Soil microbial processes in a pine silvopastoral system in NW Patagonia

GONZALEZ-POLO, MARINA; BAHAMONDE, HÉCTOR A.; PERI, PABLO L.; MAZZARINO, MARÍA JULIA; FARIÑA, CLARA; CABALLÉ, GONZALO

AGROFORESTRY SYSTEMS

SPRINGER

Lugar: Berlin; Año: 2019 vol. 93 p. 255 - 266

0167-4366

The conversion of native vegetation totree plantation (afforestation) implies a drasticchange in life forms and as a consequence, changesin the microenvironmental conditions, and the quantityand quality of organic matter entering the soil.This could affect soil microbial communities and theprocesses catalyzed by them. In Patagonia, afforestationwith exotic, fast-growing tree species was acommon practice but the consequences on theecosystem remain poorly quantified. The objectivewas to study the effects of pine afforestation on litterdecomposition, soil organic matter, soil microbialactivity and associated biogeochemical functions in asemiarid area of NW Patagonia. We hypothesizedthat afforestation would decrease litter decompositionrate and soil biological activity including net Nmineralization, due to changes of environmentalconditions and organic matter quality. We measuredin situ and potential soil net N mineralization, soilmicrobial biomass-C, soil enzyme activities (β-glucosidase, acid phosphatase and leucin-aminopeptidase)and litter decomposition rate. We alsocharacterized soil pH, electrical conductivity,extractable P and total C and N. Pine plantationsclearly affected decomposition rates of native grassvegetation, which was 10% lower under pine canopycover, and decreased soil microbial biomass. Acidphosphatase activity and leucin-aminopeptidaseactivities were also marginally reduced. On the otherhand, we did not find any significant effects of pineson soil chemical properties and N transformationsafter 13 years of plantation. Because effects dependstrongly on time, the decrease of soil microbialbiomass, acid phosphatase activity and grass decompositionrate (and the trend to lower enzyme activitiesrelated to P and N) under pine cover could be anevidence of possible changes on the long-term.