Global environmental changes in the high tropical Andes

The high tropical Andes harbours vital ecosystems that sustain biodiversity, carbon storage, and environmental service provision for millions of people. They are identified as one of the most vulnerable terrestrial ecosystems to global environmental changes, particularly to climate change and land use conversion. Despite their vulnerability and the importance of global biodiversity conservation and Andean societies, they are among the least studied ecosystems in the world. In this thesis, I studied the patterns of summit plant community's across the tropical section of the Andes. Further, I studied what environmental factors influence plant community composition, species diversity, and thermal niche traits in high tropical alpine ecosystems. Based on the thermal niche traits, I assessed the potential vulnerability of species and communities to climate warming, considering the effect of the climate variability hypothesis on the species niche breadths. Further, I synthesised the current state of knowledge and assessed the current and projected landscape changes in the high Andes due to the combined effect of glacier retreat and climate warming. I reviewed documented glacier changes and landscape evolution over past decades to millennia and assessed projected future glacier shrinkage until 2100 for two case studies in the Andes of Ecuador and Peru. I also evaluated the capacity of high Andean ecosystems to recover from land use changes using the aptitude to store and take up carbon together with plant diversity. Lastly, I carried out an applied research analysis aimed at informing conservation policy formulation in continental Ecuador through defining critical areas for biodiversity conservation.