全球旱地饱和水汽压差和根区土壤水分变化对植被生产力的影响及其成因  

Influences of vapor pressure deficit and root-zone soil moisture changes on vegetation productivity and its causes across global drylands

作　　者：於嘉禾 王卫光[1,2,3] 陈泽峰 YU Jiahe;WANG Weiguang;CHEN Zefeng(The National Key Laboratory of Water Disaster Prevention,Hohai University,Nanjing 210098,China;Yangtze Institute for Conservation and Development,Nanjing 210098,China;College of Hydrology and Water Resources,Hohai University,Nanjing 210098,China)

机构地区：[1]河海大学水灾害防御全国重点实验室,南京210098 [2]长江保护与绿色发展研究院,南京210098 [3]河海大学水文水资源学院,南京210098

出　　处：《生态学报》2024年第11期4808-4819,共12页Acta Ecologica Sinica

基　　金：国家自然科学基金(51979071)。

摘　　要：旱地约占全球陆地面积的40%,而水分是旱地植被生长的一大限制要素。尽管土壤水分与饱和水汽压差对植被生长的重要性已经得到了广泛证实,然而目前二者对植被生产力影响的空间异质性及其形成因素仍未得到深入研究,这对研究旱地生态系统对气候变化的响应带来了挑战。为了填补这一认知空白,研究收集了多源气象、根区土壤含水率和总初级生产力产品,基于随机森林算法量化了植被总初级生产力对根区土壤含水率和饱和水汽压差的敏感性,结合土地覆盖数据和分档平均方法分析了敏感性空间异质性的形成机制。结果表明:全球旱地饱和水汽压差与植被生产力总体呈显著上升趋势;根区土壤水分对植被生长的影响以正效应主导,饱和水汽压差对植被生长的影响以负效应主导;相较于森林和灌木,饱和水汽压差对植被生长的负效应及根区土壤含水率对植被生长的正效应在农田、草地和苔原及半干旱区更为强烈;植被生产力对饱和水汽压差和根区土壤水分的敏感性在数量上总体呈显著的线性负相关性。综上,植被种类和气候条件是导致全球旱地植被生产力对土壤水分和饱和水汽压差敏感性空间异质性的重要因素。Drylands account for about 40%of the global land area,while water is a major limiting factor for vegetation growth in drylands.Although the importance of the difference between soil moisture and vapor pressure deficit on vegetation growth has been widely confirmed,the spatial heterogeneity of the effects of soil moisture and vapor pressure deficit on vegetation productivity and its formation factors have not been studied deeply,which posed a challenge for researches on the response of dryland ecosystems to climate change.To fill this knowledge gap,the multi-source meteorology,root-zone soil moisture and the gross primary productivity products were collected to quantify the sensitivity of gross primary productivity to root-zone soil moisture and vapor pressure deficit with the random forest algorithm on the basis of landcover data and binned average analysis.The results showed that vapor pressure deficit and vegetation productivity increased significantly in global drylands.The effect of root-zone soil moisture on vegetation growth was dominated by positive effect while the effect of vapor pressure deficit on vegetation growth was dominated by negative effect.Compared with forest and shrub,the negative effect of vapor pressure deficit on vegetation growth and the positive effect of root-zone soil moisture on vegetation growth were more intensive in farmland,grassland,tundra and the semi-arid climate zone.The sensitivity of vegetation productivity to vapor pressure deficit and root-zone soil moisture had a significant negative linear correlation.In conclusion,vegetation species and climatic conditions are important factors contributing to the spatial heterogeneity of vegetation productivity sensitivity to soil moisture and saturated vapor pressure deficit across global drylands.

关 键 词：全球旱地 总初级生产力 根区土壤水分 饱和水汽压差 敏感性 干旱指数 

分 类 号：Q948[生物学—植物学]