Leaf carbon isotope ratios of plants from a subtropical monsoon forest.

Carbon isotope ratios were used to survey the distribution of photosynthetic pathways among taxa, the relationship between photosynthetic pathway and habitat light levels, and the relationship between intercellular CO levels of C plants and habitat light levels within a subtropical monsoon forest in southern China. Of 128 species, most (94) possessed the C photosynthetic pathway; 33 species possessed the C pathway and all of these were restricted to high light locations. There was one epiphytic CAM species. The C species were classified as occurring in open, intermediate, and closed canopy sites. Among C species, carbon isotope ratios tended to become more negative with decreasing light availability in the habitat.