Basic Info:


PO Box 15004, Flagstaff, AZ 86011-5004
Phone: (928) 523-9555
Fax: (928) 523-1266
itep@nau.edu

Basic Information

Rangelands
Rangelands comprise nearly 40% of the landmass of the United States. Largely unsuitable for cultivation, rangelands are primarily used for grazing livestock. Navajo Nation sheepherders, for example, depend on quality rangeland to raise their herds of sheep, a tradition central to their lives. The value of rangelands, however, extend beyond livestock support. Rangelands provide habitat for rich biodiversity, clean air and water, and open space for recreation and spiritual rejuvenation.

Rangelands are defined by the predominance of grasses, shrubs, forbs, and other grass-like plants. They include grasslands, shrublands, woodlands, savannahs, tundra, most deserts, and riparian and wetland plant communities, including marshes and wet meadows. Because of the exceptional diversity of habitats and climatic regions that rangelands encompass, it is difficult to make broad generalizations on how they are impacted by climate change. Nevertheless, some long-term trends are apparent.

A ubiquitous threat to rangelands is encroachment by non-native, invasive species, some of which benefit from increased levels of atmospheric CO2. Higher in biomass than most native species, invasives greatly increase the threat of wildfire. Warmer, drier summers in the western United States will likely intensify this threat. Some regions, such as the Great Plains, have adapted to regular fire regimes. In the rangelands of the Southwest, however, fires have historically occurred only once every several decades. Changes to this natural cycle could transform diverse desert scrub, scrub-steppe, and desert savannah/grasslands to monocultures of invasive grasses and other plant species.

As biodiversity is lost, landscapes will become more susceptible to erosion. In the West, where precipitation is expected to become less frequent and more intense, heavy rainfall events can wash away nutrient-rich topsoil. Intervening dry periods cause wind erosion, which can have serious consequences for air quality. Higher amounts of dust settling on mountain snowpack accelerates snowmelt and exacerbates water shortages during the summer months.


Unfortunately, forests are being rapidly destroyed in many parts of the world. They are cleared for agriculture or pasture, logged, mined, and degraded by human land-use practices, such as fire suppression. When forests are cleared, the stored carbon is released back into the atmosphere. Scientists estimate that tropical deforestation alone is responsible for 20% of all anthropogenic carbon dioxide emissions that contribute to global warming.

Forests, indispensable for their role in the carbon cycle, will not themselves endure climate change unchanged. As the climate warms, ecosystem composition will likely shift. Trees will die and species will change. Such shifts can decrease or even reverse the carbon uptake of a forest, causing a "carbon flux." Additional carbon in the atmosphere will then further catalyze climate change, creating a negative loop of intensification.


While warming temperatures are partly to blame, trees must also contend with more-frequent and severe disturbance events such as droughts, insects, and fires. Trees already stressed by drought are most susceptible. Massive tree die-backs result from bark beetle infestations, drought, and warmer temperatures; this is already evident in the piƱon-juniper woodlands of the American West and Canada's boreal forests. According to the IPCC, boreal forests-coniferous forests covering parts of Alaska, Canada, northern Europe, and Russia-are most vulnerable to disturbance events.

As temperatures warm, mountain and other high-altitude habitats will be increasingly encroached upon by adjacent lowland biomes.ii In turn, boreal forests will likely migrate northward and invade arctic tundra. Some models project that with a doubling of atmospheric CO2, forests will replace between 11 and 50% of tundra.

One of the most significant elements of climate change impacts associated with changing land composition is the loss of biodiversity and other ecosystem services, such as water and air filtration. Such risks are especially virulent in biodiversity "hotspots," such as equatorial and temperate rainforests. According to IPCC research, most species extinction and extirpation related to climate change will occur in the early 21st century. Climate change will only exacerbate the worldwide extinction crisis caused by other anthropogenic factors, most notably tropical deforestation. The International Union for the Conservation of Nature reports that one in four mammals may be at risk.

For some Native peoples, forests are the embodiment of harmony and balance-a complex system working together seamlessly to create a balanced web of life. Their value lies beyond the price of timber, and thus their destruction is more catastrophic for Native people. From time immemorial, indigenous cultures have relied on forests for food, shelter, and medicines, as well as spiritual and mental health. Global warming may disrupt the ability of forests to provide subsistence for those who rely on them-plants, animals, and humans alike. For example, climate change is impacting Native basket weavers of the American Northeast who rely on brown ash. Drought and insect infestations have predisposed the tree species to high mortality rates, which will intensify as climate change progresses. Other tribes are finding medicines and other traditional plants difficult or impossible to collect as forest composition changes. As climate change disrupts the forest system, traditional life ways may likewise be thrown into turmoil until Earth once again finds her balance.


  1. Fischlin, A. et al. 2007. "Ecosystems, their properties, goods, and services. Climate Change 2007: Impacts, Adaptation and Vulnerability." Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson [Eds.]. Cambridge University Press, Cambridge, 211-272. p. 227.

  2. Fischlin, A. et al. 2007. "Ecosystems, their properties, goods, and services. Climate Change 2007: Impacts, Adaptation and Vulnerability." Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson [Eds.]. Cambridge University Press, Cambridge, 211-272. p. 228.