Figure 1: Scheme of the wrapping experiment (Photo (a): Exp. 1)
and the girdling and removal experiment (Photo (b): Exp. 2), with
drawings showing the treatments applied to mistletoes and pine twigs on
the right-hand site. In Exp. 1, mistletoe clusters were covered with
gas-tight plastic sheets and aluminum foil to prevent direct13C label uptake during the whole-tree13CO2 labeling experiment; non-wrapped
controls were allowed to take up13CO2. In Exp. 2, the bark including
phloem was girdled for three branches per tree before the whole-tree
labeling to create an isolated environment without top-down carbon
transportation via the host’s phloem, and each of these three branches
was randomly assigned to mistletoe removal, pine needle removal, or
intact control.