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Abstract Detail



Ecophysiology

Gagnon, Dominique [1], Wilson, Adrienne [1], Marcotte, Susara J.E. [1], Porter, Jacob [1], Cote, Kathleen [1], Ryser, Peter [1].

Herbaceous perennials of Northern Ontario wetlands with single-season or multi-season roots: relations to environmental factors.

Perennial herbaceous species of Northern Ontario wetlands can be classified in two distinct types of root turnover strategies: species which each spring make new roots for only one growing season, and species with roots which overwinter and lasting several growing seasons. All these species lose their leaves each winter, species with annual roots overwintering as rhizomes, bulbils or tubers. The two root turnover strategies are comparable to leaf turnover strategies of trees, i.e., deciduous and evergreen habits. In trees the occurrence of the two habits is related to length and favourableness of the growing season, and severity of the unfavourable season. It is not known which environmental factors are important for the success of the two root turnover strategies. We investigated environmental relations of the species with either single-season or multi-season roots. Field investigations show that species with annually renewed roots avoid sites with low soil temperatures, and tend to occur on sites with lower soil organic matter content, the higher amount of mineral soil possibly indicating more available nutrients. They produce less roots late in the season compared to species with overwintering roots. Garden experiments show that species with annually renewed root systems have lower leaf and root tissue densities and faster shoot relative growth rates (RGR) than species with overwintering roots. Their shoot growth is more sensitive to low soil temperatures. However, despite their higher potential RGR and association with warmer sites, shoots of species with annually renewed roots grow in the field in spring more slowly than those of the species with overwintering root species. This is probably due to the necessity to build a new root system before more below-ground resources can be acquired. Compared to species with overwintering roots, species with the strategy of annually renewed roots are more strongly constrained by environmental quality, and seem to have a competitive disadvantage in spring. On the other hand, their potentially higher relative growth rates indicate a potential advantage after disturbance. These relationships show similarity to those observed in deciduous and evergreen trees, but several years of observations of the sites with these species have not shown what the disturbance may be that provides the strategy of annually renewed root systems an advantage at certain sites.


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1 - Laurentian University, Biology, Ramsey Lake Road, Sudbury, ON, P3E 2C6, Canada

Keywords:
Root lifespan
wetland
plant functional trait.

Presentation Type: Oral Paper:Papers for Topics
Session: 41
Location: Salon 16/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 11:30 AM
Number: 41006
Abstract ID:917
Candidate for Awards:None


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