Treesearch

We simulated fuel reduction treatments on a 16,000-ha study area in Oregon, US, to examine tradeoffs between placing fuel treatments near residential structures within an urban interface, versus treating stands in the adjacent wildlands to meet forest health and ecological restoration goals. The treatment strategies were evaluated by simulating 10,000 wildfires with random ignition locations and calculating burn probabilities by 0.5-m flame length categories for each 30- x 3-m pixel in the study area. The burn conditions for the wildfires were chosen to replicate severe fire events based...

Oaks (Quercus spp.) are an important species group in the forests of Wisconsin. The State’s timberland typed as oak-hickory forest was estimated at 2.9 million acres in 1996. Growing stock volume for red oak was estimated at 2.4 billion cubic feet, whereas select white oak volume was estimated to be 927 million cubic feet. Oak wilt, the oak disease of greatest concern in Wisconsin, is widespread in the lower two-thirds of the State. Harvest activities in oak stands may result in introduction of the disease agent, Ceratocystis fagacearum (Bretz), into the stand or promote intensification of...

Alterations to natural herbivore and disturbance regimes often allow a select suite of forest understory plant species to dramatically spread and form persistent, mono-dominant thickets. Following their expansion, this newly established understory canopy can alter tree seedling recruitment rates and exert considerable control over the rate and direction of secondary forest succession. No matter where these native plant invasions occur, they are characterized by one or more of the following: (1) the understory layer typically has greater vegetation cover and lower diversity than was common...

The emerald ash borer (EAB, Agrilus planipennis Fairmaire) is threatening to decimate native ashes (Fraxinus spp.) across North America and, so far, has devastated ash populations across sections of Michigan, Ohio, Indiana, and Ontario. We are attempting to develop a computer model that will predict EAB future movement by adapting a model developed for the potential movement of tree species over a century of climate change. We have two model variants, an insect-flight model and an insect-ride model to assess potential movement. The models require spatial estimates of EAB abundance and ash...

In recent years, unprecedented tree mortality has occurred throughout the national forests owing to insect infestations and disease outbreaks. The magnitude and extent of mortality, coupled with the lack of routine monitoring in some areas, has made it difficult to assess the damage, associated ecological impact, and fire hazard in a timely and cost-effective manner. To aid forest managers in assessing the damage, a cost-effective multistage sampling method, using high-resolution digital aerial photography, was developed to estimate overall mortality across large areas. The method was...

The objective of our paper is to provide practitioners with suggestions on how to select appropriate methods for risk assessment of bark beetle infestations at the landscape scale in order to support their particular management decisions and to motivate researchers to refine novel risk assessment methods. Methods developed to assist and inform management decisions for risk assessment of bark beetle infestations at the landscape scale have been diverse, ranging from simple empirical correlations to complex systems models. These approaches have examined different bark beetle species, forest...

We reviewed probabilistic regional risk assessment methodologies to identify the methods that are currently in use and are capable of estimating threats to ecosystems from fire and fuels, invasive species, and their interactions with stressors. In a companion chapter, we highlight methods useful for evaluating risks from fire. In this chapter, we highlight methods useful for evaluating risks from invasive species. The issue of invasive species is large and complex because there are thousands of potential invasive species and constant movement of new and established plants, plant material,...

The objective of this research project is to develop and validate a method for using satellite images and digital geospatial data to map the distribution of southern pine beetle (SPB) habitats across the pinelands of east Texas. Our approach builds on a work that used photo interpretation and discriminant analysis to identify and evaluate environmental conditions suitable for SPB infestation. Because current implementations of Billings and Bryant’s method by the Texas Forest Service (TFS) use manual photo interpretation, they are relatively costly, labor intensive, and require sampling....

The southern pine beetle, Dendroctonus frontalis (Zimmerman) (Coleoptera: Curculionidae: Scolytinae) (SPB), is an indigenous invasive species that infests and causes mortality to pines (Pinus spp.) throughout the Southern United States. The hemlock woolly adelgid, Adelges tsugae (Annand) (Homoptera: Adelgidae) (HWA), is a nonindigenous invasive species that infests and causes mortality to Eastern hemlock (Tsuga canadensis (L.) Carr.) and Carolina hemlock (T. caroliniana Engelm.) throughout their range in Eastern North America. Both of these insect species occur in the Southern Appalachians,...

The sagebrush (Artemisia spp.) ecosystem is one of the most imperiled in the United States. In the Great Basin ecoregion and elsewhere, catastrophic wildland fires are often followed by the invasion of cheatgrass (Bromus tectorum L.), eliminating or altering millions of hectares of sagebrush and other shrublands. Sagebrush in the Great Basin also is threatened by displacement from encroaching pinyon-juniper woodlands. Despite these changes, the ecoregion retains some of the Nation’s largest remaining expanses of sagebrush, most of which are federally managed. Because of these losses and...