Ryser, Peter , Hoogzaad, Yvonne P. G. , Kamminga, A. Timo , Nieman, Tim .
Root survival and mortality of cool-temperate wetland graminoids in autumn and winter.
Timing of leaf senescence is an important aspect of the ecology of species and ecosystems in cool-temperate climates. In contrast to above-ground turnover, not much is known about timing and extent of root mortality in herbaceous perennials at the end of the growing season. In three projects we assessed for eleven wetland graminoids of northeastern Ontario, Canada, whether their roots die back for the winter, and whether the species-specific timing of senescence corresponds to interspecific variation in leaf senescence. For six of the species differences between fine and axile root mortalities until mid December were assessed. For eight of the species effect of nutrient availability during summer on root end-of season and winter mortality until late March was assessed. Root mortality was assessed using TTC. In contrast to the common assumption that fine roots of herbaceous species die for the winter, most of the species had very low root mortalities in autumn and winter, especially species of the genera Scirpus and Carex. The grasses Calamagrostis canadensis, Glyceria canadensis and Phalaris arundinacea showed slight reductions in root vitality in course of the winter, but more than 70% of the roots remained alive. In contrast, fine roots of Dulichium arundinaceum and fine roots of Sparganium androcladum completely died by the end of October. Lateral root mortality was only slightly higher than that of axile roots. Nutrient effects were small. The data indicates that in many graminoid species of cool-temperate wetlands fine roots survive the winter. This may be due to low respiration costs in the cool soils, and a competitive advantage of an established root system in the fall. The high root mortality in autumn of two of the species may be an adaptation to potential winter and spring disturbance in the characteristic habitats of these species.
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1 - Laurentian University, Department of Biology, Ramsey Lake Rd, Sudbury, Ontario, P3E 2C6, Canada
2 - University of Amsterdam, Institute for Biodiversity and Ecosystem Dynamics – Physical Geography, Amsterdam, 1018 WV, The Netherlands
Presentation Type: Oral Paper:Papers for Topics
Date: Monday, July 28th, 2008
Time: 3:00 PM