## 3 Results
### GPP Response to Limiting Factors Per Land Cover Class: Statistical Analysis
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**2000**} & \multicolumn{4}{c}{**2007**} & \multicolumn{4}{c}{**2010**} \\ \hline \multirow{2}{*}{**Order**} & **Adjusted** & \multirow{2}{*}{**RMSE**} & \multirow{2}{*}{**Order**} & **Adjusted** & \multirow{2}{*}{**RMSE**} & **Order** & **Adjusted** & \multirow{2}{*}{**RMSE**} \\  & **R\({}^{2}\)** & & & & & & & \\ \hline
**Ln N dep** & 0.441 *** & 0.194 & N dep & 0.378 *** & 0.212 & N dep & 0.346 *** & 0.211 \\
**Precip** & 0.468 *** & 0.190 & Temp & 0.402 *** & 0.207 & Precip & 0.395 *** & 0.203 \\
**Sunsh** & 0.470 ** & 0.189 & Precip & Excl & & Sunsh & 0.402 *** & 0.202 \\
**Temp** & Excl & & Sunsh & Excl & Temp & 0.408 *** & 0.201 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Order of variables entered into the model and adjusted R\({}^{2}\) for croplands, according to the addition of a new variable to the model: N dep: N deposition, Ln N dep: Natural logarithm of N deposition, Temp: Temperature, Precip: Precipitation, and Sunsh: Sunshine. Excl: Variable excluded from the model. *** Statistically significant \(p<0.01\). *** Statistically significant \(p<0.001\). \begin{table}
\begin{tabular}{c c c c c c} \hline  & \multicolumn{2}{c}{**2000**} & \multicolumn{2}{c}{**2007**} & \multicolumn{2}{c}{**2010**} \\ \hline  & **Coefficients** & **95\% CI** & **Coefficients** & **95\% CI** & **Coefficients** & **95\% CI** \\ \hline
**Const** & \(-0.8075\)**\({}^{***}\)** \(\pm\) 0.0704 & \(-0.9456\)\(-\)0.6695 & \(0.1089\)\(\pm\) 0.0971 & \(-0.0815\)\(-\)0.2994 & \(0.0783\)\(-\)0.0587 & \(-0.0367\)\(-\)0.1934 \\
**Ln N dep** & \(0.6270\)**\({}^{***}\)** \(\pm\) 0.0121 & \(0.6033\)\(-\)0.6507 & \(0.5469\)\({}^{***}\)** \(\pm\) 0.0136 & \(0.5201\)\(-\)0.5736 & \(0.6095\)\({}^{***}\)** \(\pm\) 0.0119 & \(0.5862\)\(-\)0.6329 \\
**Precip** & \(-0.0002\)**\({}^{***}\)** \(\pm\) 0.0000 & — & \(-0.0003\)**\({}^{***}\)** \(\pm\) 0.0000 & — & \(-0.0003\)**\({}^{***}\)** \(\pm\) 0.0000 & — \\
**Sunsh** & \(0.0075\)**\({}^{***}\)** \(\pm\) 0.0013 & \(0.0051\)\(-\)0.0100 & \(-0.0057\)**\({}^{***}\)** \(\pm\) 0.0016 & \(-0.0088\)\(-\)0.0026 & \(-0.0066\)**\({}^{***}\)** \(\pm\) 0.0010 & \(-0.0086\)\({}^{***}\)** \(\pm\) 0.0047 \\
**Temp** & \(0.0103\)**\({}^{***}\)** \(\pm\) 0.0018 & \(0.0068\)\(-\)0.0139 & \(0.0279\)**\({}^{***}\)** \(\pm\) 0.0020 & \(0.0240\)\(-\)0.0319 & \(0.0123\)**\({}^{***}\)** \(\pm\) 0.0016 & \(0.0091\)\(-\)0.0155 \\ \hline \end{tabular}
\end{table} 
Table 7: Regression coefficients with heteroscedasticity-consistent standard errors for grasslands. Const: Constant, Ln N dep: Natural logarithm of N deposition, Temp: Temperature, Precip: Precipitation, and Sunsh: Sunshine. \({}^{***}\) Statistically significant \(p<0.001\). \begin{table}
\begin{tabular}{c c c c c c} \hline  & \multicolumn{2}{c}{**2000**} & \multicolumn{2}{c}{**2007**} & \multicolumn{2}{c}{**2010**} \\ \hline  & **Coefficients** & **95\% CI** & **Coefficients** & **95\% CI** & **Coefficients** & **95\% CI** \\ \hline
**Const** & \(-0.1581\)\(\pm\) 0.0783 & \(-0.3116\)\(-\)0.0046 & \(0.5791\)**\({}^{***}\)** \(\pm\) 0.0123 & \(0.5549\)\({}^{*}\)** \(\pm\) 0.0633 & \(1.018\)**\({}^{***}\)** \(\pm\) 0.0540 & \(0.9123\)\({}^{*}\)** \(\pm\) 1.124 \\
**N dep** & \(0.4115\)**\({}^{*}\)** \(\pm\) 0.0114 & \(0.3891\)\(-\)0.4338 & \(0.0197\)**\({}^{**}\)** \(\pm\) 0.0008 & \(0.0181\)\(-\)0.0212 & \(0.0185\)\({}^{*}\)** \(\pm\) 0.0009 & \(0.0168\)\(-\)0.0203 \\
**Precip** & \(-0.0001\)**\({}^{***}\)** \(\pm\) 0.0000 & — & — & \(-0.0001\)**\({}^{***}\)** \(\pm\) 0.0000 & — & \(-0.0001\)**\({}^{***}\)** \(\pm\) 0.0000 & — \\
**Stansh** & \(0.004\)**\({}^{**}\)**\(\pm\) 0.0012 & \(0.0017\)\(-\)0.0064 & — & — & \(-0.0062\)**\({}^{***}\)** \(\pm\) 0.0011 & \(-0.0083\)\({}^{**}\)**\(\pm\) 0.0042 \\
**Temp** & — & — & \(0.0192\)**\({}^{**}\)**\({}^{**}\)**\({}^{**}\)**