INVESTIGADORES
GARIBALDI Lucas Alejandro
congresos y reuniones científicas
Título:
Ontogenetic changes in tree insect herbivory and foliar traits in dry and wet southern beech Patagonian forests
Autor/es:
MAZÍA, C. N.; GARIBALDI, L. A.; CHANETON, E. J.; KITZBERGER, T.
Lugar:
San Carlos de Bariloche
Reunión:
Congreso; VI Southern Connection Congress; 2010
Resumen:
As plants pass through
successive life stages, marked changes occur in apparency, structural
complexity, growth rate and nutritional quality, which can all influence plant
susceptibility to herbivory. Several models were proposed to account for
predictable herbivory patterns with plant ontogeny. Based on different
assumptions, existing models make contrasting predictions encompassing linear
and non-linear herbivore responses to composite changes in host apparency,
nutrient content and defence levels among age-size classes. Yet, there have
been few tests of the effect of ontogeny on herbivory, especially in forest
ecosystems. We examined leaf damage by different insect guilds for three
age-size classes of Nothofagus pumilio trees, in dry (800 mm/yr) and wet
(3000 mm/yr) forests of northern Patagonia, Argentina. In each forest, we
sampled the canopy of saplings (< 1m tall), juveniles (3-4 m) and adult
trees (>10 m), and measured physical and chemical leaf traits for each plant
(n = 14). Early in the growing season, leaf area damaged was higher in saplings
and juveniles than in adult trees in both forests, and remained so later in the
season in the wet forest. In contrast, in the dry forest, insect damage
markedly increased towards the end of the season on adult trees, which blurred
earlier differences among age classes. There were significant, habitat-specific
differences in foliar traits among tree classes, but these could not account
for herbivory patterns neither in the wet nor in the dry forest. Overall, we
found partial support for the hypothesis that insect herbivory declines as
trees grow from a deep understorey layer into the upper forest canopy. However,
ontogenetic changes in tree folivory appeared to depend on the forest habitat.