The influence of environmental factors and management on stands of Phragmites australis. II. Effects on yield and its relationships with shoot density.
Abstract
The performance of Phragmites australis growing on plots in an experimental field in the Netherlands is described in terms of leaf area and biomass of shoots and rhizomes. Treatments in the form of burning in the spring, mowing, and removal of shoots in the winter, were applied in both wet and dry areas. Damage to just-emerging shoots in April or early May by burning (wet- and dry-burned plots) or early ground-frost (dry-burned and dry-mown plots) retarded growth of leaves and shoots for about 1-2 weeks, but the relative growth rate and maximal levels reached were not significantly lower than in the undamaged situation. Heavy damage by late ground-frost (dry-burned plot) or by the stemboring larvae of Archanara geminipuncta (Haw.) (wet-undisturbed plot) lowered the maximal shoot biomass by about 25-35%. Heavy infestation by the rhizome-boring larvae of Rhizedra lutosa (Hb.) (dry-undisturbed and dry-mown plots during later years) gave losses in yield of about 45-60%.