Carbon, nitrogen and respiratory activity in the microbial biomass of soils in native forests and grasslands in South Patagonia

GARGAGLIONE V.; GONZALEZ POLO M.; BIRGI J.; TOLEDO S.; PERI P.L.

AGROFORESTRY SYSTEMS

SPRINGER

Lugar: Berlin; Año: 2022 vol. 96 p. 957 - 968

0167-4366

Soil microorganisms contribute to soil carbon storage, soil respiration and nutrient cycling.In south Patagonia, there are scarce studies on carbon (C) and nitrogen (N) in soil microbial biomass (MB). The aim of this work was to evaluate C and N content in soil MB, and soil microbial respiration according to diferent sites and forest uses: Nothofagus antarctica primary forests (PF), silvopastoral forests (SPF) and open site (OS). For MB determination, soil samples (0–10 cm depth) were collected in spring (November) and summer (February) over two years. Soil microbial biomass C (SMB-C) was determined using the chloroform fumigation-extraction method and soil microbial biomass N (SMB-N) by a modifcation of the fumigation–incubation method. Signifcant diferences were observed in SMB-C according to site, forest use and year. Morro Chico ranch presented the lowest SMB-C (721.4 µg C g−1) whereas Tres Marías had the highest (1216.6 µg C g−1). For forest use, the gradient PF >SPF >OS was observed. SMB-N also presented diferences and SPF had signifcantly lower SMB-N (110.9 µg N g−1 soil) than PF (137.5 µg N g−1 soil) and OS (141.76 µg N g−1 soil). The total cumulative respiration was 9657, 10,560 and 12,780 mg C kg−1 for SPF, OS and PF, respectively. Our results support the hypothesis that silvopastoral use of N. antarctica forests afects SMBC. This should be considered if N. antarctica trees are going to be remove to install silvopastoral systems, because this clearly afects soil microorganisms, and in consequence, soil carbon dynamics.