The End of Doom (38 page)

Since tropical forests are thought to harbor huge amounts of biodiversity, because of forest regrowth the pace of species extinctions will likely be lower than many of the more dire projections suggest. At a 2009 conference on deforestation, Eldredge Bermingham, then director of the Smithsonian Tropical Research Institute in Panama, declared: “It's a question of whether or not the biodiversity crisis has been overhyped.” He added, “The increase in secondary forest that we are observing may provide a buffer against extinction. Therefore, the extinction crisis isn't as serious as had been touted.”

Other recent research suggests that species extinction rates have been exaggerated. In January 2013, three biologists published a study in
Science
reporting that there is no evidence that extinction rates are as high as many are claiming. “Surprisingly, few species have gone extinct, to our knowledge. Of course, there will have been some species which have disappeared without being recorded, but not many, we think,” declared Nigel Stork, deputy head of the Griffith School of Environment. Stork also noted that many of the planet's biological hot spots containing high levels of biodiversity are now protected areas.

As mentioned earlier, the extinction rates projected by computer models are based on the species-area curve derived from the theory of island biogeography. In many ways, researchers have been treating areas of tropical forest surrounded by farmland as though they were isolated “islands” surrounded by water. This practice now appears to be wrong. An important 2014 study published in the journal
Nature
finds that in fact farmland and secondary forests are not very much like actual islands. The study looked at the prevalence of species of bats by comparing landscapes of tropical forests surrounded by coffee plantations and pastures with remnant tropical forests on real islands created when an area was flooded to make a lake as part of the Panama Canal. They discovered that unlike on real islands, bats do not go locally extinct in forests embedded in farming landscapes. In fact, the researchers found that “almost one-half of the common bat species were more prevalent in coffee plantations than in forests and only 5 of the 30 species sampled avoided plantations altogether.” Instead of island biogeography, the researchers propose a theory of “countryside biogeography” that takes note of the fact that a lot of species, not just bats, can cope with and even thrive in landscapes encompassing natural and modified areas.

The new tools afforded researchers by countryside biogeography render, according to the authors of the 2014
Nature
study, “more optimistic predictions of biodiversity loss than classic tools because they incorporate the conservation value of the countryside.” One of the authors of the new
Nature
study, Stanford University researcher Chase Mendenhall, agreed, “The current model of nature reserves works toward separating humans and nature. That's good to a point, but it can't be the only approach. Today, the world's biodiversity is living with humans, not apart from them. Increased integration looks like the way forward.”

The Myth of Pristine Nature

Indeed, more biologists are developing a greater appreciation for how the nature that exists all around us can and should be conserved. “Nature is almost everywhere. But wherever it is, there is one thing nature is not: pristine,” explains science journalist Emma Marris in her engaging 2011 book
Rambunctious Garden: Saving Nature in a Post-Wild World
. She adds, “We must temper our romantic notion of untrammeled wilderness and find room next to it for the more nuanced notion of a global, half-wild rambunctious garden, tended by us.” These assertions will distress both environmental activists and many ecologists who are in thrall to the damaging cult of pristine wilderness and the false ideology of the balance of nature. But it should encourage and inspire the rest of us.

University of Maryland ecologist Erle Ellis urges us to think about the biological world as being increasingly composed of anthropogenic biomes, or anthromes. Anthromes are novel ecosystems formed through interactions between human activities and natural landscapes and waters. Anthromes include urban, village, agricultural, and range landscapes. Ellis and his colleagues point out that anthromes are mosaics of land used for agriculture or infrastructure and unused or lightly used areas (e.g., steep slopes, wetlands, woodlots) that typically include remnant ecosystems harboring native species.

Lots of environmentalists abhor the notion that Earth is an extensively modified used planet. They believe that novel human-made ecosystems are “degraded” and they often seek to try to return landscapes back to some preferred ecological baseline condition. “For many conservationists, restoration to a pre-human or a pre-European baseline is seen as healing a wounded or sick nature,” explains Marris. “For others, it is an ethical duty. We broke it; therefore we must fix it. Baselines thus typically don't act as a scientific before to compare with an after. They become the good, the goal, the one correct state.” But what is so good about historical ecosystems?

Marris argues that this preference for setting and trying to maintain ecological baselines was generated from the cult of pristine wilderness preached by nature romantics like John Muir. Muir is famous for advocating that the Yosemite Valley in California's Sierra Nevada Mountains be turned into a national park. As Marris notes, wild nature for Muir was a necessity for “tired, nerve-shaken, overcivilized people” suffering from “the vice of over-industry and the deadly apathy of luxury.” And for some people it might be—but that is not a scientific claim about ecosystems and their “integrity.”

In fact, there is precious little scientific support for the ideology that pristine nature is somehow “better” than the m
é
lange that humanity has created by moving species around the globe. For example, Marris visits Hawaii, where half of the plant species now living on the islands are non-native. One brave younger ecologist, Joe Mascaro, studies novel ecosystems that are developing on Hawaii that incorporate both native and non-native species. Among other things, Mascaro “found that the novel forests, on average, had just as many species as native forests” and “that in many measures of forest productivity, such as nutrient cycling and biomass, novel forests matched or outproduced the native forests.”

Marris contrasts Mascaro with another ecologist, Christian Giardina, who helps manage the Laupahoehoe Natural Area Reserve in Hawaii, from which he wants to extirpate non-natives. Yet even Giardina muses, “Are we so religious about this biodiversity ethic that we need to be called on it?” He answers his own question: “If you really dig down to why we should care, you end up with nothing. You are running on faith that we should care.”

Although Marris doesn't cite him, she is plowing much the same intellectual ground as George Mason University philosopher Mark Sagoff. Sagoff has challenged ecologists to name any specifically ecological criterion by which scientists can objectively determine whether an ecosystem whose history they don't know is inhabited by species that have self-organized and coevolved without human interference or a hodgepodge of introduced species that share no evolutionary history. Ecologists, in fact, cannot objectively distinguish between pristine and hodgepodge.

“Imagine that an alien scientist from outer space were to visit both New Zealand and Great Britain,” suggest biologists Dov Sax and James Brown, from Brown University and the University of New Mexico, respectively. “Would this individual be able to distinguish which species are native and exotic, and would it be able to demonstrate that invaders have caused more damage or disruption to ecological processes than natives?” Their answer to both questions is no.

“If there were any but magical thinking behind the idea that ecosystems are complex, adaptive systems, scientists could tell by observation and experiment which biotic components play by the rules and which do not. They could tell which is an ancient complex, adaptive, heirloom ecosystem, and which a recent hodgepodge,” observes Sagoff. “In fact, biologists apparently have no way to tell other than by documenting the history of a site whether it represents (1) an ancient, co-evolved community and its states or (2) an agglomeration of colonizing species gathered in the wake of human activity.” Since it is the case that “biologists cannot tell by observation or experiment which system is ‘co-evolved' and which ‘novel' or, indeed, which species are long-timers and which newcomers, then it becomes a question of faith not science” that pristine ecosystems exhibit some kind of superior integrity to human-influenced ecologies.

What Balance of Nature?

Even worse, the widespread notion of the “balance of nature” turns out to be scientifically specious. Early in the twentieth century influential ecologist Frederic Clements developed the theory that ecological communities act like superorganisms working together through a directional and deterministic process of succession toward a stable climax state. Each participant in the climax ecosystem supposedly is fitted tightly into niches as a result of coevolving together. Once achieved, the climax state is exquisitely balanced unless disturbed.

In contrast to these holistic notions, ecologist Henry Gleason, a contemporary of Clements, developed his “individualistic” hypothesis, arguing that ecosystems were assembled by chance, depending on what species got to the landscape first and were successful in living with other species as they arrived. There was no deterministic climax toward which discrete ecosystems were aiming.

For the most part, twentieth-century ecologists fell into Clements's camp. This concept of nature has had significant consequences for our modern understanding of the human role in the environment. University of Maryland public policy professor Robert Nelson observes that Clements's “theory of the climax state also includes a moment when original sin arrived in the world. Human beings were not part of the original ecological order, as Clements described it, but a foreign element.” Just as in the biblical account of Adam and Eve in the Garden of Eden, the human quest for knowledge has disturbed prelapsarian harmony, unleashing evil across the natural world. “Only if human beings renounced their false pride and arrogance and humbly accepted a lesser place within creation, leaving the climax state to evolve undisturbed, would there be any hope for the future,” comments Nelson. “So far as practically possible, nature should be left untouched by human hands.” Clearly, this conviction informs the prognostications of doom by environmentalist soothsayers such as Rachel Carson, Paul Ehrlich, Lester Brown, Bill McKibben, Jeremy Rifkin, the Club of Rome, and so many others during the past half a century.

Appreciating Novel Ecosystems

Today, most ecologists recognize that Gleason was far more right than Clements. There is no balance of nature and assemblages of plants and animals occur mainly by chance. For example, University of California at Davis researcher Arthur Shapiro asserted in a May 2014 lecture at the Commonwealth Club in San Francisco that most evidence is against the idea of stable interdependent communities as the norm in nature. Wheaton College biologist John Kricher concurs: “As a result of research over the past several decades, ecologists have come to understand the reality of ecosystem dynamics, and have largely abandoned the notion that nature exists in some sort of meaningful natural balance.” Plants and animals come together and find conditions that enable them to survive in the same shared space. As evidence, Shapiro cites the research of University of Minnesota ecologist Margaret Davis, who found that pollen core data shows that trees recolonizing lands after glaciation don't move in “communities.” The tree species migrate at different rates. Consequently, contemporary northern temperate forests are composed of an assemblage of species that mixed together as they raced northward out of various separate refugia as the glaciers retreated at the end of the last ice age.

Of course, species do interact, not because most of them coevolved into tight relationships, but through ecological fitting. Ecological fitting is the process whereby organisms colonize and persist in novel environments, use novel resources, or form novel associations with other species as a result of the suites of traits that they carry at the time they encounter the novel condition. If species could not take advantage of new resources or locations, then it would be impossible for introduced species to survive in novel environments.

One of the more fascinating novel ecosystems has been created on Ascension Island during the past 150 years. Ascension Island is about as isolated as a piece of land can get, sitting in the Atlantic Ocean about midway between Africa and South America. When the British claimed authority over the uninhabited barren hunk of stone in the early nineteenth century, it was frequently likened to a “cinder” or a “ruinous heap of rocks.” The new owners named Ascension's central peak White Mountain, after the color of the bare rocks of which it was composed.

In 1846, botanist Joseph Hooker from the Royal Botanic Gardens at Kew visited Ascension and decided to try transplanting a wide variety of plants onto the island. A century and a half later, the result has been an “accidental rain forest.” White Mountain, now renamed Green Mountain, is covered with an extensive cloud forest consisting of guava, banana, wild ginger, bamboo, the Chinese glory bower and Madagascan periwinkle, Norfolk Island pine, and eucalyptus from Australia. Because of the man-made microclimate, what used to be a desert island now features several permanent streams.

Ascension Island undercuts the conventional ecological wisdom that tropical rain forests are supposed to take millions of years to form. Species don't need to coevolve to create fully functioning ecosystems; they make the best of what they have. And what happened on Ascension has been happening all around the world as people have moved thousands of species from their native habitats to new locales, increasing species richness. Wherever human beings have gone in the past two centuries, we have increased local and regional biodiversity.