Using photographic image analysis to assess ground cover: a case study of forest road cutbanks

Abstract

Road prisms, including cutbanks, road surfaces, and fillslopes, can be important contributors of sediment to streams in forested watersheds. Following road construction, cutbanks and fillslopes are often seeded, mulched, and sometimes fertilized to limit erosion and sedimentation. Assessing the success of vegetation establishment on cutbanks and fillslopes is a common task of forested land managers. This study developed and applied a photographic image analysis method to assess percent ground cover along an entire cutbank of a cut-and-fill haul road in the Monongahela National Forest in Tucker County, West Virginia. Variable-sized sections were employed to quantify the vegetative cover. Measurements obtained by this technique were similar to more commonly applied fixed-area plots, and it proved to be a useful tool for land managers who require a more repeatable quantification of ground cover than is possible through visual assessments. Cutbank slope and aspect also were analyzed to determine their potential impact on cutbank vegetation establishment. Slope was not a significant variable in explaining differences in vegetation cover; however, aspect did affect vegetation establishment. South-facing aspects had significantly lower percent vegetation cover than northeast, east, northwest, and north northwest aspects after the first year following seeding and throughout the entire study. Mean percent cover on the south-facing cutbanks was 32% over all time periods, compared to 60% to 73% for the other represented aspects. This result was expected since south-facing slopes generally are drier in the growing season and are subject to more freeze-thaw cycles in the winter. Timber felled onto the cutbank also decreased vegetative cover in the short term on north and north northwest aspects, but vegetation quickly became reestablished on these aspects with their favorable growing conditions.

Measuring bluff erosion part 2: pairing aerial photographs and terrestrial laser scanning to create a watershed scale sediment budget

“…Greater numbers of freeze-thaw cycles may lead to greater erosion rates as freeze-thaw cycles reduce bluff strength (Wynn and Mostaghimi, 2006a;Thomas et al, 2009;Van Klaveren and McCool, 2010). Since west-and south-facing bluffs experience warmer afternoon temperatures leading to a greater number of freeze-thaw cycles (Hall, 2007;Bold et al, 2010), aspect may affect the number and depth of freeze-thaw cycles (Hall, 2007;Wynn and Mostaghimi, 2006a;Bold et al, 2010) and thus the rate of bluff retreat. Thus, aspect is a potential external control on bluff retreat rate, independent of the action by the river.…”

Effects of plant roots on the soil erosion rate under simulated rainfall with high kinetic energy

“…In mountainous areas covered by forests, severe soil erosion often occurs on slopes with bare soil such as cut and fill slopes formed during road construction (Bold et al 2010) as well as after slope failure caused by heavy rain and/or earthquakes (Kobayashi et al 2004;Lin et al 2006). Continuous soil erosion increases the suspended sediment load in streams (Mizugaki et al 2008) and limits vegetation growth (Sidle et al 2006).…”

The effects of soil properties and vegetation cover on the sedimentation of forest roads

“…Scientific understanding of factors influencing soil loss from forest road can effectively be used by managers in the design and sustainable management of road networks (Pappas et al, 2008;Olive and Marion 2009). Road prisms, including cutslopes, road surfaces, and fillslopes, can be important contributors of sediment to streams in forested watersheds (Bold et al, 2009;Morgan, 2005).…”