Treesearch

Genetic improvement of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in New Zealand was initiated in 1955 with large provenance trials established in the late 1950s. These trials showed that material of Oregon and Californian origin was growing faster than other provenances. Additional collections were made to further evaluate provenance performance from these two areas, and in 1996 additional trials were established at four low-altitude sites across New Zealand.Genotype ×environment (GxE) interaction between these sites was found to be important for diameter at breast height (DBH),...

Curbing the loss of biodiversity is a primary challenge to conservationists. Estimates of current rates of species loss range from 14,000 - 40,000 species per year (Hughes et al., 2007), and although a variety of factors are implicated, habitat loss is repeatedly cited as an important cause (Sala et al., 2000). Most ecosystems are under some degree of threat, however the loss of biodiversity associated with the destruction of tropical forests is a central concern (Bradshaw et al., 2009). Tropical forests are occupied by 60% of the planet’s species (Dirzo and Raven, 2003), yet they are also...

Nitrogen export from small forested watersheds is known to be affected by N deposition but with high regional variability. We studied 10 headwater catchments in the northeastern United States across a gradient of N deposition (5.4 − 9.4 kg ha−1 yr−1) to determine if soil nitrification rates could explain differences in stream water NO3− export. Average annual export of two years (October 2002 through September 2004) varied from 0.1 kg NO3−-N ha−1 yr−1 at Cone Pond watershed in New Hampshire to 5.1 kg ha−1 yr−1 at Buck Creek South in the western Adirondack Mountains of New York. Potential...

Forest materials represent great potential for advancing our goals in the 21st century for sustainable building, energy independence, and carbon sequestration. A critical component of an improved system for producing bioproducts and bioenergr from forest materials is the ability to sort trees, stems, and logs into end-product categories that represent their highest potential values. Nondestructive testing and evaluation technologies have been explored by scientists, engineers, and managers around the world for their ability to assess wood and fiber properties of individual trees, stems,...

Radiocarbon dating of historical and archaeological wood can be complicated, sometimes involving issues of “inbuilt” age in slow-growing woods, and/or the possibility of reuse or long delays between felling and use of the wood. Terminus dates can be provided by dating the sapwood, or the outermost edge of heartwood, while a date from the pith can give an indication of the first years of growth. A sequence of samples from specific points within the bole can be used to determine the growth rate of the tree. Such a combined dating strategy is particularly useful in cross-referencing dates...

In central Argentina, the Chinese tree glossy privet (Ligustrum lucidum) is an aggressive invasive species replacing native forests, forming dense stands, and is thus a major conservation concern. Mapping the spread of biological invasions is a necessary first step toward understanding the factors determining invasion patterns. Urban areas may function as propagule sources for glossy privet because it has been used as a landscaping tree for over a century. The objectives of this paper were to 1) map the patterns of glossy privet expansion from 1983 to 2006 using a time series of Landsat...

The successful establishment of non-native species in new areas can be affected by many factors including the initial size of the founder population. Populations comprised of fewer individuals tend to be subject to stochastic forces and Allee effects (positive-density dependence), which can challenge the ability of small founder populations to establish in a new area. Although the conceptual relationship between initial colony size and establishment success has been previously documented, it is not trivial to estimate precisely the colony size needed to ensure colony persistence. Over the...

Despite the pervasiveness of spatial synchrony of population fluctuations in virtually every taxon, it remains difficult to disentangle its underlying mechanisms, such as environmental perturbations and dispersal. We used multiple regression of distance matrices (MRMs) to statistically partition the importance of several factors potentially synchronizing the dynamics of the gypsy moth, an invasive species in North America, exhibiting outbreaks that are partially synchronized over long distances (approx. 900 km). The factors considered in the MRM were synchrony in weather conditions,...

Hybridization between introduced biological control agents and native species has the potential to impact native biodiversity and pest control efforts. This study reports progress towards predicting the outcome of hybridization between two beetle species, the introduced Laricobius nigrinus Fender and the native L. rubidus LeConte. L. nigrinus is a predator from western North America introduced to hemlock stands in the eastern United States as a biological control of the hemlock woolly adelgid [Adelges tsugae Annand (Hemiptera: Adelgidae)]. Laricobius rubidus is a closely related eastern...

Fungi from coarse woody debris samples containing or lacking termites were isolated, and identified from upland and bottomland hardwoods and pines in northeast Mississippi. Samples yielded 860 unique fungal isolates, with 59% identified to genus level. Four phyla, six classes, 10 orders, 14 families, and 50 genera were recovered. The fungal groups encountered by decreasing taxonomic diversity were Imperfect Fungi, Ascomycota, Zygomycota, Basidiomycota, and unknown fungi. The most frequently encountered fungi were Penicillium (81 occurrences), Nodulisporium (57), Cladosporium (37), Trichoder...