# Median to Strong Rainfall Intensity Favors Carbon Sink in a Temperate Grassland Ecosystem in China
## 4 Discussions
### Implications for Grassland C Cycling to Precipitation Patterns Change  
In conclusion, projected changes in the magnitude and frequency of precipitations necessitate identifying potential mechanisms of influence on carbon cycle in grasslands. Our study provides a fresh view in connection with changes in effects of rainfall patterns on the ecosystem carbon cycle. We found that net ecosystem CO2 uptake (-1*NEE) first increased, and then decreased, along with precipitation patterns, which was attributed to variations in soil moisture. In order to accurately evaluate the carbon cycle-precipitation relationship, we strongly suggest analyzing changes in rainfall treatments, especially for long-term events, taking into consideration ecological stress memory. We also found a discrepant relationship between rooting dynamics and soil moisture depth, highlighting that the response of root to precipitation may depend on rainfall patterns. Therefore, our conclusions on the effect of changes in rainfall patterns on plant root dynamics are helpful in understanding the response of plant communities to variations in rainfall regimes. Additionally, our results underscore the meaningful consideration of the relationship between NEE and soil temperature in the early growing season in current ecosystem models.  
The following are available online at [[http://www.mdpi.com/2071-1050/11/22/6376/s1](http://www.mdpi.com/2071-1050/11/22/6376/s1)]([http://www.mdpi.com/2071-1050/11/22/6376/s1](http://www.mdpi.com/2071-1050/11/22/6376/s1)), Figure S1: Daily precipitation (bars) and average soil moisture (0-40 cm, SWC, lines) during the growing season in 2015, 2016 and 2017 over a semarid grassland, Figure S2: Responses of aboveground biomass (AGB) to rainfall treatments. CK: ambient control, Figure S3: Responses of NEE (net ecosystem exchange), ER ( ecosystem respiration), and GPP (gross primary production) to different rainfall treatments in middle growing season (from June to August) in 2015, 2016 and 2017, Figure S4: The relationship between normalized NEE (net ecosystem exchange), ER (ecosystem respiration), and GPP (gross primary production) and soil moisture at different depth (0-10 cm and 10-20 cm) in early growing season, Figure S5: The relationship between NEE (net ecosystem exchange), ER (ecosystem respiration), and GPP (gross primary production) and soil moisture at different depth (0-10 cm and 10-20 cm) in early growing season, Table S1: Results (i.e., \(p\) values) of repeated measures ANOVAs on the effects of rainfall treatment (P), experimental year (Y), and their interactions on biotic and abiotic variables, Table S2: Results from linear mixed effects model analysis of SoilM (soil moisture) and SoilT (soil temperature) at the depth of 0-10 cm and 10-20 cm effects on NEE (net ecosystem exchange), ER (ecosystem respiration), and GPP (gross primary production) in early growing season (May to June), Table S3: Results from linear mixed effects model analysis of SoilM (soil moisture) and SoilT (soil temperature) at the depth of 0-10 cm and 10-20 cm effects on NEE (net ecosystem exchange), ER (ecosystem respiration), and GPP (gross primary production) in middle growing season (May to June).  
**Author Contributions:** Conceptualization, Z.H. and S.L.; methodology, Z.H., Q.G. and K.D.; data curation, K.D. and G.H.; writing--original draft preparation, Z.H. and G.H.; writing--review and editing, Z.H. and G.H.; funding acquisition, Z.H.  
**Funding:** This research was jointly supported by National Key R&D Program of China (2016 YFC0501603, 2017 YFA060481), the National Natural Science Foundation of China (Grant NO. 31922053, 31570437), and the Startup Foundation for Talented Scholars in South China Normal University (S82360).  
**Conflicts of Interest:** The authors declare no conflicts of interest.