Role of re-seeding and seedling recruitment for sustainable Lotus corniculatus based pastures in dry hill and high country

Abstract

Birdsfoot trefoil (Lotus comiculatus L.) is a species with considerable potential for hill and high country of the South Island; however, difficulties in maintaining satisfactory stands due to problems with persistence have been reported. Plant recruitment through natural reseeding is considered a necessary tool for the maintenance and improvement of birdsfoot trefoil stands in the USA, but research which investigates the role of soil seedbanks, seedling recruitment and stand management for improving the persistence of birdsfoot trefoil in the drier hill and high country of the South Island of New Zealand is limited. Two field experiments in the dry hill and high country of Otago monitored changes in stand populations and seedling emergence of birdsfoot trefoil under differing grazing management. At Ardlui Station on the Coastal Otago Plateau, seedling emergence was greatest in autumn rather than spring after spelling over the flowering period. Despite considerable numbers of autumn seedlings (128 seedlings/m2), less than 1 seedling/m2 survived to contribute to the stand after 12 months. Plant populations did,however increase in 199l/92 following adequate rainfall in the previous autumn. Spring emerged seedlings did not survive through summer. At Omarama Station in the southern Mackenzie Basin, plant populations of birdsfoot trefoil continued to decline despite the presence of seedlings in spring and autumn. Results imply that natural reseeding cannot be relied upon to improve birdsfoot trefoil plant populations unless favourable climatic conditions prevail during spring or autumn. Keywords: establishment, Lotus corniculatus, management, natural reseeding, persistence, seedling recruitment, soil seedbanks, survival