Effect of soil compaction and organic matter removal on two earthworm populations and some soil properties in a hardwood forest

Earthworms can alter the physical, chemical, and biological properties of a forest ecosystem. Any physical manipulation to the soil ecosystem may, in turn, affect the activities and ecology of earthworms. The effects of organ ic matter removal (logs and forest floor) and soil compaction on earthworm activities were measured in a central hardwood region (oak-hickory) forest in the Missouri Ozarks. Soils in this region are characterized by a cherty residuum that is primarily of the Clarksville series (Loamy-skeletal, mixed , mesic Typic Paledults). Earthworms were collected from a 15 cm depth each spring and fall for 2 years by the handsorting method and estimated on a p er meter square basis. Two earthworm species, Diplocardia ornata and Diploc ardia smithii, were the most dominant native species found in the site. Org anic matter removal decreased the average individual biomass of both specie s. However, these species responded differently to soil compaction. Soil co mpaction affected D. ornata adversely and D. smithii favorably. This sugges ts that the degree of soil compaction was not restrictive to D. smithii (2- mm die) but it was to D ornata (5 mm dia). Moreover, the apparent better so il environmental conditions resulting from the remaining organic matter in compacted soil enhanced D. smithii population anti, growth. Sampling positi on affected D. ornata but not D. smithii. Other factors influencing the eco logy and activity of these two species will require further study.