H. Teughels et al., COMPETITION IN A GLOBAL CHANGE ENVIRONMENT - THE IMPORTANCE OF DIFFERENT PLANT TRAITS FOR COMPETITIVE SUCCESS, Journal of biogeography, 22(2-3), 1995, pp. 297-305
Plant traits of both structural and physiological nature have been rep
orted to play an important role in the outcome of a competitive intera
ction. In this experiment a survey of the importance of characteristic
s such as height, leaf area and vertical distribution, leaf inclinatio
n, light transmission through a leaf and through the canopy together w
ith leaf photosynthesis rates, was made for two grasses: Lolium perenn
e L. and Festuca arundinacea Schreb. Both species were grown in a comp
etitive set-up with minimal belowground interactions under four differ
ent global change conditions of CO2 concentration and air temperature
(ambient, elevated CO2 concentration 700 mu mol mol(-1), increased air
temperature+4 degrees C, combined) in naturally sunlit air-conditione
d half-open plastic greenhouses. Plants were grown for a whole growing
season with regular (every 4 weeks) clippings at 3.5 cm height. Resul
ts demonstrate that Lolium has a much greater competitive ability when
compared to Festuca (aggressivity = 0.465). This may be a consequence
of the slightly higher leaf photosynthesis rates (+15%) in combinatio
n with a larger amount of foliage area, which could result in a higher
canopy photosynthesis. The greater leaf area remaining after mowing m
ay lead to an additional advantage for Lolium. Height, leaf inclinatio
n, optical properties and the vertical distribution of leaf area seem
to be of minor importance in this experiment. Global change treatments
(elevated CO2 concentration and increased temperature) influence leaf
photosynthesis rates predominantly and have little or no direct effec
t on structural traits such as height, leaf angles and vertical leaf d
istribution; nor do they exert an influence on light transmission thro
ugh a leaf or through the canopy. However, treatment effects on leaf a
rea can add to explain differences in canopy photosynthesis. In this c
ompetition experiment, focused on above-ground interactions, both a st
ructural (leaf area) and a physiological feature (leaf photosynthesis)
contribute to the competitive success of a species.