A principal components analysis of some biochemical activities in a climosequence of soils

Ten biochemical properties, comprising oxygen uptakes with and without added glucose, dehydrogenase, invertase, amylase. protease, urease, phosphatase, and sulphatase activities, and the invertase/amylase ratio, were measured in a climosequence of nine soils in tussock grasslands in New Zealand. Generally, these properties had no consistent distribution pattern. Some activities, however, were greater in the more developed soils of the sequence while others were lower in the “alpine” soil.The influence of 10 environmental and soil factors on the activities was assessed by principal components analysis. Nearly 90% of the total variance could be accounted for by only three components. The amounts of variance in individual activities accounted for by these components differed, but were usually high. The percentage of organic C, soil moisture regime, and mean annual temperature accounted for much of the variance in all three components; total N was unimportant. As a result of the principal components analysis, the soils could be grouped biochemically into arrangements that were consistent with either the pedological classification of the soils or the influence of a dominant environmental factor. The usefulness of principal components analysis for other ecological studies of soil biochemical properties is indicated.