In most ecological problems we are endeavouring to define various aspects of plant/animal/environment interactions. The object of taking measurements is to:
(1) find the magnitude of particular effects or interactions and;
(2) to determine their reliability.
This is a brief, non-mathematical survey of some of the most common methods of numerically classifying large numbers of individuals according to their attributes. The article is intended as an introduction to the subject, and is not intended to be in any way definitive. An appendix briefly discusses the results of a simple classification exercise.
In 1898 Cockayne described succession in subalpine vegetation which had been burnt eight years previously at Arthurs Pass. In 1932 Cockayne and Calder repeated the observations and Calder established ten charted transects, which were re-charted during the summer of 1965-66.
In subalpine scrub, the path of the succession is broadly as follows, although details vary from site to site:
1 year after the fire: appearance of Marchamia and ruderal angiosperms.
Plant growth is probably controlled by a combination of all environmental factors. But in particular situations some factors will exert greater influence than others. so that, for practical purposes, it is unnecessary to consider all factors in attempting to predict plant growth. The interaction between plant and environment could be one ofseveral types:
(a) the major aspect of growth is influenced by a single factor,
(b) growth is influenced by a few factors and each is of similar importance,
In August 1966, the entire population of hitherto undisturbed feral goats on Macauley Island, Kermadec Group, New Zealand, was destroyed. Of 3,200 animals (4/ acre) 1,047 were examined after death. Primary coat colours were black (37.8%), tan (11.9%) and white (0.7%). Horns were mostly of the twisted 'prisca' type, maximum lengths being 20.3 in. for males and 9.5 in. for females. Of 118 mandibles 8% showed a range of abnormalities including localised excessive wear, diseased alveolar bone and loss of teeth. Life expectancy at birth was 4.5 years.