Climate Change as a Challenge to Bird Conservation in Arid and Semi-arid Regions of North America
Tens of millions of migratory birds are dependent on wetland and riparian stopovers in arid and semiarid regions of North America during migration. Under current conditions, these habitats are declining in quantity and quality. Global climate change would superimpose even greater stress to these ecosystems, as indicated by global climate model predictions of higher temperatures and less precipitation in the southwestern U.S. Climate changes predicted for these regions thus may alter the spacing and quality of these critical wetland and riparian stopover habitats and thereby influence the survival and reproduction of migratory birds. This study investigates how these changes would influence the survival and reproduction of migratory birds. The research addresses specific questions that include (1) How will climate change alter the spacing and quality of critical wetland stopover habitats? (2) What are the long-term demographic consequences of climate change on sandpipers? (3) What are the sensitivities of migrating songbirds to loss of riparian forests due to global change and water-use patterns? and (4) What is the relative sensitivity to climate change of guilds of wetland birds? To answer these questions, FORT scientists will evaluate current and new global climate model predictions of temperature, precipitation, and storm intensity; analyze existing data sets; and draw heavily from the published scientific literature and climate, hydrology, and population models. Results of this study will assist wildlife managers within the Department of the Interior and other resource management agencies that are concerned with protection of migratory species and habitats critical for migration and breeding success.
Test Riparian Revegetation Methods along the Virgin River, Zion National Park
The North Fork of the Virgin River, which flows through Zion National Park, was channelized in the early 1900s to protect the newly built (and now historic) road and Zion Lodge situated along the river. Wire caging filled with rocks (revetments) were installed, which stabilized and heightened the river’s banks. Although the effort has been successful in preventing flooding, channelization has had ecological repercussions. Historically, cottonwood and willow forest dominated the canyon floor, providing habitat and forage to native fauna and important aesthetic values to humans. Today, the forest is composed solely of aging trees, as natural flood processes that supported phreatophyte seedling establishment no longer occur. As a result, non-native plants are invading and dominating the understory (primarily tamarisk [Tamarix ramossisima], cheatgrass [Bromus tectorum], and ripgut brome [Bromus rigidus]). The decline of native riparian forests is a concern throughout the western United States, especially in arid environments where riparian zones support a disproportionately high percentage of the overall regional biodiversity. Zion's General Management Plan prescribes revetment removal along a 2-mile stretch of river where the most enduring and extensive revetments occur. The goal is to restore natural connectivity between the river and its floodplain, thus reinvigorating ecological processes and native biota; however, more than 5,000,000 square feet of ground will be disturbed during removal and recontouring. Without active revegetation, the disturbed area will be susceptible to soil erosion and further invasion of exotic plants. Well-designed experiments are needed to test revegetation methods along the Virgin River on a small scale prior to dechannelizing efforts.