Road Networks

What is the need?  

  • Management and mitigation of impacts due to roads and other linear disturbances (trails, pipelines, etc) requires reliable assessment and monitoring data. 
  • There are currently no broadly accepted protocols.

This approach integrates a variety of standard field protocols that are currently accepted for application by the BLM and NRCS with supplemental indicators and GIS analysis.

Why “Interpreting Indicators of Rangeland Health”? IIRH was designed to assess differences in rangeland health independent of cause and it has been widely applied to areas where grazing is the dominant land use. Our results indicate the approach is appropriate for assessing impacts of roads and other infrastructure development. 

What can it be used for?

  • Assess current status
  • Identify appropriate monitoring indicators
  • Identify appropriate monitoring locations

Where quantitative data are needed to support qualitative assessment, or as a baseline for monitoring, collect monitoring data on 3 transects in star-pattern with random orientation.

How to apply IIRH for plots containing roads:

  • Option A: complete a single evaluation for entire plot
  • Option B: complete a single evaluation for all areas not directly impacted by linear disturbance (where assume disturbances completely degraded – no evaluation)
  • Option C: complete separate evaluations for directly and indirectly impacted parts of the plot

The choice of option A, B, or C should be determined based on road classification, usage, or other management considerations and be included with route inventory information.   Complete normal IIRH for non-road (control) plot(s).

IIRH evaluations can be analyzed statistically using non-parametric (χ2) analysis comparing the distributions of departure ratings or the road and non-road plots. 

Landscape-scale analysis of road impacts requires a probability-based plot selection technique that allows for the comparison of the ecological function of areas near roads to areas of similar ecological potential and management but located far from roads and trails.


Herrick, J.E., J.W. Van Zee, K.M. Havstad, L. M. Burkett and W.G. Whitford. 2005. Monitoring Manual for Grassland, Shrubland and Savanna Ecosystems. USDA-ARS Jornada Experimental Range, Las Cruces, NM. Distributed by University of Arizona Press.

Pellant, M., P. Shaver, D. Pyke and J.E. Herrick. 2005. Interpreting Indicators of Rangeland Health, Version 4. Interagency Technical Reference 1734-6. Bureau of Land Management, Denver, CO.

Duniway, M., J. Herrick, D. Pyke, and  D. Toledo P. 2010. Assessing Transportation Infrastructure Impacts on Rangelands: Test of a Standard Rangeland Assessment Protocol. Rangeland Ecology & Management 63(5):524-536.

For more information contact Jeff Herrick (