Abstract:

The biomass and the energy of the Casuarina equisetifolia and Acasia crassicarpa community, the C. equisetfolia and Pinus elliottii community, pure C. equisetifolia community were studied in Dongshan County, Fujian Province. The results showed as follows: the biomass and energy of C. equisetfolia and A. crassicarpa community was the highest by 16 700.64 g·m^-2 and 341 685.70 kJ·m^-2 respectively; The second is C. equisetifolia and P. elliottii community, 10 104.62 g·m^-2 and 210 128.30 kJ·g^-1; The pure C. equisetifolia community was the third, 5 129.87 g·m^-2 and 105 751.40 kJ·m^-2 respectively. There were more biomass and energy in the mixed communities than that in the pure community. Gross caloric value of fractions was as followed: the gross caloric value of fractions of C. equisetifolia and A. crassicarpa was 19.83～21.52 kJ·g^-1 and 20.00～23.27 kJ·g^-1 in their mixed community; The gross caloric value of fractions of C. equisetifolia and P. elliottii was 19.47 ～20.83 kJ·g^-1 and 20.54 ～21.54 kJ·g^-1 in the mixed community; The gross caloric value of fractions of C. equisetifolia was 19.98 ～21.27 kJ·g^-1 in the pure C. equisetifolia community. The gross caloric value of fractions of C. equisetifolia was different because of different community, the highest was in the C. equisetifolia and A. crassicarpa community, the second was in the pure C. equisetifolia community, and that in the C. equisetifolia and P. elliottii community was the lowest. There was obviously mixed efficiency in different mixed patterns. The biomass of the C. equisetifolia and A. crassicarpa community was 1.65 times as that of C.equisetifolia and P. elliottii community, and 3.26 times as that of the pure C. equisetifolia community. There was the same tendency about energy. The energy of the C. equisetifolia and A. crassicarpa community was 1.63 times as that of the C. equisetifolia and P. elliottii community, and 3.23 times as that of the pure C. equisetifolia community. While the biomass and energy of the C. equisetifolia and P. elliottii community was 1.97 times and 1.99 times as those of the pure C. equisetifolia community respectively. As a conclusion, there were more biomass and energy in the mixed communities than those in the pure community, the mixed community had higher productivity and better ecological structure and function than the pure community.

Key words: Energy, Biomass, Community, Casuarina equisetifolia, Protection forest