- Coconuts are a native species that naturally occur on the littoral edge of tropical Indo-Pacific forests
- They do not invade and over-run natural ecosystems
- There is no evidence that coconuts have ever displaced any of the other species that occur on the littoral edge of mature ecosystems
- Australia has a diversity of unique native coconut phenotypes
- Currently thousands of coconuts are being actively poisoned or cut down based on the poorly researched belief that they are an invasive species
- This has already resulted in irreplaceable loss of unique Australian coconut biodiversity and will result in the extinction of more phenotypes
THE previous two articles in this series (see links below) present a substantial body of evidence that coconuts are native to Australia and that a substantial proportion of the coconuts that grow along the littoral edge are of native Australian origin, rather than the distinct phenotype (niu vai) that was introduced for commercial cultivation, primarily in the 1890s. The introduction of coconuts was a failure and did not have a great influence on the large diversity of native Australian phenotypes that occur along the littoral edge of the coastlines of tropical Australia. Let’s take a closer look at coconut ecology…
This article will focus on coconut ecology in general, with examples from the Douglas Shire in Far North Queensland. All coconuts are the same species, Cocos nucifera L., whether they are of native Australian origin or were introduced. Australia has a rich diversity of native coconut phenotypes however all of these, including introduced types, have the same ecological requirements and functions.
Thousands of native coconuts have been and are still being destroyed in Australia due to decisions based on data-free assumptions rather than on evidence-based science. These actions are based on poor quality research being used to state that coconuts are not native to Australia and that they are all introduced. There is an extensive body of data showing that that a substantial proportion of coconuts in Australia are native in origin and therefore by definition are not weeds. This data has been ignored.
The statements that coconuts are transformer weeds that damage littoral rainforests are data-free opinions with no long-term evidence showing how they detrimentally transform the ecosystems over time and cause a loss or reduction of species. The evidence based science shows that they do not cause ecological damage to littoral rainforests in the Indo-Pacific and are natural part of the ecology.
Coconuts occur with the main littoral edge forest species throughout the tropical Indo-Pacific They are regarded as a native species and are therefore seen as a critically important species in these ecosystems throughout the Indo-Pacific.
A littoral ecosystem grows on the extreme sea edge up to the high tide line. They are different from mangroves that are inundated with salt water at high tide. The littoral edge species need fresh water and cannot tolerate prolonged inundation by salt water. This article uses the term the littoral edge as a distinct zone, composed of specialist species, that needs to be distinguished from the zones that are further back from the high tide sea edge, even when the species gradually merge.
Further back from the littoral edge, the diversity of plants increase forming a range of coastal forest ecosystems. These forest are often classified as littoral forests, however technically they are coastal forests as many of their species do not grow on the littoral edge due to the being susceptible to exposure to high levels of salt spray from the prevailing winds and salt water inundation in king tides.
Tropical littoral rainforests occur throughout the Indo-Pacific from Africa, India, South East Asia and across the Pacific Islands to the tropical Pacific coasts of the Americas. The main species that dominate the littoral edge of these forests are found throughout much of the tropical Indo-Pacific, including tropical Australia. They have the ability to grow right up the high tide line because they can tolerate salt spray from the prevailing winds and the periodic inundation of salt water from king tides and tidal surges. This level of salt kills most other species so the number of species that have adapted to this harsh environment are limited.
Common Indo-Pacific littoral edge forest species include Callopyllum inophyllum, Terminalia cattapa, Hibiscus tiliaceus, Scaevola taccada, Casuarina equisetifolia, Cocos nucifera, Barringtonia asiatica, Melaleuca leucadendra, Morinda citrifolia, Millettia pinnata, Pouteria obovata syn. Planchonella obovata, Pandanus tectorius and Ficus microcarpa. Their seeds float across seas or are spread by migratory birds to colonise new areas. All of these widespread Indo-Pacific species are common in Australia. Coconuts grow naturally in this region of the littoral edge with these species.
Coconuts cannot grow on beaches that do not have adequate rainfall or ground water and they will rarely grow on rocky headlands. They need to grow on beaches where there is good rainfall and/or adequate groundwater. Coconuts need high humidity to set fruit, and for it to reach maturity. Temperatures reaching 36oC and humidity lower than 20% for extended periods, such as the dry season in many parts of northern Australia will desiccate their fruit. Periods of humidity lower than 50% will reduce fruit set. Temperatures below 21oC will also reduce fruit set and long periods below it will prevent flowering and fruit set. Coconuts like most littoral rainforest species cannot tolerate fire and can only grow in areas with regular landscape burning where the sand forms a natural fire break.
Consequently most of the coast of Australia is not suitable for self-sown coconuts and that is why they are rare on most of the beaches of tropical Australia. The exception are the beaches where littoral rainforests grow due to adequate rainfall and/or ground water. There are only a few regions in Australia where large numbers of self-sown coconuts can be found, such as the Wet Tropics, Whitsundays, Mackay and the Lockhart River – Iron Range coastal areas of Queensland.
Coconuts are naturally spread by drift across the sea and self-sow just above the drift line on beaches. Research conducted in Hawaii showed that after four months of immersion in sea water many coconuts can germinate when the conditions are right after they reach land. Paleo-archeological research show that coconuts had colonised Pacific islands thousands of years before the arrival of humans.
Coconuts need full sun and do not grow and fruit under a canopy. Consequently they are mostly found on the sea edge of littoral forests. They grow towards the sea edge to get the extra light reflected off the water to increase photosynthesis. This also facilitates dropping their nuts into the tidal zone so that they can be dispersed to new areas. Most self-sown nuts geminate above the king tide zone. They can be spread further inland by tidal surges from storms and cyclones and up tidal creeks and estuaries. Some nuts will spread a few metres away from their parent tree by rolling and bouncing.
Coconuts have no natural mechanism to spread inland to invade forests. They cannot roll up hill from the beach. Consequently coconut trees that are growing a large distance away away from the littoral zone have been planted by people, as they do not have the ability to spread their nuts naturally to these areas. This is why self-sown palms are mostly restricted to the edges of littoral forests.
Coconut palms cannot tolerate full shade. They never reach maturity under a canopy and will slowly die. The mature palms that are taller than the canopy are a result of palms that grew when the area was open and cleared as they need full sunlight. The forest has since regenerated around them. They have not grown from under a canopy and emerged out of it. When these palms die from old age, their offspring will not survive to become mature fruiting palms under a canopy. Consequently coconuts rarely grow inside mature undisturbed littoral forest.
Coconuts can grow in open areas of damaged littoral forests, because they can get access to full sunlight. This has occurred in the beaches with the highest numbers of coconuts such as Four Mile, Cooya, Newell, Wonga, Cape Tribulation and Cowie Beach in the Douglas Shire. This is largely due to human activities such as fire or clearing opening up the canopy so that coconuts as full-sun pioneer species can grow.
The first Europeans to set foot on the beach of Cape Tribulation, 200 years ago, in June 1821, reported an open grassed woodland area with a well constructed traditional owners village. The historical records show that the northern, middle and southern sections of Wonga Beach were grassed woodlands that had Traditional Owner family villages. The arrival of European settlers resulted in further degradation of the littoral rainforests surrounding these woodland areas.
The first report of Four Mile Beach in 1877 showed that it was littoral rainforest with open and well-grassed woodland areas around Island Point. In 1975, according to the survey by Tracey and Webb, there was no littoral rainforest on the foreshore of Four Mile Beach. This was primarily due to burning and grazing. The scars of the fires can still be seen on the old remnant, melaleuca trees. The littoral rainforest started to regenerate when the burning and grazing stopped. The coconuts growing in the forest did not stop the regeneration – they have been part of it.
There is no evidence that coconuts have caused a decline in any of the species on the littoral edge of these rainforests. The opposite is the case. All the littoral rainforest areas that have been allowed to regenerate in the Douglas Shire that have seen increases in coconuts have also seen increases in the other species that make up littoral forests. The belief that coconuts will take over littoral forests if they are not removed is a data-free assumption. This does not happen anywhere in the world where littoral forests are allowed to regenerate naturally.
The literature shows that coconuts, rather than out-competing other species, are out-competed by numerous tree species. Many tree species grow faster than coconuts and shade them out, preventing them from fruiting. Manuals on the commercial cultivation of coconuts include the fact that many tree species grow faster than coconuts and will shade them out, as a major problem for nut production. They regard the trees as the invasive species.
Several of the littoral species such asTerminalia cattapa, Hibiscus tiliaceus, Casuarina equisetifolia, Melaleuca leucadendra and Ficus microcarpa quickly outgrow coconuts and shade them out in littoral rainforests that are regenerating. Shaded coconuts gradually die. This process is occurring naturally where littoral forests are allowed to regenerate.
The littoral forest areas with the least disturbed forest foreshores have the least number of coconut palms. Left to their own ecological devices these forests find a balance and coconut palms become a component in this ecology. They do not dominate at the expense of other littoral species. There are very few coconuts on the littoral edge of the forests from Cape Tribulation to just before Cowie Beach as this section is amongst the least disturbed examples of littoral forest in the Wet Tropics of Australia. The two exceptions are Cowie Beach and Cape Tribulation beaches that were open woodlands created by indigenous burning, creating the perfect ecological conditions for self-sown coconuts to grow along the littoral edge of the regenerating rainforest. Even with high numbers of coconuts these beaches still have a high diversity of Indo-Pacific littoral edge species. These littoral rainforests are regenerating with coconuts.
Emmagen Beach, north of Cape Tribulation, is a good example of a least disturbed littoral rainforest. There are oral history records of a coconut grove at the mouth of the creek that was called ‘Kulngurbu’ and was owned by the Kuku Yalanji, that predates European settlement. If coconuts were transformer weeds that damage littoral rainforests, the littoral rainforest on Emmagen Beach should be overrun with coconuts, given that they have had hundreds of years to invade the forest. The fact is that the opposite has happened. This grove does not exist anymore and there are only a few palms that survive further down the beach.
These surviving palms are examples of unique Australian coconut phenotypes. Unfortunately they have been identified to be destroyed by the Douglas Shire Council as transformer weeds. This proposed destruction is the worst type of cultural and environmental vandalism, given that these trees have a historical cultural significance for the traditional owners and that their destruction will result in the extinction of unique Australian biodiversity.
Erosion Claims about Coconuts
Coconuts are blamed for causing beach erosion in Australia. Blaming coconuts for beach erosion is not supported by the evidence in Australia and around the world.
The main cause of beach erosion now is the sea level rise due to climate change.
The majority of areas with coconuts do not have erosion. All the above images show coconuts growing without causing erosion. Where there is erosion, this has been caused by sea level rises, natural movements of rivers and creeks and the natural variations in sand levels. Beach erosion is increasing along many of the coasts in Australia and most of these eroded coasts do not have coconuts.
Coconuts are planted in many places around the world to prevent beach erosion. Research shows that their deep roots stabilise the frontal dune and their fallen fronds and nuts, prevent erosion by the wind and tides by trapping sand to build up the dunes. The decomposition of the fronds and nuts puts valuable organic matter into the sand, increasing the fertility. This assists the growth of understory species such as Scaevola taccada.
Four Mile Beach and the nearby section of beach south of the Mowbray river provide clear evidence to debunk the claims that coconuts cause beach erosion. The images below show Four Mile Beach with numerous coconuts on the littoral edge with no beach erosion. The image of the section of beach between the mouth of the Mowbray River and Yule Point shows the littoral forest that has no coconuts being severely eroded with trees being undermined and washed onto the foreshore.
If the claims that coconuts cause beach erosion were true, then the section of Four Mile Beach with the coconuts on the littoral edge should have the erosion and the beach south of the Mowbray River, only a few kilometres away without coconuts on the foreshore should not have erosion. The images of these two similar beaches only a few kilometres apart show that the international experts are correct.
Coconuts help to prevent erosion.
Ensuring that there are coconuts on the littoral edge to help build up the foreshore dunes should be an adaptation strategy to help combat the erosion that will be caused by sea level rises due to climate change.
Conclusions About Coconut Ecology
Coconuts are a native species that naturally occur on the littoral edge of tropical Indo-Pacific forests. They do not invade and over-run natural ecosystems. Ecosystems that have been severely disturbed by humans can sometimes have large numbers of coconuts as they are pioneer species that need full sun. Over time, as the disturbed littoral forests regenerate, the majority of tree species will out-compete coconuts, leaving them to mostly grow on the outer littoral edge, their preferred habitat. There is no evidence that coconuts have ever displaced any of the other species that occur on the littoral edge of mature ecosystems.
Australia has a diversity of unique native coconut phenotypes. These need to be preserved in their preferred habitat, the littoral edge of tropical forests. Currently thousands of coconuts are being actively poisoned or cut down based on the poorly researched belief that they are an invasive species. This has already resulted in irreplaceable loss of unique Australian biodiversity and will result in the extinction of more phenotypes.
ABOUT THE AUTHOR / André Leu is the International Director of Regeneration International, a global NGO that promotes food, farming and land use systems that regenerate and stabilise eco systems, climate systems, the health of the planet and people. He, along with the other founders of Regeneration International, started the world wide regenerative farming movement. André is the Author of the ‘Myths of Safe Pesticides’ and ‘Poisoning our Children’. He is the co-author with Dr Vandana Shiva of ‘Biodiversity, Agroecology, Regenerative Organic Agriculture – Sustainable Solutions for Hunger, Poverty and Climate Change’. André first came to the Douglas Shire in 1971 and has, with his wife Julia, an organic tropical fruit farm in Lower Daintree.