粤港澳大湾区植被CUE变化及与气候变化的关系

基于MOD17数据，采用趋势分析和相关分析法，研究了2000~2019年粤港澳大湾区植被生产力和植被碳利用率（CUE）变化及其与气候变化的关系.结果表明，粤港澳大湾区总初级生产力（GPP）和净初级生产力（NPP）均值分别为1.80和0.89kg·C/m²，呈中部低四周高的空间格局，CUE均值为0.51，呈中部和东南部略高于四周的空间格局；GPP和NPP总体呈增加趋势，其年际变化率均值分别为0.01和0.001kg·C/（m²·a），GPP年增长率远高于NPP年增长率，不同植被类型GPP和NPP也呈增加趋势.植被CUE则呈逐年下降趋势，其年际变化率均值为-0.002a^-1，由于气候因子变化对光合作用速率和呼吸作用速率产生的不同程度影响，从未来发展趋势看，68.22%的区域表明CUE仍呈下降趋势，植被碳固定能力减弱；不同植被类型CUE存在差异，其中农田CUE平均值最高，为（0.511±0.014），森林和草地CUE分别为（0.500±0.019）和（0.501±0.020），从变化趋势看，不同植被类型CUE呈极显著下降趋势（P < 0.01）；GPP与气温、累积降雨和累积净太阳辐射量总体呈正相关关系，其所占比例分别为94.52%、53.36%和90.58%，NPP与气温、累积降雨和累积净太阳辐射量总体上也表现为正相关关系，其所占比例分别为86.86%、71.10%和85.97%.然而，CUE与气候因子的关系却有所不同.CUE与气温和累积降雨呈正相关关系，但与累积太阳辐射呈负相关关系，不同植被类型GPP、NPP和CUE与气温、累积降雨量呈正相关关系，GPP和NPP与累计净太阳辐射呈正相关关系，但CUE与累积太阳辐射却呈负相关关系.

Spatiotemporal variation of CUE and its correlation with climate change in Guangdong-Hong Kong-Macao Greater Bay Area

The variation and correlation with climate change of vegetation productivity (GPP and NPP) and CUE in Guangdong-Hong Kong-Macao Greater Bay Area (GBA) were analyzed based on trend analysis and correlation analysis by using MOD17 dataset during 2000~2019. Our results indicated that: (1) the mean value of GPP, NPP and CUE were 1.80kg·C/m², 0.89kg·C/m² and 0.51, respectively. The spatial patterns of GPP and NPP displayed an increase trend from middle part of the GBA to the around, while CUE showed an inverse spatial pattern. (2) GPP and NPP showed an increase trend during the period of 2000~2019 with the change rate of 0.01kg·C/(m²·a) and 0.001kg·C/(m²·a), respectively, and the variation rate of GPP was higher than that of NPP. The increasing trends of GPP and NPP among vegetation types were also observed. However, CUE displayed a decrease trend at approximately -0.002a^-1, and more than 68% of the whole area showed a decrease CUE in future, which indicated a gradually weakened capacity of vegetation carbon sequestration due to the possible reasons of different sensitive of photosynthesis and autotrophic respiration caused by cumulative net solar radiation. Additionally, the highest CUE was found for farmland, approximately (0.511±0.014), followed by forest and grassland, and the CUE were (0.500±0.019) and (0.501±0.020), respectively. Moreover, CUE for different vegetation types were all displayed a significant decreasing trend (P < 0.01) during study period. (3) GPP was positively correlated with temperature, cumulative precipitation and cumulative net solar radiation, and accounted approximately 94.52%, 53.36% and 90.58%, respectively. The relationship between NPP and climate factors was similar to that of GPP, and the proportion were 86.86%, 71.10% and 85.97%, respectively. However, positive relationships were found between CUE and temperature and cumulative precipitation, while negative relationship was found between CUE and cumulative net solar radiation. Similarly, GPP and NPP were all positive with climate factors for different vegetation types, and relationship between CUE and temperature as well as cumulative precipitation for different vegetation types were also positive. However, negative relationship was found between CUE and cumulative net solar radiation for three vegetation types.