A new ecological study of novel human-influenced ecosystems should change the debate about whether farmers should be sharing land with nature or sparing land for nature.
Sparing land for nature
Lately the sparing-v-sharing argument seems to have been going the way of the sparers. Much discussion has centered on a critique by Cambridge University’s Ben Phalan two years ago on “how to meet rising food demand at the least cost to biodiversity.” From two studies in Ghana and India, Phalan found that “more species were negatively affected by agriculture than benefited from it” and that “land sparing is a more promising strategy”.
The take-home lesson was that we need more high-tech, high-yield farms and some solid fences between them and land strictly protected for nature. In other words, forget agro-ecology, it won’t deliver.
Lots of people like this. Conservation organizations get their own land to play with, often part-funded by agribusinesses, who are equally happy to have greens off their backs. It also fits an emerging agenda for commodifying nature through carbon trading and habitat banking, a strong theme at last year’s Rio+20 summit.
Whether the sparing strategy makes sense for nature depends, in part, on whether the choice is a zero-sum game. If agribusiness stimulates a land rush into nominally protected areas then the sparing proves illusory.
But it also depends on whether we are seeing nature right. And a major new book by ecologists and biogeographers on Novel Ecosystems, edited by Richard Hobbs of the University of Western Australia and others, suggests that conventional conservation is in denial about the ecological value of farmed forests and other agro-ecological landscapes.
Ecologists, the authors argue, systematically dismiss novel ecosystems – defined as ecosystems altered by humans and containing non-native species. They see them at best as valueless degraded versions of pristine habitats, and at as worst dangerous, because they contain non-native species that could spread.
But in the real world, most ecosystems are novel. Apparently pristine rainforests are frequently secondary growth on ancient farmland, Erle Ellis of the University of Maryland Baltimore County argues in the book.
Typically too, even the most invaded and most novel ecosystems have more biodiversity than what went before, since extinctions are rare and are almost always outnumbered by new arrivals. That applies at all scales from well-known “victims” of alien invasions like New Zealand to agro-ecological systems like the canopy coffee farms of Cameroon.
Sharing land with nature
Hobbs and colleagues argue that, except in the rare cases where alien species go on the rampage, conservationists should embrace such ecosystems, rather than shun them. And that means embracing agro-ecological systems, which are both major sources of forest products and rich in biodiversity, both native and alien.
Christian Kull of Monash University in Australia recently banged the drum for novel forest-based farming systems such as the rubber gardens of Indonesia, the cacao farms of Cameroon and rice smallholders in Madagascar. As he wrote in the journal Environment, these systems “blur boundaries between human and natural, native and non-native, production and conservation”. He called them “melting pots” – a deliberate riposte to the “hot spots” of biodiversity that conventional conservationists most treasure.
The new thinking about novel ecosystems should also change how we think about ecological restoration on abandoned land, such as former plantations. Ecologists mostly want to recreate a past “pristine” habitat. They usually start by trying to eliminate alien invader species. But if the idea of pristine is usually bogus – and in any case usually unattainable -- that should open the door to other options, say Hobbs and colleagues.
One option would be to give nature its head. The model here is Puerto Rico, a US island territory in the Caribbean and one of the few areas of the tropics where there has been major recent reforestation. Following the abandonment of sugar-cane farming, forests have regrown across half the island.
The new forests contain many alien species, brought to the island by humans in past centuries. Most interesting from an ecological point of view, aliens such as African tulip trees have been critical to the reforestation, pioneering regrowth and bringing native birds, reptiles and insects with them. It couldn’t have happened without them, says Ariel Lugo of the International Institute of Tropical Forestry, who has charted this rewilding.
Another option on abandoned plantations, of course, would be to assign the land for agro-ecology of the kind that the plantation may originally have replaced. It happens by default sometimes, when the plantation fences come down and nobody puts up new ones. But the case for it as a sustainable and desirable new land use is rarely made.
That is a pity. Especially now. For, if there is no pristine nature left, then all ecosystems are novel and all are of potentially equal worth for conservation. Seen through the prism of novel ecosystems, agro-ecology is not a poor-man’s substitute for either the conservation of “pristine” habitat or for high-tech farming. It is both productive and of high conservation value.
The case for sharing, rather than sparing, suddenly got stronger.
About the Author:
Fred Pearce is a journalist and author based in London, UK. He writes regularly for New Scientist magazine, the Guardian newspaper and Yale e360 web site. His books include Peoplequake, When the Rivers Run Dry and, mostly recently, The Land Grabbers.