Evidence of a threshold in soil erodibility generating differences in vegetation development and resilience between two semiarid grasslands |
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| Affiliation: | 1. Área de Botánica, Departamento de Ciencias Agroforestales, EiFAB, Campus Duques de Soria, Universidad de Valladolid, 42004 Soria, Spain;2. Facultad de Ciencias Forestales y Recursos Naturales, Laboratorio de Dendrocronología y Cambio Global, Universidad Austral de Chile, Valdivia, Chile;3. Center for Climate and Resilience Research (CR2), Santiago, Chile;4. Instituto de Ciencias de la Tierra, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile;1. Instituto Mediterráneo de Estudios Avanzados, IMEDEA (CSIC-UIB), C/Miquel Marqués 21, 07190, Esporles, Illes Balears, Spain;2. Universidad de Málaga, Departamento de Biología Animal, Campus de Teatinos s/n, 29071 Málaga, Spain;3. Centro Oceanográfico de Málaga, Instituto Español de Oceanografía, Puerto Pesquero s/n, 29640 Fuengirola, Málaga, Spain;1. University of Guilan, Rasht, Iran;2. Department of Soil Science, Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran;3. Department of Irrigation Eng., Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran;4. Faculty of Environmental Sciences, Environmental Future Centre, Griffith University, Nathan, Queensland 4111, Australia;1. Doctoral Candidate, Department 3354, University of Wyoming, Laramie, WY 82071, USA;;2. Associate Professor, Department 3354, University of Wyoming, Laramie, WY 82071, USA;;3. Professor, Biological Sciences East, The University of Arizona, Tucson, AZ 85721, USA |
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| Abstract: | The typical patchy structure of dryland vegetation is a result of soil–plant feedbacks occurring in water-limited areas. The resilience of dryland ecosystems depends largely on the persistence of fertility islands associated with vegetated patches, which determines the efficiency of the vegetation regarding recolonising the gaps that result from disturbances. In this study, we investigated the mechanisms underlying soil–plant interactions throughout the process of the growth and senescence of alpha grass (Macrochloa tenacissima) and the subsequent disintegration of islands of fertility and microtopography formed during the process at two nearby alpha grass communities exhibiting different degrees of development. The life cycle of alpha grass and the rise and disintegration of the underlying microrelief were accompanied by feedback changes in the content of soil C fractions presenting different times of cycling and incorporation to the soil, the collection of particles from splash erosion, redistribution phenomena related to particles of different sizes, and erosion of the most easily erodible materials. Despite their ecological and geographical proximity, the study sites differ with respect to the persistence, after plant death, of fertility islands, which almost disappear in one case, while they remain in the other, constituting a resource for the growth of new plants and resulting in greater development and resilience in the community. A subtle erodibility threshold emerges as a cause of the considerable differences in vegetation between the two sites. |
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