บทคัดย่อ :
The carbon-nitrogen (C/N) ratio of soil organic matter is related to the patterns of nitrogen immobilization and mineralization during organic matter decomposition by microorganisms (Swift et al. 1979). Its value decreases as decomposition proceeds (Swift et al. 1979), is negatively correlated with the rate of nitrogen mineralization in decomposition experiments by soil incubation (Tsutsumi 1987a), and can indicate the decomposition rate in terrestrial ecosystems (Jordan 1985). The studies of soil carbon and nitrogen in tropical forest ecosystems (Jordan 1985), such as lowland rain forests (Uhl & Jordan 1984, Yoda & Kira 1982), seasonal forests (Hase & Folster 1982), and montane rain forests (Edwards 1982, Edwards & Grubb 1982), and various types of forests along altitudinal gradients (Marrs et al. 1988, Yoda & Kira 1969), have suggested an increase of the soil C/N ratio with a decrease in temperature and an increase in moisture (Jenny 1941). However, it also depends on the nitrogen contents of the litter itself (Jordan 1985, Swift et al. 1979), local variations in soil conditions according to topography and parent material (Tsutsumi 1987b). In an analysis of the structure and environmental relationships of seven tropical forest stands, Jordan (1985) found that the first principal component, which accounted for 63% of the ecosystem variance, was highly correlated (r = 0.94) with total soil nitrogen. Nitrogen has great effect on plant growth, affecting cell number and cell size (Chapin 1980). The availability of soil nitrogen to plants is determined largely by its mineralization during the decomposition of organic matter (Jordan 1985, Swift et al. 1979). Therefore we may expect a relationship between the C/N ratio and tree growth. This was
เอกสารอ้างอิง :
Yamakura, T., & Sahunalu, P. (1990). Soil carbon/nitrogen ratio as a site quality index for some South-east Asian forests. Journal of Tropical Ecology, 6(3), 371-377.
