Identifying Plant Functional Traits to Assist Ecological Intervention in a Drying Landscape
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Edith Cowan University Research Online Theses: Doctorates and Masters Theses 2016 Identifying plant functional traits to assist ecological intervention in a drying landscape Ana Luiza Muler Edith Cowan University Follow this and additional works at: https://ro.ecu.edu.au/theses Part of the Ecology and Evolutionary Biology Commons, Environmental Studies Commons, and the Plant Sciences Commons Recommended Citation Muler, A. L. (2016). Identifying plant functional traits to assist ecological intervention in a drying landscape. https://ro.ecu.edu.au/theses/1944 This Thesis is posted at Research Online. https://ro.ecu.edu.au/theses/1944 Edith Cowan University Copyright Warning You may print or download ONE copy of this document for the purpose of your own research or study. The University does not authorize you to copy, communicate or otherwise make available electronically to any other person any copyright material contained on this site. 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Identifying plant functional traits to assist ecological intervention in a drying landscape This thesis is presented for the degree of Doctor of Philosophy Ana Luíza Muler Edith Cowan University School of Science 2016 DECLARATION I certify that this thesis does not, to the best of my knowledge and belief: i. incorporate without acknowledgment, any material previously submitted for a degree or diploma in any institution of higher education; ii. contain any material previously published or written by another person except where due reference is made in the text of this thesis; iii. contain any defamatory material; or iv. contain data that have not been collected in a manner consistent with ethics approval. Ana Luiza Muler August 2016 ii ABSTRACT Mediterranean-type ecosystems (MTEs) are among the most vulnerable to land use and climate change and many attempts are in place to restore these ecosystems. Therefore, it is necessary to assess differences in plants’ ability to withstand water-stress, including biotic interactions. Such knowledge helps us understand community assembly, which is crucial for ecological intervention. This study involved: (1) reviewing the literature on traits that can differentiate functional types; (2) adapting the methodology to measure leaf water potential at turgor loss point (πtlp) for small-leaved species; (3) using these traits to quickly identify water-use strategies of adult plants from Southwest Australia; (4) identifying the water-use strategies that juveniles have to survive first summer drought; and (5) determining whether there is facilitation between a deep-rooted species and seedlings through hydraulic redistribution. The selection of functional response traits was based on their association with water-stress, with effect traits, and on methodologies that are easy, inexpensive and applicable for Mediterranean species. Relevant traits were identified from the literature, including: leaf carbon isotope composition, leaf nitrogen and phosphorus contents, leaf mass per area, πtlp, and xylem vessel morphology. Measurements of πtlp through osmometry of extracted sap and through Pressure-volume curves were compared. Selected traits were then measured for 15 species from different eco-hydrological habitats. Drought resistance of juveniles was assessed by measuring water relations, rooting depth/pattern and carbon reserves use of species from different eco-hydrological habitats. Lastly, seedlings were grown isolated or near donor plants. Water status and growth were measured, and stable isotopes were used to investigate water pathways within and between plants. A strong correlation between the methodologies for measuring πtlp was found. With analysis of these traits, it was possible to cluster adult species, from the Swan Coastal plain, into five functional groups that corresponded to their rooting depths. During drought, Banksia seedlings reduced stomatal conductance and appeared to use carbon reserves, whereas Gompholobium tomentosum seedlings tolerated higher water deficits, despite reduced stomatal conductance. Lastly, although seedlings were able to absorb hydraulically redistributed water, they grew, transpired and survived more when isolated from the deep-rooted plant. iii In the literature review, theoretical analyses on functional traits and speculations on functional groups were made through a conceptual diagram. The osmometry technique is a suitable replacement for Pressure-volume curves since its estimations of πtlp were accurate in small and large-leaved species. The functional traits approach can be transferable to other MTEs for application by restoration practitioners, as the traits selected were effective in determining functional groups, and were relatively easy and cost effective. The seedlings’ responses to summer drought were consistent with their habitats and root-depth, which is an important factor for niche differentiating and community assembly. Competition between seedlings and deep-rooted plants supported the updated stress-gradient hypothesis. In conclusion, analyses of water-use strategies of Mediterranean species during summer allow predictions of differences in drought resistance. When this functional approach is applied for ecological intervention, restoration practitioners can select species with a better match to future environmental conditions of MTEs, particularly in large species sets. iv ACKNOWLEDGMENTS There are many people that helped me through this journey and that without them I would not have completed this thesis. First, I would like to thank my family for all the support. In special my mum, who has always showed me the importance of studying. Thank you mum, education can indeed transform a person; it is freedom, you were right! Also, I thank my dad and sisters, who also motivated me to persuade my dreams. I made great friends during my time in school that I also would like to thank: Luisa Cardoso, Luciana Lazzarini, Bruno Vaz, Roberto Hatada, Demian Alves, Rafael Dedos, Leandro Costa, Caio Pereira, and many others from Anglo school that shared special moments with me. From the State University of Campinas, I would like to thank a special group called “06N”, named by all students that started Uni in 2006 at evening time. We attended to many lectures, practical laboratories and fieldwork together. We studied together for difficult exams and party a lot too. I will never forget it. I would have done it all again with you guys! Thanks so much! Also, I would like to thank all my housemates during my graduation. It was incredible! In special Flávia Paniz, who I had to share the bedroom with, and used to wake me up with her night studying of social sciences. Thanks Flá to keep me informed of all events, politics and conflicts in the world. I wish I could have had you around here in Australia. I had an amazing experience with teaching in a non-profit school, dedicated to people who cannot afford education in Brazil. I learned a lot with all the other teachers and with the students. All those days of experimenting and teaching made be a richer person, many thanks to all from “via popular” school. Also, I was lucky to have spent some time participating on the research group of the professor Rafael Oliveira at State University of Campinas. Thank you, Rafael, for your kindness; you were the first to show me the amazing things plants can do! I really appreciated the group meetings and endless fieldwork. Thanks to all the students from this group of research, it was a great experience! I learned so much in that time that made me think of ecosystems in a different way. It got me so excited that I end up coming to Australia to study a fascinating ecosystem in Southwest Australia. First, I did Honours under the supervision of Hans Lambers and Erik Veneklaas, who helped me with different tasks: Improving my English, understanding Ecophysiology, and conducting a research project. I really appreciated it, thank you once again for all the great help! v I would like to thank my supervisors at Edith Cowan University, Eddie J.B. van Etten, William D. Stock and Raymond H. Froend, who assisted me through my PhD. Special thanks to Caroline Canham for all the great help in the field, laboratory and with helpful discussions about my results. Without you, I would not have concluded this thesis. Thank you so much! I also would like to thank all the technicians at ECU for the great help with all practical concerns of my experiments. I have learnt a lot with you! Many thanks! I am also very grateful to Christopher Kavazos for helping me with all the multivariate analyses, also in the field, in the lab and driving that enormous car! I cannot thank you enough for all that! Also, I would like to thank all my friends from ECU: Maryam Abdolahpour, Flavia Tarquinio, Pierre Bouvais and many other postgraduate students. Thanks so much! Finally, but most importantly, I thank my partner Bruno. You were and will always be an inspiration to me. Your passion for science and nature is contagious! I couldn’t be happier sharing a life with a person like you! Thanks for all the endless support (and patience)! vi LIST OF PUBLICATIONS INCLUDED AS PART OF THE THESIS This thesis is presented as a series of manuscripts that are to be submitted for publication in international journals.