Record ID No. |
1622 |
Author(s) |
Olsrud M., Michelsen A. , 2009 |
Affiliation |
Univ Copenhagen, Dept Biol, Sect Terr Ecol, Oster Farimagsgade 2D, DK-1353 Copenhagen, Denmark |
Title |
Effects of shading on photosynthesis, plant organic nitrogen uptake, and root fungal colonization in a subarctic mire ecosystem |
Source. Vol.(no):Page |
Botany - Botanique. 87(5): 463-474p. |
Categories |
Arbuscular Mycorrhiza |
Subjects |
Biochemistry |
Sub-subjects |
Miscellaneous |
Country |
Denmark, Europe |
Abstracts |
Arctic dwarf shrub ecosystems are predicted to be exposed to lower light intensity in a changing climate where mountain birch forests are expanding. We investigated how shading at 0%, 65%, and 97%affects photosynthesis, organic N uptake, C and N allocation patterns in plants, and root fungal colonization in an ericoid dwarf shrub ecosystem. The ecosystem was labeled by injection of [2-C-13, N-15] glycine into the soil, and the uptake of N-15 and C-13 in roots and leaves 24 h later was analysed. Fungal colonization in hair roots was determined visually. Hair root C-13: N-15 ratios showed that dwarf shrub ecosystems are capable of taking up organic N as intact glycine both under high irradiance levels and under shaded conditions when photosynthesis is strongly reduced. The allocation of N-15 to green leaves of Rubus chamaemorus L. Increased with shading, whereas the allocation of C-13 to leaves of both deciduous and evergreen plant species decreased. Species dominance was correlated with uptake of C-13, i.e., the most productive species also took up the highest amount of glycine. The ecosystem exhibited a tendency towards lower colonization by ericoid mycorrhizal fungi and dark septate endophytes in hair roots when shaded. Thus, shading has implications for processes central to both C and N cycling in subarctic ecosystems. This should be considered in projections of ecosystem responses to climate change and expanding mountain birch forests. |