Influence of Timber Harvesting Operations and Streamside Management Zone Effectiveness on Sediment Delivery to Headwater Streams in Appalachia

Daniel Bowker,Christopher Barton,Jeffrey Stringer

doi:10.3390/f11060623

Abstract

Disturbances created by timber harvesting equipment and associated haul roads and skid trails can create overland sediment flows (sediment paths), especially in steeply sloping terrain, leading to stream sedimentation. This study investigated the effect of variables associated with GPS tracked harvest equipment movement, skid trail development and retirement, topography, and streamside management zone (SMZ) width and tree retention on sediment delivery to streams. While the intensity of harvest equipment traffic was not correlated with sediment path development, the presence and location of skid trails were. All of the sediment paths were found to originate at water control structures, influenced by microtopographic features, on the skid trails directly adjacent to SMZs. Mesic slopes were associated with increased sediment path development across all SMZ configurations. Two factors, the accumulation of coarse logging debris in the SMZ and the increased distance of skid trails to streams, were both correlated with decreased sediment path development. The study provides insight into how these variables interact and can be used to develop site-specific guidelines for SMZs in steeply sloping terrain that could improve their efficiency and effectiveness.

Highlights

Timber harvesting has the potential to negatively impact streams and riparian habitats by increasing nutrient inputs, elevating water temperatures, and delivering sediment to streams [1,2].The latter is the most important pollutant in many forested areas [2,3,4] and a significant issue for ground skidding operations
This study shows that site-specific streamside management zone (SMZ) guidelines can improve SMZ performance
Our study indicated that the relationship between slope aspect and soil moisture, buffer width, placement of skid trail water control structures, and logging debris accumulation affect the generation of sediment paths, demonstrating the importance of site specificity in best management practices (BMPs) guideline development

Summary

Introduction

Timber harvesting has the potential to negatively impact streams and riparian habitats by increasing nutrient inputs, elevating water temperatures, and delivering sediment to streams [1,2]. The latter is the most important pollutant in many forested areas [2,3,4] and a significant issue for ground skidding operations. In order to minimize these impacts, most states’ best management practices (BMPs) include riparian or streamside management zones (SMZs), minimally disturbed buffer strips intended to filter flows of sediment and nutrients from disturbed ground and reduce the effect of canopy removal on stream temperature [8,9]. Robust data on SMZ effectiveness are not available for many forest types and physiographic regions

Methods

Results

Conclusion