In recent years STEP had become increasingly concerned about the potential impact of Spanish Moss on our bushland and so in December 2023 they asked members to send through details of any Spanish Moss growing on trees. They then undertook a preliminary survey from Cowan to Marrickville to determine what tree species it grew on. What they found was disturbing.
Turpentine (Syncarpia glomulifera) is the most severely affected of all the 76+ species of plants they recorded Spanish Moss growing in. Infestations can be so dense and widespread that whole trees are festooned. Spanish Moss flourishes over Turpentine leaves and worryingly it appears it may be able to kill mature trees by preventing photosynthesis. Locally, Turpentine trees are important trees in the critically endangered Sydney Turpentine-Ironbark Forest (STIF) and Blue Gum High Forest (BGHF) as well as in sandstone gullies. Their loss would be disastrous. Worse still, Turpentines are common trees in fertile forests from the Queensland border to near Ulladulla and our evidence suggests that Spanish Moss could damage Turpentines all the way along the coast and ranges. We are not sure why it flourishes so well on Turpentines but we are prepared to speculate that leachates from the fungi on the leaves encourages its growth.
More bad news for our rainforests and wet sclerophyll forests is that Lilly Pilly (Acmena smithii), Cheese Tree (Glochidion ferdinandi) and Brush Box (Lophostemon confertus), all major components of our east coast rainforest, can be severely affected while Coachwood (Ceratopetalum apetalum), and Blueberry Ash (Elaeocarpus reticulatus) can certainly carry Spanish Moss. In addition to damaged or dead trees, threats to ecosystems include subtle effects such as altered water and nutrient cycles, changed predator prey interactions, habitat alteration, moderation of the microclimate and transformed fire regimes. Changes such as these are one of the greatest conservation threats to biodiversity in Australia.
The good news is that eucalypts, bloodwoods and Sydney Red Gum (Angophora costata) seem to be resistant to it. We only repeatedly recorded Spanish Moss flourishing on Red Mahogany (Eucalyptus resinifera).
Spanish Moss is obviously well loved by many gardeners, but STEP is not sure that gardeners realise how rapidly it can grow and spread. What today may be a gentle grey ornamental addition to the garden may overwhelm it with dense heavy screens of moss up to 3 m long over a few years. Overseas, festoons over 8 m long have been recorded. The artistic addition to the garden today may be a nightmare tomorrow. You may think that your garden is safely distant from bushland, but we recorded a jump of 70 m from the nearest Spanish Moss when it was used by Noisy Miners in their nest. All gardens must therefore be viewed as sources of infestations.
Physical control will be difficult as it is an air plant and has no contact with the ground. In most cases as they found it out of reach, sometimes 15 m up a tree.
Efforts are now underway to get the plant listed as a weed so that Councils are more motivated to take action. We are calling on:
- Gardeners not to spread it, to remove all of it they can reach and put it in the green bin
- Local authorities such as local councils and NPWS to remove it from all public places, including trees on nature strips
- It is added to the next iteration of the Greater Sydney Regional Strategic Weed Management Plan and all other relevant regional strategic weed management plans
- It classified at a level that enables its eradication and containment, prohibition of sale and distribution, e.g. as a regional priority weed
- Research into why Turpentines are a favoured host and the ecological effects of Spanish Moss on bushland
- Research into control methods
Swaying veils of grey in dead or dying trees and simplified bushland is not something to look forward to. Let’s not risk it.
The full report is available here.