INVESTIGADORES
GURVICH Diego Ezequiel
artículos
Título:
Predicting cover types in a mountain range with long evolutionary grazing history: a GIS approach
Autor/es:
CINGOLANI, A.M.; RENISON, D.; TECCO, P.A.; GURVICH, D.E.; CABIDO, M.
Revista:
JOURNAL OF BIOGEOGRAPHY
Editorial:
Blackwell
Referencias:
Año: 2008 vol. 35 p. 538 - 551
ISSN:
0305-0270
Resumen:
ABSTRACT
Aim To determine how the distribution and cover of different vegetation types
are affected by physical factors and livestock in a mountain range with a long
evolutionary history of grazing.To determine how the distribution and cover of different vegetation types
are affected by physical factors and livestock in a mountain range with a long
evolutionary history of grazing.
Location Upper vegetation belt of the Co´ rdoba mountains (17002800 m a.s.l.,
31º34¢ S, 64º50¢ W) in central Argentina.Upper vegetation belt of the Co´ rdoba mountains (17002800 m a.s.l.,
31º34¢ S, 64º50¢ W) in central Argentina.¢ S, 64º50¢ W) in central Argentina.
Methods Using GIS, we analysed the relationships of plant cover types to
physical features (physiography and topography) and indicators of accumulated
livestock pressure (distance to human settlements and roads) through
multinomial logistic regression. We predicted a present vegetation map which
was validated with a real map. We then constructed two maps simulating
minimum and maximum values of accumulated livestock pressure for the whole
area. Map comparisons allowed evaluation of the possible influence of livestock,
both in extension and intensity.Using GIS, we analysed the relationships of plant cover types to
physical features (physiography and topography) and indicators of accumulated
livestock pressure (distance to human settlements and roads) through
multinomial logistic regression. We predicted a present vegetation map which
was validated with a real map. We then constructed two maps simulating
minimum and maximum values of accumulated livestock pressure for the whole
area. Map comparisons allowed evaluation of the possible influence of livestock,
both in extension and intensity.
Results Both physical features and livestock pressure influenced the occurrence
of vegetation units. The overall accuracy of the predicted map at the pixel level
was low (26%) indicating low habitat specificity of the vegetation units. We
suggest that some part of the unaccounted for variance was due to livestock
pressure patterns that were not fully captured by our indicators. Our models
proved adequate for predicting the total percentages of vegetation units at coarser
scales. The extrapolations showed that under a history of low livestock pressure,
such as in sites far away from human settlements and roads, the area would be
dominated by woodlands, tussock grasslands and natural rock outcrops. Under a
history of heavy livestock pressure, in turn, rock exposed by erosion, tussock
grasslands and natural rock outcrops would dominate.Both physical features and livestock pressure influenced the occurrence
of vegetation units. The overall accuracy of the predicted map at the pixel level
was low (26%) indicating low habitat specificity of the vegetation units. We
suggest that some part of the unaccounted for variance was due to livestock
pressure patterns that were not fully captured by our indicators. Our models
proved adequate for predicting the total percentages of vegetation units at coarser
scales. The extrapolations showed that under a history of low livestock pressure,
such as in sites far away from human settlements and roads, the area would be
dominated by woodlands, tussock grasslands and natural rock outcrops. Under a
history of heavy livestock pressure, in turn, rock exposed by erosion, tussock
grasslands and natural rock outcrops would dominate.
Main conclusions Vegetation units showed low habitat specificity, and were
associated with accumulated livestock pressure, indicating that livestock and its
associated activities are important factors structuring the landscape and have
important consequences for the integrity of the ecosystem. Results suggest that
although this system evolved with large herbivores, it has experienced irreversible
degradation processes, and intensification of current domestic livestock pressure
is likely to lead to even more land degradation.Vegetation units showed low habitat specificity, and were
associated with accumulated livestock pressure, indicating that livestock and its
associated activities are important factors structuring the landscape and have
important consequences for the integrity of the ecosystem. Results suggest that
although this system evolved with large herbivores, it has experienced irreversible
degradation processes, and intensification of current domestic livestock pressure
is likely to lead to even more land degradation.