气候变化和人类活动对云南省植被净初级生产力的影响

Effects of Climate Change and Human Activities on Net Primary Productivity in Yunnan Province

深入理解气候变化和人类活动对植被变化的驱动机制对于生态保护和可持续发展有重要的科学意义。本研究基于MOD17A3/NPP产品数据,采用线性趋势分析、Mann-Kendall显著性分析、Hurst指数和二阶偏相关分析,探讨云南省2001-2021年植被NPP的时空分布特征和未来持续性以及植被NPP与气候条件的关系。采用偏导趋势残差法分离和量化气候变化和人类活动对植被NPP的影响。结果发现,空间上,2001-2021年云南植被NPP年均值南高北低。不同植被类型NPP值(单位:gC∙m^(-2))从大到小依次为:林地(1106.7 gC∙m^(-2))、灌木(964.4 gC∙m^(-2))、农田(946.6 gC∙m^(-2))和草地(878.8 gC∙m^(-2))。植被NPP随海拔上升先增后降。(2)在研究时段内,植被NPP年均值为1020.8±30.7 gC∙m^(-2),最小值和最大值分别出现在2010年(950.0)和2019年(1062.1)。植被NPP呈显著增加趋势,增加率为2.1 gC∙m^(-2)∙a^(-1)(p<0.05),增加和显著增加的面积分别占研究区总面积70.0%和26.3%。不同植被类型NPP的增加率(单位:gC∙m^(-2)∙a^(-1))从大到小依次为:草地(4.1 gC∙m^(-2)∙a^(-1))、农田(3.5 gC∙m^(-2)∙a^(-1))、灌木(2.8 gC∙m^(-2)∙a^(-1))和林地(1.3 gC∙m^(-2)∙a^(-1))。Hurst指数均值为0.60,植被NPP未来变化趋势持续增加和由减少转为增加的面积占总面积的55.5%和9.3%,表明大部分地区植被NPP未来仍将持续增加。(3)2001-2021年云南省平均气温显著增加,降水和太阳辐射波动减少。大部分地区植被NPP与气温、降水和太阳辐射正相关,气温对植被NPP的影响大于降水和太阳辐射。(4)气候变化和人类活动对云南植被NPP变化的相对贡献率分别为27.1%和72.9%,正贡献的面积分别占研究区总面积的59.4%和64.6%,相对贡献率>60%的面积占比分别为12.7%和73.4%。大部分地区人类活动对植被NPP的影响大于气候变化。云南植被改善主要受气候变化和人类活动的共同作用的影响,植被退化则主要受人类活动主导和两者共同作用的影响,生态保护、恢复工程对云南植被改善有着显著的促进作用。

Net primary productivity(NPP)directly and truly reflected the dynamic changing process of terrestrial vegetation ecosystem.Understanding the driving mechanism of climate change and human activities on vegetation change was of great scientific significance to ecological protection and sustainable development.Based on MOD17A3/NPP product,using linear trend analysis,Mann-Kendall significance analysis,Hurst index and partial correlation analysis,the temporal and spatial distribution characteristics of vegetation NPP in Yunnan Province from 2001 to 2021,the future sustainability and the relationship between vegetation NPP and meteorological conditions were discussed.Residual analysis used to quantitatively assess the relative contributions and combined action of climate change and human activities to the vegetation NPP.The result as follow:(1)Spatially,the annual mean NPP value of Yunnan vegetation from 2001 to 2021 was high in the south and low in the north.The order of values from the high to low was woodland(1106.7 gC∙m^(-2)),shrub(964.4 gC∙m^(-2)),agricultural land(946.6 gC∙m^(-2))and grassland(878.8 gC∙m^(-2))in different vegetation types.The vegetation NPP increased and then decreased with increasing altitude.(2)During the study period the annual mean vegetation NPP was 1020.8±30.7 gC∙m^(-2),with minimum and maximum values occurring in 2010(950.0 gC∙m^(-2))and 2019(1062.1 gC∙m^(-2)),respectively.The vegetation NPP showed a significant increase with an increase rate of 2.1 gC∙m^(-2)∙a^(-1)(p<0.05).The increasing and significantly increasing areas accounted for 70.0%and 26.3%of the total area of the study area,respectively.The vegetation NPP of different vegetation types showed a similar variation trend.The increasing rates showed grassland(4.1 gC∙m^(-2)∙a^(-1))>farmland(3.5 gC∙m^(-2)∙a^(-1))>shrub(2.8 gC∙m^(-2)∙a^(-1))>forestland(1.3 gC∙m^(-2)∙a^(-1)).The average value of the Hurst index was 0.60.The proportion of the area that would continue to increase and change from decrease to increase was 55.5%and 9.3%,respectively.This indicated that the vegetation NPP would continue to increase in most areas in the future.(3)The average temperature in Yunnan Province showed a significant increase from 2001 to 2021,while precipitation and solar radiation showed a fluctuating decrease.These climatic factors positively correlated with vegetation NPP in most areas,and the effect of temperature on vegetation NPP was greater than that of precipitation and solar radiation.(4)The relative contribution rates of climate change and human activities to vegetation NPP change in Yunnan were 27.1%and 72.9%,respectively,with positive contributions accounting for 59.4%and 64.6%of the total area of the study area,and relative contribution rate greater than 60%accounting for 12.7%and 73.4%of the area,respectively.The impact of human activities on vegetation NPP was greater than that of climate change in most areas.The vegetation improvement in Yunnan was mainly caused by the combined effect of climate change and human activities,while the degradation was mainly caused by the human activities and the combined effect.The ecological protection and restoration projects had a significant contribution to the improvement of vegetation NPP in Yunnan.