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首页> 外文学位 >The Effects of Climate Warming on Tree Seedling Physiology, Growth and Survival at the Temperate-Boreal Forest Ecotone in Minnesota, USA.
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The Effects of Climate Warming on Tree Seedling Physiology, Growth and Survival at the Temperate-Boreal Forest Ecotone in Minnesota, USA.

机译：美国明尼苏达州的温带-北方森林交错带气候变暖对树木幼苗生理，生长和生存的影响。

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摘要

As global climate warms, plant distributions are predicted to shift due to altered disturbance, precipitation and seasonal temperature regimes. Areas currently occupied by the northern temperate and boreal forests are projected to undergo significant changes in response to climate warming. Northward migration of temperate and southern boreal species could alter community composition, diversity and productivity in forested ecosystems. Critical to understanding potential forest shifts is gaining a better understanding of warming effects on young tree seedlings, the survival and recruitment of which will influence future forest composition. In this dissertation, I examine the effects of climate warming on tree seedling physiology, growth and survival in species common to the temperate-boreal forest ecotone using both glasshouse and field experiments.;To examine tree seedling physiological response to the dual-stress of high temperature and low light, I grew six species in two temperature environments (25°C day/19°C night or 30°C day/24°C night) in glasshouses. Later, I imposed a low light treatment (<1% light) designed to move seedlings below their whole plant light compensation points. Tree seedlings germinated and grown in elevated temperature had lower plant biomass, lower non-structural carbohydrate reserve pools and tissue concentrations relative to seedlings grown in cooler temperatures. After subjected to low-light stress, seedlings in elevated temperature showed higher dark respiration rates and mortality relative to seedlings grown in a cooler temperature environment. Non-structural carbohydrates are an important means by which plants respond to environmental stress and promote survival. To examine how allocation to and use of NSC reserves varies across resource gradients, I planted tree seedlings in one of four light environments (5%, 10%, 30% and 60% canopy openness) in a field experiment. I found that NSC reserve use and accumulation varies among species, within species across a light gradient and seasonally in conjunction with growth phenology. Within species, seedlings accumulated higher reserves when growth was limited by light availability (low light) or when light was sufficient to allocate to both growth and reserve accumulation (high light). Finally, I planted six species into three light environments (10%, 30% and 60% canopy openness), and in one of two temperature treatments within light environment (ambient or passively warmed) to examine the interactive effects of warming and light environment on seedling growth and survival. I provide evidence that warming, generally, has positive effects on growth and productivity in six species common to the temperate-boreal ecotone in low and intermediate light levels, but generally negative effects in high light. Overall, this dissertation suggests that elevated temperature may inhibit tree seedling productivity and resilience to environmental stress when coupled with additional environmental stress (i.e. very low or very high light), but increase productivity in moderate resource environments.
机译：随着全球气候变暖，预计由于干扰，降水和季节性温度制度的变化，植物分布也会发生变化。预计目前北部温带森林和北方森林所占地区将随着气候变暖而发生重大变化。温带和北方北方物种向北迁移可能会改变森林生态系统中的群落组成，多样性和生产力。了解潜在的森林转移至关重要的是，人们需要更好地了解变暖对幼树幼苗的影响，其存活和补充将影响未来的森林组成。本文主要通过温室和田间试验研究了气候变暖对温带-北方森林过渡带常见树种幼苗生理，生长和存活的影响。在低温和弱光的条件下，我在温室中的两种温度环境（25°C白天/ 19°C晚上或30°C白天/ 24°C晚上）中种了6种。后来，我实施了弱光处理（<1％光照），旨在将幼苗移到整个植物的光照补偿点以下。与在较低温度下生长的幼苗相比，在高温下发芽和生长的树木幼苗具有较低的植物生物量，较低的非结构性碳水化合物储备库和组织浓度。在低光照条件下，相对于在较凉的温度环境中生长的幼苗，高温下的幼苗显示出更高的暗呼吸速率和死亡率。非结构性碳水化合物是植物应对环境胁迫并促进生存的重要手段。为了研究NSC储备的分配和使用如何随资源梯度的变化而变化，我在田间试验中在四种光照环境（5％，10％，30％和60％的树冠开放度）之一中种植了树苗。我发现NSC保护区的利用和积累在物种之间，物种内部，在整个光梯度内以及随生长物候而季节性变化。在种内，当生长受到光的可用性（弱光）限制或当光足以分配给生长和储备积累（高光）时，幼苗积累了更高的储量。最后，我将六个树种种植到三个光照环境（树冠开放度为10％，30％和60％）中，并在光照环境（环境或被动加热）中进行两种温度处理之一，以研究升温和光照环境对幼苗生长和存活。我提供的证据表明，在弱光和中等光照条件下，变暖通常会对温带-北方过渡带共有的六个物种的生长和生产力产生积极影响，而在强光条件下通常对消极影响。总体而言，该论文表明，升高的温度可能会在与其他环境压力（即非常低或非常高的光照）结合使用时抑制树木幼苗的生产力和对环境压力的适应能力，但在中等资源环境下会提高生产力。

著录项

  • 作者

    Peebles, Kala L.;

  • 作者单位

    University of Minnesota.;

  • 授予单位 University of Minnesota.;
  • 学科 Plant sciences.;Environmental science.;Environmental management.;Climate change.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 148 p.
  • 总页数 148
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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