Ecological zonation of tall wheatgrass ami puccinellia cansed by the interaction of salinity and waterlogging?

摘要

The perennial pasture grasses tall wheatgrass (Thinopyrum ponticum) and puccinellia (Puccinellia ciliata) show ecological zonation in salt-affected land in south-western Australia, with tall wheatgrass occurring in moderately saline waterlogged situations and puccinellia occurring in slightly more saline waterlogged areas. Quantifying the causes of zonation will help in targeting plant species to specific parts of the landscape. Hence, the aims of the work presented here were to study several variables thought to be driving the ecological zonation of tall wheatgrass and puccinellia. Plants of both species were grown in a glasshouse under free-draining conditions. In experiment 1 plants were irrigated with 200 or 0 mM NaCl and grown in sand at either pH 4.5 or 8.5. In experiment 2 plants were irrigated with 200 mM NaCl and either 0.05, 2 or 10 mM Ca~(2+). In experiment 3 plants were treated with 0,100, 200,400 or 600 mM NaCl. These three studies show that salinity, calcium or pH alone do not explain the observed ecological zonation of puccinellia and tall wheatgrass. Waterlogging may therefore be a more important driver of ecological zonation.