Treesearch

The impacts of insects and pathogens on forests vary from natural thinning to extraordinary levels of tree mortality, but the fact that insects and diseases kill trees does not necessarily make them enemies of the forest (Teale and Castello 2011). If disturbances, pests, and diseases are viewed in their full ecological context, then some amount can be considered “healthy” to sustain the structure of the forest (Manion 2003, Zhang and others 2011) by causing the tree mortality that culls weak competitors and releases resources that are needed to support the growth of the surviving trees...

Free-burning fire has been a constant ecological presence on the American landscape, the expression of which has changed as new climates, peoples, and land uses have become predominant (Pyne 2010). It is an important ecological mechanism that shapes the distributions of species, maintains the structure and function of fire-prone communities, and is a significant evolutionary force (Bond and Keeley 2005).

Droughts are common in virtually all U.S. forests, but their frequency and intensity vary widely both between and within forest ecosystems (Hanson and Weltzin 2000). Forests in the Western United States generally exhibit a pattern of annual seasonal droughts. Forests in the Eastern United States tend to exhibit one of two prevailing patterns: random occasional droughts, typical of the Appalachian Mountains and of the Northeast, or frequent late-summer droughts, typical of the southeastern Coastal Plain and the eastern edge of the Great Plains (Hanson and Weltzin 2000).

Tree mortality is a natural process in all forest ecosystems. Extremely high mortality, however, can also be an indicator of forest health issues. On a regional scale, high mortality levels may indicate widespread insect or disease problems. High mortality may also occur if a large proportion of the forest in a particular region is made up of older, senescent stands.

Lichen community composition is well known for exhibiting response to air pollution, and to macroenvironmental and microenvironmental variables. Lichens are useful indicators of air quality impact, forest health, and forest ecosystem integrity across the United States (McCune 2000, reviews in Nimis and others 2002, USDA Forest Service 2007).

America’s private forests provide a vast array of public goods and services, including abundant, clean surface water. Forest loss and development can affect water quality and quantity when forests are removed and impervious surfaces, such as paved roads, spread across the landscape. We rank watersheds across the conterminous United States according to the contributions of private forest land to surface drinking water and by threats to surface water from increased housing density. Private forest land contributions to drinking water are greatest in the East but are also important in Western...

Recent advances in planning and ecological software make it possible to conduct highly technical analyses to prioritize conservation investments and inform local land use planning. We review these tools, termed conservation planning tools, and assess the knowledge of a key set of potential users: the land use planning community. We grouped several conservation software tools into five themes: reserve selection, habitat connectivity, species distribution and viability modeling, threats, and climate forecasting. We found that professional planners frequently use GIS tools and are generally...

The authors conducted a review of ultrasonic testing and evaluation of wood and wood products, starting with a description of basic ultrasonic inspection setups and commonly used equations. The literature review primarily covered wood research presented between 1965 and 2013 in the Proceedings of the Nondestructive Testing of Wood Symposiums. A table that lists the wood species used in the reviewed studies is included.

We revisit the common standards recommended by Ralph et al. (1993, 1995a) for conducting point-count surveys to assess the relative abundance of landbirds breeding in North America. The standards originated from discussions among ornithologists in 1991 and were developed so that point-count survey data could be broadly compared and jointly analyzed by national data centers with the goals of monitoring populations and managing habitat. Twenty years later, we revisit these standards because (1) they have not been universally followed and (2) new methods allow estimation of absolute abundance...

Characterizing wildfire risk to a fire-adapted ecosystem presents particular challenges due to its broad spatial extent, inherent complexity, and the difficulty in defining wildfire-induced losses and benefits. Our approach couples stochastic wildfire simulation with a vegetation condition assessment framework to estimate the conditional and expected response of vegetation condition to wildfire. We illustrate application of this framework for the Bridger-Teton National Forest (BTNF) in western Wyoming, USA. Results illustrate generally positive net effects of wildfire on vegetation...