Schädler Martin, Jung Gertraud, Brandl Roland, Auge Harald
Department of Community Ecology, UFZ Centre for Environmental Research Leipzig-Halle, Theodor-Lieser-Strasse 4, 06120 Halle, Germany.
Oecologia. 2004 Jan;138(2):242-52. doi: 10.1007/s00442-003-1425-y. Epub 2003 Oct 18.
We investigated the effects of insect herbivory on a plant community of a productive old-field community by applying foliar and soil insecticides in a full factorial design. During the first 3 years of succession, insecticide treatments had only minor effects on total cover abundance and species richness. However, species ranking within the plant community was strongly affected by soil insecticide but not by foliar insecticide. Creeping thistle, Cirsium arvense, dominated the experimental plots with reduced root herbivory, while square-stemmed willow-herb, Epilobium adnatum, dominated the control and the plots with foliar insecticide. When soil insecticide was applied, cover abundance of monocarpic forbs increased and cover abundance of polycarpic herbs decreased compared to the control. However, this effect was due to a few abundant plant species and is not based on a consistent difference between life history groups. Instead, application of soil insecticide promoted persistence of species that established at the start of succession, and suppressed species that established in the following years. We conclude that below-ground herbivory reduces competitive ability of resident species and, thus, facilitates colonization by late-successional species. Hence, soil insects can exert strong top-down effects on the vegetation of productive sites by affecting dominant plant species and altering competitive balances.
我们通过采用全因子设计施用叶面和土壤杀虫剂，研究了昆虫取食对一个高产弃耕地群落植物群落的影响。在演替的前三年，杀虫剂处理对总盖度丰度和物种丰富度仅有轻微影响。然而，植物群落内的物种排名受土壤杀虫剂的强烈影响，而不受叶面杀虫剂的影响。匍匐蓟（Cirsium arvense）在根系取食减少的实验地块中占主导地位，而方茎柳叶菜（Epilobium adnatum）在对照地块和施用叶面杀虫剂的地块中占主导地位。与对照相比，施用土壤杀虫剂时，单次结果的多年生草本植物的盖度丰度增加，多次结果的草本植物的盖度丰度降低。然而，这种影响是由少数丰富的植物物种导致的，并非基于生活史组之间的一致差异。相反，施用土壤杀虫剂促进了演替开始时建立的物种的持久性，并抑制了随后几年建立的物种。我们得出结论，地下取食降低了本地物种的竞争能力，从而促进了后期演替物种的定殖。因此，土壤昆虫可以通过影响优势植物物种和改变竞争平衡，对高产场地的植被产生强烈的自上而下的影响。
