Can lowland plants shifting upwards outcompete mountain plants in terms of pollination efficiency?

Many plant species are moving to higher elevations due to global warming, but the effects of these elevational shifts on plant-pollinator interactions are not well understood. This study aimed to examine how flower visitation and seed set of lowland plants change after they shift uphill, and whether they compete for pollinators with plants native to the mountains. We conducted an experiment using two plant groups: lowland species pre-planted in a greenhouse and transplanted to both lowland and mountain sites, and mountain species. Pollinators were recorded at lowland sites for planted species and at mountain sites for both planted and native species. We also used pan traps in white, yellow, and blue colours to collect pollinators at both sites. Afterwards, seed sets of the planted species were counted to compare pollination success between elevations. Flower visitation rates on planted species were not significantly affected by elevation, although pollinator abundance in pan traps was higher in the mountains. The pollinator spectrum varied across elevations and plant species, influenced by flower and pan trap colour. However, planted species produced more seeds at lowland sites, indicating higher pollination success there. Overall, we found no evidence of competitive advantage for range-shifting lowland species in terms of pollination.