# Impacts of Compound Hot-Dry Events on Vegetation Productivity over Northern East Asia
## 5 Conclusions  
This study employed factor-controlled experiments using the CLM5 model to dissect the impacts of CHD events on vegetation productivity and to assess the roles of various meteorological factors. Despite some biases compared to observational data, CLM5 could effectively simulate the eco-hydrological responses during CHD events. Within the TCZ, GPP exhibited a particularly sensitive response to CHD events, while outside the TCZ, this response was relatively weak. In ecosystems primarily composed of grasslands within the TCZ, insufficient precipitation was identified as the primary cause of GPP decline, with high temperatures playing a secondary negative role. Conversely, in high-latitude forested areas outside the TCZ, the suppressive effect of high temperatures on GPP was more pronounced than that of drought. Under CHD conditions, confounding or nonlinear effects among meteorological factors were primarily identified in forest ecosystems, potentially exacerbating the negative anomalies in GPP. By quantifying the impacts of drought and heat on GPP changes during CHD events, this study identified dominant factors influencing GPP across ecosystems and analyzed associated biophysical processes. It offers valuable insights into vegetation productivity responses to hot and dry conditions, emphasizing the importance of understanding interactions between drought, high temperatures, and other meteorological factors in different ecosystems across northern East Asia. The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/f15030549/s1](https://www.mdpi.com/article/10.3390/f15030549/s1)]([https://www.mdpi.com/article/10.3390/f15030549/s1](https://www.mdpi.com/article/10.3390/f15030549/s1)): Figure S1: Changes in autotrophic respiration (AR) (a), net primary productivity (NPP) (b), ecosystem respiration (ER) (c), and net ecosystem productivity (NEP) (d) during the four compound hot-dry (CHD) events. Figure S2: Changes in soil moisture (SM) caused by the combined effect of (a) precipitation, incident radiation, and 2 m humidity (PRQ), (b) incident radiation and 2 m humidity (RQ), and (c) 2 m temperature and incident radiation (TR), and (d) the individual effect of incident radiation (R) during the four CHD events. Figure S3: Same as Figure S2, but for vapor pressure deficit (VDP). Figure S4: Same as Figure S2, but for evapotranspiration (ET). Figure S5: Same as Figure S2, but for canopy conductance (Gc). Figure S6: Same as Figure S2, but for maximum carboxylation rate (Vmax). Figure S7: The eco-hydrological response of the 2 m temperature's (T) effect, calculated as _SE_Q_ minus _SE_Clim_. Figure S8: The eco-hydrological response of 2 m specific humidity's (Q) effect, calculated as _SE_Q_ minus _SE_Clim_. Conceptualization, M.Y. ; methodology, M.Y., S.S. and J.K.; software, J.K. and Y.X. ; validation, J.K.; formal analysis, J.K. and M.Y. ; investigation, J.K.; resources, M.Y. and B.Z. ; data curation, J.K.; writing--original draft preparation, J.K.; writing--review and editing, M.Y. ; visualization, J.K.; supervision, M.Y. and S.S.; project administration, M.Y. and B.Z. ; funding acquisition, B.Z. and M.Y. All authors have read and agreed to the published version of the manuscript. This research was funded by the National Natural Science Foundation of China (grant numbers 41991285 and 42075115). **Data Availability Statement:** The FluxSat GPP data were obtained from [[https://avdc.gsfc.nasa.gov/pub/tmp/FluxSat_GPP/0.05x0.05](https://avdc.gsfc.nasa.gov/pub/tmp/FluxSat_GPP/0.05x0.05)]([https://avdc.gsfc.nasa.gov/pub/tmp/FluxSat_GPP/0.05x0.05](https://avdc.gsfc.nasa.gov/pub/tmp/FluxSat_GPP/0.05x0.05)) (accessed on 15 July 2023). The daily observational data for SM and ET were sourced from the GLEAM dataset, which can be found on a server and accessed through SFTP. The passwords to access the data can be obtained from [[https://www.gleam.eu](https://www.gleam.eu)]([https://www.gleam.eu](https://www.gleam.eu)) (accessed on 27 August 2023).