Treesearch

Spruce beetle (Dendroctonus rufipennis) is the primary mortality agent of mature spruce species in Western North America (Jenkins and others 2014a, Schmid and Frye 1977). The species preferentially colonizes hosts with reduced defenses, including diseased trees or downed material produced by wind events, snow avalanches, and landslides, as well as trees affected by abiotic stressors, such as high temperature, drought, and/or fire. The majority of colonization of live spruce occurs following downed tree disturbances in mature spruce forests. Outbreaks modify stand structure and composition...

As forest communities continue to experience interactions between climate change and shifting disturbance regimes, there is anincreased need to link ecological understanding to applied management. Whitebark pine (Pinus albicaulis) and limber pine (P. flexilis) are important high-elevation five-needle pines in the central and northern Rocky Mountains. Populations of both species face considerable challenges from mountain pine beetle (Dendroctonus ponderosae), white pine blister rust (Cronartium ribicola), and successional displacement resulting from altered natural disturbance regimes.

A typology of urban vacant land was developed, using Roanoke, Virginia, as the study area. A comprehensive literature review, field measurements and observations, including photographs, and quantitative based approach to assessing vacant land forest structure and values (i-Tree Eco sampling) were utilized, along with aerial photo interpretation, and ground-truthing methods, to identify and catalog vacant parcels of land.; The following types of urban vacant land were identified: post-industrial (3.34 km²), derelict (4.01 km²), unattended with vegetation (17.3 km²), natural (2.78 km²), and...

Quantifying the forest water budget is fundamental to making science-based forest management decisions. This study aimed at developing an improved water budget for the El Yunque National Forest (ENF) in Puerto Rico, one of the wettest forests in the United States. We modified an existing monthly scale water balance model, Water Supply Stress Index (WaSSI), to reflect location watershed conditions, by incorporating a new empirical evapotranspiration (ET) equation derived from global eddy covariance data for rainforests. Modeling results indicated that the mean water yield was about 1795 mm...

Tree mortality is a natural process in all forest ecosystems. High mortality can be an indicator of forest health problems. On aregional scale, high mortality levels may indicate widespread insect or disease impacts. High mortality may also occur if a large proportion of the forest in a particular region is made up of older, senescent stands. The approach presented here seeks to detect mortality patterns that might reflect changes to ecosystem processes at large scales. However, in many cases, the proximate cause of mortality may be discernable. Understanding proximate causes of mortality...

Elemental concentration in lichens is a popular and cost-effective tool to bioindicate pollution load at plots (Donovan and others2016, Paoli and others 2014, Root and others 2015) and to complement costly instrumented monitoring to help assess environmental health. From recent development of lichen elemental bioindicators for air pollution in the U.S. upper Midwest (Will- Wolf and others 2017a, 2017b, In press) for the U.S. Department of Agriculture, Forest Service, Forest Inventory and Analysis Program (FIA), we learned important lessons about suitability of lichen species in large-scale...

Tree crown conditions are visually assessed by the U.S. Department of Agriculture, Forest Service, Forest Inventory and Analysis (FIA) Program as an indicator of forest health. These assessments are useful because individual tree photosynthetic capacity is dependent upon the size and condition of the crown. In general, trees with full, vigorous crowns are associated with more vigorous growth rates (Zarnoch and others 2004); when trees undergo stress, the first symptoms are often visible in the crown. Furthermore, tree crowns form the overstory structure of the forest and directly influence...

Whitebark pine (Pinus albicaulis Engelm.) is a keystone species that provides a variety of ecosystem services, such as soil stabilization and protracted snowmelts. Found in many upper subalpine forests in Western North America (Arno and Hoff 1989), whitebark pine is an important high-elevation food source for grizzly bears (Bjoernlie and others 2014) and numerous other wildlife species (Tomback and others 2001, 2014). A rapid, widespread decline in whitebark pine throughout its range has been observed and reported for about 30 years (e.g., Arno 1986, Arno and Hoff 1989, Shanahan and others...

Wild and prescribed fire injury to trees can produce mortality that is not immediately apparent, and environmental stress subsequent to a fire may also contribute to tree mortality in the years after a fire (Hood and Bentz 2007). In order to predict post-fire tree mortality from fire injury variables before tree mortality is clearly apparent, dozens of statistical logistic regression models have been developed (see Woolley and others 2012 for a review), and some are incorporated within larger fire behavior and effects models and computer models used to support land management decisions...

The Northwest Forest Plan (NWFP, or Plan) signified a movement away from intensive focus on timber management that was common through the 1980s and toward an ecosystem management approach, which aims to conserve ecological conditions and restore natural resources while meeting the social, cultural, and economic needs of present and future generations (Brussard et al. 1998). The NWFP emerged in response to expanded scientific knowledge about forests and shifting public values about resources and their management. An important goal of the NWFP was to protect forest values of late-successional...