The Relationship between Attributes of Plants Represented in the Germinable Seed Bank and Stocking Pressure in a Semi-arid Subtropical Rangeland

Abstract

A range of diaspore and mature plant attributes of the species represented in the germinable seed bank of a semi-arid subtropical Queensland sheep rangeland was investigated. The attributes of both the diaspores themselves and the plants that produced them changed as distance from water increased. Close to the water source, species with prostrate or erect growth habit and with low palatability and capsular fruits were common, whereas further from the water source plants with ascending growth habits, high palatability and mericarpic fruits were more frequent. At close proximity to water, species with diaspores that germinated rapidly, were unornamented, with unassisted dispersal and rounded in shape were common, whereas at greater distance from water, species tended to possess diaspores which germinated slowly, were ornamented (possessed awns, barbs, or hairs), with an elongated shape. Longevity of the plants (annual or perennial) was not significantly affected by distance from water. The dormant, vegetative and reproductive phases of plants that are successfully incorporated into the germinable soil seed bank can, therefore, be related to success under the different stocking intensities present at different distances from water.