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| Titel |
Modelling natural grass production and its spatio-temporal variations in a semiarid Mediterranean watershed |
| VerfasserIn |
Susanne Schnabel, Javier Lozano-Parra, Marco Maneta-López |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250093360
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| Publikation (Nr.) |
 EGU/EGU2014-8001.pdf |
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| Zusammenfassung |
| Natural grasses are found in semiarid rangelands with disperse tree cover of part of the
Iberian Peninsula and constitute a resource with high ecologic and economic value
worth, being an important source of food for livestock, playing a significant role in
the hydrologic cycle, controlling the soil thermal regime, and are a key factor in
reducing soil erosion and degradation. However, increasing pressure on the resources,
changes in land use as well as possible climate variations threaten the sustainability
of natural grasses. Despite of their importance, the spatio-temporal variations of
pasture production over whole watersheds are poorly known. In this sense, previous
studies by other authors have indicated its dependence on a balance of positive and
negative effects brought about by the main limiting factors: water, light, nutrients and
space. Nevertheless, the specific weight of each factor is not clear because they are
highly variable due to climate characteristics and the structure of these agroforestry
systems.
We have used a physical spatially-distributed ecohydrologic model to investigate the specific
weight of factors that contribute to pasture production in a semiarid watershed of 99.5 ha in
western Spain. This model couples a two layer (canopy and understory) vertical local closure
energy balance scheme, a hydrologic model and a carbon uptake and vegetation growth
component, and it was run using a synthetic daily climate dataset generated by a stochastic
weather generator, which reproduced the range of climatic variations observed under
mediterranean current climate.
The modelling results reproduced satisfactorily the seasonality effects of climate as
precipitation and temperatures, as well as annual and inter-annual variations of pasture
production. Spatial variations of pasture production were largely controlled by topographic
and tree effects, showing medium-low values depending of considered areas. These low
values require introduction of feed to livestock. Valley bottoms, areas with low slopes,
and spaces with low tree density are characterized by higher pasture production.
Temporal variations of pasture production largely depended on the availability of soil
moisture, which in turn depended on the temporal distribution of rainfall. This
ecohydrologic model constitutes a valuable tool to investigate water and energy
fluxes, as well as vegetation dynamics in semiarid rangelands, as was proved by a
quantitative assessment of the quality of the simulations. The range of applications
and possibilities contained in the model opens a wide field for future research. |
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