Importance of BLM Roadless Areas in the Western US

Executive Summary

March 2000

Not since the early 1970s have roadless areas on public lands been of such intense interest to policy makers. This report focuses primarily on the Bureau of Land Management (BLM) and reviews (1) the natural setting for the major ecoregions making up the deserts and shrub steppe of the western U.S., (2) their current protection status, and (3) major ecological threats. We review the ecological impacts of roads on native biodiversity with special emphasis on rangelands and discuss the various human uses that impact these natural landscapes.

The BLM is responsible for managing 264 million acres of public land (approximately 1/8 of the total land area of the U.S.) - approximately 175 million acres of this in the western U.S. and the focus of this report. These lands comprise a wide variety of natural habitats including grasslands, deserts, steppe communities, wetlands, and forests many of which contain highly specialized plant and animal species. Current protection statistics show that deserts are relatively more protected than shrub steppe or grassland ecoregions, but all eight ecoregions examined require additional protections and more ecologically sustainable management practices to meet widely recognized conservation goals.

Since World War II, roads have exploded onto the American landscape. Total miles of interstate highway have increased 450 percent since 1960, and over four million miles of roadway now exist in the U.S. The scientific literature has overwhelmingly reported serious negative impacts roads have on native biodiversity. One consequence of roads and associated human activities is habitat fragmentation, which leads to local extinctions of some species and overall ecosystem degradation. Roads promote the spread of exotic species and are a major source of air and water pollution causing serious declines in aquatic biodiversity. Roads cause direct mortality of many species and modify animal behavior. More important than these direct impacts, roads provide human access to otherwise natural ecosystems resulting in even more serious consequences to native biota and natural processes.

Throughout the arid west, groundwater depletion and water diversion has changed the natural landscape in dramatic ways by altering the natural hydrologic regimes of these regions. Entire natural communities have been lost or altered as a consequence. Riparian areas, important special habitats in these ecosystems, have been converted or degraded in a number of ways including exotic species invasion (e.g., salt cedar, Tamarix spp.).

Mining of fuels and minerals has left a significant imprint on natural habitats throughout the west. Surface and open pit mining for coal and other materials has impacted extensive regions as vegetation and topsoil are stripped to gain access to resources. Reclamation of these fragile ecosystems often requires long recovery periods and is often technically difficult and expensive. In some cases, full restoration is not possible. In addition, mining exploration and production impacts far larger areas than just the immediate mine site through roads and other human infrastructure. Streams are often polluted with a wide range of toxins as runoff from pits and mine spoils reach far downstream - many of these far-reaching impacts often continue long after the mine has been abandoned.

Invasion by exotic species, whether intentional or unintentional, is second only to habitat loss as the leading cause of species endangerment. Invasion of exotics on public lands has been estimated to be > 5,000 ac/day with most control strategies being reported as ineffective. In some major habitat types (e.g., sagebrush communities) continuing degradation by invasive exotics overshadows all other concerns. In many instances, roads become one of the major conduits for exotic species invasions. Cheatgrass (Bromus tectorum) is expected to dominate or completely convert over half of the native sagebrush habitat in the country. In the Sonoran Desert, introduced grasses are fundamentally changing natural habitats wherever they become naturalized. Perhaps more troubling than the fact that exotic species are seriously changing the natural history of the arid and semiarid West is that these changes may be irreversible.

Although once considered a non-consumptive use, damage related to recreation activities especially off-road vehicles (ORV) or off-highway vehicles (OHV) is now considered one of the more pervasive impacts on rare species in the west. Approximately half of BLM lands are open to ORV use with another 44 percent designated as limited access; however, many limited access areas may actually be open. Only six percent of all BLM land is closed to ORVs. ORVs cause intense soil disruption damaging the living layer on many desert and steppe soils (the crytogamic crust) reducing soil moisture infiltration rate, soil porosity, and soil permeability all having immediate and direct impact on native vegetation. They have been shown to significantly alter natural distributions of many grass and forb species, cause damage to other species, and reduce numbers, diversity, and biomass of vertebrates. The fate of certain endangered species such as the desert tortoise (Gopherus agassizii) is of special concern with regards to ORV use. Impacts from noise and direct harassment have also been widely reported.

Livestock grazing has had perhaps the largest influence of any land management practice on native ecosystems of western rangelands. Unrestricted grazing has led to severe desertification of 37 percent of the southwestern U.S. and has altered the productivity, cover, and species composition of large regions. According to the BLM, over 68 percent of its rangelands are in unsatisfactory condition. Grazing has caused damage to soils, upland vegetation, riparian areas, and a wide range of animal species requiring natural habitats. Grazing also has been identified as the single most important limiting factor in wildlife populations in the west. Livestock grazing has been listed as a significant factor in the decline of 76 listed and candidate wildlife species including 36 fish, 14 birds, nine mammals, eight amphibians, two reptiles, and seven invertebrates. It also has been listed as one of the most important factors in the decline of sage grouse - a good umbrella and indictor species for healthy natural sagebrush habitats. Finally, grazing and related management has contributed greatly to the invasive exotics problem.

In terms of ecological benefits, roadless areas provide (1) relatively intact wildlands, (2) essential habitat for many native species and communities at risk, (3) important water resources, (4) "buffer areas" from exotic species invasions and edge effects, (5) strongholds for native aquatic biota, (6) critical range for ungulates and other species, and (7) landscape and regional connectivity. While not all conservation goals can be achieved by protecting remaining roadless areas, they do provide an extremely important foundation.

As the human population of the West continues to grow and the demands on the native ecosystems increases, we find ourselves at a time where significant steps taken to protect our remaining roadless areas can have long lasting ecological benefits. Now is the time to conduct extensive roadless area inventories and the appropriate ecological analyses to determine to what degree these roadless areas maintain native biodiversity and natural processes. Until we gain a better understanding, it is prudent that we hold the line on further road building and prevent abusive land management practices on the remaining roadless areas on the BLM throughout the West. Current evidence strongly suggests that protection of these areas may be our best opportunity for arresting the decline of native biodiversity and the many ecosystem services that are fundamentally important to sustainable human societies.

For more information, please contact Jim Strittholt .