Treesearch

Invasive forest pathogens can harm cultural, economic, and ecological resources. Here, we demonstrate the potential of endemic tree pathogen resistance in forest disease management using Phytophthora ramorum, cause of sudden oak death, in the context of management of tanoak (Notholithocarpus densiflorus), an ecologically unique and highly valued tree within Native American communities of northern California and southern Oregon in the United States. We surveyed resistance to P. ramorum on the Hoopa Valley Indian Reservation and Yurok Indian Reservation in a set of study sites with variable...

A 20-year experiment was reported on the effects of climate variability and management in California's ponderosa pine plantations. Pine trees were grown in three different climatic and edaphic zones treated with herbicide to reduce competition from understory plants and/or fertilizer to stimulate growth. We found that management increased tree growth and, in most but not all cases, the combination of understory suppression and fertilization stimulated productivity beyond the expected growth potential of each site. In addition, wet sites have the most productive forests overall, but they...

Background: Increasingly frequent and severe drought in the western United States has contributed to morefrequent and severe wildfires, longer fire seasons, and more frequent bark beetle outbreaks that kill largenumbers of trees. Climate change is expected to perpetuate these trends, especially in montane ecosystems,calling for improved strategies for managing Western forests and conserving the wildlife that they support.Woodboring beetles (e.g., Buprestidae and Cerambycidae) colonize dead and weakened trees and speedsuccession of habitats altered by fire or bark beetles, while serving as...

Extreme wildfires in coniferous forests produce large areas of dead trees (snags) that are expected to provide much needed habitat for the Black-backed Woodpecker, a postfire associate. In an attempt to better understand extreme fire effects (including increasing fire size and decreasing diversity of fire effects), we monitored Black-backed Woodpeckers during the 2014 and 2015 breeding seasons following two wildfires (the 2013 Rim and 2014 King fire) that burned in the Sierra Nevada, USA under extreme fire conditions. Despite an extensive sampling effort including 1025 broadcast surveys...

Much of California, U.S. experienced a severe drought in 2012–2015 inciting a large tree mortality event in the central and southern Sierra Nevada. We assessed causal agents and rates of tree mortality, and short-term impacts to forest structure and composition based on a network of 11.3-m fixed-radius plots installed within three elevation bands on the Eldorado, Stanislaus, Sierra and Sequoia National Forests (914–1219, 1219–1524 and 1524–1829 m on the Eldorado, Stanislaus, Sierra; 1219–1524, 1524–1829, and 1829–2134 m on the Sequoia), where tree mortality was most severe. About 48.9% of...

Limber pine in the Great Basin responds to climate change in a diversity of ways, as shown by studies of current and paleo-historic forests. Expected movements of limber pine up in elevation with warming climates are only one of several other -- and unexpected -- responses. The latter include shifts out from mid-elevation forests into sage-steppe shrublands following disruption of local inversions; shifts down in elevation into low, north-facing ravines; and shifts in slope aspect. Climate refugia locations are proposed and researchers are urged to consider non-traditional responses of...

Wind and weather in mountainous areas are complex because of the underlying terrain. Typically, regional computer models are needed with sufficiently high resolution to resolve such complex conditions. However, this high-resolution weather information usually becomes available only when the critical time in fighting a severe fire event is long past, thus the advantage of using high-resolution weather models for fire management seems limited. To address this problem, we have developed an experimental system called FireBuster that is designed to streamline and automate many intermediate...

Assessment and preservation of biodiversity has been a central theme of conservation biology since the discipline's inception. However, when diversity estimates are based purely on measures of presence–absence, or even abundance, they do not directly assess in what way focal habitats support the life history needs of individual species making up biological communities. Here, we move beyond naïve measures of occurrence and introduce the concept of “informed diversity” indices which scale estimates of avian species richness and community assemblage by two critical phases of their life cycle:...

Over 147 million dead trees were detected in the Sierra Nevada by the U.S. Forest Service Aerial Detection Survey (ADS) from 2010 to 2018 (USDA 2019). The massive tree mortality, evident in swaths of conifers with red needles, was mostly due to the 2012–2016 drought. While levels of mortality have declined in the last 2 years, the consequences will last for years to come. Trees that died will eventually fall over and surface fuels will accumulate — already the accumulation of millions of tons of dead material on forest floors is outpacing county resources to remove it. Urgent ongoing...

We present the first comprehensive inventory and analysis of rock glaciers in the hydrographic Great Basin (GB), United States, documenting 842 features (mean 9.9 ha; range 0.1–201 ha) across thirty-two mountain ranges. These encompassed 8° latitude (from 36.5°N to 44.3°N) and 11° longitude (from −110.7°W to −121.4°W), and composed 83.1 km2, or 1.1 percent, of the cumulative area above the lowest rock glacier elevation. Forty-five percent of the features were mapped as intact (containing ice) and occurred across sixteen mountain ranges. Rock glaciers conservatively contained cumulative...