The Roleof Plant Species in the Structure and Function of Soil MicrobialCommunities:  An Experimental Evaluation

Broughton, L.C. and K.L. Gross

Presented at the ASM at Snowbird (2000-08-02 to 2017-12-05 )

How important are plant species in influencing the structure and function of soil microbial communities? We attempted to answer this question by examining the structure and composition of soil microbial communities from six old fields at the Kellogg Biological Station in southwestern Michigan that differed in plant species composition, productivity, and soil characteristics. Aboveground productivity ranged from 188 to 592 g/m2 across sites, while plant species density ranged from 2 to 16 species/m2. We grew a common plant species, Andropogon gerardi, in each soil to determine if this influenced the composition and activity of the soil community. Plants were grown for 110 days in the greenhouse. We measured plant performance in each soil type and also compared how soil characteristics (e.g. moisture, percent organic matter, nitrogen) and the activity and composition of the soil microbial community differed in the presence and absence of A. gerardi. We assessed the composition of the soil microbial community using Ecolog and PLFA. Soils differed in fertility and this affected plant biomass and allocation patterns. In both the A. gerardi treatments, soils differed in microbial activity and PLFA patterns. The presence of A. gerardi increased the mean, but decreased the variation, in microbial activity among soils. In addition, soils from + A. gerardi treatments differed in PLFA patterns from the no plant controls. This suggests that plant species composition can affect the composition and activity of the soil microbial community.

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