Citation:

Oconnor, T. Measuring soil fauna in stormwater green infrastructure. In Proceedings, International Low Impact Development Conference 2023, Oklahoma City, OK, August 06 - 09, 2023. American Society of Civil Engineers (ASCE), Reston, VA, 135-145, (2023). https://doi.org/10.1061/9780784485002

Impact/Purpose:

This research is to ascertain whether stormwater controls are providing habitat for nearby soil fauna or whether the conditions of the GI stormwater controls are selecting soil fauna that are adaptable to frequent inundation, other conditions such as low organic matter content or proprietary media mixes that could be harmful to soil fauna. A wet extraction method is available on the “Bug Guide” website, which is run by Iowa State University, Department of Entomology, which is based on a method described in USDA publication Plant Disease Reporter. This method and modifications based on equipment availability and other observations will be described in detail and will be the basis for wet extractions of live organisms within GI. Sites were sampled both on and off the grounds of the EEC. The extractions were performed at the Urban Watershed Research Facility (UWRF). In addition to soil fauna extraction, this QAPP details two other soil analytical methods, i.e., determination of soil bulk density and quantification of soil organic carbon via loss on ignition. Bulk density is the principal physical attribute of relevance for faunal biodiversity and plant growth. Soil fauna biodiversity and density are influenced by numerous soil factors but in particular organic matter.

Description:

Measuring soil fauna in stormwater green infrastructure Abstract Stormwater controls in urban environments that use plants are being promoted as green infrastructure. To better understand these controls and relationship to the environment, soil fauna extraction was performed on a variety of stormwater controls from urban locations including rain gardens and detention basins. Urban wooded areas were also used for background comparisons. Additional metrics, including bulk density, loss on ignition (LOI) and soil moisture were also performed on samples. Several ecological indices were calculated and statistically tested. Three groupings were identified for 27 samples collected over a two-year period: background (8), rain gardens (13) and other stormwater controls (6). Statistical testing of these groupings by the Shapiro-Wilk W test indicated several indices were considered parametric. A one-way analysis of variance of the number of taxa and the Shannon diversity index was considered significant (p< 0.05). Comparisons of sample enumerations and indices to other metrics were not linear. Analysis of organic matter was expected to show a linear correlation though the fauna extraction method may have confounded this analysis and literature also indicated that maximum organic content may not coincide with maximum fauna observations. 

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