Ecohydrology of ecosystem transitions : a meta-analysis
Date
2014
Journal Title
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Volume Title
Publisher
John Wiley & Sons
Abstract
A vast body of literature demonstrated that anthropogenic disturbances such as overgrazing and fire are key drivers of abrupt
transition between vegetation types in ecosystems. In this study, we propose that the hydrological context (described in terms of
rainfall, evapotranspiration and water yield) is a first-order, primordial determinant of the propensity of ecosystems to undergo
transition. This implies that the anthropogenic disturbance is a second-order determinant that is strongly conditioned by the first
one. Through the meta-analysis of existing studies, a collection of 685 geo-referenced study cases was organized to study the
hydrological characteristics of three climatic regions and three ecosystems that vary in their relation between woody and grassy
plants. Thus, humid, sub-humid and dry climatic regions, respectively, receiving >1000, 500–1000 and <500mmyear 1, were
studied, and possible transition mechanisms among grasslands/savannas, shrublands and forests were analysed. The results
showed that the ecohydrological context determines the probabilities of ecosystems transitions in different climatic regions and
the prevalence of alternative transition mechanisms. We showed that transition of forests into other ecosystems is highly
improbable in high-precipitation regions, more probable and likely subject to a bi-stable and reversible regime in sub-humid
regions, and highly probable and irreversible in dry regions. Factors such as runoff, deep-water drainage, fire, flammable/
nonflammable biomass and overgrazing were considered as hypothetical transition mechanisms. As a novel finding, we
demonstrate that ecohydrology, as a determinant of transition, is a factor that operates at a hierarchical level higher than that of
the human-driven disturbance. A synthetic graphical model was proposed to characterize resilience (the capacity of ecosystems
to withstand transition) in the three study climatic regions.
Description
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Journal Article (peer-reviewed)
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Keywords
HYDROLOGY, EVAPOTRANSPIRATION, GRASSLANDS, SAVANNAS, BIOMASS, WATER BALANCE, RESILIENCE, ANTHROPOGENIC FACTORS, ENVIRONMENTAL DEGRADATION, BIOCLIMATOLOGY, MATHEMATICAL MODELS, DEFORESTATION, ECOSYSTEMS, CLIMATE CHANGE
Citation
Viglizzo, E.F., Nosetto, M.D., Jobbágy, E.G., Ricard, M.F., & Frank, F.C. (2014). The ecohydrology of ecosystem transitions: a meta-analysis. Ecohydrology, 1-11. doi:10.1002/eco.1540