The USA alone has more wilderness than the entire continent of Africa does, but the natural world is not the same as it was 20, 50 or 100 years ago.  And the natural world than was far different than preceding generations.

Late 20th century conservation adopted an arbitrary point in time and declared that nothing should change beyond that point, but it was never a reasonable policy. 21st century conservation needs to be a little more practical. While American farmers have successfully dematerialized and produce far more food on less land and with less environmental strain than at any point ever, the rest of the world will be a long time catching up. If, as expected, the world is going to reach 9 billion people by 2050, the bulk of the world will not be able to farm the way the US does, and that means they will need a holistic approach to conservation that includes farmland - even if farmland is not 'natural' to conservationists stuck in the past.

The developing world is likely to use more land to produce food - when people are hungry, animal habitats are a lower priority, so managed conservation, where humans are not treated as enemies of nature and where altered agricultural landscapes play vital roles in nurturing wildlife populations, is the way to go.


But to make real progress, exaggeration has to stop. In the past, people readily accepted error-filled metrics like it takes a gallon of gas to make a pound of beef or it takes 140 liters of water to make a cup of coffee. If modern conservation is not going to be a marginal luxury for wealthy western nations, numbers have to be real and the public has to trust them.

Toward that goal, scholars writing in Nature show that the metric used to predict extinction rates and ecological risk, and therefore to make conservation policy recommendations, is wrong, and unsurprisingly overly pessimistic in its errors.


a–c, Conceptual diagrams showing hypothesized patterns of biodiversity in a minimally altered ecosystem (a) and corresponding countryside (b) and island (c) ecosystems derived from hypothetical land conversion either to agriculture or a lake, respectively. d–f, Proposed patterns of biodiversity for minimally altered (d), countryside (e) and island (f) ecosystems, depicted by rank–abundance plots. In each rank–abundance plot, the most abundant species at each site is given a species rank of 1, the second most abundant is 2, and so on. Pin labels mark sites and habitats with letters in each ecosystem and are referenced in the rank–abundance plot. In the countryside and island ecosystems, letters represent sites located in the mainland or reserve interior (A), mainland or reserve edge (B), forest fragment or true island (C) and deforested habitat or water matrix (D). We speculate that species loss generally occurs after landscape alteration, but there is wide variation between countryside and island ecosystems in how biodiversity changes in terms of species loss, changes in abundances and the formation of novel assemblages of biodiversity among habitats, because of the resources afforded in human-made habitats in countryside ecosystems. Credit: doi:10.1038/nature13139

The researchers point to an alternative framework that promises a more effective way of accounting for human-altered landscapes and assessing ecological risks, and therefore making conservationists trusted guides for the public on environmental issues once again.

Current estimates bordering on doomsday prophecy claims that about half of Earth's plants and animals will go extinct over the next century because of human activities. They blame agricultural. Since 99.999% of all extinct species we never even knew existed it was always difficult to claim a daisy chain of disaster.

In Nevada, the Federal government used assault weapons and special operations armor against American citizens to protect land supposedly at risk due to man; in that case, a few hundred cows they claimed were going to kill off a local turtle and set off a domino effect of ecological doom. How many nuclear bomb tests were done in Nevada? Over 1,000, so the idea that a few cows was going to ruin the environment was not based on evidence, it was based on Senator Harry Reid having an interest in putting a solar facility there.

Politics, like natural landscapes, is not some pristine, unchanging island. In the past, conservationists catered to exaggeration. They stopped being trusted guides for the public on complex issues. Those conservationists insisted that once natural landscapes are fractured by human development or agriculture, migration corridors for wildlife are broken, blocking access to food, shelter and breeding grounds.

An academic metric was developed to estimate the number of species in such fractured landscapes, where patches of forest surrounded by farms resemble islands of natural habitat. It was called the "equilibrium theory of island biogeography" and it became a pillar of biological research because it's a simple equation used to estimate the number of species in a habitat.

It's also wrong.



An Artibeus lituratus bat eats a fig. Credit: Christoph Meyer


Yet the "equilibrium theory of island biogeography" still drives the default strategy of conserving biodiversity by designating nature reserves. This strategy sees reserves as "islands in an inhospitable sea of human-modified habitats" and doesn't adequately account for biodiversity patterns in many human-dominated landscapes.

"This paper shows that farmland and forest remnants can be more valuable for biodiversity than previously assumed," said co-author Daniel Karp, a NatureNet postdoctoral fellow at the University of California, Berkeley.

"If we're valuing coffee fields and other human-made habitats at zero, we're doing a disservice to ourselves and wildlife," says Chase Mendenhall, a Stanford doctoral student in biology and the study's lead author..

To test the island theory against a more holistic theory of agricultural or countryside biogeography, the researchers turned to bats acutely sensitive to deforestation. Their study focused on bat populations within a mosaic of forest fragments and farmland in Costa Rica and on islands in a large lake in Panama. The researchers also did a meta-analysis of 29 studies of more than 700 bat species to bolster and generalize their findings globally.

Island biogeographic theory accurately predicted bats' responses to forest loss on the Panamanian islands system, but didn't come close to accurately forecasting similar responses in the Costa Rican countryside landscape. For example, the island theory predicted that the Costa Rican coffee plantations would have inadequate habitat to sustain a single species of bat. In reality, plantations in the countryside typically supported 18 bat species, compared to the 23 to 28 supported by tropical forest fragments and nature reserves.

"Conservation opportunities for tropical wildlife are tightly linked to adequate management of these human-modified habitats," said co-author Christoph Meyer, a researcher at the University of Lisbon's Center for Environmental Biology.

Overall, as forest cover disappeared, the rate of species loss was "substantially and significantly higher" in the island ecosystem, and species abundances were "increasingly uneven" compared to the countryside ecosystem, the study found.

The reason for the discrepancies, according to the study's authors, is that island biogeographic theory was originally based on actual islands surrounded by water, and does not account for factors such as a countryside landscape's ability to support more species and slow extinction rates compared to true island ecosystems. Especially in the tropics, island biogeographic theory's application is "distorting our understanding and conservation strategies in agriculture, the enterprise on which the future of biodiversity most critically hinges," the study's authors wrote.

"Not only do more species persist across the 'sea of farmland' than expected by island biogeographic theory, novel yet native species actually thrive there," said co-author Elizabeth Hadly, Professor in Environmental Biology at Stanford. "This indicates that human-altered landscapes can foster more biological diversity than we anticipated."


A new approach




The fate of much of the world's wildlife is playing out in human-altered landscapes that are increasingly threatened by chemical inputs such as herbicides and pesticides. Biodiversity is not the only loser. People are losing many of nature's benefits such as water purification provided by forests and wetlands and pest control provided by birds and bats.

The study's findings point to the need for new approaches that integrate conservation and food production, to make agricultural lands more hospitable to wildlife by reducing chemical inputs, preserving fragments of forest and other natural habitats and rewarding farmers and ranchers for the benefits that result.

"A theory of countryside biogeography is pivotal to conservation strategy in the agricultural ecosystems that comprise roughly half of the global land surface and are likely to increase even further in the future," the researchers wrote.



Citation: Chase D. Mendenhall, Daniel S. Karp, Christoph F. J. Meyer, Elizabeth A. Hadly& Gretchen C. Daily, 'Predicting biodiversity change and averting collapse in agricultural landscapes', Nature April 16 2014 doi:10.1038/nature13139