Climate-induced plasticity in leaf traits of riparian plants

Aim: Leaf inputs from riparian vegetation and its decomposition play a key
role in energy and nutrients transfer in many stream ecosystems. Instream
leaf-litter decomposition is mainly driven by leaf traits. Therefore,
understanding and predicting leaf traits variation with current
environmental changes and its putative effects on stream food webs is a
critical challenge. Most studies have focused on the assumed higher
interspecific leaf traits variability, with little research addressing an
intraspecific perspective. Location: Andalusia, Spain Methods: We assessed
the relative effects of climate and soil on the intraspecific variability
in leaf traits of four common woody riparian species in permanent
low-order Mediterranean streams along a wide aridity gradient. We used a
space-for-time substitution approach to predict leaf traits changes and
consequences for stream food webs in a future climate change scenario.
Results: We found that climate had a major influence on intraspecific
variability of leaf traits, but with opposite patterns depending on plant
functional type. Results indicated that leaf quality—linked to
palatability and decomposability—of Alnus glutinosa, Salix atrocinerea and
Rubus ulmifolius (deciduous/semideciduous) will decrease with the
forecasted aridification, whereas that of the evergreen Nerium oleander
will increase. Main conclusions: Our findings suggest a decrease of
intraspecific leaf-quality in riparian deciduous species with global
warming in a relatively short term, which, in a longer term, may add to
the forecasted dieback of deciduous species in riparian corridors of
temperate climate zones. These forecasted changes have the potential to
significantly impair ecosystem functioning of Mediterranean mountain
streams currently under deciduous gallery forests.