The objective of this work was to evaluate the influence of the organic and nutritional quality on the activity and C and N contents of the microbial biomass in different structures of litter from a Mountain Atlantic Forest from around the Desengano State Park-RJ, Brazil. Litter samples were collected in September 1999. The litter structures were leaves, branches, and superficial roots; fine debris (F structure); and organic matter smaller than 2 mm (H structure). The nutritional and organic litter quality influenced the activity of the microbial biomass. The leaves had the most efficient microbial biomass in the immobilization of C and N. The qCO2 (metabolic quotient) was an indicator for the stress condition and presence of cellulose and polyphenol for the microbial biomass in the different structures. The formation of three distinct groups was observed by the Tocher group technique. The first group consisted of superficial roots and H strucuture; the second comprised leaves and the third group consisted of F strucuture. Through the relative contribution of the characters to the divergence between components, the variable that most contributed was polifenol: N ratio, followed by carbon microbial biomass, polifenol, cellulose and lignin: N ratio.
leaves; litter; microbial biomass; microbial activity; organic and nutritional quality
