Assessing Transportation Infrastructure Impacts on Rangelands: Test of a Standard Rangeland Assessment Protocol

Abstract

Linear disturbances associated with on-and off-road vehicle use on rangelands has increased dramatically throughout the world in recent decades. This increase is due to a variety of factors including increased availability of all-terrain vehicles, infrastructure development (oil, gas, renewable energy, and ex-urban), and recreational activities. In addition to the direct impacts of road development, the presence and use of roads may alter resilience of adjoining areas through indirect effects such as altered site hydrologic and eolian processes, invasive seed dispersal, and sediment transport. There are few standardized methods for assessing impacts of transportation-related land-use activities on soils and vegetation in arid and semi-arid rangelands. Interpreting Indicators of Rangeland Health (IIRH) is an internationally accepted qualitative assessment that is applied widely to rangelands. We tested the sensitivity of IIRH to impacts of roads, trails, and pipelines on adjacent lands by surveying plots at three distances from these linear disturbances. We performed tests at 16 randomly selected sites in each of three ecosystems (Northern High Plains, Colorado Plateau, and Chihuahuan Desert) for a total of 208 evaluation plots. We also evaluated the repeatability of IIRH when applied to road-related disturbance gradients. Finally, we tested extent of correlations between IIRH plot attribute departure classes and trends in a suite of quantitative indicators. Results indicated that the IIRH technique is sensitive to direct and indirect impacts of transportation activities with greater departure from reference condition near disturbances than far from disturbances. Trends in degradation of ecological processes detected with qualitative assessments were highly correlated with quantitative data. Qualitative and quantitative assessments employed in this study can be used to assess impacts of transportation features at the plot scale. Through integration with remote sensing technologies, these methods could also potentially be used to assess cumulative impacts of transportation networks at the landscape scale.

Biological soil crust and disturbance controls on surface hydrology in a semi‐arid ecosystem

“…Our study suggests that the disturbance of dark well‐developed biocrusts through anthropogenic forces (Belnap and Eldridge , Duniway et al. , Duniway and Herrick ) may have greater adverse effects than the disturbance of less‐developed light biocrusts. Additionally, the presence of light biocrust patches upslope of dark biocrust patches, and with minimal vegetation in between, may place the latter at risk of sediment deposition, especially during extreme rainfall events, as greater water quantity or velocity can increase potential soil loss.…”

Regulation of precipitation‐associated vegetation dynamics on catchment water balance in a semiarid and arid mountainous watershed

“…The spatial patterns of vegetation exert strong controls on horizontal and vertical gradients in SWC (Breshears et al, 2009;Duniway et al, 2010;Potts et al, 2010) because vegetation can affect the amount and distribution of precipitation throughfall (Holwerda et al, 2010;Zimmermann et al, 2009) for soil infiltration and loss of soil water to the atmosphere via ET. In semiarid to arid ecosystems, transpiration is the major process to cause soil water to release into the atmosphere and evaporation of intercepted water can cause less water to infiltrate into soil.…”

A holistic strategy for adaptive land management

“…Simple indicators of OHV presence are necessary but not sufficient to assign cause. An additional hypothesis (not shown) that areas with evidence of OHV activity are more degraded than similar areas (e.g., same ecological site) without evidence of activity must be tested using a combination of qualitative (IIRH) and quantitative soil and vegetation indicators (Duniway et al 2010). Each of the two major branches ultimately leads to decisions about whether, what, and where to monitor.…”