## 3 Results
### Estimation of Spatial Measurement Models
#### 3.2.2 Spatial Durbin Model Results  
Regression results were compared using SDM random effect, spatial fixed effect, time fixed effect, and spatiotemporal fixed effect. The spatiotemporal fixed effects produced more significant results. Integrating with the Hausman test, the fixed effect model was chosen, as it exhibited lower endogeneity. Finally, a spatiotemporal fixed effect model was selected for analysis, and the results are presented in Table 4.  
\begin{table}
\begin{tabular}{c c c c c} \hline  & **SDM\_ind** & **SDM\_time** & **SDM\_spatiotemporal** & **SDM\_random** \\ \hline
**Tem** & \(1.217\)*** & \(0.728\)** & \(1.237\)*** & \(0.523\) \\ \hline  & (\(3.67\)) & (\(2.16\)) & (\(3.74\)) & (\(1.57\)) \\ \hline
**Pre** & \(-0.238\) & \(-0.120\) & \(-0.155\) & \(-0.245\) \\ \hline  & (\(-0.50\)) & (\(-0.27\)) & (\(-0.33\)) & (\(-0.56\)) \\ \hline
**Evp** & \(8.543\)*** & \(8.778\)*** & \(8.659\)*** & \(8.545\)*** \\ \hline  & (\(11.07\)) & (\(12.42\)) & (\(11.25\)) & (\(12.18\)) \\ \hline
**Win** & \(-0.725\)** & \(-1.700\)*** & \(-0.692\)* & \(-1.602\)*** \\ \hline  & (\(-2.04\)) & (\(-5.33\)) & (\(-1.96\)) & (\(-5.03\)) \\ \hline
**Ssd** & \(-6.794\)*** & \(-6.569\)*** & \(-6.840\)*** & \(-6.597\)*** \\ \hline  & (\(-8.36\)) & (\(-8.72\)) & (\(-8.44\)) & (\(-8.79\)) \\ \hline
**Rhu** & \(0.113\)** & \(0.078\)** & \(0.098\)** & \(0.105\)*** \\ \hline  & (\(2.53\)) & (\(2.04\)) & (\(2.19\)) & (\(2.80\)) \\ \hline
**Gst** & \(-1.777\)*** & \(-1.360\)*** & \(-1.806\)*** & \(-1.124\)*** \\ \hline  & (\(-5.07\)) & (\(-3.84\)) & (\(-5.18\)) & (\(-3.21\)) \\ \hline \_cons** & & & & \(0.498\)*** \\ \hline
**Wx** & & & & (\(4.28\)) \\ \hline
**Wx Tem** & \(-1.561\)*** & \(-0.803\)** & \(-1.733\)*** & \(-0.612\)* \\  & (\(-4.32\)) & (\(-2.29\)) & (\(-4.78\)) & (\(-1.77\)) \\ \hline
**Wx Pre** & \(-0.080\) & \(0.612\) & \(-0.479\) & \(0.784\)* \\  & (\(-0.15\)) & (\(1.28\)) & (\(-0.89\)) & (\(1.65\)) \\ \hline
**Wx Evp** & \(-9.396\)*** & \(-9.257\)*** & \(-8.840\)*** & \(-9.240\)*** \\  & (\(-11.42\)) & (\(-12.29\)) & (\(-10.21\)) & (\(-12.62\)) \\ \hline
**Wx Win** & \(0.174\) & \(1.375\)*** & \(-0.001\) & \(1.296\)*** \\  & (\(0.45\)) & (\(4.02\)) & (\(-0.00\)) & (\(3.82\)) \\ \hline
**Wx Ssd** & \(8.992\)*** & \(7.078\)*** & \(8.950\)*** & \(7.279\)*** \\  & (\(10.04\)) & (\(8.88\)) & (\(9.89\)) & (\(9.23\)) \\ \hline
**Wx Rhu** & \(-0.196\)*** & \(-0.092\)** & \(-0.169\)*** & \(-0.127\)*** \\  & (\(-3.86\)) & (\(-2.25\)) & (\(-3.29\)) & (\(-3.17\)) \\ \hline
**Wx Gst** & \(2.044\)*** & \(1.417\)*** & \(2.025\)*** & \(1.205\)*** \\  & (\(5.55\)) & (\(3.83\)) & (\(5.51\)) & (\(3.32\)) \\ \hline
**Spatial** & & & & \\
**rho** & \(0.543\)*** & \(0.587\)*** & \(0.523\)*** & \(0.580\)*** \\  & (\(20.41\)) & (\(22.01\)) & (\(18.91\)) & (\(22.40\)) \\ \hline
**Variance** & & & & \\
**sigma2\_e** & \(0.285\)*** & \(0.470\)*** & \(0.283\)*** & \(0.440\)*** \\  & (\(27.18\)) & (\(27.27\)) & (\(27.23\)) & (\(21.94\)) \\ \hline
**lgt\_theta** & & & & \(2.566\)*** \\  & & & & \\  & & & & \\ \end{tabular} \({}^{*}\), ***, and ***, respectively, indicate the significance levels at \(10\)%, \(5\)%, and \(1\)%.  
\end{table}
Table 4: Estimated results of SDM.  
Results (Table 5) showed that annual average temperature, evaporation, and relative humidity had significant positive effects on NPP (\(p<0.01\)). In contrast, annual average sunshine duration and ground temperature had significant negative effects (\(p<0.01\)). Additionally, annual average wind speed showed a significant negative effect on spatial carbon sequestration (\(p<0.1\)). However, annual average precipitation showed mixed results across multiple models, with no consistent effects.