Data from: Co-occurring congeners coordinate drought and shade tolerance traits along gradients of canopy openness

By capturing tissue-level responses, physiological traits related to water
status and photosynthesis are increasingly being used to explain
species-level responses to environmental conditions such as shade or
drought. Such mechanistic traits, able to link plant physiology directly
to environmental conditions, could inform broader studies of changing
community composition in an era of drastic shifts in climate or
disturbance regimes. However, understanding the extent of
inter/intraspecies trait variation and how such traits vary along common
environmental gradients remains an open question in understanding
physiological traits as species-level characteristics. To address this, we
quantified gas exchange traits, turgor loss point (ΨTLP), isotopic
discrimination, stem hydraulic conductivity (KS), and associated
functional traits in co-occurring individuals of Viburnum lentago, V.
trilobum, V. acerifolium, and V. rafinesquianum, while also quantifying
canopy coverage and soil conditions. All four Viburnum displayed
significant trait variation in gas-exchange traits, ΨTLP, and heavy carbon
isotope discrimination along gradients of canopy openness. Particularly,
plants in shadier environments were more photosynthetically active at
lower light levels, yet showed lower drought tolerance (higher ΨTLP) and
more strict stomatal regulation than individuals grown in open gaps. While
physiological traits showed trends along gradients of light availability,
soil depth and texture explained little trait variation. While V.
acerifolium displayed a more conservative, shade-tolerant trait syndrome,
little significant difference was found in traits between the congeners,
highlighting the potentially limited resolution of physiological traits to
differentiate trait syndromes of closely related, co-occurring species.