Limits...
Analyzing the impacts of off-road vehicle (ORV) trails on watershed processes in Wrangell-St. Elias National Park and Preserve, Alaska.

Arp CD, Simmons T - Environ Manage (2012)

Bottom Line: These observations of trail evolution relative to stream and wetland crossings together with process studies suggest that ORV trails are altering watershed processes.These changes in watershed processes appear to result in increasing drainage density and may also alter downstream flow regimes, water quality, and aquatic habitat.Addressing local land-use disturbances in boreal and arctic parklands with permafrost soils, such as WRST, where responses to climate change may be causing concurrent shifts in watershed processes, represents an important challenge facing resource managers.

View Article: PubMed Central - PubMed

Affiliation: Alaska Science Center, U.S. Geological Survey, Anchorage, AK 99508, USA. cdarp@alaska.edu

ABSTRACT
Trails created by off-road vehicles (ORV) in boreal lowlands are known to cause local impacts, such as denuded vegetation, soil erosion, and permafrost thaw, but impacts on stream and watershed processes are less certain. In Wrangell-St. Elias National Park and Preserve (WRST), Alaska, ORV trails have caused local resource damage in intermountain lowlands with permafrost soils and abundant wetlands and there is a need to know whether these impacts are more extensive. Comparison of aerial photography from 1957, 1981, and 2004 coupled with ground surveys in 2009 reveal an increase in trail length and number and show an upslope expansion of a trail system around points of stream channel initiation. We hypothesized that these impacts could also cause premature initiation and headward expansion of channels because of lowered soil resistance and greater runoff accumulation as trails migrate upslope. Soil monitoring showed earlier and deeper thaw of the active layer in and adjacent to trails compared to reference sites. Several rainfall-runoff events during the summer of 2009 showed increased and sustained flow accumulation below trail crossings and channel shear forces sufficient to cause headward erosion of silt and peat soils. These observations of trail evolution relative to stream and wetland crossings together with process studies suggest that ORV trails are altering watershed processes. These changes in watershed processes appear to result in increasing drainage density and may also alter downstream flow regimes, water quality, and aquatic habitat. Addressing local land-use disturbances in boreal and arctic parklands with permafrost soils, such as WRST, where responses to climate change may be causing concurrent shifts in watershed processes, represents an important challenge facing resource managers.

Show MeSH

Related in: MedlinePlus

Examples of our focus study segment on Tanada Lake Trail showing (a) partly vegetated trail on mineral soil (soil monitoring station STT-6), b unvegetated trail on organic soils with ponding (soil monitoring station STT-3), c trail stream crossing (TC-4) and channel initiation point with mineral soil and partly underlain by till, and d trail stream crossing (TC-3) and channel initiation point with organic soil and underlain by shallow permafrost
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3298735&req=5

Fig2: Examples of our focus study segment on Tanada Lake Trail showing (a) partly vegetated trail on mineral soil (soil monitoring station STT-6), b unvegetated trail on organic soils with ponding (soil monitoring station STT-3), c trail stream crossing (TC-4) and channel initiation point with mineral soil and partly underlain by till, and d trail stream crossing (TC-3) and channel initiation point with organic soil and underlain by shallow permafrost

Mentions: To understand how and to what extent ORVs influenced soil temperature regimes, we monitored ground temperatures for one year at 10- and 50-cm depth to characterize freeze and thaw conditions near the surface and near the base of the active layer, respectively. We selected three types of trail conditions in which to monitor soil temperature, with two replications of each type: (1) dry mineral soil, (2) dry organic soil, and (3) saturated (ponded) organic soil (Fig. 2). We hypothesized that the last type would show the greatest deviation from reference conditions. At each trail site, we installed temperature sensor pairs (Onset Model TMC6-HD, ±0.2°C) directly into trail centers and 1 m from the trail edge. Trail center and edge sensor pairs were set to log temperature at hourly intervals using 4-channel external data loggers (Onset U12). Data collections spanned the period from 2-Sept-2008 to 10-Sept-2009. In addition to the in-trail and trail-proximal sites, sensors were installed at two sites approximately 50 m up-gradient and 50 m down-gradient from the trail course to serve as references. Instruments were checked and data were downloaded in late June and again in early September 2009. Each time data were downloaded, four active-layer depth (ALD) measurements were made as depth-to-refusal with a steel probe at 50 cm distance from the sensor, one in each cardinal direction, in order to compare ALD progression among monitoring sites.Fig. 2


Analyzing the impacts of off-road vehicle (ORV) trails on watershed processes in Wrangell-St. Elias National Park and Preserve, Alaska.

Arp CD, Simmons T - Environ Manage (2012)

Examples of our focus study segment on Tanada Lake Trail showing (a) partly vegetated trail on mineral soil (soil monitoring station STT-6), b unvegetated trail on organic soils with ponding (soil monitoring station STT-3), c trail stream crossing (TC-4) and channel initiation point with mineral soil and partly underlain by till, and d trail stream crossing (TC-3) and channel initiation point with organic soil and underlain by shallow permafrost
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3298735&req=5

Fig2: Examples of our focus study segment on Tanada Lake Trail showing (a) partly vegetated trail on mineral soil (soil monitoring station STT-6), b unvegetated trail on organic soils with ponding (soil monitoring station STT-3), c trail stream crossing (TC-4) and channel initiation point with mineral soil and partly underlain by till, and d trail stream crossing (TC-3) and channel initiation point with organic soil and underlain by shallow permafrost
Mentions: To understand how and to what extent ORVs influenced soil temperature regimes, we monitored ground temperatures for one year at 10- and 50-cm depth to characterize freeze and thaw conditions near the surface and near the base of the active layer, respectively. We selected three types of trail conditions in which to monitor soil temperature, with two replications of each type: (1) dry mineral soil, (2) dry organic soil, and (3) saturated (ponded) organic soil (Fig. 2). We hypothesized that the last type would show the greatest deviation from reference conditions. At each trail site, we installed temperature sensor pairs (Onset Model TMC6-HD, ±0.2°C) directly into trail centers and 1 m from the trail edge. Trail center and edge sensor pairs were set to log temperature at hourly intervals using 4-channel external data loggers (Onset U12). Data collections spanned the period from 2-Sept-2008 to 10-Sept-2009. In addition to the in-trail and trail-proximal sites, sensors were installed at two sites approximately 50 m up-gradient and 50 m down-gradient from the trail course to serve as references. Instruments were checked and data were downloaded in late June and again in early September 2009. Each time data were downloaded, four active-layer depth (ALD) measurements were made as depth-to-refusal with a steel probe at 50 cm distance from the sensor, one in each cardinal direction, in order to compare ALD progression among monitoring sites.Fig. 2

Bottom Line: These observations of trail evolution relative to stream and wetland crossings together with process studies suggest that ORV trails are altering watershed processes.These changes in watershed processes appear to result in increasing drainage density and may also alter downstream flow regimes, water quality, and aquatic habitat.Addressing local land-use disturbances in boreal and arctic parklands with permafrost soils, such as WRST, where responses to climate change may be causing concurrent shifts in watershed processes, represents an important challenge facing resource managers.

View Article: PubMed Central - PubMed

Affiliation: Alaska Science Center, U.S. Geological Survey, Anchorage, AK 99508, USA. cdarp@alaska.edu

ABSTRACT
Trails created by off-road vehicles (ORV) in boreal lowlands are known to cause local impacts, such as denuded vegetation, soil erosion, and permafrost thaw, but impacts on stream and watershed processes are less certain. In Wrangell-St. Elias National Park and Preserve (WRST), Alaska, ORV trails have caused local resource damage in intermountain lowlands with permafrost soils and abundant wetlands and there is a need to know whether these impacts are more extensive. Comparison of aerial photography from 1957, 1981, and 2004 coupled with ground surveys in 2009 reveal an increase in trail length and number and show an upslope expansion of a trail system around points of stream channel initiation. We hypothesized that these impacts could also cause premature initiation and headward expansion of channels because of lowered soil resistance and greater runoff accumulation as trails migrate upslope. Soil monitoring showed earlier and deeper thaw of the active layer in and adjacent to trails compared to reference sites. Several rainfall-runoff events during the summer of 2009 showed increased and sustained flow accumulation below trail crossings and channel shear forces sufficient to cause headward erosion of silt and peat soils. These observations of trail evolution relative to stream and wetland crossings together with process studies suggest that ORV trails are altering watershed processes. These changes in watershed processes appear to result in increasing drainage density and may also alter downstream flow regimes, water quality, and aquatic habitat. Addressing local land-use disturbances in boreal and arctic parklands with permafrost soils, such as WRST, where responses to climate change may be causing concurrent shifts in watershed processes, represents an important challenge facing resource managers.

Show MeSH
Related in: MedlinePlus