Global Change

Principal Investigators (alphabetically by last name): Craig D. Allen, USGS Fort Collins Science Center, Jemez Mountains Field Station; Jill S. Baron, USGS Fort Collins Science Center, Colorado State University; Daniel B. Fagre, USGS Northern Rocky Mountain Science Center, Glacier Field Station; Donald McKenzie and David L. Peterson, USDA Forest Service, Pacific Northwest Research Station, Cascadia Field Station; Nathan L. Stephenson, USGS Western Ecological Research Center, Sequoia – Kings Canyon Field Station

Introduction

The objective of the Western Mountain Initiative (WMI) is to understand and predict the responses – emphasizing sensitivities, thresholds, resistance, and resilience – of Western mountain ecosystems to climatic variability and change.

The rate and magnitude of ecosystem responses to changes in the global atmospheric environment are variable and uncertain, ranging from gradual to abrupt, from moderate to profound. The least understood and least predictable responses are those of greatest importance to policy makers and land managers:  responses that are both abrupt and profound. Recent examples of such responses include ongoing drought-induced forest mortality on millions of acres in New Mexico, Arizona, and southern California, and the increasingly large area burned by severe wildfires in the western United States during the past two decades. In both cases, ecosystem thresholds were exceeded relatively quickly, leading to large and often unexpected changes that will have long-term consequences for ecosystem structure, function, and production of goods and services.

In the face of expected climatic change over the next several decades, are significant changes in ecosystem structure and processes likely to become more common? Are these changes predictable? What are the characteristics of ecosystems likely to respond quickly or gradually, profoundly or minimally? How will ecological and economic productivity be affected at various spatial and temporal scales?

Mountain ecosystems of the western United States are ideally suited to address these questions. First, they lend themselves to ecological inquiry because they have: (1) compressed climatic and biogeographic zones containing many ecosystems within relatively small areas; (2) rich paleoecological resources, which record past environmental changes and consequent ecosystem responses; and (3) common ecological drivers, such as snowpack and fire, which facilitate comparisons across ecosystems. Second, because national parks and wilderness of the montane West have experienced minimal human disturbance, effects of environmental changes on ecosystems can be inferred with fewer confounding influences than on intensively managed lands. Third, Western mountain ecosystems are important to society, providing water, wood products, carbon sequestration, biodiversity, and recreational and spiritual opportunities. Finally, more than a decade of USGS research at seven Western mountain parks provides the foundation for broad syntheses of existing knowledge.

For the period 2003-2008, WMI has placed particular emphasis on addressing four key questions regarding Western mountains:

• How are climatic variability and change likely to affect disturbance regimes (particularly fire)?
• How are changing climate and disturbance regimes likely to affect the composition, structure, and productivity of vegetation (particularly forests)?
• How will climatic variability and change affect hydrologic processes in the mountainous West?
• Which mountain resources and ecosystems are likely to be most sensitive to future climatic change, and what are possible management responses?

Contact Information

Nathan L. Stephenson
USGS Western Ecological Research Center, Sequoia
Kings Canyon Field Station
47050 Generals Hwy Unit 4
Three Rivers, CA  93271
Phone: 559-565-3176
E-mail: nstephenson@usgs.gov