Fox Laurel R, Morrow P A
Department of Biology, University of California, 95064, Santa Cruz, CA, USA.
Department of Ecology, Evolution and Behavior, and Department of Plant Biology, University of Minnesota, 55455, Minneapolis, MN, USA.
Oecologia. 1992 Feb;89(2):214-222. doi: 10.1007/BF00317220.
We manipulated soil fertility and insect attack for two species of Eucalyptus in natural stands of subalpine woodland on shallow, infertile granitic soils. E. pauciflora and E. stellulata responded in similar ways to simultaneous insecticide and fertilizer treatments. Eliminating herbivorous insects produced the largest changes - improved plant growth, increased leaf N and P, and reduced leaf specific density. Fertilizer regime modified some leaf properties, but had little effect on tree growth. E. stellulata trees were initially shorter than E. pauciflora, but grew faster without herbivores; by the end of the experiment both species were the same size when herbivores were removed. Foliage N and P levels increased most in trees with the most balanced fertilizer addition (NPK), and increased in all trees protected from insects, regardless of fertilizer regime. In this system, herbivorous insects exacerbated the effects of nutrientpoor soils, and may affect dominance of Eucalyptus species in mature forests.
在亚高山林地的天然林分中，我们在浅薄、贫瘠的花岗岩土壤上，对两种桉树进行了土壤肥力和虫害处理。多花桉和小叶桉对同时进行的杀虫剂和肥料处理的反应相似。去除食草昆虫产生的变化最大——植物生长改善、叶片氮和磷含量增加、叶片比密度降低。施肥方式改变了一些叶片特性，但对树木生长影响不大。小叶桉最初比多花桉矮，但在没有食草动物的情况下生长更快；到实验结束时，去除食草动物后两种树大小相同。在添加最均衡肥料（氮磷钾）的树木中，叶片氮和磷水平增加最多，并且在所有免受虫害的树木中都有所增加，与施肥方式无关。在这个系统中，食草昆虫加剧了土壤养分贫瘠的影响，并可能影响成熟森林中桉树种的优势地位。
