PARENT SESSION
Poster Session 20: Invasive Species
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Plasticity and allometry of biomass allocation in an invasive perennial weed, Alternanthera philoxeroides: The effect of water, light and nutrient availability.
Geng, Yupeng1, Pan, Xiaoyun1, Xu, Chengyuan *,2, Zhang, Wenju1, Li, Bo, Chen, Jiakuan, 1 Institute of Biodiversity Science, Shanghai, P.R.China2 Lamont Doherty Earth Observatory, Palisades, NY, USA
ABSTRACT- Plasticity of plant biomass allocation in response to variable resource availability may result from ontogenetic drift (allometric growth) or true adjustment of growth trajectories or both. The developmentally explicit model predicts that, for annual herbs with decreasing root:shoot ratio in growth, apparent plasticity results from ontogenetic drift may be sufficient to overcome most but very severe below-ground resource limitation, while, true plasticity would be necessary to balance the resources capture in the case of above-ground resource stress. According to the mechanism underlying the model, for those species with increasing root:shoot ratio during the growth (i.e. some woody species or perennial herbs), the pattern would be reverse. We tested this hypothesis with an invasive perennial weed, Alternanthera philoxeroides, by comparing the biomass allocation both at the same age and at the same size along three resources gradients separately (i.e. light, water and nutrient availability). Plants displayed significant plasticity in biomass allocation across each of the three resource gradients: aboveground or underground stress respectively increased, or decreased the root:shoot ratio. Our results supported the developmentally explicit model: apparent plasticity occurred under variable light (above-ground resource) availability condition, while true adjustment of allometric trajectory was found for water and nutrient (below-ground resource) stress. Given that the root play important role during the population regeneration after winter or accident disturbance, the invasiveness of A. philoxeroides may benefit from the flexible adjustment of root mass allocation with relation to variable resources availability.
Key words: plasticity, allometry, developmentally explicit model, Alternanthera philoxeroides