Forest Soil Erosion and the Influence of Roads in Watersheds: Past, Present and Future Challenges

Abstract

Soil erosion has remained a point of concern in land management through the past century. Over the past three decades, the understanding of soil erosion mechanisms, prediction and control have been vastly improved due to concentrated efforts by scientists and researchers in all sectors (Grace, 2017; Neary et al., 2009; Sheridan and Noske, 2007). The primary objectives of this presentation are to provide a comprehensive review of forest soil erosion research as a means of contextualizing the current state of the knowledge “what we know” and future needs “what we don‘t know” related to forest soil erosion quantification and prediction. We will present issues related to forest soil erosion, explore the contribution of forest roads, provide the lessons learned in forest soil erosion and erosion control, and explore the gaps in the current understanding that are critical to addressing future challenges facing soil erosion quantification and prediction. This work further aims to explore the challenges associated with the influence of shifting climate regimes on soil erosion by water. Soil erosion and sediment yield from forest watersheds are a small fraction of that from most other land uses, though disturbances in these watersheds can result in accelerated soil erosion and water quality impacts. Specifically, forest roads have been attributed to account for most soil erosion and delivered sediment in forested systems. There has been considerable effort over the past 30 years to quantify, mitigate, and predict the impact of forest roads on soil erosion and water quality to address the challenges associated with forest road components. Numerous investigations have been undertaken to quantify erosion and sediment yield from various road components, quantify fate of eroded sediment and sediment delivery ratios, mitigate soil erosion losses, and improve prediction technology. The following fundamental gaps/challenges are identified: 1) the disconnect between erosion and delivery of sediment to the stream, 2) the influence of changing climate regimes on soil erosion mechanics and predictions, 3) the challenges in translation of soil erosion losses at the local scale to actual delivered sediment at the watershed scale, 4) the lack of data and investigations linking soil erosion from forest roads or upslope activities to sediment delivery to stream systems, or directly attributing a single source to water quality impairment, 5) quantifying the impacts of intensifying precipitation on soil erosion losses and enhancing decision support tools to consider changing climates, 6) lack of reliable field experimental data, and 7) data limitations in developing and refining decision support tools for improved designs and management of forest roads.