Die Kleinnager in Rekultivierungsgebieten des rheinischen Braunkohlenreviers: Wiederbesiedlung und Einfluss auf die forstliche Rekultivierung.
1987
Halle S.
The immigration of small rodents in an afforestation area was investigated by continuous trapping. Apodemus sylvaticus and Microtus arvalis, the dominant species of rodents in the nearby farmland, were present in the younger areas. Five years after afforestation Microtus agrestis, Clethrionomys glareolus and Apodemus flavicollis gradually penetrated into the region from the contiguous woodland. A. sylvaticus was found to be the characteristic small mammal of younger grounds, steady colonization occurred in the second year after afforestation. The maximum density during autumn was 100 ind./ha, which is unusually high. M. arvalis preferred plots dominated by gramineas, however on the forested sections, populations remained unstable and were dependent on continuous immigration. Their maximum density amounted to 60 ind./ha which is rather low for this species. We calculated that in 1 ha 133 kg faeces, 33 l urine and 52 kg of fine chaff were produced per year, with subsequent positive effects on soil development and nutrient turn-over. An average of 5550 holes/ha was counted, and the burrow system was calculated to be about 2300 m/ha. This tube system improves soil ventilation, and faciliates the infiltration of moisture. Gnawing caused yearly damage of 0.4 per cent of the standing growth, and could therefore be neglected. Gnawing at the roots by M. arvalis was the most common damage.
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