Quintanilla, M. 2009. Acoustical and nematode community assessment for ecosystem characterization. Ph.D. Dissertation, Michigan State University, East Lansing, Michigan, USA.
Ecosystems with different levels and types of human management were compared and characterized using nematode community structure methodologies and acoustical recordings. Conventional tillage, no-till, bio-based (organic), early and mid-successional fields with a history of tillage and mature deciduous forest sites were compared using these two methodologies. These methodologies were used to characterize the biological and physical aspects of these ecosystems with different levels of human management. For the nematode community structure analysis, nematodes naturally found in the soils from the conventional tillage, no-till, bio-based, successional fields and deciduous forest systems from Kellogg Biological Station Long Term Ecological Research (KBS/LTER) were identified to the lowest possible taxon and the results analyzed for taxon biodiversity, evenness, ecosystem stability and nutrient enrichment. Multivariate canonical correspondence analyses were performed in order to find associations between nematode taxa, ecosystems and soil characteristics. The results were compared and images of the nematodes identified can be found at http://www.nemasoil.com. As expected, the greatest biodiversity, evenness and ecosystem stability were often found in the deciduous forest and field succession ecosystems, and the lowest levels of the same parameters were most often found in the no-till and conventionally-tilled ecosystems. The acoustical methodologies were used to measure both biological and physical characteristics of ecosystems. The physical characteristics, such as soil aggregate stability, of soils with different levels of human management were measured with acoustical methods and the results were compared to conventional methods. Soil aggregates from conventional tillage, no-till, and native systems were immersed in water and the sounds of the rapid hydration were recorded with hydrophones for 30 seconds. The results were as expected and agreed with conclusions arrived at using conventional methods. The greatest stability and lowest sound intensity was found in the native ecosystems and the greatest sound intensity and lowest aggregate stability was found in the conventionally-tilled ecosystems, with the no-till ecosystems being intermediate. Acoustical recordings were used additionally to characterize the biological insect sounds from the same ecosystems used previously at KBS/LTER. The native ecosystems had significantly more insect sounds, especially at night, compared to any of the human-managed ecosystems. In the native ecosystems, the sounds were in a wave cubic regression form, with the sounds increasing and decreasing at regular time intervals. Additionally, acoustics were used to determine the biological activity of compost, using water as an activating agent. In conclusion, our methods showed that both nematode community structure methods and acoustical methods can be effectively used to characterize ecosystems.
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