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Peter Ryser

Peter Ryser

Full Professor

School of Natural Sciences
Science, Engineering and Architecture
S-624, Science Building Sudbury Campus


I studied Biology at ETH Zurich. My Ph.D. thesis was on interactions between plants in species-rich grasslands under the supervision of Andreas Gigon. I spent lots of time in the field watching the seedlings grow and die, which triggered the wish, not only to be able to observe the survival or death, but also to ask the plants "How are you?". I learned how to ask this question, and how to hear the plants' answer during my postdoctoral stay in Utrecht, the Netherlands, where work with Hans Lambers brought me to my current research track on whole plant ecophysiology, including the roots. I continued this work in Zurich and for the last 12 years I have been working at Laurentian University studying factors which underlie the ecological diversity of wetland species. The diversity of sedges, rushes, bulrushes, beaked rushes, twig-rushes, spike rushes, burr-reeds, cattails etc. in these habitats, all with a similar growth form but different ecological requirements, make them perfect for comparative functional ecology trying to understand how they are adapted to their environment. When living in Sudbury, one is confronted by the legacy of industrial damage in the past, and I also investigate the effects of heavy metal contamination on plants.


  • Dipl.Sc.Nat., Natural Sciences, ETH Zurich
  • Dr.Sc.Nat. Biology, ETH Zurich
  • Habilitation and Venia Legendi in Plant Ecology, ETH Zurich

On The Web


I investigate plant functional traits which underlie variation in species ecological behaviour, focusing on biomass turnover, i.e. on the one hand growth rate and resource acquisition, and on the other hand, organ life span and resource conservation. My current research projects deal with plants of Northern Ontario wetlands emphasizing below ground traits such as root turnover. I also investigate plant responses to soil heavy metal contamination.


  • Teaching

    BIOL2306E Diversity of Plants

    BIOL2356E Principles of Ecology

    BIOL3317E Plant Ecophysiology

    BIOL4317E Plant-Animal Interactions

    BIOL5316E Ecophysiology of Plant Stress


    • Ye Z. and Ryser P. 2021. Root porosity contributes to root trait space of wetland monocotyledons independently of economics traits. Plant and Soil.
    • de Silva N.D.G., Murmu J., Chabot D., Hubbard K., Ryser P., Molina I., and Rowland O. 2021. Root suberin plays important roles in reducing water loss and sodium uptake in Arabidopsis thaliana. Metabolites 11, 735.
    • Freschet G.T., Roumet C., Comas L.H., Weemstra M., et al. 2021. Root traits as drivers of plant and ecosystem functioning: current understanding, pitfalls and future research needs. New Phytologist 232, 1123-1158.
    • Freschet G.T., Pagès L., Iversen C., Comas L.H., et al. 2021. A starting guide to root ecology: strengthening ecological concepts and standardizing root classification, sampling, processing and trait measurements. New Phytologist 232, 973-1122.
    • Ryser, P., Puig, S., Müller, M. and Munné-Bosch, S. 2020. Abscisic acid responses match the different patterns of autumn senescence in roots and leaves of Iris versicolor and Sparganium emersum. Environmental and Experimental Botany, p.104097.
    • Courchesne, D.N., Wilson, A.Z. and Ryser, P. 2020. Regional distribution patterns of wetland monocots with different root turnover strategies are associated with local variation in soil temperature. New Phytologist 226, 86-97.
    • Byne, K. and Ryser, P. 2020. Spring temperatures affect senescence and N uptake in autumn and N storage for winter in Rhynchospora alba (Cyperaceae). Journal of Experimental Botany 71, 1551-1561.
    • Nieman, T., Hoogzaad, Y., Marcotte, S.J. and Ryser, P. 2018. Contrasting root overwintering strategies of perennial wetland monocots. Botany 96, 653-661.
    • Kim, J.H., Lee, S.I., Kim, B.R., Choi, I.Y., Ryser, P. and Kim, N.S. 2017. Chloroplast genomes of Lilium lancifolium, L. amabile, L. callosum, and L. philadelphicum: Molecular characterization and their use in phylogenetic analysis in the genus Lilium and other allied genera in the order Liliales. PloS one 12, p.e0186788
    • Santala K.R., Monet S., McCaffrey T., Campbell D. and Ryser P. 2016. Using turf transplants to reintroduce native forest understory plants into smelter-disturbed forests. Restoration Ecology 24, 346-353. doi: 10.1111/rec.12316
    • Anderson R. and Ryser P. 2015. Early autumn senescence in red maple (Acer rubrum L.) is associated with high leaf anthocyanin content. Plants 4, 505-522; doi:10.3390/plants4030505.
    • Tanentzap F.M., Stempel A. and Ryser P. 2015. Reliability of leaf relative water content (RWC) measurements 1 after storage: consequences for in situ measurements. Botany 93, 535-541. (
    • Poorter H. and Ryser P. 2015. The limits to leaf and root plasticity: what is so special about specific root length? New Phytologist 206, 1188–1190. (

    • Tanentzap F.M. and Ryser P.  2015. Decreased resistance to embolism in red maple (Acer rubrum L.) saplings within a heavy metal contaminated region. Environmental and Experimental Botany 109, 40–44.

    • Yücel C.K., Bor M. and Ryser P.  2014. Interspecific diversity in root antioxidative enzyme activities reflect root turnover strategies and preferred habitats in wetland graminoids. Ecology and Evolution 4, 831-840.

    • De Silva N.D.G, Cholewa E., and Ryser P. 2012. Effects of combined drought and heavy metal stresses on xylem structure and hydraulic conductivity in red maple (Acer rubrum L). Journal of Experimental Botany 63, 5957-5966.

    • Kirkey F.M, Matthews J. and Ryser P. 2012. Metal resistance in populations of red maple (Acer rubrum L.) and white birch (Betula papyrifera Marsh) from a metal-contaminated region and neighbouring non-contaminated regions. Environmental Pollution 164: 53-58.

    • Ryser P., Gill H.K. and Byrne C.J. 2011. Constraints of root response to waterlogging in Alisma triviale. Plant and Soil 343: 247-260

    • Vernescu, C. and Ryser, P. 2009. Constraints on leaf structural traits in wetland plants. American Journal of Botany 96: 1068-1074.

    • Ryser P. and Kamminga A.T. 2009. Root survival of six cool-temperate wetland graminoids in autumn and early winter. Plant Ecology & Diversity 2: 27-35