Disruption of plant-soil-microbial relationships influences plant growth

1. Differential dispersal of plant and microbial propagules may result in the geographical disassociation of plant populations from their local abiotic conditions and microbial communities, especially in the face of species introductions and changing climates. 2. To assess the potential consequences of disrupting historical relationships between plant populations, microbial communities and soil conditions, we grew Carpinus caroliniana seedlings from populations across the species range in combinations of sterilized soils and soil microbial communities, in soils collected from sites with or without conspecific trees. This controlled environment study simulated the consequences for seedling growth of independently or jointly disrupting the historical plant population-soil match, plant population-microbial community match and microbial community-soil match. 3. Seedlings grown in soils from areas without conspecifics had lower biomass, but benefited from inoculation with their historical microbial communities. For conspecific-cultured soils, growth was optimized when seedlings grew with novel microbial communities, but only when microbial communities were local with respect to abiotic soil conditions. Correlative evidence suggests that this may stem from alignment of ectomycorrhizal fungal communities to abiotic soil conditions. 4. Synthesis. Maintaining historical plant-microbial community relationships may benefit plant species spreading into new areas; however, for movement within current ranges, maintaining the historical relationship between microbial communities and the abiotic aspects of soils may have more important consequences for early growth.