Seed rain in grassland, herbfield, snowbank, and fellfield in the alpine zone, Craigieburn Range, South Island, New Zealand

Abstract

Seed rain studies were conducted in 1988 and 1989 in the Craigieburn Range, South Island, using pit traps in four alpine plant communities: fellfield, snowbank, herbfield, and snow tussock grassland. Seeds and fruits from a total of 34 species were trapped, and the average number trapped over two seasons was 1921 m⁻². Peak seasonal dispersal was in early and middle March in the tussock grassland, herbfield, and snowbank communities. Considerable variation in species and numbers trapped occurred between seasons, between communities, and within communities. Most species appeared to disperse less than 50 cm from the nearest sources, and distance was generally a better predictor than height of release for number of seeds trapped. The seed rain in most vegetation was uneven and generally significantly clumped. Species producing seeds or fruits with relatively low terminal velocities, low mass, and morphological features such as pappuses, wings, or awns dominated the seed rain. Viability tests showed that some species had a much lower viable seed rain than their total seed rain would suggest.

Keywords:

• alpine
• seed dispersal
• Craigieburn Range
• tussock grassland
• herbfield
• snowbank
• fell field