THE CLIMATE, NATIVE VEGETATION, AND SOILS OF SOME GRASSLANDS AT DIFFERENT ELEVATIONS IN BRITISH COLUMBIA

Abstract

The soils and native vegetation of 28 sites near Kamloops, B.C., were described and soil samples collected. The sites represented a difference in elevation of 600 m. Stations were established at five selected sites to measure air temperature and rainfall during April to October.On well-drained sites of southern exposure there was a definite sequence of vegetation zones, namely, Artemisia tridentata, Stipa–Poa, and Festuca scabrella. These zones coincided closely with Brown, Dark Brown, and Black Chernozemic soils respectively. Changes in the vegetation zones were neither uniform nor gradual and appeared to be related to sharp climatic differences.Calculated gradients show that mean maximum, mean minimum, and mean temperatures and precipitation are not as highly distinguishing features of the climate as are the P/E ratios if soil organic carbon can be taken as an ’integrated index’ of climate.There is little change in vegetation within the Artemisia zone and this is associated with a low soil organic carbon gradient for the Brown soils. Air inversions in the lower part of this zone appeared to result in a similar precipitation effectiveness as that for the upper part. Soil organic carbon values are higher in the Stipa–Poa zone but forage yields in this zone are much lower than would be expected from consideration of these values.Outstanding changes in plant species across two phases of the Festuca zone and a high soil organic carbon gradient through the Black soils appeared to be a result of a high negative mean minimum temperature gradient which accounts for a high P/E ratio gradient.