Treesearch

The Sierra Nevada region is characterized by high topographical and climatological diversity (Dettinger et al. 2018), extending 400 mi north to south and 70 mi east to west. Elevations are higher in the southern end of the range, with Mount Whitney (14,505 ft) being the highest peak in the contiguous United States; peaks in the northern part of the range are generally less than 8,800 ft (Minnich and Padgett 2003). The western portion of the Sierra Nevada region is characterized by a Mediterranean climate, with cool, wet winters and warm, dry summers. The western portion of the Sierra...

The Sierra Nevada contains 24 major river basins that provide water to downstream ecosystems and human communities. Water resources and ecosystem services are derived from snowpacks accumulated at high elevations, replenishing soil moisture through snowmelt and generating streamflow during the spring and early summer. Streamflows produced from Sierra Nevada snowpack account for about 30 percent of California’s total water supply, provide about 60 percent of water consumed by the state’s population, and generate nearly half of the state’s hydroelectric power (Bales et al. 2011a, Dettinger...

The Sierra Nevada is a biologically diverse and socially important region of California, providing water, timber, rangeland, recreation, and many other ecosystem services. A significant amount of infrastructure (roads, bridges, structures, etc.) is needed to support these services. In recent years, a period of major drought has led to tree mortality and wildfires. Rainstorms following wildfires have caused debris slides, washouts, and erosion. Billions of dollars of damage to roads, trails, culverts, bridges, dams, campgrounds, buildings, and other infrastructure have been caused by...

Rapid climate warming at northern high latitudes is driving geomorphic changes across the permafrost zone. In the Yamal and Gydan peninsulas in western Siberia, subterranean accumulation of methane beneath or within ice-rich permafrost can create mounds at the land surface. Once overpressurized by methane, these mounds can explode and eject frozen ground, forming a gas emission crater (GEC). While GECs pose a hazard to human populations and infrastructure, only a small number have been identified in the Yamal and Gydan peninsulas, where the regional distribution and frequency of GECs and...

A vulnerability assessment was conducted on the effects of climate change on infrastructure and outdoor recreation in the Sierra Nevada, including adaptation options that minimize negative impacts of climate change and facilitate a transition to a warmer climate. At vulnerable or flood-prone sites, resilience near stream crossings and in floodplains can be enhanced by designing infrastructure to withstand more frequent and severe flood events, and by upsizing or upgrading existing infrastructure to withstand flooding. Some roads and other infrastructure can be decommissioned or moved to...

Masting is the synchronous and highly variable production of fruit within a population. Although several hypotheses have been proposed to explain why and how masting evolved in plants as a reproductive strategy, the factors that trigger a large reproductive effort in a particular year are still not well understood. While both weather and resources have been proposed to play an important role, testing these hypotheses has been challenging due to a lack of longterm data and appropriate experimental designs. In this manuscript, we used 18 years of acorn production data to analyze the relations...

The Pacific Southwest Region of the U.S. Department of Agriculture, Forest Service (USFS), in collaboration with the USFS Pacific Northwest and Pacific Southwest Research Stations and the Office of Sustainability and Climate, formed a science-management partnership and conducted a climate change vulnerability assessment for infrastructure and recreation in Sierra Nevada national forests. The vulnerability assessment set the stage for developing adaptation options in a series of science-management workshops. The outcomes of the effort, called the Sierra Nevada Infrastructure and Recreation...

Context: Spatial patterns of high-severity wildfire in forests affect vegetation recovery pathways, watershed dynamics, and wildlife habitat across landscapes. Yet, less is known about contemporary trends in landscape patterns of high-severity burn patches or how differing federal fire management strategies have influenced such patterns. Objectives: We assessed fires managed for ecological/ resource benefit and fires that are fully suppressed and investigated: (1) whether spatial patterns of high-severity patches differed by management strategy, (2) whether spatial patterns were related to...

Cities worldwide are engaging in large-scale greening projects motivated by the wide range of documented ecological, economic, and social benefits of urban forests. Urban forested natural areas are a critical component of the total urban forest but are often overlooked and typically lack formal management frameworks. One approach to addressing this deficiency may be to borrow from traditional ecological management frameworks and practices (that is, silviculture). Although urban forested natural areas share similarities with rural forests, the impacts of urbanization on forest stand...

Data-driven decision making is the key to providing effective and efficient wildfire protection and sustainable use of natural resources. Due to the complexity of natural systems, management decision(s) require clear justification based on substantial amounts of information that are both accurate and precise at various spatial scales. To build information and incorporate it into decision making, new analytical frameworks are required that incorporate innovative computational, spatial, statistical, and machine-learning concepts with field data and expert knowledge in a manner that is easily...