The soil seed bank of a kauri (Agathis australis) forest remnant near Auckland, New Zealand

Abstract

The “transient” and “persistent” components of the soil seed bank beneath a kauri forest remnant are described. The methodology employed separates recent seed rain (collected in trays over a two year period) from dormant viable seed with longevity >2 years (soil beneath trays). A total of 46 vascular plant species, and 908 individuals, were recorded from tray and sub-tray samples. Species composition of trays and sub-trays varies markedly. Trays are dominated by four woody, native species; Kunzea ericoides, Coprosma arborea, Myrsine australis, and Carpodetus serraius. Sub-tray samples show an accumulation of seeds from light-demanding weedy species, including many adventives such as Solatium mauritianum, Phytolacca octandra, and Cirsium vulgare. In addition, seeds of two woody, native species, Cordyline australis and Geniostoma rupestre, are abundant. Detrended correspondence analysis (DECORANA) shows clear differences between floristic composition of trays and sub-trays and, further, between on-site vegetation and components of the soil seed bank. These differences are explained in terms of seed longevity, seed accumulation rates, suitability of site conditions for growth of individual species, and the role of seed dispersal agents, especially birds.