Influence of pressurized ventilation on performance of an emergent macrophyte (Phragmites australis)

Vretare, V Weisner, SEB

V. Vretare et Seb. Weisner, Influence of pressurized ventilation on performance of an emergent macrophyte (Phragmites australis), J ECOLOGY, 88(6), 2000, pp. 978-987

35

INGLESE

Article

Environment/Ecology

JOURNAL OF ECOLOGY

0022-0477 → ACNP

88

6

2000

978 - 987

ISI

0022-0477(200012)88:6<978:IOPVOP>2.0.ZU;2-3

1 Pressurized ventilation, which increases gas exchange between aerial and submerged plant parts, has been found in various emergent macrophyte specie s. We investigated the potential for this mechanism to affect growth, morph ology and biomass allocation in Phragmites australis in glasshouse experime nts. 2 Inhibition of pressurized ventilation by perforation of stems above the w ater surface resulted in decreased oxygen concentrations in stem bases and rhizomes. Perforation caused little mechanical damage. 3 Allometric methods were used to evaluate treatment effects on biomass all ocation and morphology. 4 Inhibition of pressurized ventilation resulted in decreased allocation to belowground weight and decreased rhizome penetration into the substrate in two of three experiments. Treatment also decreased growth rate, rhizome le ngth and number of rhizomes when substrate had a high organic content. In t he third experiment, growth clearly decreased in deep water, although inhib ition of pressurized ventilation did not affect growth, biomass allocation or morphology at either of the water depths tested. 5 Decreased allocation to below-ground parts and decreased rhizome lengths may be adaptations to allow the oxygen concentration in roots and rhizomes to be maintained above a critical level when the oxygen supply is low. 6 Pressurized ventilation may improve the performance of P. australis but o nly under certain conditions (e.g. not when growth rate is low or the subst rate has a high redox potential).