The Role of Keystone Herbivores in Regulating Ecosystem Function: An Experimental Approach Using Long-Term Herbivore Removals

关键食草动物在调节生态系统功能中的作用：一种使用长期食草动物移除的实验方法本研究调查了两种主要的昆虫食草动物如何影响松柏林地。松针虫会使幼年松树落叶，而钻杆蛾则会杀死成熟树木的嫩枝。这些食草动物的影响是地区性的，似乎与环境压力呈正相关。利用两个长期的蛾类和鳞片清除试验(分别为15年和13年)，我们建议在三类树上考察食草动物的生态系统效应：1)被蛾或介壳虫侵染的易感树，2)每年至少13年从其上移走这些草食动物的敏感树，以及3)自然抗蛾或鳞片的树。通过比较有无慢性草食的树木/土壤系统，我们可以更好地了解草食动物如何影响美国西南部主要植被类型松柏林地的生产力和养分循环。

ABSTRACT9816001KochThe Role of Keystone Herbivores in Regulating Ecosystem Function: An Experimental Approach Using Long-Term Herbivore RemovalsThis study examines how two major insect herbivores impact pinyon pine-juniper woodlands. The pinyon needle scale insect defoliates juvenile pines while the stem-boring moth kills shoots of mature trees. The impact of these herbivores is regionally extensive and appears to be positively correlated with environmental stress. Taking advantage of two long-term moth and scale removal experiments (15 and 13 years, respectively) we propose to examine the ecosystem effects of herbivory in experimental plots with three classes of trees, 1) susceptible trees infested with moth or scale insects, 2) susceptible trees from which these herbivores have been removed annually for at lease 13 years and 3) trees that are naturally resistant to moth or scales. By comparing tree/soil systems with and without chronic herbivory, we can better understand how herbivores affect productivity and nutrient cycling in pinyon-juniper woodlands, a major vegetation type of the southwestern United States.