Earlier Precipitation Enhances Dryland Annual Primary Production

Abstract

AbstractClimate change is causing shifts of precipitation seasonality that is anticipated to cause variations in terrestrial primary production over many parts of the world. However, how vegetation production responds differently to shifting seasonal precipitation timing along bioclimate gradients remains unclear. Here, we used two proxies of primary production, namely gross primary production and sun‐induced chlorophyll fluorescence derived from satellite observations over 2001–2020 to investigate the effects of advanced or delayed precipitation on interannual variations in production along a wide range of aridity gradient and vegetation types in China. We found contrasting responses of primary production between dryland and humid ecosystems. In the dryland, earlier precipitation greatly enhanced annual accumulated production, owing to higher soil moisture during the early growing season that often lasted to the late growing season by lagged effect. However, delayed precipitation depressed production throughout growing season because of the decreased ability of vegetation to absorb and utilize light energy, even though water stress was alleviated during late growing season. Conversely, in the humid region, advanced precipitation led to slight decreases of annual production as a result of combined effects of lower radiation and lagged leaf flush during the early growing season. It is necessary to consider the effects of shifting precipitation seasonality on terrestrial primary production as a driver of changes in carbon uptake capacity, especially in dryland.