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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >The role of vegetation in mitigating the effects of landscape clearing upon dryland stream response trajectory and restoration potential
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The role of vegetation in mitigating the effects of landscape clearing upon dryland stream response trajectory and restoration potential

机译：植被在减轻景观清除对旱地水流响应轨迹和恢复潜力的影响中的作用

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Dryland rivers are recognized for limited research and high uncertainties with respect to understanding biogeomorphic processes. This study uses aerial photography, sediment analysis, palynology indicators and hydraulic modelling to investigate the role of riparian vegetation in influencing the response of systems to disturbance, the trajectory of channel evolution and the potential for management. The study focuses on cleared and uncleared sites in the Yerritup catchment, along the south coast of Western Australia, that occur along a transect with a consistent stream gradient and landscape topographic setting. Downstream reaches show no gross botanical change, but gradual sediment deposition across the floodplain of up to 40cm based on palynological and sedimentary indicators. Channel response in the cleared section by incision, widening and floodplain degradation began rapidly after land clearing, but is driven by large flood events. Degradation of riparian vegetation has significantly increased the sensitivity of the system. The cleared reaches have transformed from a low-capacity channel, under-adjusted to the prevailing flow regime, to the large present channel that is now over-adjusted to the predominantly low to moderate seasonal (occasional flood) flow regime. Modelling of pre-settlement erosive potential reveals that the entire system was naturally sensitive to change, and was primed to erode once riparian vegetation was removed. The trajectory of channel evolution and the role of riparian vegetation is examined in relation to undisturbed reaches in the system and an appreciation of the historical range of variability in geomorphic response. Analysis of the patterns of contemporary vegetation growth identify the potential to re-establish vegetation where it is elevated from saline baseflow. However, the system is assessed as being close to a threshold where restoration is no longer possible and remediation options become more limited as eco-hydraulic and hydrochemical changes continue.
机译：在了解生物地貌过程方面，旱地河流的研究有限且不确定性很高。这项研究使用航空摄影，沉积物分析，孢粉学指标和水力模型研究了河岸植被在影响系统对干扰的响应，河道演变轨迹和管理潜力方面的作用。该研究的重点是西澳大利亚州南海岸Yerritup流域中已清理和未清理的地点，这些地点沿着具有一致的溪流坡度和景观地形设置的样带发生。下游河段没有显示出明显的植物学变化，但根据孢粉和沉积指标，整个洪泛区的沉积物逐渐沉积，最高可达40cm。开阔土地后，开挖，扩宽和洪泛区退化导致的清澈河道响应迅速开始，但受大型洪水事件驱动。河岸植被的退化大大增加了系统的敏感性。清理过的河段已经从低流量通道（已被低估到当前的流量状态）转变为现在的大流量通道，现在已被过度调整到主要是低到中等的季节性（偶尔洪水）流量状态。结算前侵蚀潜力的模型表明，整个系统对变化自然敏感，一旦河岸植被被清除，它们就会被侵蚀。考察了河道演变的轨迹和河岸植被的作用，并与系统中不受干扰的河段以及地貌响应变化的历史范围进行了比较。对当代植被生长方式的分析确定了从盐碱流升高植被的潜力。但是，该系统被评估为接近阈值，随着生态水力和水化学变化的不断进行，修复将不再可能进行，并且补救方案变得更加有限。

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