Abstract:By means of calorimetry measurement, the standing crop of energy, net energy production and energy conversing efficiencies of two mangrove communities, i. e. Bruguiera sexangula community & Kandelia candeI community, were determined and discussed in the present paper.The results of measurement of caloric values for various components showed that there were some differences in caloric value among components of these two mangrove communities. In general, leaves and flowers possessed higher caloric values, while roots and bark of trunk possesses lower caloric values.The standing crop of energy in B. sexangula community was 178,627 kcal. m-2, much larger than that in K. candel community (70,547kcal·m-2). There existed different distributions of energy in the various components and different layers of community. Net energy production was 15,772 kcal·m-2.a-1 for B. sexangula community (1983) and 10,456 kcal m-2·a-1 for K. candel community (1982). To the photosynthetical active radiation on the stand, their energy converting efficiencies were 3.01% and 2.01% respectively, compared with other plant communities in nature, mangrove forests possess relatively larger energy production and higher energy converting efficiencies.From the results mentioned above, it can be concluded that mangrove forests show their own characteristics on standing crop and production of .energy and play an important role in mangrove ecosystems. Therefore, it is worthy to protect and exploit mangrove forests.