Larson D W
Department of Botany, University of Guelph, N1G 2W1, Guelph, Ontario, Canada.
Oecologia. 1984 Apr;62(1):118-125. doi: 10.1007/BF00377384.
Umbilicaria muhlenbergii and Umbilicaria papulosa are two similar lichens which show extensive habitat overlap. Current theory predicts that for those resources that are limited, and of critical importance to both species, segregation is demand for or use of those resources ought to be present. Controlled experiments showed that the upper and lower cortical surfaces of the two species functioned in very different ways so that U. muhlenbergii is wetted most rapidly by runoff and mist-like precipitation whereas U. papulosa is wetted most rapidly by large raindrops. An analysis of the meteorological conditions in the natural habitat for the two lichens shows that the four months providing significant productivity in U. papulosa are the same months with a very high frequency of thunderstorms (which produce large drops). Conversely, the months which produce the greatest production in U. muhlenbergii are spread out over most of the year. When water is supplied after periods of dryness, the two species absorb it at different times and from different sources. This difference supports current ideas about niche segregation in plants but represents the first time it has been demonstrated for lichens.
穆氏脐衣和丘疹脐衣是两种相似的地衣，它们的栖息地有广泛重叠。当前理论预测，对于那些有限且对两个物种都至关重要的资源，应该存在对这些资源的分隔需求或使用差异。对照实验表明，这两个物种的上下皮层表面功能差异很大，因此穆氏脐衣通过径流和雾状降水最快被湿润，而丘疹脐衣通过大滴雨水最快被湿润。对这两种地衣自然栖息地气象条件的分析表明，丘疹脐衣具有显著生产力的四个月与雷暴（产生大滴雨水）频率非常高的月份相同。相反，穆氏脐衣产量最高的月份分布在一年的大部分时间里。在干旱期后供水时，这两个物种在不同时间从不同来源吸收水分。这种差异支持了当前关于植物生态位分隔的观点，但这是首次在地衣中得到证明。
