the annual NPP had depended more frequently on precipitation fluctuation. The correlation coefficient between NPP and precipitation was 0.86, indicating precipitation was the dominant driving force in vegetation dynamics. The correlation coefficient between NPP and temperature was -0.42. While temperature, sown area of feeding, the total livestock at the year-end and the number of sheep in Hunshandak Sandyland showed a decrease trend, the sand land NPP had increased rapidly and remarkably.