March 21, 2019 — 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 specialized 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 (37-acre) 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 armor 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 includes shattered ecosystems in Madagascar, West Africa and the Andean mountains of South America — habitat restoration is an urgent priority.
Imagine a landscape with just 1 percent 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 1 percent.
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 urbanized, the final remnants of native habitat may offer the only way that many people can experience the wonders and psychological benefits of untrammeled 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 imperiled biodiversity and human welfare, and we must battle to keep them afloat.
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Does this new research suggest that is not the case? Doesn’t appear so...
Thanks for your always inspiring thought pieces!
Just one comment on the many small, quite a few large, and some gigantic approach to saving habitat patches—those small ones you mention are often in places with dense human populations, like your Madagascar example and often near urban centers as well.
Because of that, they often have many other values to society beyond just biodiversity that make it much easier to justify saving, restoring and expanding them—water sources; spiritual sites; etc. When they are found near urban centers, like in the case of patches in the Atlantic Rainforest of Brazil, they often also are important sites for recreation, scientific research, environmental education, and nature based tourism.
A great example is a place I lived 20 years, Costa Rica. By far their most visited national park is not any of their bigger lowland rainforest parks like Corcovado or Tortuguero; It is puny little Manuel Antonio National Park, just a couple of thousand hectares, on the Pacific coast, which happens to have the northernmost range extension of the only species of squirrel monkey to make it north of Panama. It gets 400,000 visitors a year…
On the other hand, most Costa Ricans have barely heard of their largest, most diverse terrestrial national park—La Amistad, in the Talamanca Range on the border with Costa Rica, which has high endemism, still viable populations of big critters, tremendous ecological and altitudinal variation and important hydrological resources, etc. However, it is out of sight and out of mind compared to Manuel Antonio and several other very small volcano parks near San Jose that get the lion’s share of park visitation in Costa Rica while only a few thousand ha in size.
Thanks to those small parks that are highly visited by locals and foreign visitors alike, people value conservation more generally, and ecotourism generates lots of jobs, tax revenue and livelihoods—even if most folks never visit the most ecologically significant areas in the PA system of that country, whose budgets are covered in part by the entrance fees generated by the small highly visited parks.
Regards,
James R. (Jim) Barborak
Co-Director, Center for Protected Area Management
Department of Human Dimensions of Natural Resources
Warner College of Natural Resources, Colorado State University
Fort Collins, CO 80523-1480
Jim.barborak@colostate.edu
Skype: jimbarborak
Office: 970-491-2117; Cell: 970-631-0228
The SLOSS debate--which raged for several years--did end up with a pretty clear consensus that large, intact tracts of habitat were more valuable than small, splintered habitats of similar area for conserving the most vulnerable species.
For instance, 'nested-subsets analysis' revealed that the species found in small fragments were generally a relatively impoverished subset of those in big fragments. Small fragments tended to be dominated by habitat generalists and highly adaptable species, rather than, for example, large extinction-prone predators.
That key insight, and a lot of other research on fragmented habitats, often highlighted the many values of large, intact habitats for nature conservation.
So, your point, Pavan, is quite correct: the SLOSS debate did lead most researchers to conclude that the many extinction-prone species (in the sense of being vulnerable to habitat loss, fragmentation, and human hunting and persecution) do survive much better in larger, intact habitats.
But the other side of the coin--How valuable (or not) are small, highly isolated fragments?--has been less clear. The broad conclusions from island biogeography research and nested-subsets analysis have tended to downplay their importance.
Some notable authors have argued against this idea but it's still become fairly entrenched--and as a result, there's been a tendency among some scientists and conservationists not to fret too much when small, isolated patches of habitat get bulldozed for land development.
However, the new research I highlighted suggest is that even small and highly isolated habitat remnants can be surprisingly important for biodiversity.
Highly isolated fragments have a tendency to be the last remnants of unique ecosystems and to sustain the last survivors of locally endemic species (those that naturally live only in small, restricted areas).
And even very small fragments can be super-important for aiding and accelerating habitat restoration.
Hence, there really is no such thing as "unimportant" native habitat. It's all important--but in different ways and for different reasons, depending on the local landscape context.
Bottom line: Whenever possible, save wilderness.
And if you live in a place where most of the native habitat has vanished, my advice is to fight like hell to save the last bits.
In fire-prone landscapes of western North America, forest refugia come in all different shapes and sizes. They are the fundamental footprint of wildfire history across the landscape. It's remarkable how closely adnate biodiversity is in relation to these patches of forest. Two closely related species of woodpecker in western forests distribute their populations so that one species occupies the smaller scattered stochastic elements of forest, i.e., that arise through chance in the wildfire process; the other species, smaller in size, occupies the larger non-stochastic patches of forest that have stronger firebreak potential. The basis for evolution of larger size and musculature of the former woodpecker, together with camouflage of its plumage, is a function of the need to fly considerably more and over greater distance to forage between these scattered clumps of trees. The other species doesn't really have to go very far at all; their dinner table is all around them.
These aspects of the landscape are also proving to have important clues in coming to understand how nature firebreaks the landscape ... as we face the daunting prospect of massive forest fires worldwide. We certainly are going to need to borrow from mother nature's lessons if we are to have any hope of managing wildfires within something closer to normality in the here and now.
But, looking to the future, my favourite examples are in Hong Kong where KFBG https://www.kfbg.org/eng/ are using seeds from rare trees in isolated feng shui woodlands to restore a rich and highly diverse forest on Tai Mo Shan (Hong Kong's highest mountain).
No patch of native vegetation is worthless!
FYI and in response to Pavan:
Lenore Fahrig, Carleton University, gave a fantastic address to the US-IALE meeting in Chicago about a year ago. I recall that it's central theme was to "Challenge authoritative dogma with data" and the example given was on large versus small conservation areas. Lenore was thorough in reviewing the data and finding no inherent benefit from larger areas versus smaller areas, in terms of value per unit area. Conclusion: data do not support the belief that small patches have less conservation value than larger areas (per unit area). https://academicminute.org/2017/08/lenore-fahrig-carleton-university-habitat-fragmentation/
Cheers,
-Keith L. Kline (ORNL & kkline@UTK.edu)
Small patches of native vegetation can serve as biological corridors.