Drought affects the competitive interactions between Fagus sylvatica seedlings and an early successional species, Rubus fruticosus: responses of growth, water status and delta C-13 composition
Mn. Fotelli et al., Drought affects the competitive interactions between Fagus sylvatica seedlings and an early successional species, Rubus fruticosus: responses of growth, water status and delta C-13 composition, NEW PHYTOL, 151(2), 2001, pp. 427-435
Competitive interactions between European beech (Fagus sylvatica L.) seedli
ngs and the early successional species Rubus fruticosus, and the role of wa
ter availability, are reported and discussed in relation to management prac
tices and climatic changes in beech ecosystems of Central Europe.
Responses of growth, water status, gas exchange and carbon isotope composit
ion (delta C-13) to two competition and three irrigation treatments were ex
amined in a factorial-design glasshouse study.
Under regular irrigation, coexistence with R. fruticosus did not significan
tly affect growth, water potential and gas exchange of beech seedlings. How
ever, moderate water shortage caused a twofold reduction in beech biomass a
nd changes in root: shoot ratios. Drought lowered transpiration rates and p
redawn water potentials (below the xylem embolism threshold) for F. sylvati
ca; delta C-13 of leaves and fine roots increased (discrimination was reduc
ed). By contrast, significantly lower delta C-13 of R. fruticosus foliage i
ndicated an improved water status. Competitive interference intensified the
effects of reduced irrigation.
Water availability regulates the competitive interactions between beech see
dlings and R. fruticosus. Natural regeneration of beech seedlings may be in
hibited by interference from a species such as R. fruticosus, especially du
ring summer drought, as predicted by actual climate models.