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- Title
STUDIES ON ENCHYTRAEIDAE 5. FACTORS CAUSING SEASONAL FLUCTUATIONS IN NUMBERS.
- Authors
Nielsen, C. Overgaard
- Abstract
The seasonal variation in numbers of Enchytraeidae during the period Oct. 1953–Nov. 1955 is described from different stations and the moisture status in three stations is described for the period Oct. 1954–Oct. 1955. The summer minimum of Enchytraeidae is caused by desiccation, and the population decrease is directly related to the degree and duration of the desiccation. pF values about c. 4 kill active Enchytraeidae almost instantaneously through fatal water loss, cocoons are killed after more prolonged exposure to pF values of c. 4. Activity of Enchytraeidae is possible at pF values ⩽ c. 3 (field capacity). In stations with permanently available water (pF ⩽ c. 3) the summer minimum is probably caused by lethal soil temperature (> c. 25-30° C for some time). In stations with a fluctuating capillary potential lethal pF values seem to be reached before lethal temperatures. Therefore, under Danish conditions, desiccation is probably a more important factor than temperature, although it is not possible to separate them.
- Subjects
ENCHYTRAEIDAE; MOISTURE; COLD (Temperature); CONDENSATION; RAINFALL; TEMPERATURE
- Publication
Oikos, 1955, Vol 6, Issue 2, p153
- ISSN
0030-1299
- Publication type
Article
- DOI
10.2307/3564852