INVESTIGADORES
GOLLUSCIO Rodolfo Angel
artículos
Título:
Long-term dynamics of a semiarid grass steppe under stochastic climate and different grazing regimes: A simulation analysis
Autor/es:
PARUELO JM; S PÜTZ; G WEBER,; M BERTILLER; RA GOLLUSCIO; MR AGUIAR; T WIEGAND
Revista:
JOURNAL OF ARID ENVIRONMENTS
Editorial:
Elsevier
Referencias:
Año: 2008 vol. 72 p. 2211 - 2231
ISSN:
0140-1963
Resumen:
We built a grid-based spatial explicit stochastic model that simulates grazing events and
basic processes like seedling establishment, growth or mortality of the dominant
species in the grass steppes of Patagonia. After evaluating the model with field data, we
performed simulation experiments aimed to explore the interaction of precipitation and
grazing regimes on vegetation dynamics. Grazing generated a reduction in tussock
density which results in a decline in aboveground net primary production (ANPP). Both
response variables presented a non-linear behavior including high temporal variability
and delay effects, which may prolong for decades. There was a clear threshold in the
response of the variables to stock density, though changes become evident only when a
highly selective grazing scenario was used. Under high stock density conditions,
precipitation use efficiency (PUE) was 82% lower than the values for non-grazed runs.
The inter-annual variability of precipitation was more important than the grazing
regime in explaining differences in tussock density. Simulation results highlight
important issues regarding rangeland management: grazing regime might be as
important as stocking density as a degradation agent, temporal lags might obscure
degradation processes for decades, the definition of monitoring variables need to
consider their response time constants.