## 5 Conclusions  
This study evaluated the ecosystem service value of the Liaohe estuarine wetland by adopting the energy analysis method. The ecosystem service values of the Liaohe estuarine wetland were classified as either ultimate or intermediate service values based on energy flow, which avoided double counting in ecosystem service values, and increased the accuracy of the evaluation result. We concluded that the ultimate service value of this wetland ecosystem was mainly embodied in flood diversion and storage, and atmospheric adjustment services, and the intermediate service value was in maintaining biodiversity. This study can more explicitly explain the ecosystem service value of the Liaohe estuarine wetland for managers, promoting protection policies and actions in total storage capacity, reed areas, and bird populations in this wetland ecosystem. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{2}{c}{**Ultimate Service**} & \multicolumn{4}{c}{**Intermediate Service**} \\ \hline \multirow{2}{*}{**Service Index**} & **Energy** & \multirow{2}{*}{**Proportion**} & \multirow{2}{*}{**Service Index**} & **Energy** & **Proportion** \\  & **Currency** & & **(\%)** & & **Currency** \\  & **Value/\(\times\)106 \$** & & & **Value/\(\times\)106 \$** & \\ \hline Material production & 2.68 & 9.50 & Supplementing groundwater & 1431.63 & 4.02 \\ Flood diversion and storage & 6.98 & 24.75 & Water conservation & 0.03 & 0.00007 \\ Water quality purification & 1.05 & 3.72 & Nutrient recycling & 0.55 & 0.0015 \\ Gas regulation & 8.02 & 28.45 & Maintaining Biodiversity & 34,181.82 & 95.98 \\ Soil conservancy & 3.14 & 11.13 & Total & 35,614.03 & 100.00 \\ Leisure entertainment & 2.63 & 9.33 & & & \\ Scientific research and education & 3.70 & 13.12 & & & \\ Total & 28.20 & 100.00 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Proportion of service value of the Liaohe estuarine wetland ecosystem. We also noticed limitations of this energy analysis method. First, data acquisition was difficult in the region due to a lack of an ecosystem-monitoring system. It is easy for deviations from the actual results to appear with our estimation method to obtain the data. Second, the selection of the energy value units (transformity and specific energy) directly affected the credibility of the evaluation result. In this paper, the energy value unit was mainly based on the research results of [PERSON] and [PERSON], which are mostly conclusions on a global scale. Although the local energy unit value was difficult to obtain, it was more adaptable for energy calculation in the local region. Finally, the continuous evaluation of some ecosystems should be implemented based on continuous monitoring of data to recognize ecosystem-service trends, which can assist decision makers in developing better ecological-protection planning and measurement of management. Based on this study case, the calculation method of ultimate and intermediate service values of a wetland ecosystem based on energy theory can be applied to other wetland systems. The calculation results would also provide a more appropriate reference to decision makers, and draw more attention to the service process of wetland systems, promoting the simultaneous sustainable development of human society and the natural environment. [PERSON] and [PERSON] conceived and designed the experiments; [PERSON] performed the experiments; [PERSON] and [PERSON] equally contributed to this paper; [PERSON] and [PERSON] analyzed the data; [PERSON], [PERSON], and [PERSON] wrote the paper; and [PERSON] and [PERSON] reviewed the paper. This research was funded by the National Natural Science Foundation of China (No. 31670711, 31570706), the National Key Research and Development Program of China (No. 2016 YFC0500408), and the National Natural Science Foundation of Liaoning, China (No. 201602660). We thank the wetland management center of Panjin city, Liaoning Province, China and the wetland administration of Liaohe bureau for providing the support of our field survey and data.