Treesearch

The precipitous decline of the keystone species whitebark pine (Pinus albicaulis Engelm.) has resulted in dramatic changes to many high elevation ecosystems in the western U.S. and Canada. To restore these ecosystems, there is a need to establish populations of whitebark pine that will persist in the face of both natural and anthropogenic disturbances (e.g. climate change, white pine blister rust [Cronartium ribicola J.C. Fisher]). The listing of whitebark pine as endangered in Canada and its recent proposed listing as threatened in the U.S. reinforce the urgency of the need to act. This...

All native North American white pines are highly susceptible to white pine blister rust (WPBR) caused by Cronartium ribicola. Understanding genomic diversity and molecular mechanisms underlying genetic resistance to WPBR remains one of the great challenges in improvement of white pines. To compare major gene resistance (MGR) present in two species, southwestern white pine (Pinus strobiformis) Cr3 and limber pine (P. flexilis) Cr4, we performed association analyses of Cr3-controlled resistant traits using single nucleotide polymorphism (SNP) assays designed with Cr4-linked polymorphic...

Tree mortality rates have been increasing globally with mountainous regions experiencing higher temperatures and impacts from the expansion and intensification of pests and invasion by non-native agents. Western North American high-elevation forests exemplify these trends, and they often include one or more species of five-needle white pines (High-5 hereafter). These species share many characteristics critical to defining the structure and function of many subalpine forests. The main threats to High-5 populations include the non-native pathogen Cronartium ribicola, which causes the disease...

Rocky Mountain (RM) bristlecone pine (Pinus aristata), Great Basin (GB) bristlecone pine (P. longaeva), and limber pine (P. flexilis) are high-elevation five-needle pines threatened by the non-native pathogen Cronartium ribicola that causes the disease white pine blister rust (WPBR). The pathogen continues to spread, and the infection front is now in the southern Rocky Mountains and Great Basin. WPBR is increasing in these areas on limber pine and RM bristlecone pine as well as whitebark pine (Pinus albicaulis); WPBR has not yet been documented on GB bristlecone in its native range....

Crops emit a variety of volatile organic compounds (VOCs) that serve as attractants or repellents for pests and their natural enemies. Crop rotations, off-farm chemical inputs, and mechanical and cultural tactics - collectively called cropping systems – alter soil nutrients, moisture content, and microbial communities, all of which have the potential to alter crop VOC emissions. Soil legacy effects of diversified cropping systems have been shown to enhance crop VOC emissions in greenhouse studies, but how they influence emissions under field conditions remains virtually unknown. To...

Using woody biomass from public lands could attract private investments, increase carbon dioxide emission reductions from sustainably harvested low‐grade wood to mitigate climate change, provide benefits for the environment, and support rural community economies. Available for use are about 210 million oven dry tons (in the western U.S. alone) of small‐diameter wood and harvest residues that could be removed through hazard‐fuel treatments and used for bioenergy and bioproducts; representing an economic value of approximately USD 5.97 billion (109). Reaching that utilization goal requires...

Forest soil microbiomes have crucial roles in carbon storage, biogeochemical cycling and rhizosphere processes. Wildfire season length, and the frequency and size of severe fires have increased owing to climate change. Fires affect ecosystem recovery and modify soil microbiomes and microbially mediated biogeochemical processes. To study wildfire-dependent changes in soil microbiomes, we characterized functional shifts in the soil microbiota (bacteria, fungi and viruses) across burn severity gradients (low, moderate and high severity) 1 yr post fire in coniferous forests in Colorado and...

Armillaria species show considerable variation in ecological roles and virulence, from mycorrhizae and saprophytes to important root pathogens of trees and horticultural crops. We studied two Armillaria species that can be found in coniferous forests of northwestern USA and southwestern Canada. Armillaria altimontana not only is considered as a weak, opportunistic pathogen of coniferous trees, but it also appears to exhibit in situ biological control against A. solidipes, formerly North American A. ostoyae, which is considered a virulent pathogen of coniferous trees. Here, we describe...

Understanding the causes of plant invasions requires that parallel field studies are conducted in the native and introduced ranges to elucidate how biogeographical shifts alter the individual performance, population success and community-level impacts of invading plants. Three primary methods deployed in in situ biogeographical studies are directed surveys, where researchers seek out populations of target species, randomized surveys and field experiments. Despite the importance of these approaches for advancing biogeographical research, their relative merits have not been evaluated.

Establishing an effective restoration program requires baseline genetic information to make sound decisions for seed increase and transfer. For many plants this information is lacking, especially among native forbs that are critical for pollinator health. Erigeron speciosus is a widespread, perennial forb occupying montane environments in the western United States and Canada. This species is important in fostering pollinator diversity. Our study examines the population genetic patterns across the species range using reduced-representation sequencing and surveys for genome duplication using...