Treesearch

Emerald ash borer (EAB), (Agrilus planipennis Fairmaire), first identified in 2002 in southeast Michigan, has caused catastrophic ash (Fraxinus spp.) mortality in forests within the core of the invasion and has spread to 35 states and five Canadian provinces. Little is known about persistence and densities of EAB populations in post-invasion sites after most ash trees have died. We monitored EAB populations from 2014 to 2016 using double decker (DD) traps set in the midst of white ash (F. americana) trees in 30 post-invasion sites in southeast and south-central Michigan. Two DD traps were...

Uncertainty information associated with urban forest models are beneficial for model transparency, model development, effective communication of model output, and decision-making. However, compared with the extensive studies based on the applications of urban forest models, little attention has been paid to the uncertainty of the output from these models. In this study, bootstrap and Monte Carlo simulation were employed to explore the uncertainty of i-Tree Eco. We assess the uncertainties associated with input data, sampling methods and models throughout the processes of urban forest...

Thousand cankers disease (TCD) is caused by the walnut twig beetle (Pityophthorus juglandis) vectoring the fungal canker pathogen Geosmithia morbida, which can result in severe dieback and eventual death to species of walnut (Juglans spp.) and wingnut (Pterocarya spp.). This disease is most devastating to the highly valued species J. nigra (black walnut). This species is primarily grown and harvested for timber production in the Central Hardwood Region of the United States, which comprises part of its native range. Management options for TCD are limited; therefore, finding resistant...

Average annual temperature over the contiguous United States has increased by 0.7 degrees Celsius (°C; 1.2 degrees Fahrenheit (°F) for the period 1986-2016 compared to 1901-1960 (Vose and others, 2017). Warming temperatures, increased frequency of heat waves, and possibly drought have likely contributed to longer fire seasons, more extreme fire weather, and consequently, larger amounts of sagebrush (Artemisia spp.) burned each year. Future climate warming and alterations in timing of seasonal precipitation may impact the distribution of sagebrush and invasive plants, and further increase...

Restoration of habitats that have been altered by anthropogenic and natural disturbance and the introduction of invasive plant species is a significant concern in sagebrush (Artemisia spp.) ecosystems. Restoration, broadly defined here to include rehabilitation and reclamation, is most feasible when objectives are clear, residual ecosystem components are present, and environmental conditions are favorable. However, severe loss of biotic diversity and ecosystem functioning creates substantial obstacles for recovery to original or even desirable alternative, stable vegetation states. This is...

Coniferous trees, principally juniper (Juniperus spp.) and pinyon pine (Pinus spp.), have increased considerably in cover and density in the western United States since European settlement with wide ranging consequences for sagebrush (Artemisia spp.) ecosystems. A continuum of vegetation types exists across the region, from conifer-encroached shrublands to persistent pinyon-juniper woodlands and savannas. This chapter focuses on the issue of conifer expansion into sagebrush shrublands and ensuing woodland succession, not the infill of persistent woodlands and savannas. Detrimental effects...

Climate change is projected to significantly affect the vulnerability of forests across the western United States to wildfires, insects, disease, and droughts. Here, we provide recent mortality estimates for large trees for 53 species across 48 ecological sections using an analysis of 23,215 Forest Inventory plots and a Random Forest classification model. Models were also used to predict mortality in future FIA inventories under the RCP 4.5 emissions scenario. Model performance indicated species identity as the most important predictor of mortality under both current and future scenarios,...

Wildfires in sagebrush (Artemisia spp.)-dominated semi-arid ecosystems in the western United States have increased dramatically in frequency and severity in the last few decades. Severe wildfires often lead to the loss of native sagebrush communities and change the biogeochemical conditions which make it difficult for sagebrush to regenerate. Invasion of cheatgrass (Bromus tectorum) accentuates the problem by making the ecosystem more susceptible to frequent burns. Managers have implemented several techniques to cope with the cheatgrass–fire cycle, ranging from controlling undesirable fire...

Springs are the point of origin for most headwater streams and are important regulators of their chemical composition. We analysed solute concentrations of water emerging from 57 springs within the 3 km2 Fool Creek catchment at the Fraser Experimental Forest and considered sources of spatial variation among them and their influence on the chemical composition of downstream water. On average, calcium and acid neutralizing capacity (bicarbonate-ANC) comprised 50 and 90% of the cation and anion charge respectively, in both spring and stream water. Variation in inorganic chemical composition...