College of Hydrology and Water Resources, Hohai University, Nanjing, China.
National Earth System Science Data Center, National Science & Technology Infrastructure of China, Beijing, China.
Int J Biometeorol. 2020 Aug;64(8):1343-1354. doi: 10.1007/s00484-020-01913-0. Epub 2020 Apr 18.
Spring greening has been widely observed across the Northern Hemisphere (NH) using a remotely sensed vegetation index (e.g., the normalized difference vegetation index, NDVI). However, there is still a debate on the ecological effects of spring greening on seasonal carbon and water budgets. This study jointly investigated the concurrent and lagged effects of spring greening on carbon gain (gross primary productivity, GPP) and water loss (evapotranspiration, ET) in the summer-active ecosystems at mid and high latitudes of NH using remote sensing and multimodel ensemble data during 1982-2013. The results showed that the collective promotion of spring greening to concurrent GPP and ET is widespread despite variations in magnitude and significance. Both beneficial and adverse lagged effects of spring greening on summer GPP commonly appear with an obvious spatial heterogeneity and difference among climate-plant types. However, the expected significant suppression of spring greening to summer GPP was rarely observed even in the areas where spring ET was significantly promoted by spring greening. Nevertheless, when drought was taken into account, the response patterns of spring water use to spring greening varied to some extent, and the adverse lagged effect of spring greening to summer GPP appeared or strengthened in some regions, especially during the years with dry summer. Given the predicted warming of the climate and more frequent climatic extremes, the adverse effect of spring greening should be given more attention.
春季变绿现象在北半球（NH）已经得到了广泛的观测，这一现象可以通过遥感植被指数（如归一化差异植被指数 NDVI）来进行监测。然而，关于春季变绿对季节性碳和水预算的生态影响，仍存在着争议。本研究联合利用遥感和多模式集合数据，于 1982-2013 年期间，在中高纬度的 NH 地区，对夏季活跃生态系统中春季变绿对碳增益（总初级生产力，GPP）和水分损耗（蒸散，ET）的同期和滞后效应进行了联合研究。结果表明，尽管幅度和显著性存在差异，但春季变绿对同期 GPP 和 ET 的促进作用是普遍存在的。春季变绿对夏季 GPP 的滞后效应既有有利的也有不利的，并且具有明显的空间异质性和气候-植被类型差异。然而，即使在春季 ET 因春季变绿而显著增加的地区，也很少观察到对夏季 GPP 的预期显著抑制作用。然而，当考虑到干旱时，春季水利用对春季变绿的响应模式在一定程度上有所变化，并且在某些地区，春季变绿对夏季 GPP 的滞后不利影响出现或增强，尤其是在夏季干旱的年份。鉴于气候的预测变暖以及更频繁的气候极端事件，春季变绿的不利影响应该得到更多的关注。
