Connectivity in dryland landscapes: shifting concepts of spatial interactions

Abstract

Dryland ecosystems are often characterized by patchy vegetation and exposed soil. This structure enhances transport of soil resources and seeds through the landscape (primarily by wind and water, but also by animals), thus emphasizing the importance of connectivity – given its relation to the flow of these materials – as a component of dryland ecosystem function. We argue that, as with the fertile‐islands conceptual model before it, the concept of connectivity explains many phenomena observed in drylands. Further, it serves as an organizing principle to understand dryland structure and function at scales from individual plants to entire landscapes. The concept of connectivity also helps to organize thinking about interactions among processes occurring at different scales, such as when processes at one scale are overridden by processes at another. In these cases, we suggest that state change occurs when fine‐scale processes fail to adjust to new external conditions through resource use or redistribution at the finer scale. The connectivity framework has practical implications for land management, especially with respect to decision making concerning the scale and location of agricultural production or habitat restoration in the world's drylands.

Advances in restoration ecology: rising to the challenges of the coming decades

“…The management of the matrix could determine restoration outcomes for biodiversity, with three core matrix effects (movement and dispersal, resource availability and abiotic environment) being modified by five dimensions: spatial and temporal variation in matrix quality, its spatial scale, the longevity and demographic rates of species relative to the temporal scale of matrix variation, and adaptation (Driscoll et al 2013). Landscape connectivity is increasingly seen as a key conservation and restoration goal, particularly as a strategy to allow biotic movement in response to changing environments (Roever et al 2013, Tambosi et al 2014, Okin et al 2015. Deciding what and where to restore is a key challenge for future landscapescale restoration efforts (McRae et al 2012, Torrubia et al 2014.…”

Environmental controls, morphodynamic processes, and ecogeomorphic interactions of barchan to parabolic dune transformations

“…The overall coverage of the grass assemblage increases surface roughness and reduces sand transport significantly, so that a surface cover of ~15 % is sufficient to stop most sand transport (Wiggs et al, 1995;Lancaster and Baas, 1998). Perennial shrubs and some clump-like grasses, such as Ordos Sagebrush and Marram Grass (Tsoar and Blumberg, 2002), form separate individual roughness elements that modify the wind velocity profile near the surface and create zones of accelerated-and decelerated-airflows as well as landscape connectivity (Ranwell, 1972;Hesp, 1981;Okin et al, 2015).…”

Rainfall intensity switches ecohydrological runoff/runon redistribution patterns in dryland vegetation patches

“…Both issues are highly dependent on horizontal water redistribution at the patch to landscape scales (Breshears et al 1997, Davenport et al 1998, and can be affected intentionally or non-intentionally by the management of livestock grazing and associated trampling and soil compaction (George et al 2004). Recent research on water redistribution processes has focused on the effects of canopy architecture, spatial distribution of vegetation, ecosystem connectivity, and soil infiltration rate (Newman et al 2010, Ravi et al 2010, Villegas et al 2010, Urgeghe and Bautista 2014, Okin et al 2015. Notably, in these and other studies, rainfall has been typically characterized only by event size, largely due to the availability of historical daily aggregated data.…”