2000-2020年长江中下游地区耕地生产力对气候变化的动态响应

Dynamics of cropland productivity in response to climate change in the middle and lower reaches of the Yangtze River from 2000 to 2020

长江中下游地区是我国重要的粮食产区,探究其耕地生产力对气候变化的动态响应,对于应对日益增长的人类需求和不断加剧的气候变化、保障粮食安全具有重要意义.以植被净初级生产力(NPP)作为耕地生产力的评价指标,从区域尺度和格网尺度上,分析2000-2020年长江中下游地区耕地NPP的时空变化特征,并量化NPP与气候因子(气温和降水)的相关性.结果显示:(1)从区域尺度上看,研究期间耕地NPP以3.42 g m^(-2)a^(-1)的速率呈波动上升趋势,并且在2013年出现了突变点.长江以南地区的耕地NPP要高于长江以北地区,离长江越远的耕地NPP越高;从格网尺度上看,研究期间大部分耕地的NPP呈上升趋势,但是未来可能呈增长放缓或退化趋势;(2)研究区耕地NPP与年降水量、年均气温呈正相关关系,降水的影响要强于温度;降水量对耕地NPP的影响具有显著的南北差异,降水与NPP呈正相关的耕地大部分位于长江以北地区,呈负相关的耕地大部分位于长江以南地区.气温与耕地NPP的相关关系在沿长江的梯度带上具有显著的空间差异,离长江越近,NPP与气温呈负相关的耕地越多.本研究表明气候变化的湿暖化促进了耕地植被的生长,耕地NPP对气候变化的响应具有显著的空间异质性.(图7表1参45)

The middle and lower reaches of the Yangtze River are important grain-producing regions.Understanding the dynamic impact of climate change on cropland productivity in this region is essential for effective management of cropland productivity and ensuring food security.In this study,net primary productivity(NPP)was used as the index of cropland productivity,and the spatiotemporal characteristics of cropland NPP from 2000 to 2020 were explored at regional and grid scales.The results showed that:(1)the mean cropland NPP value over the 21-year period was 502.37 g m-2 a-1,and the cropland NPP exhibited a fluctuating upward trend(slope=3.42 g m^(-2)a^(-1)),with an abrupt change point observed in 2013.Moreover,the NPP of croplands south of the Yangtze River was higher than that north of the Yangtze River,and NPP values increased with increasing distance from the Yangtze River.(2)Although most cropland areas experienced an upward trend in NPP during the study period,it is projected that a majority of croplands may exhibit a slowdown or degeneration trend in NPP in the future.(3)Generally,cropland NPP showed a positive correlation with precipitation and temperature,with precipitation exerting a stronger influence than temperature.(4)The impact of precipitation on cropland NPP differed significantly between the northern and southern regions.Positive correlations between precipitation and NPP were predominantly observed north of the Yangtze River,whereas negative correlations were prevalent in the south.In addition,the correlation between temperature and cropland NPP exhibited significant spatial differences along the Yangtze River gradient,with a higher occurrence of negative correlations closer to the river.Overall,this study demonstrated that humidification and warming trends associated with climate change improved cropland NPP in the study area.However,the response of cropland NPP to climate change exhibited significant spatial heterogeneity.