State Key Laboratory of Earth Surface Processes and Resource Ecology, College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China.
State Key Laboratory of Earth Surface Processes and Resource Ecology, College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China.
Sci Total Environ. 2018 Jan 15;612:347-357. doi: 10.1016/j.scitotenv.2017.08.212. Epub 2017 Sep 1.
Various climatic and hydrological variables such as precipitation, soil moisture, stream flow, and water level can be used to assess drought conditions, however, the response of ecosystem productivity to such metrics is not very clear. In this study, we examined the sensitivity of GPP anomalies to five drought indicators: the Standardized Precipitation Index (SPI), the Standardized Precipitation-Evapotranspiration Index (SPEI), Palmer Drought Severity Index (PDSI), deficit of soil moisture (DSM), and the difference between precipitation (P) and evapotranspiration (ET) (D(P-ET)). The global spatial distributions of drying and wetting trends from 2000 to 2014 determined by these five indices were similar. Additionally, the percent of drought-impacted areas decreased over the study period, indicating a reduction in drought conditions. GPP increased over the study period in the Northern Hemisphere (NH) but decreased in the Southern Hemisphere (SH), resulting in a net increase in global GPP. GPP anomalies were more sensitive to drought indices in the SH than in the NH. Among the five indices, GPP anomalies were most closely correlated with SPI in the NH (R=0.60, P<0.05) and SPEI in the SH (R=0.93, P<0.01). Regionally speaking, annual and seasonal GPP anomalies were most sensitive to DSM and PDSI, highlighting the importance of soil moisture observations to regional drought monitoring and assessment. The results of this study are important for evaluating the impacts of drought on ecosystem production and the global carbon cycle.
各种气候和水文变量，如降水、土壤湿度、水流和水位，可用于评估干旱状况，但生态系统生产力对这些指标的响应并不十分清楚。在本研究中，我们考察了 GPP 异常对五种干旱指标的敏感性：标准化降水指数（SPI）、标准化降水蒸散指数（SPEI）、帕尔默干旱严重指数（PDSI）、土壤湿度亏缺（DSM）和降水（P）与蒸散（ET）之间的差值（D（P-ET））。这五个指标确定的 2000 年至 2014 年全球干湿趋势的空间分布相似。此外，在研究期间，受干旱影响的地区比例下降，表明干旱状况有所缓解。研究期间，北半球（NH）的 GPP 增加，但南半球（SH）的 GPP 减少，导致全球 GPP 净增加。GPP 异常对南半球干旱指标的敏感性高于北半球。在这五个指标中，GPP 异常与北半球的 SPI（R=0.60，P<0.05）和南半球的 SPEI 相关性最高（R=0.93，P<0.01）。就区域而言，年际和季节性 GPP 异常对 DSM 和 PDSI 最敏感，这凸显了土壤湿度观测对区域干旱监测和评估的重要性。本研究的结果对于评估干旱对生态系统生产力和全球碳循环的影响具有重要意义。
