Abstract

The increasing demand for timber and non-timber products from native forests in Chile and the cattle grazing has augmented the rate of degradation of these ecosystems. This process results in the need to know which of the dynamic variables are involved in its regulation. Soil quality indicators like soil organic carbon (SOC), soil microbial respiration (SMR), microbial biomass carbon (MBC), potential net N mineralization (N-min), and nitrification (N-NO3), soil aggregates, and light fraction (LF), were evaluated at two different depths of the soil in Nothofagus obliqua (deciduous) and mixed N. dombeyi - N. obliqua (evergreen-deciduous) forests, where a 30-ha silvopastoral trial was established, after this evaluation, in early 2016. The SOC, SMR, MBC, N-min and N-NO3 were significantly higher in the N. obliqua forest than the mixed forest, 8%, 17%, 17%, 40%, 20%, respectively (p<0.05). The dry weight in soil fractions did not present differences between forest types. C and N contents in the LF (labile, un-decomposed organic matter of plant origin) were higher in the deciduous forest, 9% and 20%, respectively (p<0.05). Our results suggest that soil quality was favored by the quality of organic matter in the site dominated by deciduous species, which translates into more favorable conditions for the activity of microorganisms, nitrogen dynamic, and C and N content in the light faction. The intrinsic characteristics of the plant residues associated with higher rates of decomposition, can stimulate the activity of the biota and especially the soil microorganisms, which would lead to higher values of the different indicators evaluated. This novel silvopastoral system will likely help restore the most degraded sites through improvement of the soil quality. This kind of information allows obtaining knowledge of the forest areas and their sustainability, mainly for the planning of long-term, durable silvopastoral practices.