Treesearch

Channel morphology has become an increasingly important subject for analyzing the health of rivers and associated fish populations, particularly since the popularization of channel classification and assessment methods. Morphological data can help to evaluate the flows of sediment and water that influence aquatic and riparian habitat. Channel classification systems, such as the one developed by Rosgen (1994) provide a useful shorthand for summarizing key morphological attributes of a river system. Accordingly, researchers have hypothesized that channel classifications could explain...

Estimates of forest canopy areal extent, configuration, and change have been developed from satellite-based imagery and ground-based inventories to improve understanding of forest dynamics and how they interact with other Earth systems across many scales. The number of these types of studies has grown in recent years, yet few have assessed the multiple change processes underlying observed forest canopy dynamics across large spatio-temporal extents. To support these types of assessments, a more detailed and integrated understanding of the geographic patterns of forest change processes...

Snow-covered winter Landsat time series stacks are used to develop a nonforest mask to enhance automated disturbance maps produced by the Vegetation Change Tracker (VCT). This method exploits the enhanced spectral separability between forested and nonforested areas that occurs with sufficient snow cover. This method resulted in significant improvements in Vegetation Change Tracker outputs at the 95 percent confidence interval. An estimated 34 percent of the world's forests receive sufficient snowfall to use this method.

Wildfire is one of the two most significant disturbance agents (the other being insects) in forest ecosystems of the Western United States, and in a warmer climate, will drive changes in forest composition, structure, and function (Dale et al. 2001, McKenzie et al. 2004). Although wildfire is highly stochastic in space and time, sufficient data exist to establish clear relationships between some fire characteristics and some climatic parameters. An assessment of wildfire risk in response to climate change requires brief definitions of the terms “fire hazard” and “fire risk,” which are...

We used a risk matrix to assess risk from climate change for multiple forest species by discussing an example that depicts a range of risk for three tree species of northern Wisconsin. Risk is defined here as the product of the likelihood of an event occurring and the consequences or effects of that event. In the context of species habitats, likelihood is related to potential changes in suitable habitat at various times in the future. Consequences are related to the adaptability of a species to cope with the changes, especially the increasing intensity or frequency of future disturbance...

Species distribution models for 147 bird species have been derived using climate, elevation, and distribution of current tree species as potential predictors (Matthews et al. 2011). In this case study, a risk matrix was developed for two bird species (fig. A2-5), with projected change in bird habitat (the x axis) based on models of changing suitable habitat resulting from changing climate and tree species habitat. Risk was evaluated for three time steps (2040, 2070, 2100) and based on two climate models and two emission scenarios (Hadhi vs. PCMlo).

Increment cores collected as part of the periodic inventory in the Intermountain West were examined for their potential to represent growth and be a proxy for climate (precipitation) over a large region (Utah). Standardized and crossdated time-series created from pinyon pine (n=249) and Douglas-fir (n=274) increment cores displayed spatiotemporal patterns in growth differences both between species and by region within Utah. However, the between-species interrelationship of growth was strong over much of the state and indicated both species respond similarly to climate variations. Indeed,...

Climate information is often used as a predictor in ecological studies, where temporal averages are typically based on climate normals (30-year means) or seasonal averages. While ensemble projections of future climate forecast a higher global average annual temperature, they also predict increased climate variability. It remains to be seen whether forest ecosystems will respond more to changes in mean climate conditions or changes in climate variability. Our objective was to compare the relative importance of climate mean versus variability metrics as predictors of tree mortality and...

The emerald ash borer (Agrilus planipennis Fairmaire; EAB) is a nonnative invasive insect that has caused considerable damage to ash (Fraxinus spp.) in North America. Unlike invasive organisms that can be mitigated, contained, controlled, or even eradicated, EAB continues to spread across North America. The loss of the North American ash resource is possible considering literature suggests close to 100 percent probability of host tree mortality. We modeled future spatial and temporal changes in forest composition from 2010 to 2060 with and without ash mortality anticipated from EAB spread...

Populations of pinons and junipers across the interior west have been highly dynamic over the last two centuries, undergoing an overall expansion but punctuated with regional mortality. Accumulating demographic studies across the interior west indicate the drivers of expansion and contraction of populations are compounded by regional land use legacies, but have an underlying climatic component. The key implication is that pinon and juniper distributions respond to climatic variation across spatial and temporal scales by expansion from, and contraction to, areas of long-term persistence...