# Impact of Shifts in Vegetation Phenology on the Carbon Balance of a Semiarid Sagebrush Ecosystem
## 5 Conclusions  
In this study, we investigated the influence of vegetation phenology change on ecosystem carbon fluxes using two years of PhenoCam, eddy covariance, and soil chamber measurements from one semiarid ecosystem. Our results demonstrate that long, cold, and wet winters can be critical for the carbon balance in semiarid ecosystems. Due to low temperatures and the snowpack, vegetation activity was postponed in 2019, while snow-melted water was conserved in the deep soil layers and allowed the shrubs to maintain active until September. In contrast, the warm-dry winter in 2020 allowed the US-Hn1 site to retain a high NEE magnitude and ET in February and March when NEE was generally limited by low vegetation activity due to low temperatures. In dryland areas, vegetation activityis suspended by cold and wet winters, which can dramatically alter seasonal patterns of carbon balance.  
Improving our understanding of the impacts of seasonal snowpacks on carbon cycling in semiarid ecosystems is crucial for better projection of how dryland ecosystems will respond to future changes in climate. The availability of water in such ecosystems is often a critical driver of carbon balance. The winter snowpack can fundamentally alter the temporal and spatial distributions of water availability and, thus, how dryland ecosystems will respond to changes in weather and environmental conditions. Long-term PhenoCam and eddy covariance measurements are required to comprehensively investigate the relationships between the semiarid ecosystem carbon balance and winter snowpack and climate conditions.  
Conceptualization, W.Y., Z.G. and H.L.; methodology, J.Y. and Z.G.; software, J.Y. and Z.G.; validation, J.Y., W.Y., Z.G., H.L., X.C. and Y.M.; formal analysis, J.Y., W.Y., Z.G. and H.L.; investigation, J.Y., W.Y., [PERSON], H.L., X.C., Y.M. and E.A.; data curation, [PERSON], H.L., E.A. and D.M.; writing--original draft preparation, [PERSON]; writing--review and editing, [PERSON], [PERSON], Z.G., H.L., X.C., Y.M., E.A. and D.M.; visualization, [PERSON] and Z.G.; supervision, [PERSON] and H.L.; funding acquisition, [PERSON], J.Y., Z.G. and X.C. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Science Fund for Distinguished Young Scholars, grant number 41925001; China National Postdoctoral Program for Innovative Talents, grant number BX20220366; and the Fundamental Research Funds for the Central Universities, grant number 22 qntd1911; and the US. Department of Energy (DOE), Office of Science (SC) Biological and Environmental Research (BER) program, as part of BER's Environmental System Science (ESS) program, through the River Corridor Scientific Focus Area (SFA) at Pacific Northwest National Laboratory (PNNL). PNNL is operated for DOE by Battelle Memorial Institute under contract DE-AC05-76 RL01830. The APC was funded by 41925001, BX0220366, and 22 qntd1911.  
The data presented in this study are available upon request from the corresponding author.  
We thank [PERSON], [PERSON], and many other participants for their assistance in the field. We thank the researchers and contributors for the MODIS products and the AWN weather data.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government