Most readers will be aware of the damage that introduced ‘canopy-killer’ vines such as Madeira vine (Anredera cordifolia) and Cats Claw Creeper (Dolichandra unguis-cati) can inflict on natural areas. They are perhaps the worst of a growing number of introduced invasive vine species that have become naturalised in south-east Queensland (SEQ). These are the ‘transformer’ weeds that keep many Land for Wildlife property owners busy on weekends.
But what about native vines? Can native vines become problematic? After all, they can climb up and over trees too. Can they smother and kill trees like their weedy counterparts or are they part of an equilibrium in a finely balanced natural ecosystem?
There are hundreds of species of native vines that occur naturally in South-east Queensland. They fill niches in practically every vegetation community. In rainforest, where access to sunlight is at a premium, vines or ‘lianas’ are especially well represented. In fact, they are so prominent that botanists label some rainforest communities as ‘vine-forests’.
Fortunately, the vast majority of native vines do not pose the threats caused by weedy invasive vines. Native vines perform many important ecological functions. Some species provide nectar, fruit and/or seeds for birds and other fauna. The leaves of many species are the larval food source for butterflies. Some vines fix nitrogen to the soil, while others provide specialised nesting niches for small birds. Native vines are a crucial component of local ecosystems and are integral to the survival of many species of wildlife. Some also compete with trees for resources such as water, nutrients and light as they compete with trees in a race to the top…
Climbing plants have evolved as a result of competition between plants with different growth strategies. Rather than investing energy into growing a strong, carbon-rich woody trunk, vines have adapted and utilise trees as a scaffold to climb and access the sunlight they require for photosynthesis. Vines have developed xylems that function as super-efficient pumping systems that can transport water quickly and in bulk from their roots to their leaves. This allows vines to grow more rapidly than trees and invest more energy into leaf production rather than the production of wood. Like living solar-panels, some vines spread out across the canopy and forest edges, maximising their surface area in order to capture sunlight and in the process, they deny their supporting trees of this valuable sun-drenched real estate.
However, far from surrendering in this ‘battle’ with vines, trees have developed their own competitive strategies. Some trees regularly shed their bark, preventing vines from attaching advantageous roots to their trunks, while others regularly drop limbs to release the grasp of tendrils. Species like the Cabbage Tree Palm (Livistonia australis) have developed saw-like serrations along the leaf petiole that can thwart the advances of vines by slicing through their young tendrils. These and other palms also regularly shed their leaves, preventing vines from grasping the required rung on the ladder to the top.
Eventually, all trees fall over, this is a natural process that helps drive forest succession. It is sometimes a result of tree senescence (old age) and sometimes from disturbances such as storm damage, flood or fire. These tree-falls create light filled canopy gaps that vines can rapidly colonise. The disturbance resulting from some timber harvesting practices can have a similar but multiplied effect creating a mosaic of canopy gaps throughout a forest. According to successional theory when these forest gaps are created, they are rapidly colonised by pioneer tree species and over time the pioneers give way to slower growing, longer lived tree species that make up the bulk of a mature forest. However, sun loving vines also flourish in these forest gaps and also along forest edges where access to sunlight is more readily available. In some cases, this can hinder tree establishment and stall forest succession.
Due to the incremental clearing of native vegetation, forest edges have become a more common feature in today’s landscape. After 200 years of vegetation clearing, the SEQ landscape of today is one of fragmented habitats, where once large tracts of forest have been carved into a patchwork of islands that have a much higher ‘edge to core ratio’. Linear infrastructure such as roads, rail, power and pipelines criss-cross the land creating hundreds of kilometres of ‘artificial’ forest edges. This has created ideal growing conditions for some vines, both introduced and native.
In SEQ, changed fire regimes since European settlement may also be a contributing factor to some vine expansion. When long intervals occur between fire events (planned and/or unplanned) some of the more light loving generalist species of rainforest vines will readily spread and establish in the adjoining open-forest, common examples can include Kangaroo Vine (Cissus antarctica) and Giant Water Vine (C. hypoglauca). This expansion can occur vegetatively from the rainforest ecotone or via bird facilitated seed dispersal into the adjoining open forests.
While vegetation clearing patterns may be increasing the favourable growing niches available for some vines, there is also a growing body of scientific evidence that such forest disturbances together with increasing global temperatures has tipped the balance further in favour of vines over trees, especially in tropical areas (Ngute et al 2024).
Plants absorb carbon-dioxide through tiny holes in their leaves called stomata. These holes can also lose a lot of moisture through evapotranspiration. Once a temperature threshold is exceeded, trees close their stomata to conserve water but in doing so they cease to photosynthesis, cease absorbing C02 and cease growing. The number of hours in each day and the number of days in each year that this occurs has been shown to be increasing. Unlike trees, many vines can continue growing when its hotter and drier, giving them a distinct competitive advantage in a warming climate. Some researchers have concluded that as global temperatures rise the hotter conditions may be favouring vine growth as trees struggle to photosynthesise during heat extremes. This has significant implications for the capacity of forests to capture and store the levels of carbon required to offset emissions (Van der Heijden et al 2015). It also has the potential to lead to a cascading effect of vine abundance and tree decline.
So, what, if anything can or should you do if you notice native vines smothering native trees on your property?
Vigorous native vines growing up mature trees in remnant forests do not tend to pose a problem. However, in regrowth forest, younger trees and saplings are not of a sufficient size or strength to withstand the significant weight of some vines. In this situation young trees will decline in health due to smothering and can be bent over, eventually snapping off branches or even the main trunk. When this happens, it can stall the natural regenerative process and further increase light penetration to the forest floor, favouring the vines as well as other sun loving species such as Lantana camara.
These images show native Giant Water Vine (Cissus hypoglauca) growing on the edge of regrowth eucalypt forest on the Sunshine Coast (left) and regenerating littorial rainforest in the Redlands (right). On the left you can see Tallowwoods (Eucalyptus microcorys) being covered by the vines to the point where a main trunk has been snapped. On the right, you can no longer see the trees underneath the vines, but work has been undertaken nearby to cut three species of native vine to save this mature tree (lower right).
Just as we strategically control weeds to assist the regeneration of native species, sometimes the management of vigorous native vine species is necessary to allow natural regeneration to reach its full potential. Such management interventions should be considered part of the process of assisted natural regeneration. However, a note of caution, this is NOT a case of all vines should be controlled!
Of the hundreds of species of native vine in SEQ there are only a handful of species that I have observed that fall into this category. Before actively managing any native vines, you should be certain of your species identification, determine the level of threat posed by existing and/or potential smothering and be very clear on your objectives and desired outcomes. Monitor the changes that result from your interventions and adapt management accordingly.
Most native vine species do not grow large enough to negatively impact its host and others such as the near-threatened Richmond Birdwing Vine (Pararistolochia praevenosa) that should never be cut back. If you are unsure ask your Land for Wildlife Officer for a property revisit so that you can receive site specific advice. Interventions can be as simple as cutting the stems of the vine at head height so that the foliage dies off and allows the canopy of the smothered trees to recover by shedding the weight and accessing light. This will not kill the vine, rather set it back while the tree recovers. Depending on growth rates, this process may need to be repeated a number of times until the trees are sufficiently established.
Native vines are a diverse and essential component of our regional ecosystems and many species of wildlife rely on them for survival. As many previously cleared and heavily logged rural properties in south-east Queensland revert to forest, we as custodians can play an important role in assisting this regrowth to mature with increased diversity and structure. Occasionally this may require the informed and strategic management of some native vine species.
Article by Nick Clancy
Land for Wildlife Officer
Sunshine Coast Council
References and Further Reading
Baker A (2021) The ecological consequences of rainforest expansion into fire-excluded open forests of eastern Australia. PhD Thesis.
Bernich A et al (2024) Assessing the invasion potential of five common exotic vine species in temperate Australian rainforests. NeoBiota, 90:79-96.
Campbell et al (2018) Edge disturbance drives liana abundance increase and alteration of liana-host tree interactions in tropical forest fragments. Ecology & Evolution, 00, 1-15.
Fox D (2023) Rogues of the rainforest. BioGraphic.
Goldstein G (2012) Liana abundance, tree crown infestation, and tree regeneration ten years after liana cutting in a subtropical forest. Forest Ecology and Management.
Harden G, McDonald W, Williams J (2006) Rainforest Climbing Plants, A field Guide to their identification.
Ngute et al (2024) Global dominance of lianas over trees is driven by forest disturbance, climate and topography. Global Change Biology.
Schnitzer et al (2021) Local canopy disturbance as an explanation for long-term increases in liana abundance. Ecology Letters.
Signori-Müller et al (2023) Tropical forest lianas have greater non-structural carbohydrate concentrations in the stem xylem than trees. Tree Physiology.
Van der Heijden, JS Powers JS and Schnitzer SA (2015) Lianas reduce carbon accumulation and storage in tropical forests. Proceedings of the National Academy of Sciences. 112, p.13267.