Plant Spatial Pattern Predicts Hillslope Runoff and Erosion in a Semiarid Mediterranean Landscape

Abstract

The importance of the spatial pattern of vegetation for hydrological behavior in semiarid environments is widely acknowledged. However, there is little empirical work testing the hypothetical covariation between vegetation spatial structure and hillslope water and sediment fluxes. We evaluated the relationships between vegetation structural attributes (spatial pattern, functional diversity), soil surface properties (crust, stone, plant, and ground cover, and particle size distribution) and hillslope hydrologic functioning in a semiarid Mediterranean landscape; in particular, we tested whether decreasing patch density or coarsening plant spatial pattern would increase runoff and sediment yield at the hillslope scale. Runoff and sediment yield were measured over a 45-month period on nine 8 • 2-m plots that varied in vegetation type and spatial pattern. We grouped vegetation into functional types and derived plant spatial pattern attributes from field plot maps processed through a GIS system. We found that there was an inverse relationship between patch density and runoff, and that both runoff and sediment yields increased as the spatial pattern of vegetation coarsened. Vegetation pattern attributes and plant functional diversity were better related to runoff and sediment yield than soil surface properties. However, a significant relationship was found between physical crust cover and plant spatial pattern. Our results present empirical evidence for the direct relationship between the hydrologic functioning of semiarid lands and both the spatial pattern and the functional diversity of perennial vegetation, and suggest that plant spatial pattern, physical crust cover, and functional diversity may be linked through feedback mechanisms.

Effects of plant diversity on soil erosion for different vegetation patterns

“…It has thus been suggested that the relationship between the soil 137 Cs inventory and species diversity (SHDI) can be modulated by the vegetation pattern (LSI) (Bautista et al, 2007). To reveal whether similar vegetation patterns can present the relationship between plant diversity (SHDI) and the extent of soil erosion (soil 137 Cs inventory) better than different patterns (Hou et al, 2014), these plots were divided into nine groups.…”

“…After conducting a study in northeastern Australia, Ludwig et al (2007) suggested that a greater intensity of soil erosion is usually more associated with heterogeneous vegetation patterns rather than homogeneous vegetation patterns. In addition, the relationship between plant diversity and soil erosion can be affected by the vegetation pattern (Bautista et al, 2007). It has been suggested that similar vegetation patterns can be better conditions for determining the relationship between plant diversity and soil erosion than areas with different vegetation patterns (Hou et al, 2014).…”

“…This relationship is thus ambiguous under different environmental conditions (Bautista et al, 2007). For example, a positive correlation between plant diversity and soil erosion has frequently been observed; however, a negative correlation has also been found (Turnbull et al, 2008).…”

The fate of seeds in the soil: a review of the influence of overland flow on seed removal and its consequences for the vegetation of arid and semiarid patchy ecosystems

“…As regards banded patterns, the dynamics of spotted vegetation might be more complex, as the former usually act as closed hydrological systems and the latter highly depends on the connectivity of bare areas (Saco et al, 2007). Recent studies demonstrate that it is not only the extent to which vegetation patches prevail on a slope (Parsons et al, 1996;Wainwright et al, 2000;Bochet et al, 2000;Puigdefábregas, 2005) but also the connectivity of bare areas that influences hydrological processes such as runoff and sediment transport (Bautista et al, 2007;Puttock et al, 2013). Connectivity has the advantage, as regards vegetation structure, to provide an explanatory link between abiotic and biotic components to determine the hydrological and ecological function of the system (Turnbull et al, 2008(Turnbull et al, , 2010.…”

Vegetation dynamics during different abandoned year spans in the land of the Loess Plateau of China

“…In terms of vegetation patterns, much research focuses on a two-phase mosaic structure of high-and low-vegetation cover patches, which commonly presents itself in semi-arid ecosystems (Pellerin et al 2009;Puigdefabregas 2005;Bromley et al 1997;Cerda 1997;Wilcox et al 2003). Mechanisms of patch formation and dynamics have also been conducted (Mayor et al 2008;Liu et al 2013;Aguiar and Sala 1999;Bautista et al 2007). However, most of these reports and studies focusing on the two-phase vegetation pattern were carried out on degraded land.…”