Scientific thinking changes as new evidence comes to light. One vital new insight is the importance of saving even tiny, isolated remnants of native vegetation.
Decades of research on fragmented habitats has shown that small, isolated patches of habitat are often ecologically depauperate — deficient in top predators and specialised old-growth species, and suffering from a wide variety of ecological woes.
This research correctly shows the vital importance of protecting Earth’s vanishing wilderness areas.
But such studies have also convinced some people that very small, isolated patches of native vegetation are nearly worthless. In many places, these tiny remnants are being bulldozed and razed to the ground.
That, it turns out, is dead wrong. Here are three reasons why even small tufts of native vegetation can be critically important in the face of the unrelenting expansion of the “human footprint” in many parts of the world.
1. Rescuing rare biodiversity
Imagine a forested valley rich with plants, animals and other living things — some of which occur nowhere else on Earth. Then imagine that the valley’s forests are cleared for agriculture, leaving just a football-field-sized patch of the original forest.
Because the patch is small and isolated from other forests, we’d be tempted to think it sustains only a few species, and therefore is relatively worthless in ecological terms.
But because it’s the only habitat remnant in the valley, the isolated patch might actually retain the last populations of certain species. This was the conclusion of a recent global-scale study in the journal, Proceedings of the National Academy of Sciences USA.
To save unique biodiversity, highly isolated habitat remnants may actually be incredibly valuable. For example, biologists recently discovered a beautiful rainbow-chameleon lizard – a species completely unknown to science – in a highly isolated 15-hectare patch of forest in northern Madagascar. This is evidently the only place the species still survives.
So, we need to rethink habitat isolation. To save unique biodiversity, highly isolated habitat remnants may actually be incredibly valuable.
That’s a far different approach to conservation than that propounded by adherents to the famous theory of island biogeography — which predicts that isolated habitats that are close to other habitat tracts will sustain more species than highly isolated areas.
I argued previously that this theory breaks down in various ways when applied to fragmented habitats in the real world and the new study reveals yet another chink in its armour for guiding strategies for nature conservation.
2. Restoring Ecosystems
Another new insight is that vestiges of native vegetation are remarkably important for restoring habitats. In many parts of the world – such as Earth’s 36 “biodiversity hotspots”, which include shattered ecosystems in Madagascar, West Africa and the Andean mountains of South America – habitat restoration is an urgent priority.
Imagine a landscape with just one per cent of its native vegetation remaining, the rest having been destroyed. And compare that with a landscape with no native vegetation at all.
Habitat remnants are a key source of seeds of native plants, seed-dispersing animals and native pollinators. If we allow these two landscapes to regenerate naturally, it turns out that even tiny remnants of native vegetation provide an enormous boost to species and ecosystem recovery.
This is because habitat remnants are a key source of seeds of native plants, seed-dispersing animals and native pollinators.
So, if we want to restore vegetation, saving remnants of native habitat is vital — even if it’s just the last one per cent.
3. Other Big Benefits
Habitat remnants have many further values. For instance, many provide stepping stones for mobile wildlife such as birds and bats. Such animals disperse seeds and pollinate plants, helping to spread diversity across the landscape.
Habitat remnants also help purify water supplies, filtering out pollutants and reducing silt from soil erosion.
And native-vegetation remnants are important for people — providing valuable opportunities for recreation and nature education. Research has shown that people who’ve grown up being exposed to nature value it a lot more those who haven’t. As our planet becomes increasingly urbanised, the final remnants of native habitat may offer the only way that many people can experience the wonders and psychological benefits of untrammelled nature.
The Bottom Line
Wherever you live, look closely at what is happening around you. Almost everywhere, remnants of native habitats are being destroyed, often with little thought of the consequences.
New research is revealing that those small patches of vanishing habitat are far more important to our environment and to us than we’d previously understood.
They’re lifeboats for imperilled biodiversity and human welfare, and we must battle to keep them afloat.
Professor William Laurance is a research professor at James Cook University. This article was first published on Ensia and is published with permission.
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