Mr. Sabbatini et Kj. Murphy, SUBMERGED PLANT-SURVIVAL STRATEGIES IN RELATION TO MANAGEMENT AND ENVIRONMENTAL PRESSURES IN DRAINAGE CHANNEL HABITATS, Hydrobiologia, 340(1-3), 1996, pp. 191-195
The abundance of submerged weeds, in relation to management regime and
environmental factors, was surveyed during 1992 and 1993 in drainage
channels located in four geographically-distinct areas of Britain. The
aim of the study was to ascertain, using a multivariate approach, the
degree to which species survival strategy and vegetation could be rel
ated to disturbance and stress pressures on plant survival. Indices of
disturbance and stress were constructed from combined environmental d
ata for each site. A species ordination using Canonical Correspondence
Analysis showed that the combined disturbance variable explained more
of the variability that did stress. Two main groups of species could
be distinguished. The larger group scored low on the disturbance gradi
ent and these species, with different tolerances to stress (especially
light-limitation), appeared to be those better-adapted to habitats wi
th low disturbance (e.g. Potamogeton pectinatus and Potamogeton lucens
). The smaller group comprised species which tended to occur in sites
with higher disturbance (e.g. regular cutting) such as Callitriche sta
gnalis. Using the terminology of strategy theory, most of the dominant
species could be classed as 'competitive/disturbance tolerators (CD)'
or variants of this established-phase strategy. The limitations are d
iscussed of applying the strategy approach at species level in a defin
ed habitat-type which shows a high degree of uniformity between sites,
such as artificial drainage channels.