PARENT SESSION
Poster Session #3: Herbivory.
Monday, August 6, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall

Effects of artificial root herbivory on seedling growth.

Barone, John¹, Hill, JoVonn¹, Friend, Alexander¹, ¹

ABSTRACT- Although herbivore damage can decrease plant growth and fitness, several studies have also demonstrated that some species can compensate for damage, growing as well or even better than undamaged control plants. Few studies, however, have examined how harmful root damage is to plant growth, and whether plants can compensate for root herbivory. To examine these questions, we conducted a series of greenhouse experiments manipulating levels of root damage and other factors for six plant species in different functional groups. We simulated root herbivory by trimming particular amounts of root biomass at the beginning of each experiment. In general, root removal reduced plant growth. For example, for Ipomea purpurea, fertilized plants that lost 50% of root biomass had a total dry weight that was only 59% of control plants and those that had suffered 20% root loss weighed only 91.9% of controls (P<0.001). Changes in plant growth from root damage appear to be species-specific. In Platanus occidentalis, seedlings that lost 20% and 50% of root biomass did not differ in leaf number from controls (P=0.75), but had about half of the total leaf area (P=0.004), whereas in Acer rubrum, these levels of damage led to both reduced leaf number (23% fewer in the 50% root damage treatment) and leaf area (37% in the 50% treatment). Root herbivory clearly reduced seedling growth, and in general we found little evidence of compensation.

KEY WORDS: roots, herbivory, compensation, root damage