104,031 research outputs found

    The Douglas-Fir Genome Sequence Reveals Specialization of the Photosynthetic Apparatus in Pinaceae.

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    A reference genome sequence for Pseudotsuga menziesii var. menziesii (Mirb.) Franco (Coastal Douglas-fir) is reported, thus providing a reference sequence for a third genus of the family Pinaceae. The contiguity and quality of the genome assembly far exceeds that of other conifer reference genome sequences (contig N50 = 44,136 bp and scaffold N50 = 340,704 bp). Incremental improvements in sequencing and assembly technologies are in part responsible for the higher quality reference genome, but it may also be due to a slightly lower exact repeat content in Douglas-fir vs. pine and spruce. Comparative genome annotation with angiosperm species reveals gene-family expansion and contraction in Douglas-fir and other conifers which may account for some of the major morphological and physiological differences between the two major plant groups. Notable differences in the size of the NDH-complex gene family and genes underlying the functional basis of shade tolerance/intolerance were observed. This reference genome sequence not only provides an important resource for Douglas-fir breeders and geneticists but also sheds additional light on the evolutionary processes that have led to the divergence of modern angiosperms from the more ancient gymnosperms

    Estimating Extent of Mortality Associated with the Douglas-Fir Beetle in the Central and Northern Rockies

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    Data collected from Douglas-fir stands infected by the Douglas-fir beetle in Wyoming, Montana, Idaho, and Utah, were used to develop models to estimate amount of mortality in terms of basal area killed. Models were built using stepwise linear regression and regression tree approaches. Linear regression models using initial Douglas-fir basal area were built for all study sites but produce low precision estimates. Regression tree models using initial Douglas-fir basal area of stand density index or both were also build for all sites. Regression tree models provide a more realistic approach to estimate potential mortality by creating more homogenous mortality classes with reduced variance. The models developed provide land managers with a basis for determining the potential mortality should a Douglas-fir beetle outbreak develop

    Heat-Induced Color-Intensity Change in Coastal Douglas-Fir and White Spruce

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    In a previous study, it was found that to reach the same degree of surface inactivation, Douglas-fir attained a much higher heat-induced color intensity at 520 nm than white spruce. To explain the heat-induced color-intensity change as a function of the above species, the present study measured the thermally induced spectral changes in the visible wavelength region for these species. The differential reflectance spectra for the sapwood and heartwood of coastal Douglas-fir and white spruce showed a peak in the 410- to 430-nm region, but only coastal Douglas-fir showed a second peak at 550 nm. Comparison of rate data for extracted and unextracted coastal Douglas-fir showed that its extractives contributed significantly to the heat-induced color-intensity change. Dihydroquercetin, a major phenolic extractive in coastal Douglas-fir upon heating produced a powerful chromophore group

    OLFACTORY RESPONSES OF DEER MICE TO DOUGLAS-FIR SEED VOLATILES

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    An attempt was made to identify the olfactory cues produced by Douglas-fir seeds which attract deer mice (Peromyscus maniculatus) to the seeds. The olfactometers used are described, and the merits of different statistical analyses of the data are discussed. The odors produced by whole Douglas-fir seed and by the endosperm were preferred among the fractions tested to date. Deer mice were repelled by Douglas-fir turpentine, cedar oil, and, to a lesser degree, one extract

    Identification of varieties and gene flow in Douglasfir exemplified in artificially established stands in Germany

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    Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] is an economicallyvaluable non-native tree species in Germany and is considered verypromising in view of global climate change. Therefore, the genetic characterization of Douglas-fir populations and seed stands in Germany is essential.We studied coastal and interior Douglas-fir varieties, both presentin Germany, by using eleven isoenzyme and four microsatellite loci. Byanalyzing eight reference populations of known origin we were able toidentify the two varieties on the population level using Bayesian and distance based methods. Seven populations present in Bavaria were then successfully assigned to one of the two varieties. Within varieties we found stronger grouping within the interior variety than within the coastal one. Despite lower differences within coastal Douglas-fir we have first indications for the origin of two populations. For two Bavarian populations, natural regeneration was included and genetic data revealed no significant genetic difference between adults and offspring. The parentage analysis for one of the studied stands revealed that a large proportion of adults took part in the reproduction, but some trees were more successful than othersin transferring their genes to the next generation. Our study was ableto improve variety identification of Douglas-fir using isoenzyme markers and nuclear microsatellites and study reproductive patterns, both are important issues for the management of Douglas-fir stands in Bavaria

    Modelling the Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) site index from site factors in Portugal

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    Although the speed of growth and adaptability of the north-west American conifer Douglas-fir has been recognized in Portugal, it represents only ~0.1 per cent of the total forest cover. This small area is spread across the mountainous areas of the north and centre of the country. This study models Douglas-fir productivity based on site factors and estimates the potential area for Douglas-fir in Portugal. Soil, climate and topographic data were collected on 39 plots across the range of sites where Douglas-fir grows in Portugal. The analysis of the data followed three steps: (1) selection of site factors related to the variation in the site index; (2) choice of candidate models; and (3) consideration of the best model to explain and predict the site index from site factor variables. The best multiple linear regression model explained 90 per cent of site index variation but included variables not readily available in the field. A model using digitized site data explained 54 per cent of the variation in the site index and mapped the areas with potential for Douglas-fir growth in Portugal. It is estimated that a potential Douglas-fir planting area of 250 000 ha exists where trees will exceed 17 m dominant height at age 30 years. This would correspond to 8 per cent of the existing Portuguese forest area. The best sites for Douglas-fir growth are located along north coastal to central regions at altitudes between 500 m and 1000 m with moisture deficit (precipitation minus evapotranspiration) above 1000 mm. Areas with acceptable sites for Douglas-fir growth are located in the north and centre of Portugal at 700–1000 m elevation and have a moisture deficit above 400 mminfo:eu-repo/semantics/publishedVersio

    OLFACTORY RESPONSES OF DEER MICE TO DOUGLAS-FIR SEED VOLATILES

    Get PDF
    An attempt was made to identify the olfactory cues produced by Douglas-fir seeds which attract deer mice (Peromyscus maniculatus) to the seeds. The olfactometers used are described, and the merits of different statistical analyses of the data are discussed. The odors produced by whole Douglas-fir seed and by the endosperm were preferred among the fractions tested to date. Deer mice were repelled by Douglas-fir turpentine, cedar oil, and, to a lesser degree, one extract
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