Ecology of Banksia facts for kids

The ecology of Banksia is all about how these amazing Australian plants interact with their natural home. Banksia plants have special ways to survive in tough places. They can live in dry, poor soil and still grow strong. They also have clever ways to attract animals for pollination and release their seeds after a bushfire.

However, when Europeans came to Australia, new challenges appeared for Banksia. Things like cutting down forests, picking too many flowers, and changes to how often fires happen have affected them. Also, diseases like Phytophthora cinnamomi (called "dieback") are a big threat. People are working hard to protect Banksia plants, but some types are still endangered.

About Banksia Plants

A rainbow lorikeet enjoys nectar from a Banksia integrifolia flower. It helps move pollen between plants, which is important for the Banksia to make seeds.

Banksia is a group of about 170 different species of plants in the Proteaceae family. They are famous Australian wildflowers and popular garden plants. Many people know Banksia by their long flower spikes and woody "cones" that hold seeds. But actually, less than half of all Banksia species have these cones. They can grow as small, flat shrubs or tall trees up to 30 metres high. You can find them almost everywhere in Australia, except in the very driest areas.

How Banksias Get Pollinated

Banksia flowers are often visited by honeybees and nectar-eating birds. These animals help move pollen from one flower to another, which is how plants make seeds. But did you know that small mammals also help?

These small mammals, like honey possums and yellow-footed antechinus, are often active at night. Studies show they carry a lot of pollen, just like birds! This means they are very important for Banksia plants to reproduce. Some Banksia species need animals to pollinate them, while others can make some seeds even without animal help.

Most Banksia plants prefer to mix their genes with other Banksia plants. This is called outcrossing. It means they usually don't fertilize themselves. This helps keep their genes strong and healthy.

Growing New Banksia Plants

Most young Banksia plants, called seedlings, don't survive to become adult plants. A big problem for them is not enough water, especially during droughts. Many seedlings might sprout after a bushfire, but only a few will make it through their first dry season.

Other dangers for young Banksia plants include insects like grasshoppers and mites, and animals like kangaroos and bandicoots, who might eat them.

Dangers and Diseases for Banksias

Banksia seeds are eaten by birds and insects. Other insects munch on their stems, leaves, and flowers. Some even cause strange bumps called galls. Many types of fungus also live on Banksia plants.

A very serious threat to most Banksia species is a disease called "dieback." This disease is caused by a tiny water mould called Phytophthora cinnamomi.

Protecting Banksias

Many things threaten the different types of Banksia plants. The biggest problems are diseases, changes in how often and how strong bushfires are, and land being cleared for farms, mining, cities, and roads. People also pick too many Banksia flowers, seeds, and leaves for the flower industry.

Currently, three Banksia species are listed as endangered in Australia, and two more are considered vulnerable.

Dieback Disease

The "dieback" disease is the biggest threat to Banksia. This disease attacks the roots of plants, making them rot. This stops the plant from getting water and food from the soil. Banksia plants are very sensitive to this disease and usually die within a few years if they get it.

This problem is worst in southwest Western Australia, where dieback is very common. This area has the most types of Banksia, and almost all of them can get sick from dieback. For example, almost every wild group of B. brownii shows signs of dieback. Without protection, this species might disappear in about ten years. Other types like B. cuneata, B. goodii, B. oligantha, and B. verticillata are also in danger.

Forests with dieback often have much fewer Banksia plants than healthy areas. This can change the whole plant community. For instance, in southwest Australia, Banksia often grows under Jarrah trees. Dieback kills both the Jarrah trees and the Banksia plants. Over time, other plants that are more resistant to the disease might grow there instead.

It's hard to stop dieback. People are trying different ways to slow its spread and help sick plants survive. This includes limiting access to sick areas, collecting and storing Banksia seeds, and treating plants with a chemical called phosphite. Phosphite helps plants fight off the disease and also kills the water mould. Spraying phosphite from the air can help plants survive, but it needs to be done carefully because it can affect how roots and shoots grow. Injecting phosphite directly into tree stems works well but is expensive.

Because dieback likes wet soil, it can be a big problem for Banksia plants that are watered, like those grown for cut flowers or in gardens. For some species, a solution is to graft them onto the roots of an eastern Banksia species, as many of these are more resistant to dieback.

Other diseases that can harm Banksia include the canker fungus Zythiostroma and the parasitic fungus Armillaria.

Bushfires and Banksias

How often and how strong bushfires are is very important for Banksia plants. The best time between fires changes for different species, but about twenty years is common. If fires happen too often, plants die before they can make seeds, or before they have stored enough seeds in the ground. This can make populations shrink or even disappear.

If fires don't happen for a very long time, it's also a problem. Older plants die naturally, and their seeds might not be released. Banksia plants usually need fire to open their seed pods. Dead plants don't release as many seeds as living ones do after a fire. So, long gaps between fires can waste seeds. The strength of the fire matters too. If a fire isn't hot enough to make the seeds release, then it's like the fire didn't happen for the seeds.

For Banksia plants that can regrow from their base after a fire (called "resprouters"), fires are less critical for the adult plants. But fires still kill young seedlings. So, if fires happen too often, new adult plants can't grow, and the population will slowly get smaller as the old plants die.

Many people believe that since Europeans arrived, fires have become more frequent. This is especially true near cities, where fires can be started on purpose or by controlled burns. Managing fires near cities means often having smaller, less intense fires. This is not ideal for Banksia plants, which often need strong fires that happen less often.

Land Clearing

Banksia plants often grow in areas where many people live. Because of this, large areas of Banksia forests have been cleared for farms, mining, cities, and roads. This not only means fewer Banksia plants and less habitat, but it also helps weeds and diseases spread. Banksia plants usually grow in poorer soils, so their habitats were often the last to be cleared for farming. Still, it's thought that by 1986, 55% of Banksia woodlands were gone. Species like B. hookeriana, the endangered B. cuneata, and B. goodii are threatened by land clearing.

Picking Flowers for Industry

Banksia flowers are very popular in Australia's wildflower industry, especially in southwest Western Australia. Flowers from about 29 Banksia species are picked for sale. The most popular ones are B. hookeriana, B. coccinea, and B. baxteri. In 1990, about 1000 people were licensed to pick flowers in the state, and about 675,000 B. hookeriana blooms were picked that year alone.

Picking too many flowers means fewer seeds are produced. This can lead to smaller populations of Banksia plants in the future. It's estimated that the next generation of Banksia plants in picked areas might be only half the size of current populations.

Threatened Banksia Species

Currently, 19 types of Banksia are considered rare. All of them are found only in Western Australia. They are protected by Australian laws. The Department of Environment and Conservation in Western Australia also lists some plants as "Priority Flora" if they are not well known or are rare but not yet officially threatened.

Here is a list of some threatened and priority Banksia types: