Burning giants in the tropics

Burning giants in the tropics

Hot Topics in Ecology

Burning giants in the tropics

DYP Tng, GJ Jordan and DMJS Bowman, University of Tasmania.
Rainforest in the understories of Rose Gum forest - natural phenomena or management problem?

The need to maintain a mosaic of rainforest and eucalypt forest in the Australian Wet Tropics World Heritage Area poses a perplexing conundrum for land managers. Rose Gum (Eucalyptus grandis) dominated giant eucalypt forests at the margins of World Heritage tropical rainforests are habitats for threatened marsupials like the Yellow-Bellied Glider. Rainforest developing in the understoreys of these forests is believed to threaten the dominant overstorey eucalypts and associated fauna. Land managers prescribe frequent low-intensity fires to try to stop rainforest species from establishing in Rose Gum forests understory. However, these practices are not consistent with the ecology of Rose Gum forest:

1. Rose Gums are obligate seeders and need rare, large, high-intensity landscape fires for successful regeneratation. Low-intensity fires do not stimulate Rose Gum regeneration because they do not release seeds stored in the canopy or create conditions suitable for initial growth. Repeated fires may kill young Rose Gum trees that do not have fully developed bark and these fires can reduce the protective capacity of the bark of mature trees.

2. Under current climatic conditions, rainforest expansion averages 0.6m/decade, and is occuring across all landscape conditions likely due to a global driver like increased atmospheric CO2. Using low-intensity fire to control this process is difficult because rainforest will only burn under exceptional conditions. Also, many rainforest species recover from a single fire. Natural and rare high-intensity fires will likely enable Rose Gum regeneration throughout the landscape.

The landscape ecology and plant functional biology of Rose Gum forest suggest that they are ecologically like secondary rainforest. Abstaining from prescribed burning and letting Rose Gum forests regenerate naturally from rare large fire events best approximates their regeneration ecology.

Hot Topic Lead Author: 
Name: David YP Tng
Email: davetngcom@gmail.com
Phone: 0448740116

Name: Gregory J Jordan
Email: Greg.Jordan@utas.edu.au
Phone: +61 3 6226 7237

Name: David M.J.S. Bowman
Email: David.Bowman@utas.edu.au
Phone: +61 3 6226 1943

ID Title Location Type
6891 Bowman D.M.J.S., Murphy B.P., Boer M.M., Bradstock R.A., Cary G.J., Cochrane M.A., Fensham R.J., Krawchuk M.A., Price O.F. & Williams R.J. (2013) Forest fire management, climate change, and the risk of catastrophic carbon losses. 11, 66-67. Australia and localities in the United States of America Review paper
6883 Harrington G.N. & Sanderson K.D. (1994) Recent contraction of wet sclerophyll forest in the wet tropics of Queensland due to invasion by rainforest. Pacific Conservation Biology, 1, 319-327. Far North Queensland, Australia Natural experiment
6884 Little J.K., Prior L.D., Williamson G.J., Williams S.E. & Bowman D.M.J.S. (2012) Fire weather risk differs across rainforest - savanna boundaries in the humid tropics of northeastern Australia. Aust Ecol, 37, 915-925. Far North Queensland, Australia (8 sites) Natural experiment
6885 Stanton P, Parsons M, Stanton D & Stott M. (2014) Fire exclusion and the changing landscape of Queensland’s Wet Tropics Bioregion 2. The dynamics of transition forests and implications for management Australian Forestry, 77, 58-68. Far North Queensland, Australia Review paper
6886 Stanton P, Stanton D, Stott M & Parsons M. (2014) Fire exclusion and the changing landscape of Queensland’s Wet Tropics Bioregion 1. The extent and pattern of transition. Australian Forestry, 77, 51-57. Far North Queensland, Australia Natural experiment. GIS mapping, before-and-after temporal comparison of rain forest extent
6887 Unwin GL. (1989) Structure and composition of the abrupt rainforest boundary in the Herberton Highland, north Queensland. Australian Journal of Botany, 37, 413-428. Herberton Highlands, Far North Queensland, Australia Natural experiment
6888 Warman L. & Moles A.T. (2009) Alternative stable states in Australia's Wet Tropics: a theoretical framework for the field data and a field-case for the theory. Landscape Ecology, 24, 1-13. Far North Queensland, Australia Review paper
6889 Williams P.R., Parsons M., Jensen R. & Tran C. (2012) Mechanisms of rainforest persistence and recruitment in frequently burnt wet tropical eucalypt forests. Austral Ecol. 37, 268-275. Far North Queensland, Australia Natural experiment
6811 Tng D. Y. P., Williamson G. J., Jordan G. J. & Bowman D. M. J. S. (2012) Giant eucalypts – globally unique fire-adapted rain-forest trees?. New Phytol. 196, 1001-1014. Eastern and Southwest Australia including Tasmania Review paper
6812 Tng D. Y. P., Murphy B. P., Weber E., Sanders G., Williamson G. J., Kemp J. & Bowman D. M. J. S. (2012) Humid tropical rain forest has expanded into eucalypt forest and savanna over the last 50 years. Ecol. Evol. 2, 34-45. Mt Windsor, Mt Carbine, Clohesy, Koombooloomba, and Paluma. NE Qld, Australia Natural experiment. GIS mapping, before-and-after temporal comparison of rain forest extent, and predictive projection of rain forest into surrounding habitat
6813 Tng D. Y. P., Jordan G. J. & Bowman D. M. J. S. (2013) Plant traits demonstrate that giant eucalypt forests are ecologically convergent with rainforest not savanna. PLoS One 8, e84378. Davies Creek, Mt Baldy, and Paluma. NE Qld, Australia Natural experiment comparing plant functional traits of representative tree species across rain forest - open forest boundaries.
6814 Tng D. Y. P., Goosem S., Jordan G. J. & Bowman D. M. J. S. (2014) Letting giants be– rethinking active fire management of old growth eucalypt forest in the Australian tropics. J. App. Ecol. (in press). Northeastern Southwest Australia Review paper