Earthworm (Oligochaeta, Lumbricidae) communities in common soil types under intensive agricultural practice in Latvia

Abstract

Earthworm (Oligochaeta, Lumbricidae) communities in common soil types under intensive agricultural practice in Latvia Studies of earthworm populations in the framework of the State Agricultural Land Monitoring Programme were performed during 1992-1998 at six sites representing the common soil types of Latvia. The earthworm communities were examined as indicators of soil conditions in relation to soil type, terrain, agricultural practice and meteorological factors. In total six earthworm species were found. Only two species, Aporrectodea caliginosa and Lumbricus rubellus, were present in all plots. The highest density of earthworms was observed in loamy soils on lower terrains. The lowest density was observed on sandy soils on high terrain position. In plots with intensive agricultural practice, Aporrectodea caliginosa showed the highest relative abundance reaching close to 100%, but in pastures this species was accompanied with 2-3 subdominant species. The main factors affecting earthworm density were meteorological conditions. In permanent pasture the seasonal variability of earthworm number was lower than in plots with intensive soil tillage, where earthworm density was lower. Under favourable meteorological conditions in loamy soils, a negative impact of soil management was not observed, whereas in sandy loam soils intensive tillage had a much more negative effect on worms. In pasture soils earthworms reached high density even in sandy soils.