Fire and Rangelands

Increasing fire frequencies and uncharacteristic severe fires have created a need for improved restoration methods across rangelands in western North America. Traditional restoration seed mixtures of native perennial mid- to late-seral plant species may not be suitable for intensely burned sites that have been returned to an early-seral condition.

Mitigation of ecological damage caused by rangeland wildfires has historically been an issue restricted to the western United States. It has focused on conservation of ecosystem function through reducing soil erosion and spread of invasive plants. Effectiveness of mitigation treatments has been debated recently.

Ecosystem invasibility is determined by combinations of environmental variables, invader attributes, disturbance regimes, competitive abilities of resident species and evolutionary history between residents and disturbance regimes. Understanding the relative importance of each factor is critical to limiting future invasions and restoring ecosystems.

The rangelands and dry forests of Eastern Washington are considered “disturbance-driven” ecosystems. Disturbances are simply events that disturb normal ecosystem processes: nutrient and water cycling, plant growth and reproduction, animal interactions, etc.

Cheatgrass and its cousin, red brome, are exotic annual grasses that have invaded and altered ecosystem dynamics in more than 41 million acres of desert shrublands between the Rockies and the Cascade-Sierra chain. A fungus naturally associated with these Bromus species has been found lethal to the plants’ soil-banked dormant seeds.

Recent research and species distribution modeling predict large changes in the distributions of species and vegetation types in the western interior of the United States in response to climate change.

In this article we test the notion that adaptation to climate change in grazed rangelands requires little more effort than current approaches to risk management because the inherent climate variability that characterizes rangelands provides a management environment that is preadapted to climate change.

When managing rangeland impacted by weeds, land managers often encounter plant communities where remnant desired vegetation is very scarce. When rangeland is this degraded, simply controlling weeds with the expectation that desired plants will be released from competition and return to dominate the site over time might not be adequate.

Seeding is a key management tool for arid rangeland. In these systems, however, seeded species often fail to establish. A recent study in Wyoming big sagebrush steppe suggested that over 90% of seeded native grass individuals die before seedlings emerged.

Medusahead (Taeniatherum caput-medusae [L.] Nevski), the most problematic invasive grass on many California rangelands, is difficult to control selectively in grasslands. Prescribed burning, grazing, and herbicides have been tested with some success but are not practical in all situations.