Berendse Frank
Department of Landscape Ecology and Nature Management, University of Utrecht, Opaalweg 20, Utrecht, The Netherlands.
Oecologia. 1982 Apr;53(1):50-55. doi: 10.1007/BF00377135.
The model proposed in the first paper in this series predicts that in mixtures of plant species with different rooting depths there will be an inverse correlation between the relative crowding coefficient of the deep rooting species with respect to the shallow rooting one and the frequency of the deep rooting plants. Two field experiments are reported in which this phenomenon was observed. The first experiment involved Plantago lanceolata L. and Lolium perenne L. and the second involved Plantago lanceolata L. and Anthoxanthum odoratum L. In a third competition experiment between Plantago lanceolata L. and Anthoxanthum odoratum L. it was tested whether this observed phenomenon was indeed caused by the differences between the rooting depths of these species. The experiment was divided into one series where different rooting depths were possible and one series where gauze with a narrow mesh width prevented differences between rooting depths. In the series without gauze the predicted frequency-dependence of the relative crowding coefficient was observed, whereas in the series with gauze the relative crowding coefficient was independent of plant frequency. A comparison between the yields in the series with and without gauze suggests that in mixture Plantago is forced to utilize the nutrients from deeper soil layers, whereas this is not the case in monoculture. Although such phenomena complicate the description of the process investigated, it is concluded that the model proposed provides an approximate prediction of most results of the experiments which were carried out.
本系列第一篇论文中提出的模型预测，在具有不同扎根深度的植物物种混合物中，深根物种相对于浅根物种的相对拥挤系数与深根植物的频率之间将存在负相关关系。本文报道了两项观察到这种现象的田间试验。第一个试验涉及长叶车前（Plantago lanceolata L.）和多年生黑麦草（Lolium perenne L.），第二个试验涉及长叶车前和香茅（Anthoxanthum odoratum L.）。在长叶车前和香茅之间进行的第三个竞争试验中，测试了观察到的这种现象是否确实是由这些物种扎根深度的差异引起的。该试验分为一个不同扎根深度可能存在的系列和一个窄网眼纱布防止扎根深度差异的系列。在没有纱布的系列中，观察到了相对拥挤系数的预测频率依赖性，而在有纱布的系列中，相对拥挤系数与植物频率无关。有纱布和无纱布系列产量的比较表明，在混作中，车前被迫利用更深土壤层的养分，而在单作中则不然。尽管这些现象使所研究过程的描述变得复杂，但得出的结论是，所提出的模型对所进行的大多数实验结果提供了近似预测。
