Tuatara: Volume 21, Issue 3, April 1975
The basic parameters mentioned have been numbers of individuals according to size classes for each species, trunk circumference of trees > 2 cm dbh, and canopy cover. Any additional parameters can be recorded, depending on the aims of the study. In order to reduce the chances of error, a record of the original field measurements page 89 should be kept as well as the data for derived variables such as dbh or basal area.
Sometimes it is possible to mark the positions and measure plants in the vicinity of but outside a transect. In this way sample size can be increased so that a particular species population is sampled adequately. Individual plants can be labelled, care being taken to ensure that wiring on the label does not restrict future growth.
Other types of repeated observation can be made in permanent transects apart from those relating to live plants. For example, the decay rates of fallen branches from different species in various environments is a topic about which little is known. The unexpected results which permanent transects sometimes produce, amply reward the observer for the time he takes in their recording.
Finally it must be emphasised that recording vegetation in a permanent transect invariably has some modifying effect on the plants, particularly when more than one person is recording. Every care should be taken to minimise this disturbance.
I thank Mr A. E. Ester of Botany Division, D.S.I.R., for encouraging me to publish this paper. Discussion with Mr Esler, Mr R. G. Bagnall of Victoria University and Mr A. P. Druce, Botany Division, D.S.I.R., helped to clarify several aspects of the procedure suggested.
Clapham, A. R., 1932: The form of the observational unit in quantitative ecology. Journal of Ecology 20: 192-197.
Druce, A. P., 1966: Secondary totara-titoki-matai forest on the Otaki plain. Wellington Botanical Society Bulletin 33: 22-39.
Turbott, E. G., 1948: Effect of goats on Great Island, Three Kings, with descriptions of vegetation quadrats. Records of the Auckland Institute and Museum 3: 253-272.