Vulnerability and adaptive capacity of Proteaceae family to drought

Abstract

Climate change is increasing drought events with implications for primary production and biodiversity, including ecosystem function and resilience. Severe drought stress can lead to species vulnerability to mortality with forest dieback and local extinction in the future. Predicting vulnerability of plant lineages to the impacts of drought remains a daunting task for scientists, with most predictions lacking information on the mechanistic basis of species persistence, physiological tolerance to climate variables, and adaptive capacity of species to climate change. Using an ancient and diverse plant group, the Proteaceae family, as a natural laboratory, I investigated the mechanistic basis of species persistence in drier biomes, physiological tolerance to drought, and adaptive capacity of genera to species and populations. I achieved these aims using a field-based common garden experiment (Chapter 2 and 3) and a water manipulation common garden experiment (Chapter 4). Overall, the findings of this thesis will provide empirical baseline data for future predictions, and scientific basis for adaptive management for Proteaceae, including conservation of threatened and widespread species. Based on the empirical evidence from Chapter 2 and 3, tolerance trait (stem P50) is adaptive and genetically determined thus reliable and robust for predicting species vulnerability to drought. I also provided physiological threshold data of six (6) threatened species, Grevillea hilliana, G. caleyi, G. barklyana, Hakea archaeoides, Persoonia acerosa, and P. hindii. The threatened species were all from humid biome; G. hilliana and G. caleyi were more vulnerable to drought among the threatened species thus might be a target for seedbanking and translocation. Persoonia acerosa and P. hindii were least vulnerability compared to other threatened species studied, however these species should still be monitored for dieback associated with drought. The findings of this thesis will be broadly applicable in developing a prioritization framework for species conservation under future drought scenarios.

Date of Award	2022
Original language	English