Interactions among elk, aspen, galling sawflies and insectivorous birds

摘要: Using two years of observational and experimental data, we examined the hypothesis that browsing by elk on aspen indirectly affects distribution a leaf-galling sawfly, which in turn insect diversity foraging patterns insectivorous birds. We found that: i) an analyses 33 arthropod species, presence sawflies significantly increased richness abundance 2 X 2.5 X, respectively. ii) reduced sawfly gall such 90% galls were unbrowsed ramets. iii) birds attacked 60‐74% shoots compared to 11% browsed shoots. When leaf-galler was experimentally held constant shoots, predation did not differ significantly. This result suggests avian altering galling insect. These data argue bottom-up, top-down, lateral factors can act concert affect galler, structure communities