Decreases in organic C reserves in soils can reduce the catabolic diversity of soil microbial communities

• Published in: Soil biology & biochemistry Vol. 32; no. 2; pp. 189 - 196
• Main Authors: Degens, Bradley P., Schipper, Louis A., Sparling, Graham P., Vojvodic-Vukovic, Maja
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-02-2000; New York, NY Elsevier Science
• Subjects: Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Biochemistry and biology; Biological and medical sciences; Catabolic response profiles; Chemical, physicochemical, biochemical and biological properties; Fundamental and applied biological sciences. Psychology; Land use; Microbial biomass; Microbial ecology; Microbial functional diversity; Microbiology; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Potentially mineralizable organic C; Soil; Soil organic matter; Soil science; New Zealand; Oceania; Soil organic matter; Potentially mineralizable organic C; Microbial biomass; Land use; Microbial functional diversity; Catabolic response profiles; Microbial activity; Organic carbon; Organic matter cycle; Mineralization; Cultivated soil; Catabolism; Forest soil; Biodiversity; Microbial community; Grassland soil
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/S0038-0717(99)00141-8

An understanding of the main factors influencing microbial diversity in soils is necessary to predict the effects of current land-use trends on terrestrial diversity. We used microbial catabolic evenness as a measure of one component of soil microbial diversity. Catabolic evenness was assessed by measuring the short-term respiration responses of soil to a range of simple organic compounds. Differences in catabolic evenness between pasture and other land-uses on matched soils were related to differences in organic C pools (total organic C, microbial biomass C, and potentially mineralizable C). This approach enabled comparison of land-use effects on organic C pools in relation to catabolic evenness without the effects of soil type. In general, microbial catabolic evenness was greatest in soils under pasture and indigenous vegetation (range: 19.7–23.3), and least in soils under cereal/maize/horticultural cropping (range: 16.4–19.6). Soils under mixed cropping land-uses had catabolic evenness that ranged between these extremes (range: 17.7–20.5), but under pine forestry there was no characteristic level of evenness (range: 15.1–22.3). Catabolic evenness correlated poorly with the absolute values of soil organic C pools (
r
2<0.36). However, across a range of paired comparisons between pasture and other land-uses, greater differences in microbial catabolic evenness corresponded with greater differences in organic C (
r
2=0.76) and, to a lesser degree, with differences in microbial biomass C (
r
2<0.45) or potentially mineralizable C (
r
2<0.13). Therefore, land-uses that deplete organic C stocks in soils may cause declines in the catabolic diversity of soil microbial communities. Although the implications of this for microbial processes are unknown, maintenance of soil organic C may be important for preservation of microbial diversity.