Figure 1.
δ13C values of 12 autotrophic plant species (n = 177) including the orchid C. calceolus, two partially myco-heterotrophic Cephalanthera spp. (n = 18 each) and the fully myco-heterotrophic orchid N. nidus-avis (n = 11), plotted against mean light availability. Samples were collected from an open P. sylvestris stand (diamonds), a forest dominated by Fagus sylvatica (circles) and a mixed stand (squares) in northeast Bavaria. Regression curves (solid lines) are given with 95% confidence intervals (dashed lines).