I am a plant ecophysiologist interested in mechanisms that permit plants to survive when times are tough. I focus on how the roughly 6% of plant species that exhibit a water-conserving type of photosynthesis known as crassulacean acid metabolism (CAM) respond to temperature, water-limitation and to changing concentrations of atmospheric CO2. I study Australian CAM clades, species in Central America (in collaboration with Klaus Winter at STRI, Panama), and most recently, SE Asian and New Guinea groups with collaborators in Singapore, PNG and Oxford. Australian species with CAM include many epiphytic orchids and hoyas, ant-plants, succulents of coastal and inland saline areas, temperate and tropical Calandrinia from across the continent, and a few fresh-water species.

I also (i) assist in evaluating growing Agave as a biofuel feedstock crop in the seasonally-dry tropics of Australia. AusAgave, an Australian industry partner, and I are trialling Agave for biomass production, a world first, and (ii) participate in a project that attempts to understand how Australian lowland rainforest may respond to increasing water-limitation.

Long-term projects include a census of Australian CAM species and determining how many orchids and Hoya exhibit CAM and what are the phylogenetic and environmental connections between those species.

In collaboration with Dr Jon Luly (JCU) and Prof Michelle Waycott (Adelaide), I am also attempting to understand the functional biology of Australia's tallest desert tree, Acacia peuce.

With Dr Irwan Lovadi, Tanjungpura University, and Simon Robson (CQU) I am evaluating just how sticky are sundews.

  • Carbon metabolism in CAM plants and tropical epiphytes
  • Responses of tropical plants to increasing atmospheric CO2
  • Physiology and ecology of Australian desert plants
  • Ecophysiology of Australian ant-plants
  • Biofuel feedstocks for the wet-dry tropics
  • Responses of tropical biomes to drought
  • 2012 to present - Research Associate, Smithsonian Tropical Research Institute (PAN)
  • 2012 to present - Professor, Tropical Biology, JCU (AUS)
  • 2004 to 2011 - Reader, Tropical Plant Sciences, JCU (AUS)
  • 2004 - Magdalen College Visiting Fellow, Oxford (UK)
  • 2003 - Queensland-Smithsonian Fellow, STRI (PAN)
  • 1996 to 2003 - Senior Lecturer, Tropical Plant Sciences, JCU (AUS)
  • 1993 to 1995 - Lecturer, Botany and Tropical Agriculture, JCUNQ (AUS)
  • 1987 to 1993 - Research Fellow, Waite Research Institute, University of Adelaide (AUS)
  • 1982 to 1987 - Wissenschaftlicher Mitarbeiter, Westfälische Wilhelms-Universität Münster (GER)
  • 1980 to 1982 - Post-doc, University of Wisconsin - Madison (USA)
  • 1975 to 1980 - PhD, Australian National University (AUS)
Research Disciplines
Socio-Economic Objectives

These are the most recent publications associated with this author. To see a detailed profile of all publications stored at JCU, visit ResearchOnline@JCU. Hover over Altmetrics badges to see social impact.

Journal Articles

ResearchOnline@JCU stores 75+ research outputs authored by Empro Joe Holtum from 1999 onwards.


These Higher Degree Research projects are either current or by students who have completed their studies within the past 5 years at JCU. Linked titles show theses available within ResearchOnline@JCU.

  • The effects of tropospheric ozone on tropical plant growth and functioning (PhD , Secondary Advisor)

These are the most recent metadata records associated with this researcher. To see a detailed description of all dataset records, visit Research Data Australia.


The map shows research collaborations by institution from the past 7 years.
Note: Map points are indicative of the countries or states that institutions are associated with.

  • 5+ collaborations
  • 4 collaborations
  • 3 collaborations
  • 2 collaborations
  • 1 collaboration
  • Indicates the Tropics (Torrid Zone)

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