Genetic Structure and Variation in a Southwestern Douglas-fir Population PDF Download
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Author: Laura P. Moser
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 188
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Author: Laura P. Moser
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 188
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Author: Eddy Bressler
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 108
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Author: James Hamlin
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 230
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The major objectives of this study were: (1) to determine the extent to which southwest Oregon populations of Douglas-fir [Pseudotsuga menziesii var menziesii (Mirb.) Franco) differ in quantitative genetic structure (QGS); (2) to determine whether differences in QGS are associated with the environments from which populations originate; and (3) to examine the implications of differences in QCS with regards Co expected responses of traits to selection. A two year seedling common garden study was conducted where eight populations (45 families/population), two from each of four major coniferous zones, were sampled Variation among populations in QGS was predominately associated with differences in trait means and genetic correlations among traits. The largest differences occurred between the coastal region and the high elevation inland region. The major differences in QGS were associated with differences in correlations between growth and phenology traits in the second growing season. Differences in QGS were positively associated with the extent of habitat divergence for those comparisons between trait means and genetic correlations. The paired populations within an ecological zone were more similar, in general than populations from different ecological zones Three major homogeneous associations, as measured by cluster analysis of both trait means and phenotypic correlation matrices, were found and are geographically aligned to the coastal region, a lower elevation inland region, and a higher elevation inland region of southwest Oregon. Natural selection within these general physiographic regions would appear to be one explanation for the observed patterns in this study. When selecting for increased height growth in these four major zones, differences among zones in both direct and correlated responses are expected. Expected correlated responses in phenology traits when selection is directed at height growth, while variable among zones, does not appear large enough to adversely affect adaptability to a large degree. Restriction (0% change) of phenology and/or shoot:root ratios in a restricted selection index would severely limit growth response in two of the four zones. Restricted selection indices should be used only when necessary, and their effects should be assessed prior to implementation in an applied breeding program. Knowledge of QGS of popuitions should be ascertained, so that biological impacts of breeding and/or movement of reproductive materials outside of their native habitats can be assessed.
Author: David F. Van Haverbeke
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 12
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Author: G. E. Rehfeldt
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 8
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Author: Zeki Kaya
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 246
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This study had three objectives: (1) to teat the hypothesis that multiple flushing of the terminal shoot (intermittent growth pattern) in Douglas-fir seedlings (Pseudotsuca menziesii var. menziesii) has an adaptive significance, especially in inland populations from the drier regions in southwest Oregon; (2) to evaluate the genetic and adaptive consequences of selecting for height increment in early testing programs; (3) to evaluate the utility of indirectly selecting for height increment by directly selecting for length and number of stem units. To accomplish objectives 1 and 2, seedling families were grown from two inland and two coastal sources (160 open-pollinated families in total) for two growing seasons in two test environments. In one environment ("dry") an intermittent moisture regime was created by withholding water during the growing season until seedlings reached -12 bars of moisture stress. Seedlings were then rewatered on a weekly schedule. In the other environment ("wet"), seedlings were watered weekly to maintain water stress of seedlings at lees than -3 bars. For objective 3. seedling families from one inland and one coastal source of Douglas-fir (80 open-pollinated families) were grown in plastic tubes for two growing seasons. Results supported the hypothesis that intermittent shoot growth is of adaptive significance in Douglas-fir in the first growing season. Shoot growth patterns varied genetically both between populations and among families within populations. As expected. families from drier inland environments, where periodic summer droughts are commons responded to the intermittent moisture regime with a higher frequency of multiple flushing. Families from coastal environments, where the moisture regime is more consisitently favorable during the growing seasons were less sensitive to the dry treatment and had a much higher frequency of seedlings which continued to grow despite the imposed drought. In the second growing season. patterns of intermittent shoot growth in inland and coastal families were not as expected. Shoot growth patterns did vary genetically between inland and coastal populations. Inland populations however, did not respond to the dry treatment with a greater frequency of multiple flushing. Apparently, inland families have adapted to drier environment and shorter growing season by relying predominantly on predetermined growth for height increment and are not able to respond to favorable growing conditions by extended free growth. Coastal families however, have developed a less regulated pattern of growth and rely more heavily on free growth for attaining height increment. The magnitude of genetic and adaptive effects of selecting for height increment in early testing programs depended on the origin of population and the environment of planting site. In inland populations early selection for total height increment mainly selects for predetermined growth. This would not lead to maladaptation in the more severe planting sites of inland southwest Oregon. Selected genotypes however would not be able to take advantage of longer growing season at favorable planting sites. In coastal populations early selection for height increment mainly selects for free growth. This may lead to maladaptation on even the favorable planting sites because with increased free growth. the length of the growth period is also increased. Slecting for length and number of stem units does not appear to be an efficient way of selecting for height increment in Douglas-fir. For this procedure to be effective, heritabilities of stem-unit measurements must be higher than heritability of height increment itself. Also genetic correlations between stem-unit measurements and height increment or its components (predetermined and free growth) must be strong. In this study, heritabilities of stem-unit measurements were small and correlations were weak.
Author: Donald F. Flora
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 58
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Author: W.T. Adams
Publisher: Springer Science & Business Media
ISBN: 9401128154
Category : Science
Languages : en
Pages : 423
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Tropical climates, which occur between 23°30'N and S latitude (Jacob 1988), encompass a wide variety of plant communities (Hartshorn 1983, 1988), many of which are diverse in their woody floras. Within this geographic region, temperature and the amount and seasonality of rainfall define habitat types (UNESCO 1978). The F AO has estimated that there 1 are about 19 million km of potentially forested area in the global tropics, of which 58% were estimated to still be in closed forest in the mid-1970s (Sommers 1976; UNESCO 1978). Of this potentially forested region, 42% is categorized as dry forest lifezone, 33% is tropical moist forest, and 25% is wet or rain forest (Lugo 1988). The species diversity of these tropical habitats is very high. Raven (1976, in Mooney 1988) estimated that 65% of the 250,000 or more plant species of the earth are found in tropical regions. Of this floristic assemblage, a large fraction are woody species. In the well-collected tropical moist forest of Barro Colorado Island, Panama, 39. 7% (481 of 1212 species) of the native phanerogams are woody, arborescent species (Croat 1978). Another 21. 9% are woody vines and lianas. Southeast Asian Dipterocarp forests may contain 120-200 species of trees per hectare (Whitmore 1984), and recent surveys in upper Amazonia re corded from 89 to 283 woody species ~ 10 cm dbh per hectare (Gentry 1988). Tropical communities thus represent a global woody flora of significant scope.
Author: Roy R. Silen
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 44
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Author: G. E. Rehfeldt
Publisher:
ISBN:
Category : Douglas fir
Languages : en
Pages : 8
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