Hot Topics in Ecology

Australia’s Seasonally Dry Tropical Forests need attention

Research on this underappreciated Australian biome lags behind rainforest and savanna
Synthesis by DYP Tng, DMG Apgaua, SGW Laurance, James Cook University, and DMJS Bowman, University of Tasmania
  • Seasonally dry tropical forests are gaining international prominence as an endangered biome, but their status in Australia is underappreciated
  • These forests often occur in unusual landscape settings and harbor unique and threatened biodiversity. The original extent of these forests is reduced and greater public awareness of their international significance and conservation value is needed
  • Research is still needed to properly delimit these forests and to understand their resilience to climate change and other threats
Profile of a putative Seasonally Dry Tropical Forest in semiarid northeast Australia. Inset: A visually similar forest in the Brazilian semiarid region

Seasonally dry tropical forests are among the least studied of tropical forests. However, in recent years these forests have become recognized as an endangered global biome of great economic and cultural importance. Despite this recognition, their status, range, and ecological value in Australia is still poorly appreciated, possibly because they are perceived to be species-poor derivatives of rainforests, and it has proved difficult to define and map their geographic extents.

In Australia, seasonally dry tropical forests grow in Western Australia, Northern Territory, Queensland and New South Wales, and they are often associated with unusual landforms like karsts, sandstone ravines and tablelands. These forests often exhibit dry-season deciduousness and unlike savanna, seasonally dry tropical forests harbor few grasses and they are fire-sensitive. Curious lifeforms such as bottle-shaped trees, prickly plants, and thicket-forming vines are also conspicuous in some areas.

Misleading local terms used to describe these forests, such as “Brush”, “Scrub” and “Vine thickets”, and confusingly “Dry rainforest” impedes development of national and global perspectives on the ecology and conservation status of these unique plant communities. Moving beyond local terms and seeing these forests as part of a global seasonally dry tropical forest biome will promote greater public awareness of their conservation value.

In Australia, around 75% of the original extent of these forests has been cleared. Although now largely protected, these forests still face various threats that often work synergistically, such as climate change, fire damage, mining, livestock damage and weed infestation. Ecological and biogeographical studies are therefore urgently needed to understand the resilience of seasonally dry tropical forests to multiple threats and to inform their conservation. 

Hot Topic Lead Author: 
Name: Dr David Tng
Email: davetngcom@gmail.com
Phone: 0422153916

Name: Dr Deborah Apgaua
Email: deborah.ufla@gmail.com
Phone: 0403964241

Name: Prof David Bowman
Email: david.bowman@utas.edu.au
Phone: 03 6226 1943

Name: Associate Professor Susan Laurance
Email: susan.laurance@jcu.edu.au
Phone: +61 7 423 21237

Date approved: 
Thursday, May 11, 2017 - 03:07
ID Title Location Type
9074 Apgaua, D. M. G., Santos, R. M. D., Pereira, D. G. S., Menino, G. C. D. O, Pires, G. G., Fontes, M. A. L. & Tng, D. Y. P. (2013) Beta-diversity in seasonally dry tropical forests (SDTF) in the Caatinga Biogeographic Domain, Brazil, and its implications Northeast Brazil Natural experiment
9075 Reis, G. H., Terra, M. C. N. S., Tng, D. Y. P., Apgaua, D. M. G., Coelho, P. A., Santos, R. M., Nunes, Y. R. F. (2017) Temporal vegetation changes in a seasonally dry tropical forest enclave in an ecotonal region between savanna and semiarid zones of Braz Northeast Brazil Natural experiment
9076 Sunderland, T., Apgaua, D., Baldauf C., Blackie R., Colfer, C., Cunningham, A. B., Dexter, K., Djoudi, H., Gautier, D., Gumbo, D., Ickowitz, A., Kassa, H., Parthasarathy, N., Pennington, R.T., Paumgarten, F., Pulla, S., Sola, P., Tng, D., Waeber, P., Wilm Global Review paper
9069 Gillieson, D. (2016) Natural heritage values of the Chillagoe and Mitchell-Palmer karst and caves Chillagoe-Mungana, North Queensland Review paper
9070 Moro, M. F., Eimear, N. L., de Araújo, F. S., Martins, F. R. (2016) A phytogeographical metaanalysis of the semiarid Caatinga Domain in Brazil. Botanical Reviews 82, 91–148. Brazil Pre-existing gradient
9071 Ratnam, J., Bond, W. J., Fensham, R. J., Hoffmann, W. A., Archibald, S., Lehmann, C. E., Anderson, M. T., Higgins, S. I., Sankaran, M. (2011) When is a ‘forest’a savanna, and why does it matter?. Global Ecology and Biogeography 20, 653-660. Global Review paper
9056 Curran, T. J., Clarke, P. J., Bruhl, J. J. (2008) A broad typology of dry rainforests on the western slopes of New South Wales. Cunninghamia 10, 381–405 Western New South Wales, Australia Pre-existing gradient
9057 DRYFLOR., Banda-R, K., Delgado-Salinas, A., Dexter, K. G., Linares-Palomino, R., Oliveira, A., Prado, D., et al. (2016) Plant diversity patterns in neotropical dry forests and their conservation implications. Science 353, 1383–1387. South America Pre-existing gradient and meta-analysis
9058 Fensham, R. J. (1995) Floristics and environmental relations of inland dry rainforest in north Queensland, Australia. Journal of Biogeography 22, 1047–1063. Queensland, Australia Pre-existing gradient
9059 Fensham, R. J. (1996) Land clearance and conservation of inland dry rainforest in north Queensland, Australia. Biological Conservation 75, 289-298. Queensland, Australia Pre-existing contrasts
9060 Fensham, R. J., Fairfax, R. J., & Cannell, R. J. (1994) The invasion of Lantana camara L. in forty mile scrub National Park, north Queensland. Austral Ecology 19, 297-305. Forty Mile Scrub, North Queensland Pre-existing contrasts
9061 Miles, L., Newton, A. C., Defries, R. S., Ravilous, C., May, I., Blyth, S., Kapos, V., Gordon, J. E. (2006) A global overview of the conservation status of tropical dry forests. Journal of Biogeography 33, 491–505. Global Pre-existing gradient
9062 Ondei, S., Prior, L. D., Williamson, G. J., Vigilante, T., & Bowman, D. M. (2017) Water, land, fire, and forest: Multi‐scale determinants of rainforests in the Australian monsoon tropics. Ecology and Evolution 7, 1592-1604. Western Kimberley Pre-existing contrasts, Correlational with no pre-determined gradient
9064 Särkinen, T., Iganc, I. J. R., Linares-Palomino, R., Simon, M. F., Prado, D. E. (2011) Forgotten forests-issues and prospects in biome mapping using Seasonally Dry Tropical Forests as a case study. BMC Ecology 11, 27. South America Review paper

Further information about this topic contact:

Dr David Tng
davetngcom@gmail.com
0422153916

Chair, Hot Topics Editorial Board
Dr Rachel Standish
R.Standish@murdoch.edu.au