甘肃省草地NPP时空变化及对气候因子的响应

本研究利用MOD17A3 NPP和气象数据对甘肃省天然草原2000—2019年净初级生产力(net primary productivity,NPP)进行动态监测,并利用趋势分析法和变异系数法研究近20年草地NPP时空变化规律与气候因子的响应。结果表明:近20年,甘肃省草地NPP呈波动上升趋势,增速达4.72 gC·m^-2·a^-1·(10a)^-1,草地NPP分布由东南向西北递减;20年间草地NPP呈显著增加趋势的面积占甘肃省草地的75.70%,主要分布在陇中黄土高原、河西走廊、祁连山地大部以及陇南山地;草地NPP变异系数小于0.15的面积仅占40.31%,以山地草甸、低地草甸和高寒草甸为主,草地NPP整体呈现高波动性;草地NPP与降水量的相关性最高,温性草原NPP对降水量的响应最敏感,温性荒漠草原次之,高寒草原对降水响应最低。综上所述,甘肃省草地NPP呈现增长趋势但稳定性低,对降水量的响应强于气温,生态工程对草地NPP具有促进作用,需长期实施。

Spatio-temporal Variation of NPP and its Response to Climate Factors in Grassland,Gansu Province

In this study,MOD17A3 NPP and meteorological data were used to monitor net primary productivity (NPP) dynamic of natural grassland in Gansu Province from 2000 to 2019. And spatio-temporal variation of NPP and its response to climate factors in the past 20 years were studied by means of trend analysis and variation coefficient method.The result showed that,NPP was on a fluctuating increased trend with a growth rate of 4.72 gC·m^-2·a^-1·(10a)^-1,and the NPP distribution was gradually decreased from southeast to northwest. The significantly increased area of NPP,which was mainly distributed in the Loess Plateau,Hexi Corridor,most of the Qilian Mountains and Longnan Mountains,was occupied 75.70% of the total grassland area in Gansu Province. The grassland area of NPP coefficient of variation less than 0.15 was only occupied 40.31%,taking mountain meadow,lowland meadow and alpine meadow as three main types. The overall NPP of grassland appeared with a high volatility. The correlation between NPP and precipitation was the highest,and the response sensitivity decreased in order of temperate steppe,temperate desert and alpine steppe. In conclusion,the ecological engineering should be continually implemented in Gansu province,because of its facilitation effect on NPP.