Soil Acari and Collembola Populations Affected by Logging and Slash Burning in a Coastal British Columbia Coniferous Forest 1

Acari and Collembola in soil from 3 differently treated adjacent areas—forest, clear–cut, and slash-burned—were sampled monthly for 1 year in the 2nd year after logging and slash burning. Samples were separated into 5 levels: litter, and four 225.8-cm 2 (35 in. 3 ) soil layers, each 2.54 cm (1 in.) deeper than the preceding one. Organisms were extracted for 10 days in modified Tullgren funnels, preserved in ethanol at 4°C, and identified using published keys. Densities of organisms were transformed using log 10 X + 1, and subjected to an analysis of variance. No seasonal fluctuations were found in any of the 3 areas. There was no correlation of density with soil moisture, pH , or temperature. Vegetation in the logged area differed considerably from that in the burned area. Density of Acari, Collembola, and other arthropods was reduced by logging and further by slash burning. The population levels and diversity in both logged and burned areas were relatively high, indicating that neither treatment induced total mortality, and/or there was rapid reinvasion of treated areas. For the Cryptostigmata, the population reduction posttreatment became less with depth. Density of Astigmata, Prostigmata, Mesostigmata, and Collembola in the family Isotomidae in the litter and the first 2 levels of soil was progressively reduced by logging and slash burning, but in the 3rd and 4th soil levels, density was increased, indicating that migration to deeper levels or adaptation to conditions further below the surface had occurred.