An investigation of water nutrient levels associated with forest vegetation in highly altered landscapes

Abstract

Stream pollution by nutrient loading is a chronic problem in the Midwest, United States, and greater impacts on water quality are expected as agricultural production and urban areas expand. Remnant riparian forests are critical for maintaining ecosystem functions in this landscape context, allowing water infiltration and capture of nutrients before they are lost from the system. Our objective was to identify linkages between riparian forest plant community composition and water quality in remnant forested headwater streams. We identified watersheds with embedded headwater streams in three land use categories: grazed, urban, and preserved. We assessed plant community composition and nutrient storage. We sampled the forest streams to monitor discharge rates and sediment, nitrogen (N), and phosphorus (P) loads. Herbaceous communities in preserved riparian forests had more native specialist species than urban or grazed sites. Plant N content was higher in preserved forests (17. Stream water nitrate (NO 3 -N) concentration and total P delivery were highest for streams in urban areas. The most pronounced differences for plant composition and stream discharge and pollutant loads were between preserved and urban forests. Seasonal patterns were variable. We detected a weak negative but seasonally important relationship between plant N content and stream water N. We did not detect a similar relationship for P, which may indicate saturation of this nutrient in the watershed system. Detailed knowledge about relationships between land use, plant community composition, and water quality outcomes could be used to target forest restoration efforts in landscapes highly impacted by humans. Human land use has had far-reaching effects on natural systems. There is increasingly extensive and intensive pressure for arable land to produce food, fiber, and fuel (Secchi et al. 2008), which are then translocated globally, effectively decoupling natural cycles of water and nutrients. Likewise, the places where people live and work are expanding, with exurban sprawl and pressure intensifying due to growing populations in urban areas. This in turn leads to an increase in the importation and concentration of water and nutrients and disrupts ecosystem processes (Groffman et al. 2003;Bernhardt et al. 2008). Abstract: Stream pollution by nutrient loading is a chronic problem in the Midwest, United States, and greater impacts on water quality are expected as agricultural production and urban areas expand. Remnant riparian forests are critical for maintaining ecosystem functions in this landscape context, allowing water infiltration and capture of nutrients before they are lost from the system. Our objective was to identify linkages between riparian forest plant community composition and water quality in remnant forested headwater streams. We identified watersheds with embedded headwater streams in three land use categories: grazed, urban, and preserved. We assessed plant community composition and nutrient storage. We sampled the forest st...

Land cover impacts on storm flow suspended solid and nutrient concentrations in southwest Ohio streams

“…Extensive research over the last several decades has indicated development that replaces natural land cover often significantly decreases stream water quality (e.g., Cole, Peierls, Caraco, & Pace, ; Howarth, Fruci, & Sherman, ; Mattikalli & Richards, ; McKee, Eyre, & Hossain, ; McKee, Eyre, Hossain, & Pepperell, ; Meybeck, ). However, studies that have evaluated impacts between urban and agricultural land cover on suspended solid and nutrient concentrations have yielded inconsistent and sometimes contradictory results between various U.S. ecoregions (e.g., Dodds & Oakes, ; Golay, Thompson, Mabry, & Kolka, ; Line, White, Osmond, Jennings, & Mojonnier, ; Miller et al., ; Paul & Meyer, ). In some cases, land cover impacts within a study area can also vary between the water quality parameters that are being examined (e.g., Lenat & Crawford, ; Line et al., ; Vidon et al., ).…”

Genetic Differentiation and Phenotypic Plasticity of Forest Herbaceous Species in Iowa, Central United States

“…These changes are typically the direct or indirect result of human activity, including cattle grazing, deer overabundance, nonnative earth worms, nonnative plant introductions, and heavy recreational use in urban and suburban areas (e.g., Gibson et al 2000, Mabry 2002, Rooney et al 2004, Andrés-Abellán et al 2005, Nuzzo et al 2009, Cameron et al 2015. Forests that have been subjected to these forms of disturbance, as well as new secondary forests, have fewer native herbaceous species than are present in preserved forests, and instead have understories composed of bare ground or herbaceous plant communities dominated by generalist and invasive species (Mabry 2002, Rooney et al 2004, Gerken et al 2010, Gerken Golay et al 2013b). Consequently, many woodlands across this broad region are unlikely to have a full complement of native understory species.…”

“…For example, the classic Hubbard Brook experiments in central New Hampshire emphasized the functional importance of the understory layer and introduced the vernal dam hypothesis, which suggests that spring-growing understory plants take up significant quantities of nutrients, particularly nitrogen and phosphorus, decreasing nutrient pollution in streams early in the growing season (Muller and Bormann 1976). The importance of nutrient uptake by this layer has been confirmed in numerous additional studies (Blank et al 1980, Peterson and Rolfe 1982, Tremblay and Larocque 2001, Gerken Golay et al 2013b, Gerken Golay et al 2016). In addition, these plants…”