Treesearch

Armillaria root disease is one of the leading causes of growth loss and mortality in coniferous forests of the western USA (Lockman & Kearns 2016). Recent surveys suggest Armillaria root disease is increasing on trees in Utah (John Guyon, per. comm.). To maintain forest resilience and productivity, we must determine (1) which Armillaria species are involved in current root diseases and associated mortality in forests across the region, (2) where these Armillaria species occur/will occur across the current and future landscapes, and (3) where changing climates could exacerbate this disease....

Armillaria root disease, caused by several Armillaria species, is one of most damaging tree diseases throughout the world (Wargo & Shaw 1985). In southeastern Alaska, both A. sinapina and A. nabsnona have previously been reported, but these species have generally been considered as weak pathogens or saprophytes under natural conditions in this region (Shaw & Loopstra 1988, Adams et al. 2015). More recently, however, A. sinapina has been found in pathogenic situations in Alaska (Klopfenstein et al. 2009a, Adams et al. 2015). In Shaw and Loopstra’s (1988) study, they also identified two...

Climate change is predicted to increase the impacts of Armillaria root disease as host trees become maladapted to their environment, escalating tree stress, and potentially increasing susceptibly to Armillaria pathogens (e.g., Klopfenstein et al. 2009, Kliejunas et al. 2009, Kliejunas 2011, Sturrock et al. 2011, Dempster 2017, Kubiak et al. 2017, Aslam & Magel 2018). Powerful statistical bioclimatic modeling methods [e.g., Maximum entropy (Maxent)] are available to determine probable suitable climate space and potential distribution for Armillaria species for contemporary and future time...

The brown root rot pathogen (Phellinus noxius) is causing a destructive, mortality-causing disease on diverse tropical trees that are integral to forest ecosystems in the Pacific Islands (e.g., Ann et al. 2002, Brooks 2002, Sahashi et al. 2015, Figure 1). Our previous work indicates that (1) this invasive fungal pathogen is more prevalent and aggressive than previously reported across the Pacific Islands (e.g., Northern Mariana Islands, Federated States of Micronesia, Palau, American Samoa); and (2) multiple genetic groups of this fungal pathogen are present, which indicates that the...

At a landscape level, measurements of forest health can be a fluid statistic as it relates to the specific goals of management, which differ from stand to stand (Crann et al. 2015). As a result, analyses of trees at the individual or stand level may discover previously unknown factors that influence specific tree health metrics. Above-ground dynamics, such as productivity and foliage integrity, are common measures of tree health (Trumbore et al. 2015); however, roots and their interactions with soil and microbes may have a greater impact on tree health than the above-ground dynamics.

Root disease pathogens, including Armillaria (Fr.) Staude, are a leading cause of growth loss and mortality of trees in forest ecosystems of North America (Lockman & Kearns 2016). This panglobal fungus can cause significant reductions in tree growth that can lead to mortality. Armillaria spp. have a wide host range, and they also play a vital ecological role in the carbon cycling process via wood decomposition (Raabe 1962, Baumgartner et al. 2011, Heinzelmann et al. 2019). As a native root-disease fungus, Armillaria spp. are among the oldest and largest known living organisms on Earth...

A lineage of the Mountain Sucker species complex (Pantosteus jordani) exists as a genetically and morphologically distinct taxon restricted to the Missouri River basin. This species is thought to be declining throughout its range and is assumed to be extirpated from the southern portion of its distribution. We developed a quantitative PCR-based environmental DNA assay for P. jordani to help define and monitor its current range. The assay is both specific to P. jordani and sensitive to low amounts of DNA, with a detection limit of 10 DNA copies per reaction. In vitro experiments involved...

Climate stressors on the forests of the American Southwest are shifting species distributions across spatial scales, lengthening potential fire seasons, and increasing the incidence of drought and insect-related die-off. A legacy of fire exclusion in forests once adapted to frequent surface fires is exacerbating these changes. Reducing stand densities and surface fuel loads has been proposed as a means of moderating fire behavior while reducing competition for water, but it is not established whether thinning treatments and restoration of surface fire regimes will be enough to offset the...

Bull trout (Salvelinus confluentus) are challenging to detect as a result of the species cryptic behavior and coloration, relatively low densities in complex habitats, and affinity for cold, high clarity, low conductivity waters. Bull trout are also closely associated with the stream bed, frequently conceal in substrate, and this concealment behavior is poorly understood. Consequently, population assessments are problematic and biologists and managers often lack quantitative information to accurately describe bull trout distributions, estimate abundance, and assess status and trends;...

On Guam, the estimated lifespan of Casuarina equisetifolia subsp. equisetifolia is 35 to 90 years and trees may reach a height of 24 m and a diameter at breast height of 92 cm. The majority of its trees are monecious. In 2002, it was noticed that many trees were in a slow decline and when felled, droplets often formed on their fresh stumps. In 2009, this condition was coined ironwood tree decline (IWTD). The droplets which consisted of various mixtures of plant exudates and bacterial ooze were found to contain Ralstonia solanacearum and various wetwood bacteria. Reported in 2015 and...