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Expanding Green Infrastructure Water Treatment Methods

Michael Culbertson

2017-2021

Green water management techniques may involve additional complexity and have little impact on some pollutants (Dietz & Clausen, 2005). However, “Rain gardens can retard overland runoff, reduce and delay flood peaks effectively, and play a major role in rehabilitating the water cycle.” (Ishimatsu, 2017). These projects used smaller vascular plants in initial plantings (Id.). Therefore, there is a need to determine the effects of larger, more diverse plantings on rain garden water management, pollutant filtration, wildlife populations, and potential additional benefits.

Such plantings may offer increased biomass plant tissue absorption, guttation, hydraulic lift effects, increased soil carbon/aeration, larger and deeper root systems, more extensive fungi networks. Trees with fruiting abilities along with diverse herbaceous layers may take up additional nutrients and hold them longer. Species may root graft and cooperate for greater effect. Ectomycorrhizal fungi transfer carbon and nitrogen between trees (Arnebrant, 1993; Simard, 1997). Production may affect water management and filtration by extracting fruits/nuts/berries, coppicing/pollarding for wood/mulch, and aromatic/medicinal compounds.

 

This project used field manipulation to compare methods against a control. It may significantly advance this sustainable agricultural practice and therefore qualify for SARE funding. It also produces material to support improved natural resource management. It has both human and ecological benefits.

 

Potential Benefits: increased water/nutrient retention, reduced flooding/dessication, improved well/water table conditions, increased wildlife/pollinator populations, improved soil conditions, supplemental production from marginal sites, improved current practices and outreach.

 

Objectives:

  1. Determine effectiveness of incorporating dense patterns of woody trees with diverse herbaceous layer into rain gardens for water management, wildlife benefit, and production.

  2. Use scientific data to produce outreach material for implementation sites across New England.

 

Procedure:

  1. Create three areas of equivalent area and water flow: 1) common rain garden with ground cover and small bushes similar to previous research (Dietz 2005); 2) densely planted larger woody perennials and diverse herbaceous layer with production potential, 3) grass only.

  2. Measure effects on water management, nutrient filtration, wildlife populations, production, and plant tissue.

  3. Compare data to determine potential for benefits and evaluate possible issues.

  4. Design “Installation Plan”.

  5. Produce and distribute “Outreach Material”.

 

Installation Plan Criteria: simple, affordable, effective, low maintenance, low risk of vector for significant regional disease, low potential to damage foundations (no aggressive root systems) and structures (only shrubs to small trees), minimal maintenance (tree/shrub shade and herbaceous layer prevents invasives/weeding, include nitrogen fixing species), productive potential (fruits, nuts, greens, aromatic herbs). Examples: hazelnut, aronia, asian persimmon, apple, blueberry, raspbery, spicebush, violet, mint.

 

Outreach Material Criteria: Objective testing and measurement must indicate potential benefits. Advocacy document must be truthful, accurate, respectful, positive, and inviting. Installation plan should be easily implemented in variety of locations in New England. Reasonably attractive appearance. Distribute to individuals with potential to change practice: farmers, homeowners, landscapers, garden clubs, non-profits, town public works, home gardeners, market growers, and public institutions.

Further information on design, implementation, and discussion available upon request.

References

 

Arnebrant, K., Ek, H., Finlay, R. D., & Söderström, B. (1993). Nitrogen translocation between Alnus glutinosa (L.) Gaertn. seedlings inoculated with Frankia sp. and Pinus contorta Doug, ex Loud seedlings connected by a common ectomycorrhizal mycelium. New Phytologist, 124(2), 231-242.

 

Dietz, M. E., & Clausen, J. C. (2005). A Field Evaluation of Rain Garden Flow and Pollutant Treatment. Water, Air, and Soil Pollution, 167(1–4), 123–138. https://doi.org/10.1007/s11270-005-8266-8.

 

Ishimatsu, K., Ito, K., Mitani, Y., Tanaka, Y., Sugahara, T., & Naka, Y. (2017). Use of rain gardens for stormwater management in urban design and planning. Landscape and Ecological Engineering, 13(1), 205-212.

 

Simard, S. W., Perry, D. A., Jones, M. D., Myrold, D. D., Durall, D. M., & Molina, R. (1997). Net transfer of carbon between ectomycorrhizal tree species in the field. Nature, 388(6642), 579-582.

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