## 3 Results and Discussion
### Comparison of the Results of Different Partitioning Methods  
Through the analysis of the open canopy coupled state in Section 2.2.2, transpiration and soil evaporation were separated using the coupling threshold diagnosis method proposed in Appendix A with the CEC, MREA, and FVS methods. Under sparse canopy conditions, the DLEC method achieved a solution rate of 54.01% in the separation of evapotranspiration components, with 62.18%, 50.54%, and 49.45% in each month; the CEC method achieved a solution rate of 88.61% in the separation of evapotranspiration components, with 96.06%, 91.06%, and 78.62% in each month; the solution rate of the MREA method was 58.04% in the separation of evapotranspiration components, and the solution rates were 67.63%, 57.59%, and 48.90% in each month; the solution rate of the FVS method was 53.96% in the separation of evapotranspiration components, and the solution rates were 62.99%, 52.54%, and 48.36% in each month. Among the separation methods, the solution rates were CEC > MREA > DLEC = FVS. The CEC method showed higher solution rates for sparse canopy flux fraction separation, which is consistent with forest stand studies [17] on C3 crops with 31-39% separation success [36], and it can be seen that the FVS optimization algorithm has a higher percentage of successful separation under open canopy understory conditions (48-63%). From July to September of the growing season, the total average daily growing season evapotranspiration based on the two-layer eddy correlation was 5.79 mm d\({}^{-1}\) above the canopy and 1.53 mmd\({}^{-1}\) in the subcanopy, with a T/ET of 79.02%; the monthly average ecosystem transpiration was 6.0, 6.06, and 5.31 mm d\({}^{-1}\) above the canopy, and the soil evaporation was 1.63, 1.41, and 1.56 mm d\({}^{-1}\) in the subcanopy, respectively (Table 2). T/ET showed a trend of increasing and then decreasing during the growing season at 78.62%, 81.18%, and 77.26%, respectively. Ecosystem transpiration and soil evaporation showed consistent and obvious single peaks in all three months, but the peak of the former lagged behind that of the latter (Figure 5). This is due to the regulation of environmental factors: understory evapotranspiration is mainly driven by total radiation, while above-canopy evapotranspiration contains tree transpiration and is therefore simultaneously regulated synergistically by total radiation and saturated water vapor pressure differences [9]. Figure 4: Daily variation in transpiration and standard deviation for different coupling scenarios (**a**,**b**). The gray box represents the day time form 06:00 A.M. to 20:00 P.M. Note: TR-1.1-TR-3.2.2, respectively, correspond to the ecosystem transpiration fluxes obtained by coupling diagnosis of canopy vertical-layer air mass in Table 1.  
For each month of the growing season in the open plantation canopy, both the CEC method and the FVS algorithm underestimated ecosystem evapotranspiration and overestimated ecosystem evapotranspiration compared with the DLEC method; the MREA method was in good agreement with DLEC in describing the daily variation in ecosystem evapotranspiration and had a comparable range of evapotranspiration, but it showed a significant underestimation and different daily variation in evapotranspiration. This phe