Invasion by maritime pine in Abel Tasman National Park
Degree GrantorUniversity of Canterbury
Degree NameBachelor of Forestry Science
Maritime Pine is one of two species of exotic conifers present in Abel Tasman National Park, in significant numbers. The species was first planted at Bark Bay, (ca.1900) and since then has established itself particularly well, throughout many of the southern coastal areas of the Park. The pines characteristic ecological features make it especially well adapted to colonise many of the infertile and harsh sites that exist in proximity to the Park's coastline and give it a distinct competitive advantage over the indigenous flora of the area. Spread has generally been strongest in a southerly direction, away from Bark Bay, presumably influenced by prevailing winds in addition to suitable sites for colonisation. The rate of spread of the pine was calculated as 9.1 metres/year, at Bark Bay, away from the assumed initial seed source. It is important to note though, that this rate is considerably increased by the pine's ability to form outliers of pine, significant distances away from the original seed source. The outliers were generally found to be the result of strong winds (greater than Force 6) capable of carrying seed considerable distances, on to sites suitable for colonisation by maritime pin. Consequently this serves to increase the distribution of maritime pine within the Park. This pattern of long-range dispersal has only occurred since ca. 1940 and has only become increasingly prevalent in recent years. At present then, the pine occurs along some 9.2 kilometres of the Park's coastline. The pine appears to be type specific in its invasion characteristics with low Leptospermum shrubland vegetation types being the most susceptible to invasion. The pine will not usually establish where there is a closed canopy (i.e. Podocarp/Hardwood/Beech vegetation types). Obviously the rate of spread is increasing at an exponential rate as the pine becomes more widespread in its distribution throughout the Park. For this reason a programme of control is recommended, aimed at confining the species to the Bark Bay area, where it initially originated from.