Exploring the interactions between insect pollinators and native plants, across an altitudinal gradient in the Blue Mountains

Abstract

Climate change is threatening biodiversity and ecosystem processes. Whilst the impacts on populations and species have been documented, the response of communities and plant-animal interactions is largely unknown. An altitudinal gradient can be used as a model for climate change, as temperature decreases with increasing altitude. This study explores the diversity and abundance of insect pollinators of flowering native plants, along with the species-level specificity across an altitudinal gradient in the Blue Mountains. It was hypothesised that (1) Flies will be more abundant at higher altitudes and bees will be more abundant at lower altitudes. (2) The diversity of flies will increase with altitude and the diversity of bees will decrease with altitude. (3) The specificity of flies and bees will differ between altitudes. Direct observations were performed on flowering plants to determine the most frequent floral visitors, and pan trapping sampled the pollinator assemblage at each site. Insects were sorted into Recognisable Taxonomic Units (RTUs) based on morphology. The main findings of this study were supportive of the hypotheses by revealing that altitude can significantly influence pollinator abundance and diversity. Bees were found to be more abundant and diverse at lower altitudes, whilst flies were more abundant and diverse at higher altitudes. The results were an indication that different groups of insect taxa will respond differently to future changes in climate. Results also revealed that altitudinal gradients can be used as an effective model for climate change by establishing which species may be more vulnerable to warming. Species of pollinators that were widespread and generalist are more likely to be able to adapt to a changing environment compared to pollinators that are highly specialist and restricted to a particular altitudinal band. These findings have strong implications towards improving our understanding of how terrestrial ecosystems may be more or less adapted to warming.

Date of Award	2017
Original language	English