Hjältén Joakim
Department of Wildlife Ecology, Swedish University of Agricultural Sciences, S-901 83, Umeå, Sweden.
Oecologia. 1992 Feb;89(2):253-256. doi: 10.1007/BF00317225.
To evaluate the general extent to which sex-related differences in palatability occur in boreal dioecious woody plants, males and females of five dioecious woody plant species were presented to free-ranging mountain hares (Lepus timidus) during winter. Hares strongly preferred branches from male plants when feeding on Populus tremula and Salix caprea and weakly preferred male S. pentandra. However, they did not show any sex-related preference when feeding on the other two species studied (Myrica gale and Juniperus communis). Nitrogen concentration and, to some degree, digestibility showed strong relationships with hare food preferences. By contrast, the concentration of phenolics was only weakly related to feeding preference. Phenolics could, nevertheless, still be important if only one or a few specific compounds deter hare feeding. These results indicate that sex-related differences in plant palatability in the boreal forest might be more widespread than previously believed, particularly for species of the family Salicaceae. Thus, herbivores might be responsible for the female-biased sex ratios found in willow populations in northern Scandinavia (e.g. Elmqvist et al. 1988).
为了评估北方雌雄异株木本植物中适口性的性别差异普遍程度，在冬季，将五种雌雄异株木本植物的雄性和雌性植株提供给自由放养的山地野兔（Lepus timidus）。野兔在取食欧洲山杨和欧洲花楸时强烈偏好雄性植株的枝条，对雄性五蕊柳的偏好较弱。然而，在取食另外两种研究物种（杨梅和杜松）时，它们未表现出任何与性别相关的偏好。氮浓度以及在某种程度上的消化率与野兔的食物偏好密切相关。相比之下，酚类物质的浓度与取食偏好的相关性较弱。不过，如果只有一种或几种特定化合物阻止野兔取食，酚类物质可能仍然很重要。这些结果表明，北方森林中植物适口性的性别差异可能比以前认为的更为普遍，尤其是杨柳科的物种。因此，食草动物可能是导致斯堪的纳维亚北部柳树种群中雌性偏多的性别比例的原因（例如，Elmqvist等人，1988年）。
