Impact of silvicultural practices on insect communities and herbivory on young jack pine in northern Ontario

grantor: University of TorontoThe effects of four different silvicultural treatments (no-site-preparation, trenching, blading, compacting), two harvest techniques (full tree harvest and tree length harvest) and a herbicide application on the abundance, diversity, and activity of arthropods in young jack pine stands were examined between August 1995 and 1997 in northern Ontario. Each treatment, replicated three times at each of seven sites, ranged from a minor reduction in vegetation (trenching) to complete removal of the vegetation and topsoil (blading and compacting) Arthropods were collected using sweepnets and pitfall taps while herbivory was assessed by recording evidence of feeding activity on the young trees over three years. Lower arthropod abundance and diversity were observed in highly disturbed (bladed) plots by both sweepnets and pittfall traps. Arthropod abundance, family richness and herbivore, predator and parasitoid trophic groups were positively correlated with vegetation cover, while woody debris was positively correlated with the abundance of arthropods and the herbivore assemblage. Herbivory was not changed by the various silvicultural, harvest or herbicide treatments This study suggests that arthropod diversity is best be achieved by either not the site or by trenching, and that this will not change the incidence of heibivory on the young jack pine.M.Sc