Spatial heterogeneity provides organic matter refuges for soil microbial activity in the Patagonian steppe, Argentina

• Published in: Soil biology & biochemistry Vol. 41; no. 6; pp. 1348 - 1351
• Main Authors: Gonzalez-Polo, Marina, Austin, Amy T.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01-06-2009; Elsevier
• Subjects: Agronomy. Soil science and plant productions; Argentina; Arid ecosystems; beta-glucosidase; Biochemistry and biology; Biogeochemistry; Biological and medical sciences; biomass; Carbon cycling; Chemical, physicochemical, biochemical and biological properties; enzyme activity; Extracellular enzymes; Fundamental and applied biological sciences. Psychology; grasses; Islands of fertility; microbial activity; Microbial biomass; microbial growth; Microbiology; Mosses; mosses and liverworts; nitrogen; Organic matter; Patagonia; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Semi-arid steppe; semiarid soils; shrubs; soil ecology; soil enzymes; soil fertility; soil microorganisms; soil organic carbon; soil organic matter; soil pH; Soil science; soil temperature; soil water content; spatial variation; steppe soils; vegetation; β-Glucosidase activity; Argentina; South America; America; Arid ecosystems; Biogeochemistry; Argentina; Extracellular enzymes; Mosses; Carbon cycling; Semi-arid steppe; β-Glucosidase activity; Islands of fertility; Microbial biomass; Patagonia; Microbial activity; Organic matter; Spatial variability; Heterogeneity; Fertility; Steppe; Semi arid zone; Ecosystem; Enzyme; Arid environment; Bryophyta; Refuge; Extracellular; Glycosylases; Carbon cycle; Soils; β-Glucosidase; Glycosidases; Hydrolases
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/j.soilbio.2009.03.008

In arid and semi-arid ecosystems that are frequently classified as water limited, it is unclear how spatial and temporal variability of vegetation and climate could affect microbially-mediated soil processes. Our objective was to determine how aboveground spatial heterogeneity creates characteristic soil conditions that modulate microbial growth and activity in a semi-arid Patagonian steppe. In particular, we explored how micro-environmental and biogeochemical soil characteristics generated by the native vegetation could control soil β-glucosidase activity. Both life-form (shrubs, grasses, mosses and bare soil) and season exerted strong controls on all measured abiotic (soil temperature and gravimetric soil water content, inorganic nitrogen, pH and total C and N) and biotic (microbial biomass C and β-glucosidase activity) soil characteristics. Partial correlation between β-glucosidase activity and extracellular organic C (EOC) was high across seasons (
r = 0.5;
P < 0.001) while soil water content did not correlate with soil enzymatic activity (
r = 0.09;
P > 0.05). We postulate that labile soil carbon rather than water availability functions as a principal limitation of microbial activity in this semi-arid ecosystem, and the distribution of this carbon is, in large part, determined by the patchy distribution of vegetation.