From dangerous branches to urban banyan: Facilitating aerial root growth of Ficus rubiginosa

Autoři: Angela T. Moles aff001;  Ashika Jagdish aff001;  Yameng Wu aff001;  Suzanna Gooley aff001;  Rhiannon L. Dalrymple aff001;  Phoebe Feng aff001;  Jennifer Auld aff001;  Georgia Badgery aff001;  Matilda Balding aff001;  Andrew Bell aff001;  Nora Campbell aff001;  Mark Clark aff002;  Michelle Clark aff001;  Kyle M. Crawford aff001;  Oliver de Lorenzo aff001;  Amelia Fletcher aff001;  Zoe Ford aff001;  Haley Fort aff001;  Simon B. Z. Gorta aff001;  Alexander Hagan aff001;  Frank A. Hemmings aff001;  Gabriella S. Hoban aff001;  Thomasine Hulme aff001;  Kit King aff001;  Anish Kumar aff001;  Angelique Kyriazis aff001;  Beatrice Alexandra Laitly aff001;  Joshua Markovski aff001;  Len Martin aff001;  Geoffrey McDonnell aff001;  Cindy Pan aff001;  Ruby Paroissien aff001;  Polly Reeves-Perrin aff001;  Michi Sano aff001;  Sebastian M. Schwarz aff001;  Alena Sipka aff001;  Michael Sullings aff003;  Jing Wei Yeong aff001;  William K. Cornwell aff001
Působiště autorů: School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW, Australia aff001;  Estate Management, UNSW Sydney, Sydney, NSW, Australia aff002;  Sydney Arbor Trees, Botany, NSW, Australia aff003
Vyšlo v časopise: PLoS ONE 14(12)
Kategorie: Research Article


Large urban trees have many benefits. However, falling branches pose a serious hazard to both people and infrastructure. In several tree species, aerial roots grow down from branches to the ground. These roots are capable of thickening to support the branches, lessening the risk of tree failure. Unfortunately, in urban environments most aerial roots die before reaching the ground. Here, we report a new method for encouraging aerial roots to reach the ground, developed by the second-year botany class at UNSW Sydney. Our class tested three experimental treatments on aerial roots of Ficus rubiginosa Desf. ex Vent. (Port Jackson Fig)—PVC pipes filled with sphagnum moss, PVC pipes filled with potting mix, and PVC pipes filled with sphagnum moss and topped with funnels to catch extra rainwater. All three treatments significantly improved aerial root growth, with 26 of the 30 (87%) treatment roots reaching the ground after one year compared to 0 of the 10 control roots. Our method was successful for roots up to 3 m above the ground, suggesting the potential growth rate of aerial roots is substantial when conditions are favourable. Our novel approach is an attractive and cost-effective alternative to slings and other artificial supports. This project is an example of using undergraduate practical classes to teach science while simultaneously addressing important real-world problems.

Klíčová slova:

Mosses – Plant science – Polyvinyl chloride – Root growth – Trees – Undergraduates – Urban environments – Ficus


1. Vogt J, Hauer RJ, Fischer BC. The costs of maintaining and not maintaining the urban forest: a review of the urban forestry and arboriculture literature. Arboriculture & Urban Forestry. 2015;41(6):293–323.

2. Brookes A. Preventing death and serious injury from falling trees and branches. Journal of Outdoor and Environmental Education. 2007;11(2):50.

3. Paul BK. Human injuries caused by Bangladesh’s cyclone Sidr: an empirical study. Natural hazards. 2010;54(2):483–95.

4. Schmidlin TW. Human fatalities from wind-related tree failures in the United States, 1995–2007. Natural Hazards. 2009;50(1):13–25.

5. Easterling DR, Meehl GA, Parmesan C, Changnon SA, Karl TR, Mearns LO. Climate Extremes: Observations, Modeling, and Impacts. Science. 2000;289(5487):2068–74. doi: 10.1126/science.289.5487.2068 11000103

6. Henwood K. A structural model of forces in buttressed tropical rain forest trees. Biotropica. 1973:83–93.

7. Corner EJH. The climbing species of Ficus: derivation and evolution. Philosophical Transactions of the Royal Society of London Series B, Biological Sciences. 1976:359–86.

8. Beddie A. Root behaviour in Metrosideros. Bulletin of the Wellington Botanical Society. 1953;26:2–6.

9. Jenik J. Roots and root systems in tropical trees. Tropical trees as living systems. 2010:323.

10. Gill A, Tomlinson P. Aerial roots: an array of forms and functions. The development and function of roots: Torrey, J, G, Clarkson, D, T ed (s). …; 1975.

11. Mathews M, Wee M, Ho K. Growth and development of aerial roots of a tropical ornamental, Philodendron lacerum. J Hortic Sci. 1997;72(1):27–34.

12. Meyer CF, Zotz G. Do growth and survival of aerial roots limit the vertical distribution of hemiepiphytic aroids? Biotropica. 2004;36(4):483–91.

13. Zimmermann M, Wardrop A, Tomlinson P. Tension wood in aerial roots of ficus benjamina L. Wood Science and Technology. 1968;2(2):95–104.

14. Yang X, Deng W. Morphological and structural characterization of the attachment system in aerial roots of Syngonium podophyllum. Planta. 2017;245(3):507–21. doi: 10.1007/s00425-016-2621-4 27888361

15. Patino S, Gilbert GS, Zotz G, Tyree MT. Growth and survival of aerial roots of hemiepiphytes in a lower montane tropical moist forest in Panama. J Trop Ecol. 1999;15(5):651–65.

16. Ludwig F, Middleton W, Gallenmüller F, Rogers P, Speck T. Living bridges using aerial roots of Ficus elastica–an interdisciplinary perspective. Scientific Reports. 2019;9(1):12226. doi: 10.1038/s41598-019-48652-w 31439904

17. Bengough AG, Bransby MF, Hans J, McKenna SJ, Roberts TJ, Valentine TA. Root responses to soil physical conditions; growth dynamics from field to cell. J Exp Bot. 2005;57(2):437–47. doi: 10.1093/jxb/erj003 16317041

18. van Noort F. Vanilla in Dutch Greenhouses: A Discovery–From Research to Production. Handbook of Vanilla Science and Technology. 2018:157–63.

19. Alam A, Sharma V. Horticultural Importance of Bryophytes—A Review. International Journal of Horticulture. 2015;5(19):1–7.

20. Randwick City Council. Register of Significant Trees. In: LTD PbLP, editor. Significant Trees: Other Government authorities, Institutional, Religious and Non-government Organisations2007.

21. UNSW Sydney. Sustainability Report 2016. Sustainability USa; 2016.

22. Fern K. Tropical Plants Database: Ficus rubiginosa 2018 [2018-12-02]. Available from: <>

23. Bates D, Mächler M, Bolker B, Walker S. Fitting Linear Mixed-Effects Models Using lme4. Journal of Statistical Software. 2015;67(1):1–48. doi: 10.18637/jss.v067.i01

24. Fife D. Fifer: a Biostatisticians Toolbox for Various Activities, Including Plotting, Data Cleanup, and Data Analysis. R package version. 2017;1.

25. Zhukovskaya NV, Bystrova EI, Dubrovsky JG, Ivanov VB. Global analysis of an exponential model of cell proliferation for estimation of cell cycle duration in the root apical meristem of angiosperms. Ann Bot. 2018;122(5):811–22. doi: 10.1093/aob/mcx216 29425277

26. Nowak DJ, Crane DE, Stevens JC. Air pollution removal by urban trees and shrubs in the United States. Urban For Urban Green. 2006;4(3–4):115–23.

27. Nowak DJ, Crane DE. Carbon storage and sequestration by urban trees in the USA. Environmental pollution (Barking, Essex: 1987). 2002;116(3):381. doi: 10.1016/S0269-7491(01)00214-7

28. Dwyer JF, Schroeder HW, Gobster PH. The significance of urban trees and forests: toward a deeper understanding of values. J Arboric. 1991;17(10):276–84.

29. Song XP, Tan PY, Edwards P, Richards D. The economic benefits and costs of trees in urban forest stewardship: A systematic review. Urban For Urban Green. 2017.

30. Hanchi A, Rapp M. Stemflow determination in forest stands. For Ecol Manag. 1997;97(3):231–5.

31. Sutherland WJ. Conservation science and action: John Wiley & Sons; 2009.

32. Fetcher N, Oberbauer SF, Strain BR. Vegetation effects on microclimate in lowland tropical forest in Costa Rica. Int J Biometeorol. 1985;29(2):145–55.

33. Meineke E, Youngsteadt E, Dunn RR, Frank SD. Urban warming reduces aboveground carbon storage. Proceedings of the Royal Society B: Biological Sciences. 2016;283(1840):20161574. doi: 10.1098/rspb.2016.1574 27708149

34. Livesley S, McPherson E, Calfapietra C. The urban forest and ecosystem services: impacts on urban water, heat, and pollution cycles at the tree, street, and city scale. Journal of environmental quality. 2016;45(1):119–24. doi: 10.2134/jeq2015.11.0567 26828167

Článek vyšel v časopise


2019 Číslo 12
Nejčtenější tento týden