The plant ecology of the dune system on Kaitorete Spit.
Degree GrantorUniversity of Canterbury
Degree NameMaster of Science
In a two-year study of the ecology of the dune system of Kaitorete Spit, work has been concentrated on a number of distinctive plant communities associated with specific land-form units. Throughout one whole year, at frequent intervals, systematic measurements were made of environmental factors affecting the dune area as a whole, and also within the selected communities. Parameters measured included rainfall, wind, evaporation, humidity, temperatures of the air, ground surface, and soil at various depths, and soil moisture content at various depths. Physical characteristics of soils, and sand movement were studied. For nearly two years observations on the plants were recorded, including floristic composition of the communities and their seasonal changes, and morphological and phenological attributes of most of the indigenous and adventive species. An attempt has been made to evaluate the influence of environmental factors on plant forms, phenology and plant distribution. Investigations have revealed that the Kaitorete dunes represent an extremely harsh environment for plants on account of the combination of very low rainfall, very high summer temperatures, low humidity for much of the year, strong winds, salt spray, and very low water-holding capacity of the substrate. Nevertheless, the area supports a remarkable group of plants, among which the indigenous species in particular are strikingly adapted to survive and to provide permanent ground cover, if not subjected to the additional pressures of fire and browsing animals. It is considered that deterioration of the vegetation has probably been in progress for several centuries, partly as a result of the Polynesian occupation; changes have almost certainly been accelerated during the past hundred years of European settlement. Some conservation measures are warranted for an area of such unique botanical interest.