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EFFECTS OF ENVIRONMENTAL GRADIENTS ON PLANT-HERBIVORE SYSTEMS OF WOODY PLANTS BELONGING TO THE FAGACEAE FAMILY

环境梯度对壳斗科木本植物植物-草食系统的影响

基本信息

批准号：
12440216
负责人：
KAMATA Naoto
金额：
$ 8.58万
依托单位：
Kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

Induced defense of plants, increase in fenolics and decrease in nitrogen following herbivory, is a widely recognized phenomenon in various plants. Influence of environmental clines on constitutive and induced defense of four species of Fagaceae species were studied. We tested a hypothesis that altitudinal-dependent outbreaks of the folivorous insects were caused by foliage properties in relation to environment clines along with altitude. Our results suggest that the foliage quality is one of the possible causes of site-dependent outbreaks of S. punctatella: During an increasing period, high quality food at outbreak sites promotes population growth of this insect. When beech trees suffer heavy defoliation in the non-outbreak areas, foliage quality deteriorates, which slows down S. punctatella population growth. In contrast, in outbreak areas, quality increases in the year following heavy defoliation, and this may promote population growth and outbreaks. A positive feedback process thus may operate among nutrient cycling, foliage quality and insect population growth. A fertilizing effect from herbivory was a proximate factor causing higher soil nitrogen availability in the outbreak area. Results of our experiment suggested that the amount of defensive compounds was controlled by the carbon-nutrient balance at a leaf level. The C/N balance is an important factor for biomass allocation and chemical defense. However, the effect of defoliation on the C/N balance in a plant is variable between species, probably leading to a species variability in herbivory responses.

植物的诱导防御，草食后酚类物质的增加和氮素的减少，是一种广泛存在于各种植物中的现象。研究了环境倾斜度对壳斗科4种植物构成防御和诱导防御的影响。我们验证了一种假说，即食叶性昆虫的暴发是由叶特性与环境斜率和海拔高度有关的。我们的结果表明，叶片质量是斑点跳甲暴发的可能原因之一：在一个增长期，暴发点的优质食物促进了斑点跳甲的种群增长。当山毛榉在非暴发地区遭受严重落叶时，树叶质量恶化，从而减缓了点滴虫种群的增长。相比之下，在暴发地区，在严重落叶后的第二年，质量会提高，这可能会促进人口增长和暴发。因此，在营养循环、叶片质量和昆虫种群增长之间可能存在一个正反馈过程。草食的施肥效应是导致暴发地区土壤氮素有效性较高的一个直接因素。我们的实验结果表明，在叶片水平上，防御性化合物的数量受到碳-养分平衡的控制。C/N平衡是生物量分配和化学防御的重要因素。然而，落叶对植物C/N平衡的影响在物种之间是不同的，可能导致物种对草食反应的差异。