Habitat destruction hurting more than climate change

Habitat destruction and modification harms biodiversity, and compounds the impacts of climate change and other threats to wildlife.

By Euan Ritchie, Deakin University

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Earlier this year the Great Barrier Reef experienced its worst coral bleaching event on record.

It’s been described as “like a bushfire underwater” and the reef looking like “it has been carpet bombed” .

Understandably, much of the discussion surrounding the event has focused on how such coral bleaching events are becoming more severe and frequent under climate change.

But there’s another threat that is contributing to the rapid disappearance of our extraordinarily colourful and diverse coral reefs, and other ecosystems, that doesn’t receive nearly as much attention.

The destruction, fragmentation, and modification of habitat from the oceans to the land exceeds the overall impacts of climate change , for now, and is having a devastating effect on biodiversity.

Habitat destruction and climate change are of course closely linked and along with other threats — including the overexploitation of natural resources, killing or exclusion of wildlife such as large carnivores due to conflict with people and food production, invasive species, and pollution — they compound each other , driving what many experts believe to be Earth’s sixth mass extinction event .

Destruction happening everywhere

Habitats — and the plants, animals, fungi and other life that call them home — are being destroyed across ecosystems, from the tropics to polar regions and in our cities and more regional areas.

In the case of coral reefs, the combined impacts of bleaching, smothering and pollution from agricultural erosion and sediment runoff, ocean acidification, and storms, mean that the once complex, multi-dimensional architecture of healthy, vibrant corals is often greatly reduced, replaced by simpler, algae-dominated systems .

Many species that specialise and depend upon the corals must then either move elsewhere or perish.

In Northern Australia, centuries-old trees and their hollows — which threatened species such as Gouldian finches, black-footed tree-rats, and northern brushtail possums depend upon for shelter, food, and to raise their young — were recently controversially destroyed for defence housing at Binybara/Lee Point on the edge of Darwin.

On the outskirts of Melbourne, endangered southern-brown bandicoot habitat will also soon make way for further urban development .

But habitats do not always need to be physically destroyed for species to be endangered. Greatly diminishing their quality can still have a profound impact on species.

Tasmania’s endangered Maugean skate is such a species.

First discovered in Bathurst Harbour in 1988, this skate is now thought to only survive in Macquarie Harbour. Deteriorating aquatic conditions due to oxygen depletion caused by the salmon farming industry, the production of hydroelectricity that alters stream flows, and rising temperatures due to climate change, are all thought to be responsible.

The skate is now on the brink of extinction .

The support our species need

If we are to conserve biodiversity and meet both global targets and federal government ambitions to be “Nature Positive” and have no new extinctions , the biodiversity that exists in both disturbed and less disturbed areas, and on and off formal nature reserves, would benefit from better recognition and support.

Habitat destruction is accelerating species decline and extinctions .

Tree hollows can take more than 100 years to form, but can be cut down in minutes destroying what was once a home for a bird, mammal, reptile or invertebrate .

This can have knock-on effects through ecosystems due to species interactions.

For example, bandicoots and other mammals are known to dig and turn over large amounts of soil as they search for food, and in doing so benefit soil health , the spread of fungi, and plant germination and growth.

When these links are severed, whole ecosystems can begin unravelling and ultimately, collapse.

Australia is a global deforestation hotspot , having cleared roughly 50 percent of its forests and leaving much of the remainder highly degraded.

One MCG destroyed every 90 seconds

An area equivalent to global sporting icon, the 20,000 square metre Melbourne Cricket Ground, has been estimated to be destroyed roughly every 90 seconds in Australia — giving a picture of just how confronting the scale of the issue is.

Habitat destruction and modification, and associated biodiversity decline and extinctions, are cited as major reasons in the extensive Samuel review as to why Australia’s Environment Protection Biodiversity Conservation Act is failing.

The homes of swift parrots, greater gliders, koalas, Leadbeater’s possums, and many other native species are continuing to be destroyed, despite these species being listed as threatened.

And, with increasing pressure to further develop extensive, biodiversity-rich but relatively less modified areas, such as northern Australia , for livestock grazing, cotton and gas production, laws are needed that better conserve wildlife, areas of significant habitat and ecosystems, and that promote genuinely sustainable development.

Currently, substantial land clearing and water extraction is occurring without proper oversight and assessment of perceived and actual environmental impacts.

Just as experts have called for a climate trigger in the EPBC Act to account for the impacts of proposed developments on rising emissions and climate change, law reform is needed that better recognises the value and importance of habitats, on land and in marine and freshwater systems.

The damage is already done

In many regions, much of the damage has already been done and yet the consequences are yet to be fully realised.

A drive along the Hume Highway, between Melbourne and Sydney provides a perfect example.

In many paddocks, cleared for cropping and livestock production, stand solitary large eucalypt trees, once part of extensive woodlands that extended for many hundreds of kilometres.

A keen eye will reveal that in most cases there are no young trees to take the place of the larger, older trees, so once they die, there will be nothing to replace them.

This ecological phenomenon is known as extinction debt , and is a common issue facing many long-lived species that can persist for decades or in some cases even centuries without reproduction, but once they’re gone, habitats and ecosystems may be irreversibly changed.

In the case of large paddock trees, or narrow strips of remnant vegetation that line country roads, these are the last remaining homes for arboreal mammals, microbats, reptiles, birds and other wildlife in highly fragmented landscapes.

Conservation efforts are starting from a long way behind, hence we can ill afford to keep destroying habitats. Instead, restoration efforts need to be ramped up, some areas declared ‘no go zones’ for development, and more sophisticated approaches for food production, housing construction, and infrastructure projects must be better supported.

Death by a thousand cuts

Importantly, death by a thousand cuts is not just an issue of rural areas either.

As human populations continue to increase and many move to cities seeking employment opportunities, urbanisation is also continuing at great pace, and in many cities, this is leading to a reduction, not increase in tree cover and areas of green space .

This is despite many cities being critical strongholds for wildlife , including threatened species.

Despite this dire situation, a great opportunity still exists.

If governments and policymakers truly implement a Nature Positive agenda, the benefits across society and for nature could be profound.

Australia is exceptionally well-placed in this regard, having a wealth of climate, environmental and ecological experts, and a population that is known to want governments to increase their efforts to conserve biodiversity .

Investing in environmental protection and restoration — and viewing this as a public good — will protect cultural values, drive job creation and economic growth, and ultimately, ensure we can still live in a world rich in biodiversity with all its myriad benefits .

Professor Professor Euan Ritchie is a professor of wildlife ecology and conservation at 澳大利亚迪肯大学 . His research aims to better understand species and their interactions, as well as ecosystem dynamics. This information is vital for informing more effective environmental policy, and conservation and management of biodiversity.

Originally published under Creative Commons by 360info ?.

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