. Animal Ecology. Animal ecology. dance from the newer apical growth to the older basal foliage. If the width of the branch at mid-length is measured, then the length of the foliated part times the width gives the foliage surface. The total foliage surface of representative trees is determined from felled individuals, and the total foliage surface per unit area may be computed from the known density of trees. If the arthropods vary in abundance at dif- ferent levels in the tree, representative sampling must be taken at each level. Considerable variation in ani- mal density also occurs from tre
. Animal Ecology. Animal ecology. dance from the newer apical growth to the older basal foliage. If the width of the branch at mid-length is measured, then the length of the foliated part times the width gives the foliage surface. The total foliage surface of representative trees is determined from felled individuals, and the total foliage surface per unit area may be computed from the known density of trees. If the arthropods vary in abundance at dif- ferent levels in the tree, representative sampling must be taken at each level. Considerable variation in ani- mal density also occurs from tree to tree so that sam- pling must be well distributed over the area under investigation (Morris 1960). Soil animals One must resort to a variety of methods to census the difTerent kinds of animals in the soil be- cause of great differences in their size, physical char- acteristics, and behavior (Fenton 1947, Van der Drift 1950, Kevan 1955). The uiegafaitna consists of the larger millipedes, centipedes, snails, amphibians, rep- tiles, and small mammals. Mammals must usually he trapped. For the other forms mentioned, if there are a half-dozen workers available, a plot 10 meters on a side (100 m-) may be marked out and the ob- servers, forming a line at one side, may gradually work over the plot, turning over all the leaves and sticks. This gives a good count but must be repeated in various parts of the FIG. 4 4 Tullgren modification of a Berlese funnel for quantitative sampling of soil animals. For quantitative sampling the fauna of fallen logs and decaying stumps, it is convenient to mark out an area 50 meters on a side ( hectare) and then measure the length of all logs and the height of stumps. A medium-sized log and stump are com- pletely torn apart and all animals counted. The total population for the whole area may then be calcu- lated. The inacrofauiia, consisting of the larger insects and spiders, the smaller millipedes, centipedes, and snails, and the eart
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