Evaluating the Effects of Riparian Habitat Type on Nutrient Concentrations in Agricultural Headwater Streams

Abstract

Grass filter strips and other riparian buffer types are frequently used in agricultural watersheds to reduce nonpoint source pollution, but there is only limited information available on their long‐term watershed scale effects. Our research questions were as follows: (1) does nutrient concentrations differ among agricultural headwater streams with different riparian habitat types? and (2) does the effect of riparian habitat type differ annually or seasonally? Eight streams in central Ohio were selected based on watershed size, proportion of watershed agricultural land use, and riparian habitat type. Three streams possessed unplanted riparian habitats, three streams had grass filter strips, and two streams had forested riparian habitats. Water samples for the measurement of ammonia, nitrate + nitrite, total nitrogen, dissolved reactive phosphorus, total phosphorus, and dissolved organic carbon concentrations were collected weekly from two sites in each stream from March 2007 to February 2017. Mean nitrogen and phosphorus concentrations did not differ (p > 0.05) among riparian habitat types. Mean dissolved organic carbon concentrations exhibited different (p < 0.05) annual and seasonal trends among riparian habitat types. Our results indicated that planting grass filter strips alone may not decrease nitrogen and phosphorus concentrations and highlighted the influence of riparian woody vegetation on the temporal dynamics of dissolved organic carbon concentrations.

The effect of planting grass filter strips on fishes in agricultural headwater streams

“…As recommended in previous publications (Balcerzak et al, 2022;Smiley & Rumora, 2015)-grass filter strips should not be implemented as a single practice but implemented as part of a suite of practices intended to restore multiple ecosystem functions and services. A good starting point would be combining grass filter strips with practices that can be implemented within the grass filter strip itself and have the potential to reduce input of agricultural contaminants, retain stormwater runoff and provide habitat for the biota.…”

“…(2) temperature regulation and the input of allochthonous nutrients and organic matter within shallow riparian aquatic habitats; and (3) instream nutrient concentrations (Balcerzak et al, 2022;Smiley & Rumora, 2015).…”

“…There is a copious amount of information on the short‐term effectiveness of grass filter strips in reducing nutrients, pesticides and sediment at the plot scale (Balcerzak et al, 2022; Smiley et al, 2011). Yet, information on the impacts of grass filter strips and other types of herbaceous riparian buffers on fishes in agricultural streams is limited (Smiley et al, 2011).…”

“…The initial findings from the first 4 years indicated that planting grass filter strips only widens the riparian habitats and does not affect riparian vegetative structure, geomorphology, instream habitat characteristics and water chemistry (i.e., physicochemical variables, nutrients and pesticides) of channelized agricultural headwater streams in central Ohio (Smiley et al, 2011). The results of follow‐up analyses conducted with additional data indicated that grass filter strips do not affect (1) the amount of riparian woody vegetation and vegetative structure; (2) temperature regulation and the input of allochthonous nutrients and organic matter within shallow riparian aquatic habitats; and (3) instream nutrient concentrations (Balcerzak et al, 2022; Smiley & Rumora, 2015).…”

“…Long‐term assessments of conservation practices are rare (Balcerzak et al, 2022) but needed because it has been predicted it will take at least a decade before herbaceous and forested buffers lead to changes in instream water quality and habitat (Meals et al, 2010; Newbold et al, 2010). The objective for this research project was to document the long‐term effects of planting grass filter strips adjacent to channelized agricultural headwater streams on fish community structure and instream habitat.…”