Eco-geomorphological connectivity and coupling interactions at hillslope scale in drylands: Concepts and critical examples.

The diagnosis of land degradation requires a deep understanding of ecosystem functioning and evolution. In dryland systems, in particular, research efforts must address the redistribution of scarce resources for vegetation, in a context of high spatial heterogeneity and non-linear response. This fact explains the prevalence of eco-hydrological perspectives interested in runoff processes and, the more recent, focused on connectivity as an indicator of system resource optimisation. From a geomorphological perspective and reviewing the concepts of eco-hydro-geomorphological interactions operating in ecosystems, this paper explores the effects of erosion on vegetation configuration through two case studies at different spatio-temporal scales. We focus on the structure-function linkage, specifically on how morphological traits relate with different stages in the erosional sequence, both in the abiotic and the biotic domain. Results suggest that vegetation dynamics are affected by structural boundary conditions at both scales, i.e. by surface armouring related with rock fragments at the patch scale, and by the degree of hillslope-channel coupling at the hillslope scale. Our preliminary results can serve as new working hypotheses about the structure-function interplay on hillslopes. All this, taking advantage of the recent technological achievements for acquiring very high-resolution geospatial data that offer new analytical possibilities in a range of scales. • Structure/function approach evidences erosion effects on vegetation configuration. • Composition of abiotic patches modulates source-sink dynamics by surface armouring. • Channel linear incision diffuses the upslope erosion, biasing vegetation. • Erosional sequence across-scales sets boundary conditions to hillslope connectivity. • Eco-geomorphic frameworks are needed to address explicitly space-time scale dependencies. [ABSTRACT FROM AUTHOR]