Biochemical properties of acid soils under climax vegetation (Atlantic oakwood) in an area of the European temperate–humid zone (Galicia, NW Spain): general parameters

The concept of sustainable development suggests that soil quality should be measured on the basis of the most environmentally sensitive properties of native soils under climax vegetation. The most relevant properties are biochemical. We describe the general biochemical parameters of the O and Ah horizons of 40 native Umbrisols under climax Atlantic oakwood in Galicia (NW Spain). The properties studied were: microbial biomass C (O horizons 1935±450 mg C kg−1, Ah horizons 781±253 mg C kg−1), N flush (68±20 and 26±13 mg kg−1), soil respiration (12.9±4.5 and 2.6±0.8 μg CO2-C g−1 h−1), ATP (8.91±3.20 and 2.77±1.38 μg g−1), dehydrogenase activity (555±205 and 207±58 nmol INTF g−1 h−1), catalase activity (3.9±1.1 and 2.0±0.9 mmol H2O2 consumed g−1 h−1), N mineralization capacity (113±66 and 30±13 mg N kg−1 10 d−1), and arginine ammonification rate (11.1±5.9 and 4.9±2.2 μg N-NH4+ g−1 h−1). The values reported are generally within the ranges found in the literature. The correlations between biochemical parameters and chemical variables show in these soils microbial population size and activity directly related to both organic matter and available nutrient contents.