Treesearch

John C. Frémont became “almost obsessed” with piñon pine during his wintertime traverse of the Sierra Nevada in January of 1844. Purchasing a skin bag with a few pounds of pine nuts from local Indians, he found that “when roasted, their pleasant flavor made them an agreeable addition to our now scanty store of provisions." Although the existence of junipers was well known at the time, Frémont soon would bring piñon pine to the attention of the scientific community, formally recording the name Pinus monophylla in his journal.

Global change is altering forest carbon and water balances; however, the extent to which tree species shape ecosystem-scale responses to climate, particularly in biodiverse forests, remains unclear. To address this, we simulated the effects of an envelope of future climate conditions on watershed carbon and water balances and quantified the contributions of tree species based on their xylem anatomy. We accomplished this by incorporating species-level transpiration calculations into a landscape-scale ecosystem process model. Our revised model linked the effects of forest succession, species...

This is the executive summary for the report, Climate Change Vulnerability and Adaptation in Coastal Oregon, by Halofsky et al. (2024, PNW-GTR-1024). The vulnerability assessment was developed by a science-management partnership consisting of the U.S. Department of Agriculture, Forest Service (Siuslaw National Forest, Oregon Dunes National Recreation Area, Cascade Head Experimental Forest, Pacific Northwest Region, Pacific Northwest Research Station) and Northwest Climate Hub; U.S. Department of the Interior, Bureau of Land Management (Northwest Oregon District and Coos Bay District); and...

Sustainable management of forested wetlands requires an understanding of water table (WT) dynamics affected by rainfall and evapotranspiration (ET) as well as management practices to sustain water quality, quantity, and ecosystem services. The hydrology, the most important factor influencing productivity of forested wetlands, may be characterized by measuring changes in WT depth over time. The hydrology of U.S. Southeastern Coastal Plain forested wetlands, particularly wet pine flats and pocosins, where drainage has been commonly used to improve tree growth, is relatively well understood....

U.S. law authorizes the U.S. Department of Agriculture, Forest Service to "conduct surveys to detect and appraise insect infestations and disease conditions and manmade stresses affecting trees and establish a monitoring system throughout the forests of the United States to determine detrimental changes or improvements that occur over time, and report annually concerning such surveys and monitoring" (FHP 2023). Forest insects and diseases have widespread ecological and economic impacts on forests across the United States and may represent the most serious threats to the Nation’s forests...

Wildland fire is an important natural component of many forest ecosystems that are characterized by specific combinations of fire frequency, severity, and seasonality (Greenberg and Collins 2021). It is a widespread disturbance agent in many U.S. forest ecosystems, causing widespread tree damage and mortality and impacting forest health both positively and negatively (Agee 1998, Thom and Seidl 2016, Wade and others 2000). In some ecosystems, wildland fire has been essential for regulating processes that maintain forest health (Lundquist and others 2011). For example, it is an important...

Tree mortality is a natural process in all forest ecosystems. High mortality can be an indicator of forest health problems. On a regional scale, high mortality levels may indicate widespread impacts of one or more factors, including insects, disease, fire, drought, or major storms. Regionally high mortality may also occur if a large proportion of the forest in a particular region is made up of older, senescent stands. The approach presented here seeks to detect mortality patterns that might reflect changes to ecosystem processes at large scales that could affect long-term forest sustainabil...

International forest sustainability reporting by the U.S. Department of Agriculture, Forest Service is pursuant to the Montréal Process Criteria and Indicators (C&I; Montréal Process Liaison Office 2015). That framework includes measures of forest fragmentation that have evolved substantially over three decades of reporting (Riitters and Robertson 2021). The most recent report, for the years 2001 to 2016, indicated that fragmentation continued to increase but at a decreasing rate over that time interval (Riitters and Robertson 2021). The objective of this chapter is to update the fragmentat...

Drought is an important stressor affecting forests and is commonly defined as a period of moisture deficit resulting from below-average precipitation, high temperatures, or both (Clark and others 2016). Alone or in combination with other disturbances, drought can reduce forest productivity, cause shifts in forest types, affect the ability of forests to regenerate, and diminish the capacity of forests to provide ecosystem services (Brodribb and others 2020, Vose and others 2016). As climate warms and many parts of the world become drier, droughts are expected to become more widespread,...

This work developed a precipitation-based forest exposure indicator that identified warm season (May-Sept.) changed conditions between the multidecadal wet cycle from 1940s-1999 and dry cycle from 2000-2021 for the conterminous USA. Changed moisture conditions were validated for disturbance connection by assessing bark beetle and wildfire disturbance spatial records by severity of dry exposure. Results indicated 2-fold increase in wildfire and bark beetle disturbances from 2017-2022, respectively, for western U.S. locations with highest dry exposure classes vs. where dry exposure was...