Soil microbial communities play an integral role in soil chemical processes and can directly influence plant nutrition through symbiotic interactions. Therefore, many restoration practitioners aim to improve plant survivorship and/or growth through the manipulation of microbial community structure. Our study examined how manipulation of the soil microbial community through the application of a commercial inoculum or field collected soil can influence tree sapling performance and microbial community structure and function during the restoration of a former golf course. We utilized terminal restriction length polymorphism (TRFLP) and next generation sequencing methods to examine microbial community structure, focusing on the response of arbuscular mycorrhizal fungi (AMF) communities to inoculation. Inorganic nutrient content in rhizosphere soils was analyzed and tree growth and survivorship were documented through three growing seasons.
Results/Conclusions
We found that both inoculants significantly influenced AMF community structure in both of our study species. Additionally, AMF community richness was greater in trees receiving soil transfers from a mature hardwood forest than in unmanipulated control trees. These differences coincided with indicators of increased nitrogen cycling in the rhizosphere soils of Prunus serotina, including an increased soil C/N ratio and ammonia content in rhizosphere soils of trees receiving forest soil transfers. Forest soil transfers also increased inorganic phosphorus in the rhizosphere soils of another focal species, Liriodendron tulipifera, when contrasted to control trees. Prunus tree growth was not influenced by inoculation; however, Liriodendron stem elongation was suppressed by forest soil inoculation after three years. This growth suppression may have resulted from increased belowground carbon allocation, as forest soil transfers significantly increased AMF colonization (as determined by quantitative PCR). This study provides insight into how restoration practitioners can use microbial inoculation to alter AMF community structure and functioning, subsequently influencing tree growth and nutrient cycling during the restoration of degraded lands.