# Influences of Extreme Weather Conditions on the Carbon Cycles of Bamboo and Tea Ecosystems
## 2 Materials and Methods
### Land Surface Model  
CLM ver. 4.5 (CLM4.5) [25] was used to simulate plant growth, water, and the C and nitrogen (N) cycles for the two ecosystems in this study. In CLM4.5, water, C, and N flux models are based on the offline ecosystem process model Biome-BGC ver. 4.1.2 [26; 27; 28]. The CENTURY-based soil C pool kinetics (CLM45 BGC) [29] in CLM4.5 was used in the present study. The soil-water content simulation in CLM was based on the one-dimensional Richards equation. The air forcing data used to drive the model included air temperature at a height of 2 m, precipitation, wind speed, relative humidity, surface atmospheric pressure, incident solar radiation, and incident longwave radiation (Figure 3 and Figure S1). The single-point mode of the CLM model was used for each plot.  
Green tea plants are usually fertilized in China; therefore, urea and manure were applied to the tea plot. Specifically, 209 and 174 kg N ha\({}^{-1}\) were applied in the form of urea on 16 March and 30 October of each year, respectively, and 120 kg N ha\({}^{-1}\) and 1792 kg C ha\({}^{-1}\) were applied as manure on 30 October. CLM4.5 currently has simulation options available for corn, soybean, and cereal, but no option or module exists for green tea. In this study, green tea was treated as temperate broadleaf evergreen shrub, and we added N fertilizer to the soil ammonium pool and added C to the first soil organic C pool on the corresponding application dates by revising the source codes for the C and N cycles. Specifically, urea N was added to soil layers at a depth of 2-10 cm by revising the N state update procedure in the CLM (CNNStateUpdate1 Mod.F90), in which fertilizer was added to the ammonium pool in the default CLM for corn simulations. Manure N and C were added to the first soil organic N and C pools of the uppermost three soil layers for the tea plot, respectively. To determine the optimal method to simulate bamboo growth, we compared simulations in bamboo was treated as either C3 grass or temperate broadleaf evergreen forest.  
Figure 3: Meteorological data used to drive the model. **(a)** FSDS, incident solar radiation; **(b)** FLDS, incident longwave radiation; **(c)** PBOT, atmospheric pressure; **(d)** air temperature; **(e)** wind speed, and **(f)** precipitation.  
Soil water dynamics reflect the comprehensive influences of rainfall, evapotranspiration, and lateral leaching; therefore, we used the soil water content to validate the modeling results for the water cycle. In our previous C/N modeling studies based on CLM4.5, CLM4.5 roughly captured the net ecosystem exchange (NEE) dynamics at a site in Minnesota representing the United States Corn Belt, a Douglas fir site in Washington State, a Mesquite Savanna site in Arizona, an oak pine forest site in southern California, and an Amazon evergreen forest site in Brazil [30; 31]. Moreover, CLM4.5 reproduced gross primary production (GPP), net primary production (NPP), soil organic C content, and litter and fine root masses [31]. A cumulative 8-day MODIS GPP product with a pixel size of 500 m (MOD17A2H version 6) was provided by [PERSON] et al. (2015; [[https://lpdaac.usgs.gov/dataset_discovery/modis/modis_products_table/mod17a2h_v006](https://lpdaac.usgs.gov/dataset_discovery/modis/modis_products_table/mod17a2h_v006)]([https://lpdaac.usgs.gov/dataset_discovery/modis/modis_products_table/mod17a2h_v006](https://lpdaac.usgs.gov/dataset_discovery/modis/modis_products_table/mod17a2h_v006))). In the present study, we used the MODIS GPP product and the measured soil HR at the two experimental plots, along with data from the literature, to validate the performance of the model in simulating plant growth and the C cycle. The schematic of the method that was used in the present study is shown in Figure 4.