Resource allocation in Eucalyptus

  • Courtney E. Campany

Western Sydney University thesis: Doctoral thesis

Abstract

Plants must utilize external resources including light, CO2, water and mineral nutrients to support photosynthetic carbon (C) gain. This photoassimilate is then allocated within the plant as the essential C resource for growth, maintenance and storage. Theory and observations suggest that C allocation and leaf physiology are optimized to maintain functional balance for external resource capture and to maximize C gain. However, the impacts of a changing climate may disrupt the proposed balance of C allocation between above and belowground pools. Variation in resource distribution and leaf physiology within tree canopies is also not fully understood, thus all canopy leaves may not follow theories of leaf optimal behavior. This lack of understanding regarding C uptake and the fate of assimilated C inhibits our ability to precisely test the coordination between canopy photosynthesis and growth. To address these broad ecological questions, this PhD research utilized a diverse set of experiments which manipulated resource availability and climate factors on Eucalyptus tree species. My goal was to measure aspects of resource allocation and C uptake across different scales, from leaf to whole tree, to improve understanding of the physiological processes which determine tree growth and the sensitivity of these processes to changing environments. This PhD research addressed interrelated questions regarding resource allocation in Eucalyptus tree species by linking leaf physiology to whole canopy C gain and allocation of photosynthetic C to whole tree growth. This study confirms that the distribution of photosynthetic resources constrain canopy C uptake, yet within canopy leaf physiology does not follow prevailing optimal theory regarding water use. Results from this work reveal how quantifying the fate of photosynthetic C among tissue pools, beyond biomass production, is imperative to accurately assess the impacts of environmental change on tree productivity. This research offers critical empirical data needed to refine process based models which predict canopy C gain from rates of An and forest growth models where C allocation is represented. Ultimately, this work contributes valuable information regarding the physiological and growth responses of Eucalyptus tree species essential for reconciling the impacts of resource availability and global climate change on Australian ecosystems and the productivity of Eucalyptus plantation forests.
Date of Award2016
Original languageEnglish

Keywords

  • Eucalyptus
  • ecology
  • climatic factors
  • climatic changes
  • Australia

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