Pollinator Mediated Dynamics: Evaluating Native Plant Community Resilience in the face of Plant Invasion

This thesis explores the ecological impact of non-native plant species on native plant populations and pollination dynamics, focusing on shifts in species distribution and abundance over time. A multi-pronged approach was adopted to explore this research question - a meta-analysis, an experimental study in the Western Himalayas and drawing on data from the UK Countryside Survey (1990, 2007, 2023). The meta-analysis identifies trends in how non-native species affect the pollination services of native plants, revealing that while some non-native species exert competitive pressure on native species, others facilitate pollination of natives through providing beneficial resources. In the Western Himalayas, the experimental removal of a non-native species demonstrated that its presence significantly affected the native plant-pollinator interactions. This work underscores the complexity of species interactions in invaded ecosystems and highlights the importance of adaptive management strategies to prioritize the most ecologically harmful invaders. The analysis of the UK Countryside Survey further reveals shifts in the distribution and abundance of native, archaeophyte, and neophyte species. Contrary to expectations, the study found no significant direct competition between native and non-native species based on their pollination modes. The rolling cycle of surveys between 2019 and 2023 marks the most recent stage of species monitoring, showing that changes in landscape-scale species cover are ongoing but not uniformly influenced by the introduction of non-native plants.
Overall, this thesis contributes to our understanding of the nuanced roles non-native species play in plant-pollinator interactions, demonstrating that while some can be detrimental, others can support native biodiversity under certain conditions. These findings have implications for the management of non-native species and the conservation of pollination services in both temperate and tropical ecosystems.