EFECTO DE LOS RESIDUOS VEGETALES PROVENIENTESDE DOS TRATAMIENTOS SILVíCOLAS EN UNAPLANTACIóN DE Pinus radiata D. DON SOBRE LOSCAMBIOS ESTACIONALES DE LAS ACTIVIDADESBIOLóGICAS DEL SUELO

the impact of plant residues of sylvicultural treatments on nutrient dynamic in forest soils is not well known. it is necessary to determine the effect of prunning and thinning residues left on soil surface because it has direct effects on physical-chemical properties and microbial activities. the aim of this study was to quantify and compare the effect of prunning and thinning treatment of a plantation oí pinus radiata d. don on biological activities measured after 10 year of managements in winter and spring time. this was conducted on an ultisol and the following measuring was conducted: fluorescein diacetate hydrolysis (fda), microbial biomass carbon (cbm), microbial biomass nitrogen (nbm) and the enzymes carboxymethyl-cellulase (cmc-ase), β-glucosidase (βg-ase) and acid phosphatase (ap-ase). the results showed that the fda and nbm were significantly greater (p<0.05) in pruning than in thinning in winter time. however, cbm as well as cmc-ase and pg-ase did not present differences either with the exception of ap-ase, because of p availability and ph favored the phosphatase activity. in spring, cmc-ase, βg-ase and ap-ase did not present significant differences in prunning treatment considering seasonal changes, as not well as thinning treatment. between sylvicultural treatments, were significantly greater (p<0.05) in prunning than thinning treatment. soil moisture and litter accumulation were determinant for regulatory control of biological activities. however other factors should be considered. sylvicultural waste managements in this type of ecosystem require further study considering various environmental and anthropic effects