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Using hydrological connectivity to detect transitions and degradation thresholds: Applications to dryland systems
Catena ( IF 6.2 ) Pub Date : 2019-12-09 , DOI: 10.1016/j.catena.2019.104354
Patricia M. Saco , José F. Rodríguez , Mariano Moreno-de las Heras , Saskia Keesstra , Samira Azadi , Steven Sandi , Jantiene Baartman , Jesús Rodrigo-Comino , María Julieta Rossi

In arid and semi-arid ecosystems, shortage of water can trigger changes in landscapes’ structures and function leading to degradation and desertification. Hydrological connectivity is a useful framework for understanding water redistribution and scaling issues associated with runoff and sediment production, since human and/or natural disturbances alter surface water availability and pathways increasing/decreasing connectivity. In this paper, we illustrate the use of the connectivity framework for several examples of dryland systems that are analysed at a variety of spatial and temporal scales. In doing so, we draw particular attention to the analysis of coevolution of system structures and function, and how they may drive threshold behaviour leading to desertification and degradation. We first analyse the case of semi-arid rangelands, where feedbacks between the decline in vegetation density and landscape erosion reinforces degradation processes driven by changes in connectivity until a threshold is crossed above which the return to a functional system is unlikely. We then focus on semi-arid wetlands, where decreases in water volumes promote terrestrial vegetation encroachment that changes drainage conditions and connectivity, potentially reinforcing redistribution of flow paths to other wetland areas. The analysis of dryland wetlands is based on a novel hydrologic connectivity index derived using inundation requirements for wetland vegetation associations. The examples presented highlight the need to incorporate a coevolutionary framework for the analysis of changing connectivity patterns and the emergence of thresholds in arid and semi-arid systems.



中文翻译:

使用水文连通性检测过渡和退化阈值:在旱地系统中的应用

在干旱和半干旱的生态系统中,缺水会触发景观结构和功能的变化,从而导致退化和荒漠化。水文连通性是一个有用的框架,可用于了解与径流和沉积物产生有关​​的水的再分配和结垢问题,因为人为和/或自然干扰会改变地表水的可利用性,并且会增加/减少连通性的途径。在本文中,我们说明了连接框架在旱地系统的几个示例中的使用,这些示例在各种时空尺度上进行了分析。在此过程中,我们特别关注系统结构和功能的协同进化分析,以及它们如何驱动阈值行为导致荒漠化和退化。我们首先分析半干旱牧场的情况,植被密度下降与景观侵蚀之间的反馈会加剧由连通性变化驱动的退化过程,直到超过阈值为止,在该阈值之上不太可能恢复到功能系统。然后,我们将重点放在半干旱湿地上,其中水量的减少会促进陆地植被的入侵,从而改变排水条件和连通性,从而有可能加强流径向其他湿地区域的重新分配。旱地湿地的分析基于一种新的水文连通性指数,该指数是根据对湿地植被协会的淹没要求得出的。所提供的示例强调了需要纳入一个共同进化的框架来分析干旱和半干旱系统中不断变化的连通性模式和阈值的出现。

更新日期:2019-12-09
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