Seasonal and altitudinal variation in Pteridium aquilinum (L.) Kuhn: frond and stand types

The field ecology of Pteridium aquilinum (L.) Kuhn was studied through a growing season in the northern Malvern Hills. At lower altitudes, stands reached a biomass plateau by late July extending through to late September, while at higher altitudes biomass increment was delayed and curtailed by the shorter growing season. Pteridium retained several competitive characteristics even when altitude and exposure restricted its vigour. With increased altitude, biomass allocation favoured the lamina and the underground portion of the stipe; the stipe-with-rachis component was comparatively reduced with a dwarfing of the canopy but a dense packing of pinnae. Adjustment to conditions in the stand, by the emergence and die-back of fronds, caused frond density to change through the growing season and at different altitudes. Two frond and associated stand types at contrasted altitudes were recognized by morphology and biomass.