Natural Re-Seeding and Trifolium repens Demography in Grazed Hill Pastures. II. Seedling Appearance and Survival

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Abstract
The appearance and survival of Trifolium repens seedlings from naturally deposited seed were monitored for 3 years under different sheep grazing managements and phosphate fertilizer inputs, and in four slope/aspect zones, in summer moist New Zealand hill country. A mean of 5.5 seedlings m-2 per year appeared, representing 4.2% of the seeds deposited each summer. Only 4.4% of seedlings survived to form established, stolon-bearing plants, representing a mean recruitment rate of one seedling per 5.5 m2 per year. Survival was highest on steep north-west sites (10%), and nil on flat south-west sites, reflecting likely competitive stresses from surrounding vegetation. Such low recruitment rates clearly indicate seedling regeneration plays only a minor role in T. repens persistence in this environment. Vegetative stolon densities of 3000-4000 m-2 and high rates of stolon initiation and death confirm that the species behaves essentially as a true perennial. A useful ecological role for low seedling recruitment rates in maintaining genetic diversity within the T. repens population must be recognized, however, especially in highly variable environments.