PARENT SESSION
Contributed Oral Session 57: Polar and Alpine Ecology: Carbon and Nutrient Dynamics
Tuesday, August 9, 1:30 PM - 5:00 PM, Meeting Room 513 E, Level 5, Palais des congrès de Montréal

Root architecture and nutrient allocation in tundra plants.

Björk, Robert¹, Majdi, Hooshang², Klemedtsson, Leif¹, Molau, Ulf¹, ¹ Botanical Institute, Göteborg University, Göteborg, Sweden² Department of Ecology and Environmental Research, Swedish University of Agricultural Sciences, Uppsala, Sweden

ABSTRACT- The Arctic Climate Impact Assessment (ACIA) recently reported that the Arctic is rapidly changing due to Climate Change. Likewise, the mountains of Europe are going to experience large shifts in plant composition and 41-56% of the alpine species might be on the edge of extinction according to the 1st synthesis of the Global Observation Research Initiative in Alpine Environments (GLORIA). Although the tundra ecosystems are subjected to dramatical changes as a result of Climate Change, there is little knowledge of the effect on root dynamics. Roots are crucial for soil development and nutrient cycling in most ecosystems. The further out in the root system a single root is located, the faster the root turns over. The fine roots are also having a lower C:N ratio than more developed and supporting roots. The aim of this study is to investigate the dynamic of root architecture and how tundra plants allocate carbon and nitrogen between root and shoot biomass and, moreover, how the plants respond to climatic warming. The dominant plant species (e.g. Cassiope tetragona, Vaccinium vitis-idaea and Diapensia lapponica for the dry heath) within each of four plant communities at Latnjajaure Field Station, in northern Swedish Scandes, were sampled and divided into shoot and root. To study the effects of climatic warming on the root system, soil cores were as well sampled in Open Top Chambers (OTCs) that was established in 1993. The root architecture was analysed by observing the degree of branching, colour, consistency etc. of the roots, which then were cut and sorted by diameter. To determine the C and N allocation within the plants we also quantified the shoot:root ratio. The preliminary results indicate that there is a difference between plant species in root biomass and particularly in the fraction of fine roots. As a result of a greater amount of root exudates from fine roots, these results imply that plant distribution has a great impact on the soil microbial community and activity. The large spatial variability often seen in microbial measurement within plant communities may be due to a sampling procedure, in that samples are taken from different plants′ root system.

Key words: root density, root order, soil cores, climate change