Relationships Between Plant Spatial Patterns, Water Infiltration Capacity, and Plant Community Composition in Semi-arid
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Relationships Between Plant Spatial Patterns, Water Infiltration Capacity, and Plant Community Composition in Semi-arid Mediterranean Ecosystems Along Stress Gradients Y. Pueyo,1* D. Moret-Ferna´ndez,2 H. Saiz,1 C. G. Bueno,3 and C. L. Alados1 1
Instituto Pirenaico de Ecologı´a (CSIC), Av. Montan˜ana 1005, P.O. Box 13.034, 50059 Zaragoza, Spain; 2Departamento de Suelo Y Agua, Estacio´n Experimental de Aula Dei (CSIC), P.O. Box 202, 50059 Zaragoza, Spain; 3Instituto Pirenaico de Ecologı´a (CSIC), Avda. Nuestra Sen˜ora de la Victoria s/n, 22700 Jaca, Spain
ABSTRACT Water redistribution from bare soil to vegetation patches is a key feature of semi-arid ecosystems, and is responsible for their patchy vegetation patterns. The magnitude of water redistribution depends on the properties of the bare soil (which determine the amount of water run-off) and the capacity of vegetation patches to trap water run-on. We examined the relationships between plant spatial patterns, water infiltration into bare soil, and plant community composition in semi-arid sites with different hydro-physical properties (silty and gypseous soils) in NE Spain. We also studied the effect of two stressors, aridity and grazing, on water infiltration and plant spatial patterns. Our results indicate a negative correlation of bare soil sorptivity (the capacity to absorb water by capillarity) and vegetation aggregation. There was a strong positive correlation between perennial grass cover and the spatial aggregation of vegetation, but aggregation
was not associated with positive associations of different plant types. The aggregation of vegetation was positively correlated with species richness and the overall extent of vegetation cover. Grazing reduced water infiltration into silty soils, which are prone to compaction. In contrast, soil crust affected the hydrology of gypseous soils, especially in the most arid sites, where grazing increased infiltration, reducing surface sealing due to breaking of the soil crust. Together, our results suggest that biotic and abiotic factors affect the hydro-physical properties of soils in the semi-arid ecosystems of NE Spain, which is linked to the plant communities through the spatial distribution of plants.
Received 21 October 2011; accepted 22 October 2012; published online 14 December 2012
INTRODUCTION
Author Contributions: YP and CLA conceived the study; all authors performed research; YP, DM, HS and CGB prepared and analyzed data; and YP wrote the paper with assistance from all authors.
Water redistribution is fundamental to the function of ecosystems in arid and semi-arid regions (Shachak and others 1998), often called ‘‘source-sink’’
Key words: aridity; ecohydrology; infiltration; livestock grazing; soil compaction; soil crust; Vegetation spatial aggregation; water run-off; water run-on.
*Corresponding author; e-mail: [email protected]
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Water Infiltration and Plant Spatial Patterns in Drylands (Cerda 1997; Imeson and Prinsen 2004) or ‘‘trigger-transfer-reserve-pulse’’ systems (Ludwig and others 2005)
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