INVESTIGADORES
CARMANCHAHI Pablo Daniel
artículos
Título:
Spatial and Seasonal Dynamic of Abundance and Distribution of Guanaco and Livestock: Insights from using Density Surface and Null Models.
Autor/es:
SCHROEDER NATALIA; MATTEUCCI, S.; MORENO, PABLO; GREGORIO PABLO; OVEJERO RAMIRO; TARABORELLI PAULA; CARMANCHAHI, PABLO
Revista:
PLOS ONE
Editorial:
PUBLIC LIBRARY SCIENCE
Referencias:
Lugar: Sherbrooke; Año: 2014 vol. 9 p. 1 - 12
ISSN:
1932-6203
Resumen:
Monitoring species abundance and distribution is a prerequisite when assessing species status and population viability, a
difficult task to achieve for large herbivores at ecologically meaningful scales. Co-occurrence patterns can be used to infer
mechanisms of community organization (such as biotic interactions), although it has been traditionally applied to binary
presence/absence data. Here, we combine density surface and null models of abundance data as a novel approach to
analyze the spatial and seasonal dynamics of abundance and distribution of guanacos (Lama guanicoe) and domestic
herbivores in northern Patagonia, in order to visually and analytically compare the dispersion and co-occurrence pattern of
ungulates. We found a marked seasonal pattern in abundance and spatial distribution of L. guanicoe. The guanaco
population reached its maximum annual size and spatial dispersion in spring-summer, decreasing up to 6.5 times in size and
occupying few sites of the study area in fall-winter. These results are evidence of the seasonal migration process of guanaco
populations, an increasingly rare event for terrestrial mammals worldwide. The maximum number of guanacos estimated
for spring (25951) is higher than the total population size (10000) 20 years ago, probably due to both counting
methodology and population growth. Livestock were mostly distributed near human settlements, as expected by the
sedentary management practiced by local people. Herbivore distribution was non-random; i.e., guanaco and livestock
abundances co-varied negatively in all seasons, more than expected by chance. Segregation degree of guanaco and smalllivestock
(goats and sheep) was comparatively stronger than that of guanaco and large-livestock, suggesting a competition
mechanism between ecologically similar herbivores, although various environmental factors could also contribute to
habitat segregation. The new and compelling combination of methods used here is highly useful for researchers who
conduct counts of animals to simultaneously estimate population sizes, distributions, assess temporal trends and
characterize multi-species spatial interactions.