Soil microbial and plant responses to the absence of plant cover and monoculturing in low arctic meadows

Arctic ecosystems are sensitive to disturbance yet there is little information on the fate and recovery of soil microbial communities after disturbance and persistence in the absence of plants. Neighbouring plants may facilitate seedling establishment through amelioration of the physical environment and maintenance of arbuscular fungal community in soil. The inoculum of arbuscular mycorrhizal symbionts is critical for the establishment of low-latitude arctic herbs that are obligately mycorrhizal. In the present work, we investigated plant-soil and plant-plant interactions in low arctic meadow habitat. Plant cover was experimentally removed and field plots were left without plant cover, or a monoculture of the common local herb, Solidago virgaurea, was planted on the plots or the plant cover was left intact. After two years, three herb species were sown on the plots and their growth, mycorrhizal colonization and soil microbial communities were measured. Relative fungal abundance decreased in the soil community in the treatments where the soil had been disturbed. Soil microbial community structure by functional group was maintained in the soil two years after no plant cover and microbial biomass per organic matter was not reduced. Mycorrhizal colonization potential was not impaired after two years of absence of host plants and thus it is concluded that symbiotic propagules are able to persist for two years in the absence of host plants. The Solidago monoculture did not facilitate seedling establishment nor change soil microbial community markedly in short-term. Overall, the low arctic soil microbial community was markedly resistant to disturbance. (C) 2011 Elsevier B.V. All rights reserved.