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Submitted to: Riparian Ecology and Conservation
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/19/2015 Publication Date: 12/31/2015 Citation: Smiley, P.C., Rumora, K.R. 2015. Influence of planting grass filter strips on the structure and function of riparian habitats of agricultural headwater streams. Riparian Ecology and Conservation. 2:58-71. Interpretive Summary: Grass filter strips are a commonly used agricultural conservation practice to reduce nutrient, pesticide, and sediment input into streams. Our understanding of the ecological impacts of grass filter strips is limited because previous evaluations of grass filter strips have simply focused on their ability to provide water quality benefits, and have not evaluated how this conservation practice influences the structure and function of riparian habitats. Understanding the influence of grass filter strips on the structure and function of riparian habitat of agricultural streams is critical for determining if this agricultural conservation practice is contributing to the restoration of riparian habitats adjacent to agricultural headwater streams, particularly those that exhibit riparian habitat degradation. We evaluated the influence of grass filter strips by comparing riparian vegetative structure, coarse particulate organic matter and nutrient input, and water temperatures among unplanted riparian habitats, riparian habitats with grass filter strips, and forested riparian habitats of agricultural headwater streams in central Ohio. Our key findings indicated that grass filter strips did not differ in structure and function from unplanted riparian habitats. We also observed that forested riparian habitats exhibited greater diversity in structure and greater levels of function than herbaceous riparian habitat types. Our results are novel because it represents the first documentation of the influence of grass filter strips on the structure and function of riparian habitats adjacent to channelized agricultural headwater streams. Specifically, our results indicate that current guidelines for planting grass filter strips are not contributing to the conservation and restoration of riparian habitats adjacent to channelized agricultural headwater streams. This is an important finding from a management perspective because many involved in the agricultural watershed management simply assume planting grass filter strips will contribute to watershed restoration efforts. Our results provide empirical evidence needed to challenge this assumption and to ultimately result in modified approaches for the management of riparian habitats adjacent to agricultural streams. Our results will assist state agencies, federal agencies, non-profit groups, and consulting agencies involved with the management of agricultural watersheds in developing the needed modified riparian management approaches for agricultural headwater streams. Additionally, our results provide information that will assist with climate change adaptation as it identifies that the current guidelines for commonly used agricultural practice is not effective and not likely to assist with mitigating the effects of agriculture in the face of climate change. Technical Abstract: Grass filter strips are strips of cool or warm season grasses planted adjacent to agricultural streams to reduce nutrient, pesticide, and sediment input. This conservation practice is the most frequently planted riparian buffer type in the United States. Previous studies have not evaluated how grass filter strips alter the structure and function of riparian habitats of agricultural streams. We sampled riparian vegetation, quantified coarse particulate organic matter input and nutrient input, and measured water temperature within unplanted riparian habitats, riparian habitats with grass filter strips, and forested riparian habitats of agricultural headwater streams in central Ohio. Forested riparian habitats exhibited greater percent maximum frequency of woody vegetation and reduced water temperatures than unplanted riparian habitats and grass filter strips. Forested riparian habitats also exhibited greater canopy cover, woody vegetation taxa richness, and coarse particulate organic matter input than grass filter strips and greater riparian widths and woody vegetation abundance than unplanted riparian habitats. Grass filter strips did not differ in structure and function from unplanted riparian habitats. Our results suggest that planting grass filter strips are not contributing to the restoration of structure or function of riparian habitats of channelized agricultural headwater streams. |
