DYNAMICS OF HERBIVORY IN BELIZEAN MANGAL

We report long-term observations on leaf herbivory in the mangroves Rh izophora mangle and Avicennia germinans, on the Placencia Peninsula of Belize. We labelled and traced leaves and recorded the amount of dama ge appearing over a period of 3 1 0 days. Herbivores had damaged 1-4% of total mean leaf area within the first 10 days, but damage rates lev elled off thereafter, to a final total of 4-10% damage. Herbivores did not concentrate on leaves of younger age classes. Rhizophora mangle g rowing in the high tidal zone (HHW) exhibited the highest initial and total attack rates at all but the final sampling dates. We also docume nted the dynamics of injury expansion and necrosis following artificia l injury to seedling and tree leaves. Artificial holes in leaves were associated with higher subsequent rates of herbivory that varied among leaf age classes, and particular damage types were more prevalent in previously injured leaves. Artificial holes expanded significantly mor e in young leaves of both species. Holes in young leaves of both speci es expanded by up to 45.1% in area over 50 days, consistent with a sim ilar study in Australia. Substantial necrotic areas developed around t he injury site; a secondary effect of damage not often considered in h erbivory studies. We discuss the implications of hole expansion and ne crosis in estimating error in herbivory measurements. Temporally dynam ic studies of herbivory are especially needed in tropical systems that show non-deciduous phenologies and long-lived leaves.