INVESTIGADORES
PARITSIS Juan
congresos y reuniones científicas
Título:
Insect defoliator outbreaks and environmental heterogeneity in Nothofagus forests in southern South America
Autor/es:
J PARITSIS; TT VEBLEN
Lugar:
Saguenay
Reunión:
Conferencia; 7th International Conference on Disturbance Dynamics in Boreal Forests; 2011
Resumen:
In the temperate forests of the southern Andes, Nothofagus species experience severe defoliation caused by Ormiscodes caterpillars. We examined the spatial and temporal patterns of Ormiscodes outbreaks in relation to regional scale climatic variability in northern and southern Patagonia. Our research approach combined tree-ring reconstructions of outbreaks in N. pumilio forests with spatial analyses of outbreak patterns using remote sensing and GIS, as well as laboratory experiments on larvae growth and foliage consumption. Tree-ring reconstructions show an increase in defoliation events in southern Patagonia in the late 20th compared to the previous c. 130 years. Ormiscodes outbreaks are generally associated with drier and warmer than average growing seasons. Monotypic forests of N. pumilio are more susceptible to O. amphimone outbreaks than lower elevation forests of other Nothofagus species. Additionally, stands growing in areas with intermediate to high precipitation, relative to the distribution of Nothofagus are more susceptible to O. amphimone attack than drier areas. Laboratory experiments with O. amphimone larvae indicate that higher temperature (20°C vs. 15°C) and N. pumilio foliage from mesic stands (compared to foliage from xeric stands) increased O. amphimone performance and foliage consumption rate. Our results suggest that climate warming may have promoted O. amphimone outbreaks in certain regions in Patagonia and provide a preliminary understanding of the complexity of herbivorous insect impacts on forest productivity in Patagonian Nothofagus forests.