Genecology of Douglas Fir in Western Oregon and Washington

USDA Forest Service, Pacific Northwest Research Station, 3200 SW Jefferson Way, Corvallis, OR 97331, USA.
Annals of Botany (Impact Factor: 3.65). 01/2006; 96(7):1199-214. DOI: 10.1093/aob/mci278
Source: PubMed

ABSTRACT Genecological knowledge is important for understanding evolutionary processes and for managing genetic resources. Previous studies of coastal Douglas fir (Pseudotsuga menziesii var. menziesii) have been inconclusive with respect to geographical patterns of variation, due in part to limited sample intensity and geographical and climatic representation. This study describes and maps patterns of genetic variation in adaptive traits in coastal Douglas fir in western Oregon and Washington, USA.
Traits of growth, phenology and partitioning were measured in seedlings of 1338 parents from 1048 locations grown in common gardens. Relations between traits and environments of seed sources were explored using regressions and canonical correlation analysis. Maps of genetic variation as related to the environment were developed using a geographical information system (GIS).
Populations differed considerably for adaptive traits, in particular for bud phenology and emergence. Variation in bud-set, emergence and growth was strongly related to elevation and cool-season temperatures. Variation in bud-burst and partitioning to stem diameter versus height was related to latitude and summer drought. Seedlings from the east side of the Washington Cascades were considerably smaller, set bud later and burst bud earlier than populations from the west side.
Winter temperatures and frost dates are of overriding importance to the adaptation of Douglas fir to Pacific Northwest environments. Summer drought is of less importance. Maps generated using canonical correlation analysis and GIS allow easy visualization of a complex array of traits as related to a complex array of environments. The composite traits derived from canonical correlation analysis show two different patterns of variation associated with different gradients of cool-season temperatures and summer drought. The difference in growth and phenology between the westside and eastside Washington Cascades is hypothesized to be a consequence of the presence of interior variety (P. menziessii var. glauca) on the eastside.

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    • "Based on the geographic distribution of MCWD values in the Amazon, this corresponds to an estimated median range extent of more than 3000 km (Fig. 2B). Local adaptation to drought and summer moisture stress in populations of temperate species can be found over distances of just tens to hundreds of kilometers (Rehfeldt et al. 1999; St Clair et al. 2005). We found that Amazonian species experience large differences in MCWD across species' ranges, and that these differences occur over large geographic distances. "
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    ABSTRACT: Populations occurring at species' range edges can be locally adapted to unique environmental conditions. From a species' perspective, range-edge environments generally have higher severity and frequency of extreme climatic events relative to the range core. Under future climates, extreme climatic events are predicted to become increasingly important in defining species' distributions. Therefore, range-edge genotypes that are better adapted to extreme climates relative to core populations may be essential to species' persistence during periods of rapid climate change. We use relatively simple conceptual models to highlight the importance of locally adapted range-edge populations (leading and trailing edges) for determining the ability of species to persist under future climates. Using trees as an example, we show how locally adapted populations at species' range edges may expand under future climate change and become more common relative to range-core populations. We also highlight how large-scale habitat destruction occurring in some geographic areas where many species range edge converge, such as biome boundaries and ecotones (e.g., the arc of deforestation along the rainforest-cerrado ecotone in the southern Amazonia), can have major implications for global biodiversity. As climate changes, range-edge populations will play key roles in helping species to maintain or expand their geographic distributions. The loss of these locally adapted range-edge populations through anthropogenic disturbance is therefore hypothesized to reduce the ability of species to persist in the face of rapid future climate change.
    Ecology and Evolution 09/2015; DOI:10.1002/ece3.1645 · 2.32 Impact Factor
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    • "The sampling design we used for collection of seeds were based on results from an earlier genecology study conducted across the study area (St Clair et al., 2005). Seeds were collected across seven regions in Washington, Oregon, and "
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    ABSTRACT: There is a general assumption that intraspecific populations originating from relatively arid climates will be better adapted to cope with the expected increase in drought from climate change. For ecologically and economically important species, more comprehensive, genecological studies that utilize large distributions of populations and direct measures of traits associated with drought-resistance are needed to empirically support this assumption because of the implications for the natural or assisted regeneration of species. We conducted a space-for-time substitution, common garden experiment with 35 populations of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) growing at three test sites with distinct summer temperature and precipitation (referred to as ‘cool/moist’, ‘moderate’ or ‘warm/dry’) to test the hypotheses that 1) there is large genetic variation among populations and regions in traits associated with drought-resistance, 2) the patterns of genetic variation are related to the native source-climate of each population, in particular with summer temperature and precipitation, 3) the differences among populations and relationships with climate are stronger at the warm/dry test site owing to greater expression of drought-resistance traits (i.e. a genotype × environment interaction). During mid-summer 2012, we measured the rate of water loss after stomatal closure (transpirationmin), water deficit (% below turgid saturation), and specific leaf area (SLA, cm2g−1) on new growth of sapling branches. There was significant genetic variation in all plant traits, with populations originating from warmer and drier climates having greater drought-resistance (i.e., lower transpirationmin, water deficit and SLA), but these trends were most clearly expressed only at the warm/dry test site. Contrary to expectations, populations from cooler climates also had greater drought-resistance across all test sites. Multiple regression analysis indicated that Douglas-fir populations from regions with relatively cool winters and arid summers may be most adapted to cope with drought conditions that are expected in the future.This article is protected by copyright. All rights reserved.
    Global Change Biology 08/2014; 21(2). DOI:10.1111/gcb.12719 · 8.04 Impact Factor
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    • "With adaptation of populations to the climate being unequivocal (see St Clair et al., 2005), a change in climate will have an effect on the growth and survival of individuals and populations. Yet, for provenance test results to be useful in assessing potential impacts of climate change (see Mátyás, 1994), geographic descriptors of clinal variation must be replaced by climatic descriptors (see St Clair et al., 2005; Rehfeldt and Jaquish, 2010; Joyce and Rehfeldt, 2013). The primary goal of the present study is to synthesize disparate provenance test data so that range-wide, climate-based clines in the sub-specific varieties of P. ponderosa and P. menziesii can be described statistically. "
    Forest Ecology and Management 01/2014; 324:138-146. · 2.66 Impact Factor
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