Over a century of livestock grazing, fire suppression, logging, and other Euro-American land uses have radically altered forests and woodlands in the southwestern United States. From desert grasslands to piñon-juniper woodlands, up through ponderosa pine and many mixed-conifer forests, this land-use history has generally caused declines in herbaceous ground covers and marked increases in woody vegetation. For example, many open stands of ponderosa pine with grassy understories, once maintained by frequent surface fires (photo), have become dense, unhealthy thickets of young trees and needle litter mats (Allen 1998). These forests are at dramatically increased risk of large, destructive crown fires that threaten both ecological and human communities.
Woodlands of piñon and juniper trees have increased in range and density, with much loss of herbaceous ground covers. The consequent high erosion rates are widespread. At Bandelier National Monument, the accelerated erosion rates are degrading both natural and cultural resources (Allen 2002). At adjoining Los Alamos National Laboratory (LANL), high erosion rates could move a variety of soil contaminants off-site. As a result, collaborative, interagency research (involving the USGS, LANL, National Park Service, USDA Forest Service, and Colorado State University) has been elucidating past and current ecological patterns and processes as well as testing restoration treatments.
Recently, a broad scientific, social, and political consensus has emerged that restoration of ecological sustainability in these forests and woodlands is needed. Looking at historic patterns of natural variability has proven useful in evaluating the current status of ecosystems by comparison to past conditions. In addition, understanding the natural patterns of the past helps identify ecologically justifiable restoration goals. Ecosystem restoration aims to reset current trends toward the natural range of conditions. Developing and implementing a variety of restoration approaches can immediately reduce crown fire risk, decrease erosion rates, and incrementally return more natural and resilient conditions to southwestern forests and woodlands.
Allen, C.D. 1998. A
ponderosa pine natural area reveals its secrets. Pages 551-552
in M.J. Mac, P.A. Opler, C.E. Puckett Haecker, and P.D. Doran, (eds.).
Status and trends of the nation's biological resources. Vol. 2. U.S. Department
of the Interior, U.S. Geological Survey, Reston, VA.
Allen, C.D. 2002. Runoff, erosion, and restoration studies in piñon-juniper woodlands of the southeastern Jemez Mountains. USGS Fort Collins Science Center, Jemez Mountains Field Station, Los Alamos, NM.
Allen, C.D., M. Savage, D.A. Falk, K.F. Suckling, T.W. Swetnam, T. Schulke, P.B. Stacey, P. Morgan, M. Hoffman, and J. Klingel. 2002. Ecological restoration of southwestern ponderosa pine ecosystems: A broad perspective. Ecological Applications12(5):1418-1433.
Davenport, D.W., D.D. Breshears, B.P. Wilcox, and C.D. Allen. 1998. Viewpoint: Sustainability of piñon-juniper ecosystemsA unifying perspective of soil erosion thresholds. Journal of Range Management 51(2):229-238.
Gottfried, G., T.W. Swetnam, C.D. Allen, J.L. Betancourt, and A. Chung-MacCoubrey. 1995. Pinyon-juniper woodlands. Chapter 6. Pages 95-132 in D.M. Finch and J.A. Tainter (tech. eds.). Ecology, diversity, and sustainability of the Middle Rio Grande Basin. USDA Forest Service General Technical Report RM-GTR-268. Fort Collins, CO.
Jacobs, B.F., R.G. Gatewood, and C.D. Allen. 2000. Ecological restoration of a wilderness and cultural landscapePaired watershed study, Bandelier National Monument: Interim report to U.S. Geological Survey. On file at Bandelier National Monument, Los Alamos, NM. 20 p.
Sydoriak, C.A., C.D. Allen, and B.F. Jacobs. 2000. Would ecological landscape restoration make the Bandelier Wilderness more or less of a wilderness? Wild Earth 10(4):83-90.
Wilcox, B.P., D.D. Breshears, and C.D. Allen. 2003. Ecohydrology of a resource-conserving semiarid woodland: Effects of scale and disturbance. Ecological Monographs 73(2): 223-239.