A Biodiversity Crisis

In just about any article that lists the most beautiful places in the world, islands rank as some of the most beautiful. Think Fiji, Bora Bora, Seychelles, Maldives or the Hawaiian Islands. They’re popular tourist destinations and some of the most biologically diverse places on the planet. Island biodiversity lends to their beauty and popularity, yet they’re hotspots of the global biodiversity crisis.

A recent study on the island biodiversity crisis, published in Global Ecology and Conservation, found that although islands make up only 6.7 percent of the Earth’s landmass, they are home to about 20 percent of Earth’s biodiversity. The wonders of these island paradises don’t just make good photos but are part of their unique and fragile ecosystems that provide services like food and clean water, prevent disease outbreaks, protect communities against natural disasters by acting as buffers against storms and flooding and store carbon from the atmosphere, thereby slowing climate change. Despite all of this, islands are home to about 50 percent of the world’s threatened species, and conservation and restoration policies are needed to stop it from getting worse.

Plant and animal life on islands are at a much higher risk of extinction than life on continents because many island species evolve in isolation, exploiting the diverse habitats and resources that islands offer from their coast to their summits, leading to smaller population sizes and species developing unique or somewhat strange characteristics—such as gigantism or the inability to fly—which improve their survival under the very particular conditions they live, but makes them vulnerable to disturbances such as habitat loss, overexploitation, invasive species, climate change and even diseases. There’s no greater example of these threats and their impacts than in one of the most biologically diverse regions on the planet and endangered species capital of the world—Hawai’i.

“An example from the Hawaiian Islands illustrates how multiple drivers of biodiversity change can act synergistically to produce a ‘perfect storm’ of threats to insular species,” the researchers of the study found.

For over a century, Hawai’i has suffered massive habitat loss. First, forests and native flora were transformed into sugarcane plantations and rangeland, while more recently, coastal habitats like mangroves are being removed for real estate, leading to changes in natural wildfire patterns, habitat fragmentation and diseases. Mosquitoes carrying avian malaria killed as many as 78 native bird species from the Hawaiian lowlands, and climate change exacerbates disease spread. Avian malaria has spread into the last upland haven of endangered Hawaiian honeycreepers on Kaua’i island, and a fungal disease is devastating ‘Ohi’a lehua, a native flowering evergreen tree, which many forest birds depend on. The rise in diseases due to habitat loss also affects people, linked to diseases like malaria, dengue fever, Ebola and SARS, and about 60 percent of known human diseases and 75 percent of emerging diseases come from animals. The extinction of a species also means the loss of an entire set of plant and chemical interactions, such as pollination and decomposition, which other species depend on, causing a chain reaction that further threatens biodiversity.

Another significant cause of biodiversity loss on islands is invasive species, from flowers to rodents. The Fire Tree in Hawai’i is one example of just how much an invasive species can disrupt an ecosystem, causing a chain reaction of its own. The Fire Tree’s ability to add nitrogen to soil helps invasive weeds thrive—adapted to high nitrogen levels unlike native plants—and is enabled further by invasive feral pigs who disperse the seeds of the Fire Tree and invasive weeds. Invasive species are usually brought in through trade, transport, travel and tourism. In their new environment, they face few or no parasites, predators or herbivores, allowing them to thrive and shift an entire ecosystem, flushing out native species that depend on native plants and pristine conditions to survive.

To stop further biodiversity loss and help recover threatened island species, the researchers found that conservation efforts that only target threatened island species are a short-term solution unless they can sufficiently restore lost habitats, as well as fund more scientific research and support island communities as stewards of global biodiversity. The International Union for Conservation of Nature (IUCN) stresses the importance of traditional ecological knowledge of indigenous peoples and their involvement in legislation, policy, evaluation and environmental management. However, Hawaii is one of only a handful of states in the U.S. without a National Forest System, and continental species receive significantly more conservation resources than island species.

“Endangered birds on the U.S. mainland receive roughly fifteen times as much funding per species as endangered Hawaiian birds,” the study found.

The Senate is considering a new bill (S. 554) that could help support forest conservation and research in Hawai’i. It requires the Secretary of Agriculture to consult with the Hawaii Department of Agriculture, private and nonprofit organizations and “any interested individuals” in determining the possibility of establishing a unit of the National Forest System in Hawaii and what lands to include. The aim is to protect and improve forest areas and remaining native or unique vegetation types, but it falls short of a few essential aspects that can help further protect biodiversity in Hawai’i.

Although the policy will search for potential land and habitats, it will only do so in the 6 major islands in the state of Hawai’i, leaving out many other islands and islets of Hawai’i.

“Small islands and islets located off the mainland or larger islands can act as refugia for species extinguished by humans on the mainland through hunting or the introduction of invasive alien species,” the study found, meaning more research on smaller islands is needed since they can provide havens for endangered species.

It also does not specify how much habitat or land should be conserved or restored. However, the study suggests that any action should follow the Post 2020 Global Biodiversity Framework of the UN Convention on Biological Diversity (CBD), and “establish a minimum threshold of 30 percent of the area occupied by each habitat type in each island group for its protection.”

The bill also doesn’t address the issue of the continual introduction of invasive species into Hawai’i, which according to the study, “surpasses by several orders of magnitude the rate of successful eradications.”

While more needs to be done to protect island biodiversity and the ecological life support biodiversity brings, the bill helps open the door to further conversations on research and the restoration of native Hawaiian flora and fauna, and hopefully, the inclusion of island communities and indigenous peoples in that process.


Image courtesy of Flickr. Originally published by S&S on Jan. 5, 2022.


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