Plant-Pollinator Interactions in a Northwest Arum Related to Plant Traits but Not Riparian Forest Management

Studies in Pacific Northwest riparian forests highlight the role of forest management in conserving target species, but rarely consider impacts on interspecies relationships such as pollination. We investigated plant-pollinator interactions among a native species of rove beetle, Pelecomalius testaceum, and a widespread native wetland plant species in the Pacific Northwest, Lysichiton americanus (western skunk cabbage), in an experimental framework comparing three riparian forest management regimes. Our study addressed the central question: what factors best predict pollinating beetle abundance on L. americanus in a managed Northwest landscape? We measured P. testaceum abundance on skunk cabbages in three riparian treatments in a managed forest: (1) an unlogged riparian zone, (2) a logged riparian zone with a limited buffer corridor, and (3) a clear-cut riparian zone with no remaining corridor. Across this diversity of forest treatments, we also measured inflorescence temperature, foliar damage, and plant sex. Beetle abundance was not responsive to forest management when compared across all sites, but was predictable by plant sex, geographic site, and foliar damage to plants. Beetle abundance was insensitive to temperature. Additionally, any potential responses to forest management were idiosyncratic and variable depending on plant sex. These results support the general idea that plant-pollinator interactions may be more dependent on traits of host plants than direct effects of forest management.