Earth system models predict that interannual variability in precipitation will increase under future climate change scenarios, including an increase in the frequency of extreme humid and extreme dry years. This increased interannual variation in precipitation could have profound implications for regional ecosystem carbon stocks and terrestrial carbon sequestration potential. Modelling-based and globally integrated studies have shown that productivity changes are highly uncertain in the context of increased interannual precipitation variability, which hampers accurate assessment of the impact of increased precipitation variability on ecosystem carbon stocks.
In this study, we used the data of a precipitation control experiment in the temperate semi-arid grassland of Inner Mongolia to explore the response of grassland carbon sinks to interannual changes in precipitation and its potential mechanism. Long-term meteorological records from 1953 to 2017 in the study area show a decreasing frequency in years with low precipitation variability and an increasing frequency in years with high precipitation variability. Based on precipitation fluctuations in the study area, three precipitation variability intensities (20%, 40%, and 60%) were defined in this study. The results showed that the sensitivity of total primary productivity (GPP) and ecosystem respiration (ER) to increasing precipitation was higher than that to reducing precipitation, resulting in a significant increase in the intensity of variation in precipitation. In addition, GPP responds more to precipitation changes than ER, resulting in increased precipitation variability significantly improving net ecosystem productivity (NEP), and NEP increases with increasing precipitation variability intensity. The results are partly explained by the increase in the proportion of species in plant communities that are more sensitive to increased precipitation under humid conditions, as well as the insensitive response of plant roots to reduced precipitation. The above findings also prove that the semi-arid grassland is more sensitive to extreme humid conditions, but has some resistance to extreme drought. This study provides direct evidence that increased interannual variation in precipitation increases the potential of ecosystems for carbon sequestration.
The results were published in Functional Ecology under the title "Increased interannual precipitation variability enhances the carbon sink in a semiarid grassland", which is an international mainstream journal of ecology (JCR Region 1 Top, 2021 impact factor 5.608, five-year impact factor 6.749). Dr. Ru Jingyi, a young teacher from the School of Life Sciences, is the first author of the paper, and Professor Wan Shiqiang is the corresponding author. Hebei University is the first unit and communication unit of this paper. This research was funded and supported by the National Natural Science Foundation of China
Link to the paper: https://doi.org/10.1111/1365-2435.14011