关键词: 海南岛, 碳储量, 碳密度, 碳汇

Abstract:

Tropical forest plays an important role in global carbon cycle and carbon balance. What function the tropical forest is, carbon sink or carbon source, is still a disputed question among researchers. In this paper, we use an improved estimation method of forest biomass and forest resource inventory in Hainan Island to estimate carbon storage and its dynamic changes between 1979 and 1998. Here, the data of carbon storage includes three parts: carbon content in tree layer, carbon content in understorey, and carbon content in the litter layer. The results suggest that: 1) Carbon storage increased significantly in Hainan forest after 1979 from 30.45 Tg C to 37.74 Tg C by 1998, for the annual average accumulation amount of 0.3645 Tg C,or the annual average accumulation rate of 1.197%, is much higher than that of the national level. The function of carbon sink in Hainan forest is becoming greater and greater. 2) The mean carbon density is 32.59 tC/hm 2 between 1979 and 1993. The carbon density reduced rapidly after 1979 from 38.63 tC/hm 2 to 24.41 tC/hm 2 by 1993. The value of carbon density varies with forest types and forest ages. Generally speaking, carbon density increases with forest ages. So carbon storage potential in Hainan forest will become much greater. 3) With the measures of forest protection such as forbidding cutting, enclosing land and planting trees carrying out, forest areas will expand and the structure of forest ages will change. All these will lead to the improvement of capability of carbon storage. At the condition that the global tropical forest plays a notable role of carbon source in carbon cycle, the function and social value of Hainan forest, a representative region of tropical forest in China, will become increasingly notable in the national and even global carbon cycle. There is great difference in carbon storage among different researchers. This paper also analyses and discusses the uncertainty in calculating carbon storage and points out that it is only by strengthening the study on forest community biomass in different layers and unifying and improving the methods of calculating carbon content, can the precision of carbon storage be improved. At the same time, we should verify data first before using them.

Key words: Hainan Island, carbon storage, carbon density, carbon sink