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首页> 外文学位 >Soil ecosystem responses to climate change and land-use simulations and estimation of carbon stocks in steppe and forest ecosystems in northern Mongolia.
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Soil ecosystem responses to climate change and land-use simulations and estimation of carbon stocks in steppe and forest ecosystems in northern Mongolia.

机译：蒙古北部草原和森林生态系统对气候变化和土地利用模拟的土壤生态系统反应以及碳储量的估算。

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摘要

Northern Mongolia currently sequesters 31 Tg C yr −1 but it may become a carbon source if respiration rates increase due to climate change and overgrazing, or if projected boundary shifts between forest and steppe cause a change in the carbon storage of ecosystems. The objectives of the thesis are to study soil ecosystem response to simulated climate change and grazing, and to assess C stocks in the steppe and forest. Open-top chambers (OTCs) have been frequently used for simulating climate change. However, the pattern of temperature increase by OTCs contradicted the IPCC predictions. An alternative method, open-sided chambers (OSCs), was evaluated based on its effects on abiotic and biotic factors. The results indicated that OSCs manipulated air temperature in a pattern that was predicted by IPCC models, but the overall effect was too small, hence it is not an optimal device. In the subsequent study, OTCs were used to study soil respiration response to experimental warming in three ecosystems. Temperature increase by OTCs had no effect on soil respiration in the steppe but increased soil respiration in the forest (by 0.20 g CO2 m-2 h -1), demonstrating the importance of ecosystem setting. Although warming increased soil respiration, it decreased its temperature sensitivity as well (Q10 = 5.82 in control versus 2.22 in OTC). In addition to OTCs, watering and grazing effects on CO2 effluxes (ecosystem and soil respiration) were studied across the topographical gradients in the steppe. Our results show a robust, positive effect of soil moisture on CO2 effluxes across topography, and the contrasting effects of grazing on CO 2 effluxes. Interactive effects of the treatments were minimal. Soil carbon of the forest was the same (8.3 kg C m-2) as the steppe (8.1 kg C m-2) but aboveground carbon in the forest (2.9 kg C m-2) was 3-7 times greater than that in the steppe. In summary, the results show that warming will slightly increase soil respiration in the forest, but in steppe precipitation will have stronger effect on CO2 flux than temperature change. The results also indicated that overgrazing and deforestation could trigger a greater loss of carbon.
机译：蒙古北部目前的固碳量为31 Tg C yr -1，但是如果由于气候变化和过度放牧而导致呼吸速率增加，或者如果预计的森林和草原之间的边界转移导致生态系统碳储量的变化，它可能会成为碳源。本文的目的是研究土壤生态系统对模拟气候变化和放牧的响应，并评估草原和森林中的碳库。开放式室（OTC）经常用于模拟气候变化。但是，OTC的温度升高方式与IPCC的预测相矛盾。基于其对非生物和生物因素的影响，评估了另一种方法，即敞开式腔室（OSC）。结果表明，OSC以IPCC模型预测的模式操纵空气温度，但总体效果太小，因此不是最佳设备。在随后的研究中，OTC被用于研究三种生态系统中土壤呼吸对实验变暖的响应。 OTC的温度升高对草原的土壤呼吸没有影响，但增加了森林中的土壤呼吸（增加了0.20 g CO2 m-2 h -1），证明了生态系统设置的重要性。尽管变暖增加了土壤呼吸，但它也降低了其温度敏感性（对照中Q10 = 5.82，而OTC中Q22 = 2.22）。除了OTC，还研究了草原上地形梯度上的浇水和放牧对CO2排放（生态系统和土壤呼吸）的影响。我们的结果表明，土壤水分对地形上的CO2排放具有强大的积极作用，而放牧对CO 2排放的影响则相反。治疗的相互作用影响很小。森林的土壤碳（8.3 kg C m-2）与草原（8.1 kg C m-2）相同，但森林中的地上碳（2.9 kg C m-2）是草原的3-7倍。草原。总而言之，结果表明，变暖将略微增加森林中的土壤呼吸，但是在草原降水中，CO 2通量的影响要强于温度变化。结果还表明，过度放牧和森林砍伐可能导致更大的碳损失。

著录项

  • 作者

    Sharkhuu, Anarmaa.;

  • 作者单位

    University of Pennsylvania.;

  • 授予单位 University of Pennsylvania.;
  • 学科 Biology Ecology.;Environmental Sciences.;Biogeochemistry.;Climate Change.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 173 p.
  • 总页数 173
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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