Friday, August 16, 2019
Exhibit Hall, Kentucky International Convention Center
Manqiang Liu, Ting Liu and Feng Hu, Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China
Background/Question/Methods Soil ecosystem engineers play a fundamental role in shaping ecological processes and enhancing ecosystem services. Earthworms, as a well-known engineer, have been receiving increasing attentions since the Darwin era. In contrast to the traditional view of its beneficial role in soil ecosystem, recent syntheses have explicitly pointed out more troublesome effects of earthworm presence in promoting greenhouse gas emissions, reducing soil biodiversity and decreasing plant resistance to pests. These contradictory results call for an integrative evaluation of earthworms in different aspect of ecosystem services, which could be evaluated by the multiple ecosystem functioning (multifunctionality). Based on a 13-year field experiment manipulating earthworm and organic amendment in agricultural field, we conducted a systematic study to illustrate how earthworms affected 21 ecosystem functions in four ecosystem services: plant productivity, plant nutrient availability, nutrient and carbon cycling processes, and nutrient and carbon cycling drivers.
Results/Conclusions Our results indicated that indirect effects, i.e., those mediated by functional composition and trophic connectance of soil microbial and microfaunal community are of greater importance than the indirect effects of biodiversity, abiotic environment (i.e., aggregate stability and pH) and the direct effects of earthworms. Earthworm presence enhanced multifunctionality by shifting the functional composition towards bacterial-dominated processes and strengthening the trophic connectance of soil food webs. Although earthworms significantly improved soil structure and slightly decreased microbial and microfaunal diversity (molecular or taxonic parameters), neither of these effects had a further influence on multifunctionality. Our results provide new insights in the mechanisms through which earthworms alter ecosystem multifunctionality and indicate the potential to manipulate a targeted soil community via managing pivotal components (e.g. ecosystem engineer earthworm) of soil food web to control the overall ecosystem services and disservices.
