Chemical and biochemical properties of Araucaria angustifolia (Bert.) Ktze. forest soils in the state of São Paulo

Abstract

SUMMARYAraucaria angustifolia, commonly named Araucaria, is a Brazilian native species that is intensively exploited due to its timber quality. Therefore, Araucaria is on the list of species threatened by extinction. Despite the importance of soil for forest production, little is known about the soil properties of the highly fragmented Araucaria forests. This study was designed to investigate the use of chemical and Index terms: soil quality, microbial biomass, soil enzymes, soil respiration, microbial metabolic quotient (qCO 2 ).(

Relationships between microbial activity and soil physical and chemical properties in native and reforested Araucaria angustifolia forests in the state of São Paulo, Brazil

“…The MBC indicates changes in the soil ecosystem balance (Baretta et al, 2005(Baretta et al, , 2008Silva et al, 2009;Baretta et al, 2010;Kaschuk et al, 2010). The MBC values found in this study were almost double those reported by Baretta (2007) and Bertini (2010) and are within the range of values found by Carvalho et al (2012) in soils under native and reforested Araucaria forests in the State of São Paulo, and within the range found for ecosystems of Atlantic forest (683 -1520 mg C kg -1 soil) (Kaschuk et al, 2010).…”

“…In general, the soils are acidic under both forest types and, together with the other chemical properties, are within the range of values reported by Bertini (2010) and Carvalho et al (2012) for soils under native and replanted Araucaria forest, in the State of São Paulo. Macroporosity was higher in the preserved native than the reforested area and the values found in the two ecosystems ( 0.10 m 3 m -3 ) (Table 2) were suitable for adequate oxygen diffusion and water infiltration into the soil.…”

“…Other authors found no significant differences either, in relation to soil basal respiration between native and reforested Araucaria forest, under similar experimental conditions (Baretta, 2007;Bertini, 2010;Carvalho et al, 2012).…”

“…The higher qCO 2 values in RF may indicate a higher consumption of carbon readily assimilated by the microbial community, requiring more energy for their support, associated with a condition of disorder, with greater CO 2 losses, a characteristic of ecosystems in development (Anderson & Domsch, 1993). Higher qCO 2 values in cropped soils indicate greater stress of the microbial community compared to soils with more stable systems, such as mature forests (Islam & Weil, 2000), similarly to healthy Araucaria forests harmed by fire in comparison with native Araucaria and planted Araucaria forests (Baretta, 2007;Bertini, 2010), or replanted Araucaria forests in the rainy and dry season (Carvalho et al, 2012), or agricultural cultivation with annual crops compared with Mixed Ombrophilous forest, Bini et al (2013a). This tendency to higher qCO 2 values may indicate an environment of ecological stress and degradation or a high level of productivity in this area, which is in line with the history of the RF area, more exposed to human intervention and to heavier impacts on the soilclimatic factors.…”

“…In this season, the DHA in NF and RF were 10.9 and 10.1 g TTF g -1 soil d -1 , respectively, and in summer 10.3 and 9.8 g TTF g -1 soil d -1 . The higher activity in RF than NF was related to the metabolism of viable soil microorganisms, indicating the oxidative activity of the microbial community which, together with MBC, CO 2 -C and qCO 2 , has been used as general biochemical parameter to measure the influence of management on soil quality (Gil-Sotres et al, 2005;Bastida et al, 2006;Carvalho et al, 2012;Bini et al, 2013b).…”