6 research outputs found

    Ecophysiology and Genetic Variation in Domestication of Sphaeralcea and Shepherdia Species for the Intermountain West

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    Low-water landscaping is an essential tool for water conservation in the arid Intermountain West (IMW) for managing limited supplies and population-driven increased demand. The IMW harbors a large number of drought-tolerant native species that have potential for use in the low-water use landscape (LWL). However, many species are not available in the nursery trade due to their morphological confusion and establishment difficulty in the managed landscapes. The overall goal of this study is to elucidate morphological, ecophysiological, and genetic distinctions within two IMW native plant genera containing species with high urban low-water landscape potential

    Adequacy of Morphological Traits in Discrimination Among Sphaeralcea (Globemallow) in Utah

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    Water conservation in urban areas can be enhanced by encouraging installation of lowwater landscapes in ornamental settings. Appropriate plant selection for low-water landscapes is complicated by concern about water-use efficiency of plants and as well as their aesthetic value. Sphaeralcea common to Utah are drought-tolerant and have ornamental value. However their widespread use in the industry is hindered by their complex genetics. They are difficult to differentiate morphologically due to presumed natural hybridization among populations. This leads to species misidentification and erodes consumer confidence in the native plant industry. Environmental factors also might account for variation in leaf morphological characters and decrease accuracy in species identification. The objectives of our study were to evaluate the influence of environment on leaf character trait stability, and to use molecular marker technology to investigate taxonomic relationships between species. Live plant materials were collected from several populations each of Sphaeralcea coccinea, S. grossulariifolia, S. munroana, S. parvifolia, and S. leptophylla (control). Voucher specimens were used to confirm species identification using traditional morphological characters. Live plant materials were transplanted from their native habitats into a common garden. Leaf measurements were recorded on established plants. Plants were then pruned back to basal leaves, and measurements recorded again after 6 weeks of shoot regrowth. Principal Component Analysis of leaf morphological data suggested environmentally related plasticity of leaf morphological characters in these species. DNA sequence analysis of nuclear ITS and chloroplast intergenic spacer regions, using universal primer pairs, was not adequate to resolve differences at the species level. Phylogenetic trees constructed from these data indicate relatively recent divergence of the species. The Amplified fragment length polymorphism (AFLP) technique will be used to further characterize the genetic variation among and within these species

    Potential reconstruction of paleo-vapor pressure deficit and seasonal balance from Rocky Mountain and Utah juniper ring increment

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    Vapor pressure deficit (VPD), controlled mostly by temperature, drives evapotranspiration and in turn governs both agricultural and urban landscape irrigation. Most tree species are sensitive to VPD, closing stomata to reduce transpiration at vapor deficits above 1-2 kPa. At some point temperature-VPD increase affects photosynthesis and tree growth is reduced. Stomatal sensitivity to VPD increases, and photosynthesis and growth reduced, with low precipitation, greater soil water depletion and more water stress. Tree ring growth is widely used as a proxy for hydroclimate, but the role of VPD has been overlooked, particularly as it interacts with low precipitation. We correlated tree ring growth of lower elevation (1700-2100 meter) Rocky Mountain (Juniper scopularum-RMJ) and Utah (J. osteosperma-UJ) junipers from four sites (two sites each species) in the Bear-Wasatch ranges with seasonal VPD and yearly precipitation measured at the USU campus from 1900 to 2010. At two sites, one each RMJ and UJ, soil (precipitation) and atmospheric (VPD) water deficits interacted to limit growth (tree ring indices; r=~0.6 and ~0.5, respectively). At the other two sites dry air/high VPD better explained changes in tree ring index (r=0.45-0.5) than yearly precipitation (~r=0.2), meaning that high summer temperature was the major constraint on growth. RMJ and UJ trees at the driest sites also had 4-10-fold more missing rings, another indicator of greater water stress. Rocky Mountain and Utah juniper species are not commonly used in dendrochronology studies, but these results suggest a direct climate—precipitation/VPD—impact on growth rather than a proxy relationship. Further, this direct relationship illuminates the potential to reconstruct paleo growing season evapotranspiration (ET) and seasonal water deficit (precipitation minus ET) for northern Utah back approximately half a millennia

    Morphological and Genetic Variation among Four High Desert Sphaeralcea Species

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    he herbaceous perennial species in the genus Sphaeralcea have desirable drought tolerance and aesthetics with potential for low-water use landscapes in the Intermountain West. However, taxonomy of these species is ambiguous, which leads to decreased consumer confidence in the native plant nursery industry. The goal of this study was to test and clarify morphological and genetic differentiation among four putative Sphaeralcea species. Morphological characteristics of the type specimens were used as species references in canonical variate analysis to generate a classification model. This model was then used to assign putative species names to herbarium voucher specimens and to field-collected voucher specimens to clarify genetic variation among species. Field specimens were also classified using Bayesian cluster analyses of amplified fragment length polymorphism (AFLP) genotypes. Sphaeralcea coccinea (Nutt.) Rydb. and S. grossulariifolia (Hook. & Arn.) Rydb. formed a composite group morphologically and genetically distinct from the S. munroana (Douglas) Spach and S. parvifolia A. Nelson composite group. Each composite group displayed genetic isolation by geographic distance. Also, morphological traits of S. munroana and S. parvifolia correlated to geographic distance. Taken together these results suggest that our samples represent two sympatric yet reproductively isolated groups. Distinguishing between these two Sphaeralcea composite groups can create greater consumer confidence in plant material developed for use in Intermountain West low-water landscaping

    Morphological and genetic variation among Sphaeralcea Species in a high desert environment

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    The herbaceous perennial species in the genus Sphaeralcea have desirable drought tolerance and aesthetics with potential for low-water use landscapes in the Intermountain West. However, taxonomy of these species is ambiguous, which leads to decreased consumer confidence in the native plant nursery industry. The goal of this study was to test and clarify morphological and genetic differentiation among four putative Sphaeralcea species. Morphological characteristics of the type specimens were used as species references in canonical variate analysis to generate a classification model. This model was then used to assign putative species names to herbarium voucher specimens and to field-collected voucher specimens to clarify genetic variation among species. Field specimens were also classified using Bayesian cluster analyses of amplified fragment length polymorphism (AFLP) genotypes. Sphaeralcea coccinea (Nutt.) Rydb. and S. grossulariifolia (Hook. & Arn.) Rydb. formed a composite group morphologically and genetically distinct from the S. munroana (Douglas) Spach and S. parvifolia A. Nelson composite group. Each composite group displayed genetic isolation by geographic distance. Also, morphological traits of S. munroana and S. parvifolia correlated to geographic distance. Taken together these results suggest that our samples represent two sympatric yet reproductively isolated groups. Distinguishing between these two Sphaeralcea composite groups can create greater consumer confidence in plant material developed for use in Intermountain West low-water landscaping

    Anisohydric water use behavior links growing season evaporative demand to ring-width increment in conifers from summer-dry environments

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    Key message: Compared to isohydric Pinaceae, anisohydric Cupressaceae exhibited: (1) a threefold larger hydroscape area; (2) growth at lower pre-dawn water potentials that extended longer into the growing season; and (3) stronger coupling of growth to growing season atmospheric moisture demand in summer-dry environments. Abstract: Conifers in the Pinaceae and Cupressaceae from dry environments have been shown to broadly differ in their stomatal sensitivity to soil drying that result in isohydric versus anisohydric water use behavior, respectively. Here, we first employ a series of drought experiments and field observations to confirm the degree of isohydric versus anisohydric water use behavior in species of these two families that are representative of the Interior West of the United States. We then use experimental soil drying to demonstrate how growth of anisohydric Juniperus osteosperma was more closely tied to pre-dawn water potentials than isohydric Pinus monophylla. Finally, we confirm that measured leaf gas-exchange and growth responses to drying hold real-world consequences for conifers from the Interior West. More specifically, across the past ~ 100 years of climate variation, pairwise comparisons of annual ring-width increment responses indicate that growth of Cupressaceae species (J. osteosperma and J. scopulorum) was more strongly coupled to growing season evaporative demand than co-occurring Pinaceae species (Pinus monophylla, P. edulis, P. flexilis, P. longaeva, P. ponderosa, and Pseudotsuga menziesii). Overall, these experimental and observational results suggest that an a priori distinction based on family and associated hydric water use behavior should lead to more accurate and mechanistically correct dendrochronological reconstructions of growing season evaporative demand (i.e., Cupressaceae) versus antecedent precipitation (i.e., Pinaceae) in summer-dry environments. Moreover, these differences in growth sensitivity to evaporative demand among these groups suggest that incorporating hydric water use behavior into models of forest responses to global warming can provide more accurate projections of future forest composition and functioning
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