Treesearch

Successful reforestation requires that planted or naturally regenerated seedlings are well suited to a site. Genetic studies of forest trees provide ample evidence of large differences among seed sources in adaptive traits--traits such as the timing of growth initiation and cessation, cold and drought hardiness, and growth rates. Much of this variation is related to the temperature and moisture regimes of the seed sources. In general, seed sources from near a planting site survive and grow well, whereas distant seed sources are often maladapted.

Realized gains for coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) were evaluated using data collected from 15-year-old trees from five field trials planted in large block plots in the northern Oregon Cascades. Three populations with different genetic levels (elite--high predicted gain; intermediate--moderate predicted gain; and an improved--wild seedlot) were compared at two planting spacings (l.8 x l.8 m and 3.6 x 3.6 m). The realized gains at age 15 averaged over both the elite and intermediate progeny were 17.2% for stand volume per hectare, 3.5% for mean height, and 4.3%...

The larva of Paracapnia disala (Jewett) was associated from two first order headwater streams in the H.J. Andrews Experimental Forest, Oregon, U.S.A. Larvae of this first western Paracapnia species to be associated, were studied and compared morphologically with those of the eastern Paracapnia angulata Hanson to determine if it conforms with proposed generic characters and if it has specific diagnostic characters. Habitus and character drawings and SEM's of P. disala and P. angulata larval mouthparts are presented. Wingpad presence/absence and ventral lacinial comb hair differences between...

Knots on digital images of 51 full veneer sheets, obtained from nine peeler blocks crosscut from two 35-foot (10.7 m) long logs and one 18-foot (5.5 m) log from a single Douglas-fir tree, were detected using a two-phase algorithm. The algorithm was developed using one image, the Development Sheet, refined on five other images, the Training Sheets, and then applied to all remaining sheets. In phase one, global thresholding was used to segment the image through a series of morphological operations to isolate regions likely to contain knots. In phase two, adaptive thresholding was applied to...

High-resolution macroscopic charcoal and pollen analysis were used to reconstruct an 11 000-year-long record of fire and vegetation history from Beaver Lake, Oregon, the first complete Holocene paleoecological record from the floor of the Willamette Valley. In the early Holocene (ca 11 000-7500 calendar years before present [cal yr BP]), warmer, drier summers than at present led to the establishment of xeric woodland of Quercus, Corylus, and Pseudotsuga near the site. Disturbances (i.e., floods, fires) were common at this time and as a result Alnus rubra grew nearby. High fire frequency...

Disrupting ecosystem components, while transferring and reconstructing them for experiments can produce myriad responses. Establishing the extent of these biological responses as the system approaches a new equilibrium allows us more reliably to emulate comparable native systems. That is, the sensitivity of analyzing ecosystem processes in a reconstructed system is improved by excluding the period when observed phenomena are primarily responses caused by establishing the experiment rather than effects of imposed treatments; achieved by determining the extent of any pulse of activity caused...

Most native red foxes (Vulpes vulpes) in the western contiguous United States appear to be climatically restricted to colder regions in the major mountain ranges and, in some areas, have suffered precipitous declines in abundance that may be linked to warming trends. However, another population of unknown origin has occurred in arid habitats in the Sacramento Valley of California well outside this narrow bioclimatic niche since at least 1880. If native, this population would be ecologically distinct among indigenous North American red foxes. We used mitochondrial and micro satellite...

The objective of this study was to assess the magnitude of hydraulic lift in Brazilian savannas (Cerrado) and to test the hypothesis that hydraulic lift by herbaceous plants contributes substantially to slowing the decline of water potential and water storage in the upper soil layers during the dry season. To this effect, field observations of soil water content and water potentials, an experimental manipulation, and model simulations, were used. Savannas of central Brazil exhibit consistent changes in tree density along shallow topographic gradients, from open savannas with relatively few...

Massively parallel sequencing technologies (MPST) offer unprecedented opportunities for novel sequencing projects. MPST, while offering tremendous sequencing capacity, are typically most effective in resequencing projects (as opposed to the sequencing of novel genomes) due to the fact that sequence is returned in relatively short reads. Nonetheless, there is great interest in applying MPST to genome sequencing in non-model organisms. We have developed a bioinformatics pipeline to assemble short-read sequence data into nearly complete chloroplast genomes using a combination of de novo and...

Coniferous, diffuse-porous and ring-porous trees vary in their xylem anatomy, but the functional consequences of these differences are not well understood from the scale of the conduit to the individual. Hydraulic and anatomical measurements were made on branches and trunks from 16 species from temperate and tropical areas, representing all three wood types. Scaling of stem conductivity (Kh) with stem diameter was used to model the hydraulic conductance of the stem network. Ring-porous trees showed the steepest increase in Kh with stem size. Temperate diffuse-porous trees were at the...