We used RLQ to analyse the joint structure between environmental conditions (R-table) and species traits (Q-table) by use of a species abundance table (L-table). RLQ analyses the inertia of scores of R- and Q-table linked by species scores of L-table. Then we clustered species according to their position along the RLQ axes to form functional groups.
The 鈥榩hysiological-ecological-amplitude鈥?concept could not be confirmed from the trait perspective, as the species of the 鈥榮tressful鈥?lower marsh show trait values indicating higher competitive ability (canopy height and stem mass fraction) than those of the 鈥榖enign鈥?upper parts. Also, specific leaf area (SLA) and leaf dry matter content (LDMC) of salt marsh plants were more constrained by a salt-waterlogging gradient than by a nutrient gradient. This is opposite to the leaf economics spectrum, which describes a trade-off from fast growing species with the potential of quick return of investments of nutrients to species with long leaf lifetime and low rates of photosynthesis. Our results are consistent with the theory of functional equilibrium and Tilman's allocation model, which is a shift in allocation to plant organs responsible for capturing limiting resources resulting in higher fractions of that organ relative to the whole plant body.