Title: The effect of fire on an Acacia longifolia seed bank in the south-western Cape
Abstract: The Australian Acacia longifolia (Andr.) Willd., owes its success as a weed in South Africa amongst other things to the excessive production of long-lived seed banks under existing stands of the weed. A fairly intense fire (circa 24 900 kW m− 1) was found to reduce the number of viable seeds in the seed bank to 8% of the original by either destroying or stimulating the germination of a large proportion of the seeds. Only 3% of the seeds present in the seed bank before the fire, established as seedlings after the fire, while the remaining seeds that were viable appeared to be buried too deeply to be stimulated to germinate. This was confirmed by a separate trial where seeds buried 10 mm below the soil surface were destroyed by fire. Most seeds buried 20 mm deep were stimulated to germinate while seeds buried 30 mm or deeper were largely unaffected by fire. Een van die redes waarom die Australiese plant, Acacia longifolia (Andr.) Willd., ’n indringerplant in Suid-Afrika geword het, is onder andere toe te skryf aan die vermoë van die plant om ’n groot saadbank van hardskalige sade tot stand te bring, ’n Groot persentasie van die sade wat op of net onder die grondoppervlak voorkom, word egter deur ’n redelike intense vuur (ongeveer 24 900 kW m− 1) vernietig of gestimuleer om te ontkiem. Slegs 3% van die oorspronklike saadbank het na die vuur as saailinge gevestig. Van die oorblywende sade was die 8% wat nog kiemkragtig was, skynbaar te diep begrawe om gestimuleer te word om te ontkiem. Resultate van ’n afsonderlike eksperiment waar sade wat 10 mm diep begrawe is, almal deur die vuur vernietig is, het dit bevestig. ’n Groot persentasie van die sade wat 20 mm diep begrawe is het ontkiem terwyl sade wat 30 mm of dieper begrawe is, grootliks die effek van die vuur ontsnap het.