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首页> 外文学位 >Integrated responses of overstory sweetgum (Liquidambar styracuflua L.) trees to elevated atmospheric carbon dioxide: A field experiment at the Duke Forest FACE site.
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Integrated responses of overstory sweetgum (Liquidambar styracuflua L.) trees to elevated atmospheric carbon dioxide: A field experiment at the Duke Forest FACE site.

机译：过量的甜树（Liquidambar styracuflua L.）树对大气中二氧化碳含量升高的综合响应：杜克森林FACE站点的田间试验。

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I examined the effects of long-term CO2 enrichment on leaf physiology, chemistry and phenology of overstory sweetgum (Liquidambar styraciflua L.) trees that were naturally established within an unmanaged loblolly pine plantation at the Duke Forest Free Air CO2 Enrichment (FACE) experiment. This experiment consisted of three control plots and three plots that had been continuously fumigated with elevated CO2. Elevated CO2 consistently increased photosynthesis in sun and shade leaves. Photosynthesis, however, was stimulated to a greater degree in sun leaves than shade leaves. Elevated CO2 stimulated apparent quantum yield, but there was no interaction between CO2 treatment and leaf position. A simple leaf-level model indicated that net carbon uptake per day was stimulated more in sun leaves than the shade leaves. I found no evidence of photosynthetic acclimation to CO2 enrichment in sun or shade leaves over three years. CO2 enrichment did not affect leaf nitrogen per unit leaf area (Na), chlorophyll or total nonstructural carbohydrates of sun or shade leaves. However, I found a strong relationship between Na and the modeled components of photosynthetic capacity, VCmax and Jmax, suggesting that photosynthetic capacity will be affected by changes in Na as the Duke Forest FACE experiment continues. CO2 treatment had little effect on the phenology and late season decline in photosynthesis of sweetgum leaves and, therefore, did not affect seasonal carbon gain by extending or shortening the growing season. I found a sustained reduction in stomatal conductance (g s) under elevated CO2 over four years and this effect was not different between sun and shade leaves. There was little evidence of stomatal acclimation in sun and shade leaves. Despite decreased g s under CO2 enrichment, relative stomatal limitation of photosynthesis was lower at elevated CO2 than at ambient CO2. Stomatal density was not changed by CO2 enrichment and, therefore, not associated with the CO2 induced decline in gs. Overall, my studies indicated that the effects of elevated CO2 on leaf processes of sweetgum trees have complex interactions with environmental and temporal variables that must be taken into account when considering the effects of CO2 enrichment on larger canopy and ecosystem scales.
机译：我研究了长期CO 2 富集对自然生长在不受管理的火炬树中的过高甜树（ Liquidambar styraciflua L.）树的叶片生理，化学和物候的影响。杜克森林自由空气CO 2 富集（FACE）实验中的松树人工林。该实验由三个对照样地和三个用升高的CO 2 连续熏蒸的样地组成。升高的CO 2 持续增加了日光和阴凉叶片的光合作用。然而，与阴叶相比，太阳叶对光合作用的刺激程度更高。升高的CO 2 刺激了表观量子产率，但CO 2 处理与叶片位置之间没有相互作用。一个简单的叶水平模型表明，日叶的每日净碳吸收比树荫的叶刺激更多。我发现没有证据表明在过去三年中，阳光或遮荫叶片中光合适应了CO 2 富集。 CO 2 的富集不会影响单位面积（N a ），叶绿素或太阳或遮荫叶片总非结构性碳水化合物的叶氮。但是，我发现N a 与光合能力的模型成分VC max 和J max 之间有很强的关系，这表明光合能力将随着Duke Forest FACE实验的进行，N a 的变化会受到影响。 CO 2 处理对甘蔗叶片光合作用的物候和后期下降影响不大，因此，不会通过延长或缩短生长期来影响季节性碳增加。我发现在CO 2 升高的情况下，气孔导度（ g s ）持续降低了四年，这种影响在阳光和阴影之间没有区别树叶。几乎没有证据表明日光和阴凉处的气孔适应。尽管CO 2 富集下 g s 减少，但CO 2 升高时光合作用的相对气孔限制却低于环境CO 2 。 CO 2 的富集不会改变气孔密度，因此与CO 2 引起的 g s下降无关。子>。总体而言，我的研究表明，CO 2 升高对香树叶片过程的影响与环境和时间变量具有复杂的相互作用，在考虑CO 2 < / sub>在较大的树冠和生态系统范围内进行浓缩。

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