Environmental Engineering Reference
In-Depth Information
of threatened species and on the same body's list of one hundred most dangerous invasive species. It is
regarded as at risk because—despite its widespread colonization of the new forests across the island—its
only “native” habitat is a small fragment of old Puerto Rican forest, where a fungus is wiping it out.
And it is regarded officially as a pest, worthy of eradication, in the other place where its population is
growing fast—in Hawaii, where it was accidentally introduced in the 1980s.
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Ecologists are tying themselves in knots because they refuse to recognize that these novel, hybrid
ecosystems are desirable habitats for anything. But as the sun sets across the island, the people of Puerto
Rico can simply cherish their new forests. And they can once again carouse with the common coqui.
Most conservationists have been reluctant to open their eyes to discover nature's resilience and powers
of recovery—still less to recognize the role of specialist colonizers and nonnative species in that process.
It does not fit their paradigm of how nature is organized. This blinkered approach complicates their wish
to protect and revive nature by excluding a wide range of options for rebooting the wild. As Puerto Rico
shows, nature often needs aliens and colonists and first-movers. Nature has little regard for conserva-
tionists' love of what they see as the pristine. For nature, it matters not a jot where a species comes
from, if it does a useful job. If conservationists don't wake up quickly, they risk becoming the enemies
of nature rather than its saviors.
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This matters hugely because recently messed up and novel ecosystems already dominate huge areas
of the planet. There are billions of acres of abandoned landscapes across the world: former forests, de-
graded pastures, poisoned or radioactive badlands, urban wasteland, and places where farmers simply
gave up and walked away. They are where a huge amount of surviving nature lives. They are of neces-
sity the building blocks for nature's revival. Most of it is former forestland. Much of it, unnoticed by
conservationists, is returning to bush. Edward Mitchard of the University of Edinburgh found that in
recent years, as people have moved to the cities for work, nature has been reforesting abandoned land in
Africa even faster than loggers and farmers cut it down.
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The recovery typically starts with specialist colonizers adept at moving in where others fail to tread.
Some are old hands, but many are what conservationists see as alien interlopers. Parts of Africa seem
to be repeating the experience of Puerto Rico. Either way, if conservationists are seriously interested in
reforesting Africa, then they should be paying far more attention to helping nature recover in these “de-
graded” and abandoned lands. They need to start, says Lugo, by recognizing alien colonizers as part of
the solution rather than part of the problem.
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We do not have to take it on trust that logged forests and abandoned farmland can recover their
former fecundity. As we have seen, almost all forests—even the ones widely regarded as pristine and hot
spots of biodiversity—are in a state of recovery from past use by humans. There are no virgin forests out
there, says Kathy Willis, director of science at Kew Gardens in London. This discovery, she says, “has
far-reaching implications for understanding the resilience and recovery of tropical rain forests” follow-
ing modern-day human disturbances. It shows that forests can and do recover so completely that eco-
logists cannot spot the human element. After a few hundred years they are almost indistinguishable.
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And that in turn shows that what are currently often regarded as worthless, “degraded” forests are actu-
ally the vital elements for future revival. As Willis puts it: “Maintaining such degraded systems in the
landscape might be important for building resilience to future disturbances.”
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