PARENT SESSION
Contributed Oral Session 3: Herbivory: Plant - Herbivore Interaction
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 513 E, Level 5, Palais des congrès de Montréal

Interactions of birds, arthropods, and sugar maple regeneration, a preliminary study.

Chediack, Ariadna^*,1, Scriber, Mark¹, ¹ Michigan State University, East Lansing, MI, USA

ABSTRACT- Factors that affect arthropod herbivory on sugar maple seedlings are not well known. We studied the interactions among sugar maple seedlings, arthropod herbivory, and birds as possible arthropod predators. Our objectives were to: 1) list the arthropod taxa feeding on sugar maple seedlings, 2) estimate foliage herbivory, and 3) measure the impact of birds on those arthropods. During 2001, we established six study sites in sugar maple stands in the Upper Peninsula of Michigan with nested treatments. At each site we installed three 3x3m plots: bird exclosure, insect exclosure, and control. Within each plot we tracked 10 marked seedlings: bird exclosure and insect exclosure plots had 5 seedlings with whole-plant insect exclosures and 5 without insect exclosures. The control plot had no exclosures. In each plot we did 12 min observations registering each arthropod taxa and its abundance. In each leaf of the 10 seedlings we identified and measured different types of herbivory. We saw 13 herbivory types. The most common type was free (0-95%), followed by stippling, Cecidomidae gall and skeletonizer (0-0.3%). Free herbivory was higher in the control plots, but was similar in and out insect exclosures. Other herbivory types were similar in all plots. We observed 62 arthropod taxa or morpha. The most diverse were Coleoptera, Lepidoptera, and Homoptera. Arthropod abundance was higher in bird exclosures, and lower in insect exclosures. Bird exclosures had more stippling, predator, gall former, and leaf roller and folder arthropods; control plots had more chewers, and insect exclosures had more pollinators. Our data suggest that birds decrease arthropod herbivory on sugar maple seedlings. However, more studies are needed.

Key words: arthropod herbivory, sugar maple seedlings, bird - arthropod interactions, michigan