Older plant surveys help researchers track how plants on Australian islands are changing

More than 8,000 continental islands are located just off the coast of Australia, many of which are unmanned and not short of shortage. For thousands of species, patches of these habitats evacuate the threat they face on the mainland.

Coastal islands are also a valuable resource for ecologists studying how plants communities colonize new habitats and change over time.

We have created a new public database now known as A-Islands. This is based on decades of plant research (where botanists visit certain locations and record the plants there).

This unique collection of research utilizes data on over 6,500 plant species from over 850 islands. Some vast islands stretched over kilometres, while others were as small as small apartments.

Our new study, published in the Journal of Vation Science, provides new insights into how Australian coastal islands have changed over time and will help plant monitoring and conservation efforts as the climate warms.

Scaling a steep cliff jumping from a helicopter

We built A-Islands by talking to botanists and organisations across Australia to tackle and painstakingly investigate plants from old books and records.

A-Islands consists of plant surveys of 1,350 islands dating back to the 1940s from over 135 different sources. We’re still adding more.

The story of how the data was collected was fascinating. In some cases, people camped on the island for weeks, making sure they recorded as many living creatures as possible.

We jumped off steep cliffs from several scaled small boats, or from helicopters, to access remote islands and document the plants there.

Australian islands are above weight

When collated the survey, we found that Australian coastal islands exceeded their weight due to species diversity.

At least 25% of Australian plant species live on these coastal islands, despite accounting for less than 1% of Australian land area.

The climate of these islands is almost as diverse as it spans the southern tip of Tasmania to the rocky, windy islands, to the coral atolls in the tropical environment of North Queensland.

Some species of plants have colonized hundreds of Australian islands, but most live on only a few.

These plant communities are the backbone of the island’s ecosystem and provide shelter for many endangered animals.

An unusual resource for scientists

Many of the islands featured on A-ISLANDS have been investigated multiple times over the past 100 years.

Most data in ecology tend to provide snapshots at certain times when it may be located.

In contrast, A-Islands tell us how the plant community has changed over the decades.

This is surprisingly rare in ecological studies, but is essential when scientists predict future vegetation changes as the climate changes.

New ideas

Many people see plant communities as static and changing.

However, A-Islands show that on these small coastal islands, mainland species have migrated to the islands, lasting for a while, then extinct and replaced by other species.

This concept of species constantly changing in a particular place is called species turnover. In theory, species types in island communities change over time, but the number of species remains the same over the long term, on average.

Data from A-Islands not only confirm that this happened in an unprecedented number of archipelagos, but also suggest new ideas.

Seeds like grass and small herbs tend to enter and exit the island more frequently than long-lived species.

Islands could become climate shelters

Datasets such as A-Islands become even more important as climate changes. The island is at the forefront of biodiversity loss, with more than half of the extinction of known global plants occurring on the island.

Understanding these underlying trends in species community change is important for predicting how plant communities will respond to climate change everywhere for centuries to come.

These islands are buffered from the hottest temperatures in the surrounding seas and become important climate shelters protected from mainland pressures. They will become a habitat for important plants in the future.

Over time, the A-ISLANDS dataset forms an important baseline for defining which species live in our pristine island environment.

It also helps to resolve where scientists prioritize research that needs to be done in line with climate change.

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