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Landscape analysis involves the assessment …
Forest ecosystems are complicated and ever changing. Forest landowners and managers must consider a vast array of information to meet either specific stand objectives and/or broader goals of landscape level management. In many situations, land management objectives integrate measurable products, such as timber and forage, and less tangible assets, often collectively described as aesthetics. On other lands, production of timber or other products may be primary, but a broad consideration of ecosystem functions and processes is …
The U.S. Global Change Research Program (Carter, 2003) has described the effect of climate variability on invasive plants as a mounting issue: “Some native species are unlikely to be able to adapt fast enough to the changing climate regimes, resulting in a lowered competitive edge and weakened resistance of ecosystems …
Recent research suggests the extra heating measured in cities operates, at least to some degree, at the scale of neighborhoods. In hot desert cities, such as Phoenix, Arizona, an urban forest can help keep neighborhood temperatures from reaching dangerous highs during hot summer days, particularly during heat waves.
The extra heating load that comes from replacing natural vegetation with the buildings, streets, and sidewalks that comprise cities has been recognized for many decades. Cities often average …
Urban forestry managers can find it useful to assess their cities’ programs using a cost-benefit analysis, many of which have been incorporated into the free online tool iTree, developed by the U.S. Forest Service with collaborators. Species selection can influence both the quantitative and qualitative values of the urban forest as discussed below.
The metaphor comparing biological diversity …
Urban tree programs have expenses for planting, maintenance, even sidewalk repair. Yet the benefits of urban trees in five western cities analyzed outweighed the costs by ratios of 1.37 to 3.09.
For the analysis, samples of 30 to 70 randomly selected trees from each of the most abundant species were surveyed in five cities: Fort Collins, Colorado; Cheyenne, Wyoming; Bismarck, North Dakota; Berkeley, California; and Glendale, Arizona. All of these cities were surveyed by the U.S. Forest Service during the …
An environmental threshold is often described as a tipping point. One of the enduring metaphors describing a tipping point is “the straw that broke the camel’s back”: the camel was fine until one more small unit of burden was added, and then the situation changed dramatically.
Think of bringing water to a boil. If we observe water in a vessel over heat, it …
Figure 1. Trees shade an urban parking lot.
Urban forests can help keep cities within a healthy temperature range, although the exact temperature reduction from urban forests is difficult to measure. The extent of the effect varies in space and in time, which complicates the issue, but large parks or tracts of urban trees can cool daytime summer air temperatures by about 10°F (McPherson and Simpson 1995).
Increasing the green cover of cities by 10% or …
Planting trees in urban areas can help mitigate carbon dioxide levels because trees can sequester carbon and offset some energy use for cooling, as some studies have illustrated in California.
The California Global Warming Solutions Act of 2006 (AB32) requires a reduction in greenhouse gas emissions to 1990 levels by 2020. This amounts to a reduction of 173 million metric tons from the level projected for 2020.
Aerial photography revealed 242 million potential sites for planting individual trees …
Global spread of harmful forest pest species is a possible consequence of climate change. However, because of the diverse and complex responses of insects to climatic factors, it is difficult to make general predictions. Generic modeling tools, such as BioSIM (Régnière and St-Amant 2008), use available knowledge about the responses of particular species (usually pests) to key climatic factors to predict their potential geographic range and …
