Influence of environmental factors on the abundance of naturalised annual clovers in the South Island hill and high country

Abstract

The abundance of four naturalised annual clovers (striated, cluster, suckling, haresfoot) and two sown clovers (subterranean and white clover) was investigated in relation to topographical, soil fertility and management factors on two contrasting hill/high country stations in the South Island: Glenfalloch in inland Canterbury (1 665 mm annual rainfall), and Mt Grand in Central Otago (703 mm annual rainfall). Site surveys were conducted in three hill blocks per farm, with measurements of grassland species cover, slope, aspect, grazing intensity, soil fertility, soil depth, and altitude made within quadrats along three transects at upper, middle and lower hill slope positions. The only naturalised clover present at Glenfalloch was suckling, whereas all were present at Mt Grand. The % cover of naturalised annual clovers was greater (30.1) than that of white clover (3.8) or subterranean clover (0.1) at Mt Grand. The % cover of white clover decreased with increasing altitude. The % cover of striated and cluster clover was greatest on sunny aspects, while white clover % cover was greatest on shady aspects. White clover cover increased and striated clover cover decreased with increasing available soil phosphorus. Naturalised annual clovers exhibit regeneration and persistence strategies that allow them to regenerate and grow in dry hill/high country pastures.