A sampling strategy to assess the effects of land use on microbial functional diversity in soils

Abstract

A suitable sampling strategy is necessary for broad-scale investigations of the effects of land use on microbial functional diversity in soils. We report on the development of procedures for sampling and handling field soils for assessment of heterotrophic functional diversity [by analysis of catabolic response profiles (CRPs)]. Individual CRPs were subject to factor analysis and the results were used for statistical comparisons of the soils. Transect sampling comparing CRPs in forest with pasture showed that most variation was attributable to differences between land uses, followed by field replication and laboratory replication. Differences in CRPs between pasture compared with pine forest, horticultural cropping, or maize cropping could also be determined by a similar sampling strategy. Variation in CRPs between land uses by using these sampling approaches was greater than variation within land uses. CRPs varied little between seasons in 2 land uses and samples could also be stored up to 5 months at 5°C with little change in CRPs. We recommend that microbial functional diversity (CRPs) can be assessed in different land uses without laboratory replication and that transect sampling strategies are suitable for distinguishing clear differences between land uses.