Treesearch

Hemlock woolly adelgid (Adelges tsugae Annad; or HWA) is a non-native invasive pest that attacks and kills eastern hemlock (Tsuga canadensis (L.) Carrière) and Carolina hemlock (Tsuga caroliniana Engelm.). Hemlock is a ‘‘foundation species’’ due to its strong influence on ecosystem structure and function, especially in riparian areas. HWA management involves the integrated use of multiple approaches including chemical control, biological control, cultural treatments, host resistance, and host gene conservation. Despite extensive control efforts, large areas in the eastern US, but especially...

Climate change is altering growing conditions in the temperate rain forest region that extends from northern California to the Gulf of Alaska. Longer, warmer growing seasons are generally increasing the overall potential for forest growth in the region. However, species differ in their ability to adapt to changing conditions. For example, researchers with Pacific Northwest Research Station examined forest trends for southeastern and southcentral Alaska and found that, in 13 years, western redcedar showed a 4.2-percent increase in live-tree biomass, while shore pine showed a 4.6-percent...

SPORL (Sulfite Pretreatment to Overcome Recalcitrance of Lignocellulose) pretreatment was applied to switchgrass and optimized through an experimental design using Response Surface Methodology within the range of temperature (163–197 °C), time (3–37 min), sulfuric acid dosage (0.8–4.2% on switchgrass), and sodium sulfite dosage (0.6–7.4% on switchgrass). Performance of SPORL was compared with that of dilute acid (DA) and alkali (AL) in switchgrass pretreatment. Results indicated that SPORL pretreatment improved the digestibility of switchgrass through sufficiently removing hemicellulose,...

Surface properties of wood play an important role when wood is used or processed into different commodities such as siding, joinery, textiles, paper, sorption media, or wood composites. Thus, for example, the quality and durability of a wood coating are determined by the surface properties of the wood and the coating. The same is true for wood composites where the efficiency of stress transfer from the wood component to the nonwood component is strongly influenced by the surface properties of both components.

Forests, and the wood they produce, have played an important role in human activity since before recorded history. Indeed, one of the first major innovations was utilizing fire, fueled by wood, for cooking and heating. It is very likely that early hominids used wood fires for cooking, as long as 1.5 million years ago (Clark and Harris 1985). Clear evidence of this use of wood exists from sites 400,000 years old (Sauer 1962). Since this ancient beginning, the uses of wood, and the value of the forest, have expanded dramatically, as the populations of humans and their economies grew. Wood...

There are numerous biological degradations that wood is exposed to in various environments. Biological damage occurs when a log, sawn product, or final product is not stored, handled, or designed properly. Biological organisms such as bacteria, mold, stain, decay fungi, insects, and marine borers depend heavily on temperature and moisture conditions to grow. Figure 5.1 gives the climate index for decay hazard for the United States of America. The higher the number means a greater decay hazard. The southeastern and northwest coasts have the greatest potential, and the southwest has the...

Composites made from wood, other biomass resources and polymers have existed for a long time but the nature of many of these composites has changed in recent decades. Wood-thermoset composites date to the early 1900s. "Thermosets" or thermosetting polymers are plastics that, once cured, cannot be remelted by heating. These include cured resins such as epoxies and phenolics, plastics used as wood adhesives with which the forest products industry is traditionally most familiar (see Chapter 9). For example, an early commercial composite marketed under the trade name Bakelite was composed of...

The extraordinarily long life cycles, synchronous emergences at 13- or 17-year intervals, and complex geographic distribution of periodical cicadas (Magicicada spp.) in eastern North America are a long-standing evolutionary enigma. Although a variety of factors, including satiation of aboveground predators and avoidance of interbrood hybridization, have been hypothesized to shape the evolution of this system, no empirical support for these mechanisms has previously been reported, beyond the observation that bird predation can extirpate small, experimentally mistimed emergences. Here we...

Cost-effective strategies are needed to find and remove diseased trees in forests damaged by pathogens. We develop a model of cost-minimizing surveillance and control of forest pathogens across multiple sites where there is uncertainty about the extent of the infestation in each site and when the goal is to minimize the expected number of new infections. We allow for a heterogeneous landscape, where grid cells may be differentiated by the number of trees, the expected number of infected trees, rates of infection growth, and costs of surveillance and control. In our application to oak wilt...

Managing forests to promote biodiversity requires understanding the effects of silvicultural practices on a range of forest species and communities. We evaluated carabid beetle (Coleoptera; Carabidae) responses to operational herbicide and shelterwood seed cut treatments in northern hardwood stands on the Allegheny National Forest, Pennsylvania, USA, from 1992 to 2000. There was substantial defoliation by elm spanworms (Ennomos subsignarius Hübner) or cherry scallopshell moths (Hydria prunivorata Ferguson) during four of the 9 years of this study, so we also evaluated effects of these...