A study of forest ecosystem development

Abstract

This study was made in order to elucidate, quantitatively, the changes taking place with time in a relatively simple ecosystem of Pinus radiata D. Don. on skeletal soils and integrades to Yellow-Brown Sands. Every endeavour was made to keep other soil forming factors (and the influence of other factors on the ecosystem) as constant as possible, thus satisfying the criteria for a chronosequence. Studies of this type have considerable theoretical and practical value both in Soil Science and Ecology, yet few such studies have been carried out. The locality selected for study is located on the West Coast of the North Island, west of Palmerston North on recently consolidated sand dunes (Cowie & Smith, 1958). Coastal dunes have been stabilised with marram grass and lupin and planted with P. radiata in successive stages, to prevent drifting over adjacent farmland. The district has a mean annual temperature of 12.3°C and an average rainfall off 84.8cm/annum. A survey was made of the area to select a series of similar sites in the succession from bare dunes to nearly 30 year old forest stands. Four stages were selected and three sites chosen for the first stage and six for the three older sites. At each site vegetation, above and below ground, and soil were sampled. Sub-samples were analysed in the laboratory for basic density (wood), carbon and nitrogen. An estimate has been made of the weight of organic matter and nitrogen and the distribution of these in the forest ecosystem.