Western Forests and Mountains

Forests are a key component of a healthy ecosystem. Management of these resources is vital to their protection as a recreational resource as well as an environmental resource.

ʻŌhiʻa ( Metrosideros polymorpha) is the dominant tree in Hawaiian forests, but Rapid ʻŌhiʻa Death (ROD), a newly emerging disease that stands to cause high mortality of this ecologically important tree, may lead to invasions by exotic plants as gaps open in the forest. To better understand if planting of ʻōhiʻa seedlings can be used as a restoration tool, we investigated the survival of ʻōhiʻa...

Forests are the dominant land cover along the floodplain of the Upper Mississippi River System. These forests are primarily made up of relatively short-lived and rapidly growing species, such as willow, cottonwood, silver maple, green ash, American elm, but with inclusions of slower growing and longer-lived species, such as oak and hickory species.

Relict forests (i.e., forests unable to reestablish after disturbance) may develop in the southeastern U.S. in future predicted extreme temperature, flooding, and drought.

Hawai‘i's precipitation is greatest in upland areas that are typically forested. This precipitation provides water for both people and ecosystems. Precipitation can either run off and contribute to streamflow, or infiltrate into the ground and provide water for plants, base flow to streams, or recharge to aquifers. The exact routing that water takes is controlled by many factors, including the...

Montane plant communities in widely separated intact natural environments of the world have responded to changes in precipitation and temperature regimes by shifting both margins and core distributional ranges upward in elevation. Reduced evapotranspiration rates in cooler climate zones at higher elevation may compensate for less precipitation and higher temperatures within species’ former ranges...

This research theme examines the impacts of prescribed fire on plant productivity, soil physical, chemical, and biological characteristics, and nutrient leaching. Results from this research will enable improved decision-making of how to manage fire-prone forests to maintain long-term forest fertility and productivity, especially across wide climate gradients characteristic of the Pacific Northwest...

This research theme coalesces studies of old-growth temperate forests in several major thematic areas including landscape and ecosystem controls on watershed nutrient export, wildfire disturbance legacies on biogeochemical cycling, and the imprint of tree species on soil nutrients in old-growth forests.

This research theme advance fundamental understanding of climate-biogeochemistry interactions, with wide applicability to virtually all terrestrial ecosystems.

Management decisions are made at the intersection of facts and values, and WERC's role is to assist decision-makers by bringing the best available science to the table. Dr. Nathan Stephenson seeks to help managers and policy makers reassess their missions in light of rapid and unprecedented changes, develop broad concepts relevant to adapting to such changes, and provide hands-on assistance during...

USGS WERC's Dr. Phil van Mantgem and his collaborators are using plot-based methods to describe change and vulnerability to drought in the forests of the western United States. A focus of this work is the installation and maintenance of large (1 ha) monitoring plots. Many other vegetation monitoring strategies are based on small (0.1 ha) plots, which may not be sufficient to detect changes in...

This project uses new and existing field data to assess forest restoration treatment effects across broad spatial and temporal scales. WERC's Dr. Phil van Mantgem and project partners are considering the effects of restoration treatments in terms of forest structure, forest stand development, subsequent tree mortality patterns mortality, and how climate influences the success or failure of...

Dr. Nathan Stephenson and colleagues seek to determine what changes are occurring in forests, why they are occurring, and what they mean. For example, they have documented a long-term, apparently climatically-induced increase of tree mortality rates in otherwise undisturbed old forests across the western U.S., implying that these forests could become net sources of atmospheric carbon dioxide.

Fuel conditions and fire regimes in western forests and deserts have been altered due to past land management, biological invasions, and recent extreme weather events and climate shifts. These changes have created extreme fire risk to local and regional communities, threatening their economic health related to wildland recreation, forest production, livestock operations, and other uses of public...