Soil-Geomorphic Heterogeneity Governs Patchy Vegetation Dynamics at an Arid Ecotone

Abstract

Soil properties are well known to affect vegetation, but the role of soil heterogeneity in the patterning of vegetation dynamics is poorly documented. We asked whether the location of an ecotone separating grass-dominated and sparsely vegetated areas reflected only historical variation in degradation or was related to variation in inherent soil properties. We then asked whether changes in the cover and spatial organization of vegetated and bare patches assessed using repeat aerial photography reflected self-organizing dynamics unrelated to soil variation or the stable patterning of soil variation. We found that the present-day ecotone was related to a shift from more weakly to more strongly developed soils. Parts of the ecotone were stable over a 60-year period, but shifts between bare and vegetated states, as well as persistently vegetated and bare states, occurred largely in small (<40 m2) patches throughout the study area. The probability that patches were presently vegetated or bare, as well as the probability that vegetation persisted and/or established over the 60-year period, was negatively related to surface calcium carbonate and positively related to subsurface clay content. Thus, only a fraction of the landscape was susceptible to vegetation change, and the sparsely vegetated area probably featured a higher frequency of susceptible soil patches. Patch dynamics and self-organizing processes can be constrained by subtle (and often unrecognized) soil heterogeneity.

Machine learning for predicting soil classes in three semi-arid landscapes

“…We attribute this to 566 the correlation of run-on/run-off relationships, landscape stability, and soil formation observed in this 567 region (Gile et al, 1981). Vegetation related covariates (tasseled cap greenness transformation and the 568 GRABS index) selected in covariate set 3, were likely related to the strong control of soils in determining 569 vegetation cover and composition in the study area (Bestelmeyer et al, 2006, Duniway et al, 2010. 570…”

The decreased competition in expanding versus mature juniper woodlands is counteracted by adverse climatic effects on growth

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Grazing changes topography-controlled topsoil properties and their interaction on different spatial scales in a semi-arid grassland of Inner Mongolia, P.R. China

“…For BD and Figure 4c is on the basis of Burke et al (1999), modified SOC, this was accompanied by small range values, indicating a more heterogeneous, patchy distribution of these parameters in the long-term ungrazed plot. We attribute the heterogeneity of BD and SOC to the scattering effects of recovering soil structure and advancing succession of vegetation without grazing stress, which can be ascribed to self-organising processes occurring in arid ecotons (Bestelmeyer et al 2006). The established mosaic of vegetation cover (Steffens et al 2009a) leads to spatially variable litter inputs.…”