Ecogeomorphic coevolution of semiarid hillslopes: Emergence of banded and striped vegetation patterns through interaction of biotic and abiotic processes

Saco, Patricia M.; Heras, Mariano Moreno de las

doi:10.1029/2012wr012001

Cited by 70 publications

(66 citation statements)

References 54 publications

(98 reference statements)

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“…This relationship can also be explained in terms of overland flows. Steeper slopes tend to create drainage rills leading the water downhill which break up the local patch-interpatch redistribution of resources (Saco and Moreno-de las Heras, 2013).…”

Section: Woody Plant Aggregation and The Occurrence Of Periodic Vegetmentioning

confidence: 99%

Patterns in woody vegetation structure across African savannas

Axelsson

Hanan

2017

Biogeosciences

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Abstract. Vegetation structure in water-limited systems is to a large degree controlled by ecohydrological processes, including mean annual precipitation (MAP) modulated by the characteristics of precipitation and geomorphology that collectively determine how rainfall is distributed vertically into soils or horizontally in the landscape. We anticipate that woody canopy cover, crown density, crown size, and the level of spatial aggregation among woody plants in the landscape will vary across environmental gradients. A high level of woody plant aggregation is most distinct in periodic vegetation patterns (PVPs), which emerge as a result of ecohydrological processes such as runoff generation and increased infiltration close to plants. Similar, albeit weaker, forces may influence the spatial distribution of woody plants elsewhere in savannas. Exploring these trends can extend our knowledge of how semi-arid vegetation structure is constrained by rainfall regime, soil type, topography, and disturbance processes such as fire. Using high-spatial-resolution imagery, a flexible classification framework, and a crown delineation method, we extracted woody vegetation properties from 876 sites spread over African savannas. At each site, we estimated woody cover, mean crown size, crown density, and the degree of aggregation among woody plants. This enabled us to elucidate the effects of rainfall regimes (MAP and seasonality), soil texture, slope, and fire frequency on woody vegetation properties. We found that previously documented increases in woody cover with rainfall is more consistently a result of increasing crown size than increasing density of woody plants. Along a gradient of mean annual precipitation from the driest (< 200 mm yr−1) to the wettest (1200–1400 mm yr−1) end, mean estimates of crown size, crown density, and woody cover increased by 233, 73, and 491 % respectively. We also found a unimodal relationship between mean crown size and sand content suggesting that maximal savanna tree sizes do not occur in either coarse sands or heavy clays. When examining the occurrence of PVPs, we found that the same factors that contribute to the formation of PVPs also correlate with higher levels of woody plant aggregation elsewhere in savannas and that rainfall seasonality plays a key role for the underlying processes.

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Section: Woody Plant Aggregation and The Occurrence Of Periodic Vegetmentioning

confidence: 99%

Patterns in woody vegetation structure across African savannas

Axelsson

Hanan

2017

Biogeosciences

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“…Ecohydrology is very much an applied science with a focus on problem solving (Nuttle 2002;Jackson et al 2009b;Wilcox et al 2011), but at the same time it has a firm theoretical foundation (D'Odorico et al , 2013aTurnbull et al 2012;Saco and Moreno de las Heras 2013). Because of its strong intellectual roots in research conducted on drylands-including semiarid and subhumid rangelands (Rodriguez-Iturbe and Porporato 2004;D'Odorico and Porporato 2006;Newman et al 2006)-and its "transdisciplinary" nature, ecohydrology has advanced our knowledge of rangelands (Wilcox and Newman 2005;Wilcox et al 2012a).…”

Section: Introductionmentioning

confidence: 99%

Ecohydrology: Processes and Implications for Rangelands

Wilcox

Maitre²,

Jobbágy

et al. 2017

Rangeland Systems

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This chapter is organized around the concept of ecohydrological processes that are explicitly tied to ecosystem services. Ecosystem services are benefits that people receive from ecosystems. We focus on (1) the regulating services of water distribution, water purification, and climate regulation; (2) the supporting services of water and nutrient cycling and soil protection and restoration; and (3) the provisioning services of water supply and biomass production. Regulating services are determined at the first critical juncture of the water cycle-on the soil surface, where water either infiltrates or becomes overland flow. Soil infiltrability is influenced by vegetation, grazing intensity, brush management, fire patterns, condition of biological soil crusts, and activity by fauna. At larger scales, water-regulating services are influenced by other factors, such as the nature and structure of riparian zones and the presence of shallow groundwater aquifers. Provisioning services are those goods or products that are directly produced from ecosystems, such as water, food, and fiber. Work over the last several decades has largely overturned the notion

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“…Vegetation and subsequently the below ground organic matter created stabile soil aggregates that promote water holding capacity and increase biomass. However, soil carbon is seldom included in landscape evolution simulation models, except for a few studies (such as Yoo et al, 2006;Saco and Moreno-de las Heras, 2013;Vanwalleghem et al, 2013). Saco and Moreno-de las Heras (2013) made the initial attempt, and studied the interaction between soils, vegetation and landform in semi-arid to arid environments using a coupled vegetation-pattern formation and landform evolution model.…”

Section: Soil Carbon and Soil Genesismentioning

confidence: 99%