ECOLOGICAL STOICHIOMETRY OF CARBON, NITROGEN AND PHOSPHORUS IN SOIL AND SOIL MICROBIAL BIOMASS IN THE TAOWAN WATERSHED IN THE FUNIU MOUNTAINOUS AREA, CHINA

We selected 322 sampling sites among five land use types (woodland, shrubland, grassland, orchard and farmland) in the Taowan watershed, China. We assessed the carbon (C), nitrogen (N) and phosphorus (P) contents in the soil and soil microbial biomass (SMB); the ecological stoichiometric characteristics of the samples; and the correlations between C:N, C:P, and N:P ratios in soil and those in SMB. Significant differences were noted between the atomic C:N, C:P and N:P ratios in soil and those in SMB. The soil and SMB C:N:P ratios for the five land use types can be ordered as woodland>shrubland>grassland>orchard>farmland and orchard>farmland>grassland>shrubland> woodland, respectively. The correlation between C:P in soil and C:P in SMB was significant (r=0.46, p<0.001), whereas no significant correlation (p>0.05) was found for C:N or N:P. At the land-use scale, the correlations between C:N, C:P and N:P in woodland soil and the corresponding ratios in woodland SMB were significant, and the correlations between C:N, C:P and N:P in soil and the corresponding ratios in SMB for other land use types were variable. The stoichiometric relationship of C:N:P in SMB and soil may suggest a weak homeostatic mechanism for C, N and P in SMB in terrestrial ecosystems.