Uni-Bayreuth grafik-uni-bayreuth

Sprungmarken

 

Nutrient gains from fungi by adult orchids in temperate montane habitats – A stable isotope approach

Julienne Marie-Isabelle Schiebold1, Andreas Makiola1, Gerhard Gebauer1
1 Laboratory of Isotope Biogeochemistry, University of Bayreuth

P 2.9 in Research in its Prime: First Results of Ongoing Research

Mountain regions with high plant diversity are particularly rich in orchids, but the dominant trophic strategies (e.g. autotrophy, partial, or full mycoheterotrophy) of montane orchids are not known. We screened orchids in the Northern Limestone Alps of the Austrian province of Vorarlberg for their nutrient gains and fungal partners across habitats. Leaf samples of 8 orchid species from 7 genera in the subfamilies Epidendroideae and Orchidoideae, and accompanying autotrophic non-orchid plants as references for site conditions, were collected at 7 locations ranging from closed forests to open meadows. Stable isotope natural abundance analyses were conducted to test whether carbon (C), nitrogen (N) and hydrogen (H) are gained through autotrophic means or via mycorrhizal fungi. As expected, our results show that full mycoheterotrophy occurs only in the light-limited forest dweller dependent on ectomycorrhizal fungi (Neottia nidus-avis, Epidendroideae). In contrast, most green meadow orchids mycorrhizal with saprotrophic rhizoctonias have low N gains and apparently no C gains from fungi. Nonetheless, multi-element isotope signatures including H isotope composition indicate that some putatively autotrophic green meadow orchids rely on partial mycoheterotrophy. Thus, adding H isotopes to C and N isotope signatures provides a higher resolution in assorting trophic strategies in adult orchids.

last modified 2013-09-19