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杂草竞争是影响幼苗生理生态学过程及生长的重要因素。以珍贵的阔叶用材树种水曲柳为研究对象, 通过实验生态学方法, 重点研究了在不同的杂草竞争水平上水曲柳幼苗光合日动态、光补偿点及生物量积累等生理生态反应机制, 结果表明, 杂草竞争对水曲柳幼苗的生长有非常明显的影响, 尤为突出的是, 强烈的地下竞争抑制了水曲柳幼苗根系的生长, 地上及地下竞争的综合作用, 导致水曲柳幼苗光补偿点提高, 净光合速率明显降低, 生物量积累显著减少。 相似文献
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John E. Major Alex MosselerDebby C. Barsi Britt Corriveau-DupuisMoira Campbell 《Forest Ecology and Management》2009
Our goal was to quantify and compare the impact of three silvicultural treatments (STs) on growth, light-energy processing, and needle-level morphological adaptive traits for eastern white pine (Pinus strobus L.) from large, central Ontario (ON) and small, isolated Newfoundland (NL) populations. The interest in STs is to reduce weevil (Pissodes strobi) incidence; however, there are potential adaptive changes and productivity trade-offs. The light levels for the STs were, on average, 100%, 42.0%, and 20.4% transmittance for the full-sun, and intermediate- and high-shade STs, respectively. After 8 years, overall height growth was 4.10, 3.25, and 1.70 m for full-sun, and intermediate- and high-shade STs, respectively (P < 0.001). Across all STs, ON populations had greater total height (14%), basal diameter (12%), current leader length (25%), and tree volume (49%) than NL populations (all P < 0.001). At low light levels (10 and 25 μmol m−2 s−1), high-shade ST trees had higher photochemical quenching (qP) and lower chlorophyll fluorescence (Fpc) compared with intermediate-shade and full-sun STs. At 100 μmol m−2 s−1 and beyond, full-sun ST trees had higher qP and lower Fpc than intermediate- and high-shade STs. Average total chlorophyll concentration (CHL) and content (CHLC), and carotenoid concentration (CAR), increased in response to the intermediate-shade ST but did not respond further, or decreased in the high-shade ST. Region was significant for CHL, CAR, chlorophyll a:b and CHL:CAR ratios and CHLC, with ON greater than NL, but was reversed for CHL:CAR ratio. Tree height and volume showed a curvilinear and linear relationship to light level, respectively. Tree height showed a positive linear relationship to qP, apparent photosynthesis, chlorophyll a:b ratio, and needle N (all P < 0.001). Tree height showed a negative linear relationship to Fpc, CHL:CAR ratio, specific needle area, C:N ratio, and needle area N−1 (all P < 0.001). There were modest trade-offs between weevil protection and productivity in the intermediate ST due to the compensatory physiological and morphological adaptations to the limiting light, however, the trade-off with growth at the high-shade level was severe. For NL, consideration should now be given to the introduction and mixing of seed from local seed sources with more southern mainland seed sources, which would decrease the inbreeding effect and provide wider variation for natural selection for a more fit future population. 相似文献
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White spruce (Picea glauca (Moench) Voss) is a dominant species in late-successional ecosystems along the Tanana River, interior Alaska, and the most important commercial timber species in these boreal floodplain forests. Whereas white spruce commonly seed in on young terraces in early primary succession, the species does not become a conspicuous component of the vegetation until after 60–80 years. To address what abiotic and/or biotic factors may explain the paucity of spruce in earlier stages of succession, we examined germination and growth of planted white spruce seedlings across an environmental gradient that included variation in soil physico-chemical properties in the presence and absence of mammal browsing. The effect of browsing pressure over the first four years after planting was most noticeable on the older terraces. Likewise, direct effects of hare browsing on spruce seedling mortality were only manifested at the oldest sites. Spruce germination and survival was inversely proportional to soil cation concentrations, which was largely controlled by temperature-driven evapotranspiration. High light intensities and high air temperatures significantly reduced seedling growth, whereas variation in soil moisture only explained a significant amount of variation in seedling survival. Temperatures within the needle clusters on terminal shoots reached values that adversely affect photosynthesis (>32 °C) on multiple occasions over the growing season. We conclude that the direct (temperature) and indirect (soil chemistry) effects of high insolation are major factors constraining spruce performance on early successional terraces, and that these effects can be significantly exacerbated by mammal browsing on associated deciduous vegetation. 相似文献
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AbstractSpatial distributions models (SDM) are often used in invasive pest management to understand current and potential distribution. Using data on the well-studied spotted wing drosophila as a model, we compared distribution patterns of the range-limit with commonly applied correlative and mechanistic models. Correlative models risk underestimation whereas simple mechanistic models provide overestimated range predictions, although using both approaches for the spotted wing drosophila improved range-limit predictions. Model choice when dealing with pests is central to the accurate identification of invasive species limit range and consequently for the deployment of monitoring and early detection programs. 相似文献
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地膜覆盖对旱地春玉米生理生态和产量的影响 总被引:45,自引:1,他引:44
本文通过田间试验,结合生理生态分析方法,研究了地膜覆盖对春玉米的生理生态效应及产量效果。结果表明:(1)地膜覆盖增加了土壤贮水量,促进土壤深层贮水向表层富集,加快了水分在土壤-植物-大气间的运转;(2)地膜覆盖可减少土壤热量损失,增大作物对光能的截获能力,同时也利用植物对养分的吸收作用;(3)地膜覆盖可大大地提高粮食产量,氮肥肥效及水分利用效率。 相似文献
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V. E. Cussac D. A. Fernández S. E. Gómez H. L. López 《Fish physiology and biochemistry》2009,35(1):29-42
The latitudinal extension of southern South America imposes a thermal gradient that affects the structure of marine and freshwater
fish assemblages and the biology of the species through direct exposure to the temperature gradients or by means of a web
of historical and ecological relationships. We have reviewed biological and ecological data of marine and freshwater fishes
from the southern Neotropics, including Patagonia, and report several examples of dependence on temperature, from glacial
times to today’s climate change. We were able to identify historic and present effects on the diversity of fish assemblages,
isolation, southern limits for the distribution of species, and morphological variation among populations. There is a wide
range of characteristics that exemplify an adaptation to low temperatures, including biochemical peculiarities, physiological
adjustments, and alternative life history patterns, and these appear in both freshwater and marine, and native and exotic
fishes. The consequences of stable temperature regimes in both the ocean and thermal streams deserve special mention as these
shape specialists under conditions of low selective pressure. At present, habitat use and interactions among species are being
subject to changes as consequences of water temperature, and some of these are already evident in the northern and southern
hemispheres. 相似文献
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The potential for increasing rubber production by matching tapping intensity to leaf area index 总被引:1,自引:1,他引:0
Understanding resource capture can help design appropriate species combinations, planting designs and management. Leaf area index (LAI) and its longevity are the most important factors defining dry matter production and thus growth and productivity. The ecophysiological modifications and yield of rubber (Hevea spp.) in an agroforestry system (AFS) with beans (Phaseolus vulgaris L.) were studied. The experiment was established in Southeast-Brazil, with three rubber cultivars: IAN 3087, RRIM 600 and RRIM 527. The AFS comprised double rows of rubber trees along with beans sown in autumn and winter seasons in 1999. There was about 50% higher rubber yield per tree in the AFS than the rubber monoculture. Trees within the AFS responded to higher solar radiation availability with higher LAI and total foliage area, allowing its greater interception. All three cultivars had higher LAI in the AFS than monoculture, reaching maximum values in the AFS between April and May of 3.17 for RRIM 527; 2.83 for RRIM 600 and 2.28 for IAN 3087. The maximum LAI values for monocrop rubber trees were: 2.65, 2.62 and 1.99, respectively, for each cultivar. Rubber production and LAI were positively correlated in both the AFS and monoculture but leaf fall of rubber trees in the AFS was delayed and total phytomass was larger. It is suggested that trees in the AFS were under exploited and could yield more without compromising their life cycle if the tapping system was intensified. This shows how knowledge of LAI can be used to manage tapping intensity in the field, leading to higher rubber yield. 相似文献