Treesearch

Forests sequester carbon from the atmosphere, helping mitigate climate change. In fire-prone forests, burn events result in direct and indirect emissions of carbon. High fire-induced tree mortality can cause a transition from a carbon sink to source, but thinning and prescribed burning can reduce fire severity and carbon loss when wildfire occurs. However, treatment implementation requires carbon removal and emissions to reduce high-severity fire risk. The carbon removed and emitted during treatment may be resequestered by subsequent tree growth, although there is much uncertainty regarding...

Throughout the southern US, past forest management practices have replaced large areas of native forests with loblolly pine plantations and have resulted in changes in forest response to extreme weather conditions. However, uncertainty remains about the response of planted versus natural species to drought across the geographical range of these forests. Taking advantage of a cluster of unmanaged stands (85–130 year-old hardwoods) and managed plantations (17–20 year-old loblolly pine) in coastal and Piedmont areas of North Carolina, tree water use, cavitation resistance, whole-tree hydraulic...

The weathering performance of wood coated with a combination of rutile TiO2 hierarchicalnanostructures and a sol-gel deposit of alkoxysilanes was determined by exposing three sets of specimens to UV light and water spray. The first set consisted of specimens coated with a mixture of methyltrimethoxysilane (MTMOS) and hexadecyltrimethoxysilane (HDTMOS). The second set consisted of specimens coated with nanostructural TiO2 followed by a mixture of MTMOS and HDTMOS. The third set consisted of uncoated control specimens. The wood coated with TiO2 followed by a mixture of MTDMOS and HDTMOS...

Unregulated river systems are organized in a hierarchy in which large scale factors (i.e. landscape and segment scales) influence local habitats (i.e. reach, meso- and microhabitat scales), and both differentially exert selective pressures on biota. Dams, however, create discontinua in these processes and change the hierarchical structure. We examined the relative roles of hydrology and other instream factors, within a hierarchical landscape context, in organizing fish communities in regulated and unregulated tributaries to the Upper Tennessee River, USA. We used multivariate regression...

Ash trees (Fraxinus spp.) are an important components of both natural forests and urban plantings in the United States and Canada (Federal Register, 2003; Nowak et al., 2003). There are approximately 16 species of Fraxinus native to North America (Harlow et al., 1996; USGS, 2014), each adapted to different ecological niches across a range of climates zones, soil types, and moisture gradients (Eyre, 1980). This abundant and diverse ash resource provides economic benefits, with ash timber alone valued at $282 billion (Nowak et al., 2003). For instance, green ash (F. pennsylvanica Marsh.),...

Land management practices have strong potential to modify the biogeochemistry of forest soils, with implications for the long-term sustainability and productivity of forestlands. The Long-Term Soil Productivity (LTSP) program, a network of 62 sites across the USA and Canada, was initiated to address concerns over possible losses of soil productivity due to soil disturbance from forest management. Network sites employ an experimental design consisting of three harvest intensities (bole only, whole tree, whole tree + forest floor removal) in combination with three soil compaction intensities...

Emerald ash borer, Agrilus planipennis Fairmaire (EAB), is an invasive buprestid native to northeastern Asia that feeds on ash trees (Fraxinus spp.). First detected in North America (in Michigan, United States and Ontario, Canada) in 2002, EAB has spread rapidly, in part because of movement of infested nursery stock and untreated firewood (Cappaert et al., 2005a; BenDor et al., 2006; Poland and McCullough, 2006). As of January 2014, EAB was known in an additional 21 U.S. states and one Canadian province (USDA-APHIS, 2014), and it is expected to continue spreading to other parts of the...

The emerald ash borer (EAB) (Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an invasive beetle introduced from China (Bray et al., 2011), was identified as the cause of ash (Fraxinus spp.) mortality in southeast Michigan and nearby Ontario in 2002 (Haack et al., 2002; Federal Register, 2003; Cappaert et al., 2005). Although eradication was attempted for several years after the beetle's discovery, it continued to spread throughout North America, killing ash trees in urban, forested, and riparian areas. In an effort to conserve native species of Fraxinus, researchers continue to...

As soon as emerald ash borer (Agrilus planipennis Fairmaire) (EAB) was discovered near Detroit, Michigan, USA, in 2002, surveys were initiated to delimit the extent of the infested area. These initial delimitation surveys were based on visual assessments using external symptoms because at the time no other detection tools were available and nothing was known about EAB responses to chemical or visual stimuli. Surveys were supplemented by tracing movement of nursery stock shipped from Detroit to other locations to detect new infestations of EAB. External symptoms of EAB infestation, which...