Contrasting impacts of climbing plants on host tree reproduction in a drought-stressed forest

The uploaded dataset contains all the data to run the analyses and figures
of the publication "Contrasting impacts of climbing plants on host
tree reproduction in a drought-stressed forest". Climbing plants, or
climbers, are known to negatively affect the survival and reproduction of
tropical and temperate humid forest trees through competition and
structural parasitism. These impacts are attributed to their growth
strategy, which relies on other plants for mechanical support and allows
them to divert resources away from structural investment toward vegetative
and reproductive functions. Such negative interactions may ultimately
influence the composition and dynamics of plant and animal communities
around them. Effects of climbers on hosts may differ in drought-stressed
systems because investments in foliage and reproductive structures could
favor facilitative interactions, such as abiotic stress amelioration
through shading or pollinator attraction through synchronous flowering.
Knowledge of climber-host interactions in Mediterranean and
drought-stressed forests in general is limited. To test the hypothesis
that climbers can facilitate host reproduction via synchronous flowering
in a drought-stressed Mediterranean forest, we assessed the effects of
climber cover on the probability of flowering, fruiting, and final fruit
set of Crataegus aronia, a common insect-pollinated tree. Overall, climber
cover was negatively related to flowering probability but positively
related to fruiting probability and final fruit set. These effects
differed between climbers with distinct flowering phenology relative to
the host. Non-co-flowering climber effects on flowering probability were
negative. However, co-flowering climber effects on fruiting probability
and final fruit set were positive. These positive effects on C. aronia are
in stark contrast with pervasive negative effects of lianas in tropical
moist forests. The differing effects of climbers with distinct phenology
suggest involvement of pollinator attraction. Although limited to the
studied tree species in a Mediterranean forest, the documented positive
effects of climbers in this drought-stressed forest and their relation
with synchronous flowering highlight the need for trait-based analyses of
climber –host interactions across systems, particularly to expand our
understanding of their ecological roles under varied climate conditions.