京津冀植被净初级生产力时空分布及自然驱动因子分析

Spatiotemporal Distribution of Vegetation Net Primary Productivity in Beijing-Tianjin-Hebei and Natural Driving Factors

研究植被净初级生产力(Net Primary Productivity,NPP)的时空分布及其影响机制对全球陆地生态系统的变化及碳平衡有着重要的意义。基于MOD17A3HGF数据,综合气候、地形、土壤和植被4个方面的自然因子,利用趋势分析、变异系数及地理探测器等方法,探讨了2000—2019年京津冀NPP时空演变特征及空间分布的自然因子驱动机制。结果表明,(1)时间上,2000—2019年期间京津冀植被NPP整体呈显著增长趋势,增速为5.85 g·(m^(2)·a)^(−1)(以C计)。(2)空间上,NPP高值区主要集中在北部及西部的燕山和太行山脉,低值区主要集中在西北坝上高原以及东南部平原地区;京津冀植被整体恢复显著,2000—2019年期间80.29%的区域NPP呈显著增加趋势;NPP整体情况较为稳定,平均变异系数为17.25%,其稳定区域占京津冀总面积的36.31%。(3)2000—2019年期间,平均气温、海拔、土壤类型和坡度是影响植被NPP空间分布的最主要自然因素(q>30%,P<0.01),除平均风速外的其他因子对NPP的解释力呈上升趋势。(4)各自然因子的交互作用对NPP的影响表现出非线性增强及双因子增强作用,其中平均气温与土壤类型交互作用最强(q=0.6112)。

The spatio-temporal dynamics of Net Primary Productivity(NPP)and its drivers play a critical role in understanding the global changes of terrestrial ecosystems and corresponding carbon balance.Based on the MOD17A3HGF dataset,we studied the spatio-temporal evolution of NPP in the Beijing-Tianjin-Hebei region from 2000 to 2019 using the trend analysis and coefficient of variation.Driving mechanisms from natural factors including climate,topography,soil,and vegetation were also explored for NPP variations using the Geodetector model.Our results showed that,(1)The temporal variation of NPP in Beijing-Tianjin-Hebei presented a significant growth trend from 2000 to 2019,with an rate of 5.8447 g·(m^(2)·a)^(−1)(by C).(2)In terms of the spatial distribution,high-value areas of NPP were mainly located in the Yanshan and Taihang Mountains in the north and west of the study area;and low-value areas were mainly located in the Hauts Plat in the northwest and the plains in the southeast.From 2000 to 2019,the vegetation regeneration in Beijing-Tianjin-Hebei has resulted in a significant NPP increase for 80.29%of the area.The overall situation of NPP was relatively stable,with an average coefficient of variation of 17.25%.The stable area accounted for 36.31%of the total area.(3)From 2000 to 2019,the average temperature,altitude,soil type and slope were among the most important natural factors that drove the spatial distribution of NPP(q>30%,P<0.01).All natural factors except the average wind speed showed an increasing contribution in explaining the NPP variation.(4)The impact of interaction among the factors on NPP demonstrated a nonlinear and two-factor enhancement,with the strongest interaction existing between the average temperature and soil type(q=0.6112).