Variation in Root Density along Stream Banks

Abstract

While it is recognized that vegetation plays a significant role in stream bank stabilization, the effects are not fully quantified. The study goal was to determine the type and density of vegetation that provides the greatest protection against stream bank erosion by determining the density of roots in stream banks. To quantify the density of roots along alluvial stream banks, 25 field sites in the Appalachian Mountains were sampled. The riparian buffers varied from short turfgrass to mature riparian forests, representing a range of vegetation types. Root length density (RLD) with depth and aboveground vegetation density were measured. The sites were divided into forested and herbaceous groups and differences in root density were evaluated. At the herbaceous sites, very fine roots (diameter < 0.5 mm) were most common and more than 75% of all roots were concentrated in the upper 30 cm of the stream bank. Under forested vegetation, fine roots (0.5 mm < diameter < 2.0 mm) were more common throughout the bank profile, with 55% of all roots in the top 30 cm. In the top 30 cm of the bank, herbaceous sites had significantly greater overall RLD than forested sites (alpha = 0.01). While there were no significant differences in total RLD below 30 cm, forested sites had significantly greater concentrations of fine roots, as compared with herbaceous sites (alpha = 0.01). As research has shown that erosion resistance has a direct relationship with fine root density, forested vegetation may provide better protection against stream bank erosion.

Stream Corridor Soil Phosphorus Availability in a Forested–Agricultural Mixed Land Use Watershed

“…The streambank soils of all land uses in the current study generally have a low P release potential and, in some situations, may actually serve as sinks for dissolved forms of P. The interior of cornfields and hayfields, if eroded by extreme weather events, such as happened with Tropical Storm Irene in the northeastern United States in 2011 (Vidon et al, 2018), would most likely contribute to Lake Champlain as sources of P, as they are high in TP and have higher DPS. Clearly, land use strategies that include practices such as exclusionary fencing for cattle and vegetated buffer zones are important to lower the rate of streambank erosion (Laubel et al, 2003;Wynn et al, 2004). However, these riparian strategies will need to be combined with strategies to mitigate upgradient agricultural sources, such as by drawing down soil P (phytomining, tillage, and even P sorbing amendments) and minimizing erosion.…”

Invertebrate colonization of leaves and roots within sediments of intermittent Coastal Plain streams across hydrologic phases

“…However, in low-gradient Coastal Plain streams much of the CPOM becomes buried within the sandy stream beds following floods (Metzler and Smock 1990;Smock 1990). Roots of riparian trees are important in stabilizing stream banks (e.g., Gregory and Gurnell 1988;Thorne 1990;Wynn et al 2004), and they can also be common (24% of CPOM) within intermittent Coastal Plain stream beds (Fritz et al 2006a). However, the role of roots as food or habitat for invertebrates within intermittent channels is unknown.…”

Root length density and carbon content of agroforestry and grass buffers under grazed pasture systems in a Hapludalf

“…Surface soil horizons generally have a higher density of roots as these horizons have higher nutrient and oxygen concentrations and lower soil bulk density (McGinty 1976;Gray and Leiser 1982;Coppin and Richards 1990). Wynn et al (2004) found that RLD decreased with increasing soil depth and root diameter. Findings in the current study agree with results from other studies.…”