PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Angiosperm trees outgrow conifer on fertile and infertile soils in New Zealand.
Kunstler, Georges*,1, Coomes, David2, CANHAM, CHARLES 3, 1 Cemagref – U.R. DFCF, Ecologie Appliquée des Milieux Boisés, 24, av. des Landais, Aubière, 63172, France2 Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB3 2EA, UK3 Institute of Ecosystem Studies, Box AB, Millbrook, New York, USA
ABSTRACT- A trade-off between efficient nutrient use and rapid growth rate is generally thought to underpin compositional shifts in forests growing along fertility gradients. In particular, the "hare and tortoise" theory of Bond proposes that this trade-off could explain why angiosperm trees often dominate productive habitats, while conifers are generally restricted to less productive habitats. Few studies have tested whether angiosperm and conifer juveniles exhibit the growth responses predicted by Bond, or tested whether growth responses are correlated with species dominance patterns. Here we examine trends in sapling growth on a soil chronosequence in New Zealand. The youngest alluvial soils in the sequence are shrouded in angiosperm-dominated forest with a dense fern understory, while the oldest surfaces (created 291,000 years previously) are depleted in phosphorus and dominated by conifers (podocarpaceae). Our analyses show that most species responded to variation in light in the forest understorey, but that growth tended to be correlated with foliar P and N contents. Conifer saplings were slower growing than associated angiosperms and tree-ferns on relatively nutrient-rich soils, but grew at similar rates on infertile soils. We discuss our results in the context of forests.
Key words: regeneration, growth, PAR, nutrients