Baihetan hydroelectricity project

The 2012 China Ecological Footprint Report has highlighted the cost to biodiversity of China’s rapid economic development.

Biodiversity in China is under pressure because of loss of habitat. In our study area on the upper Yangtze River, this is exacerbated by a series of proposed dams. Four large hydro-electricity schemes, each involving the construction of a large dam, are planned for this section of the river, known as Jinshajiang. When complete, an 800km section of the river forming the border between Sichuan and Yunnan will be affected. The total capacity of the four schemes is 42,460 MW, much greater than the capacity of the Three Gorges Dam.

Dramatic changes in the ecosystems of the area are likely to occur as a result of permanent flooding. The Baihetan hydroelectricity project is by far the largest of the four. This area has a relatively poor regional economy and most of the population has an income below national and provincial poverty lines. Agriculture is the main economic activity for the local population and substantial food and silk resources are grown in the area. Most of the people are from the Yi Minority Nationality. The Yi people typically farm the higher elevation areas, which are more marginal in productivity.

Inundating the lower areas means people will have to relocate to higher ground and more marginal farmland. The vegetation lower down will end up under water. It is possible that the construction of the dam will change the local climate of the valleys from warm and dry to cooler and wetter as they are filled with water. All of this is happening in a region which has been farmed for many thousands of years and is suffering from erosion due to deforestation.

Relatively little is known about the flora and fauna of these valleys, which are characterised by high mountains, steep slopes and narrow, deeply dissected valleys. The combined effects of a rain shadow and föhn winds cause an unusually dry climate. Most of the hill slopes are used for agricultural production but small patches of natural habitat remain, often at higher elevations and along watercourses.

We are documenting the bird fauna as indicators of wider biodiversity in this area. Birds have been called “flying data collectors” and are often used as indicators of change in ecosystems. As a group, birds are highly versatile, making a living in all kinds of habitats as herbivores, carnivores and omnivores. They respond to environmental change in measurable ways, in both space and time. Since they tend to be at or near the top of the food chain, they also respond to changes that accumulate through the chain.

The planned flooding of his area provides an opportunity to understand what happens to birds and ecosystems when significant landscape changes occur. However a major obstacle to investigating changing patterns in the distribution of bird species in China is a lack of basic data. Very few published lists of bird species known to inhabit Chinese farmland habitats are available and for our study area, there are no such lists.

Our work intends to address this gap and to provide advice to policy makers about biodiversity conservation within eroded, agricultural landscapes. Preliminary results from our bird surveys suggest that small, scattered pockets of forests remaining in the landscape are important habitat for birds. The approach taken to the protection of remnant vegetation in the Victorian State Government’s Native Vegetation Framework (“protect, enhance and restore”) is directly applicable in such areas.

As has been the experience in Australia, protection of streamside vegetation will also benefit human communities, helping to address soil erosion and water quality issues, both of which are considerable problems in the area. Key to this effort to protect and enhance biodiversity is to engage local farming communities in these efforts so that people are able to manage their landscapes in ways that allow them to continue to produce food and fibre and to contribute to the conservation of biodiversity.

Researcher measuring the productivity of algae in a stream. Photo: Brad Cardinale

An estimated 9 million species of living things inhabit the Earth — plants, animals, fungi and micro-organisms such as algae and bacteria. But those species are disappearing at an alarming rate, and this loss of biodiversity appears to be a major driver of environmental changes that can affect the biological and chemical processes that humans rely on, according to a new paper in the journal Nature.

“No one can agree on what exactly will happen when an ecosystem loses a species, but most of us agree that it’s not going to be good. And we agree that if ecosystems lose most of their species, it will be a disaster,” said Shahid Naeem of Columbia University, who was one of 17 scientists from around the world who worked on the paper, a review of 20 years of ecological research published this week.

The 7 billion people living on the planet now depend on those ecosystems, and the diverse array of life that comprise them, for our own existence: for food, water, fertile soil, fuel, clean air and protection from pests and disease. The ways that those organisms absorb, utilize and recycle nutrients also play a key role in our climate.

“There is now unequivocal evidence that biodiversity loss reduces the efficiency by which ecological communities capture biologically essential resources, produce biomass, decompose and recycle biologically essential nutrients,” the authors write in the paper, “Biodiversity loss and its impact on humanity.”

The paper comes 20 years after the first earth summit in Rio de Janeiro, where a majority of the world’s nations recognized that human activity was “dismantling the Earth’s ecosystems, eliminating genes, species and biological traits at an alarming rate,” the authors note. The 1992 Earth Summit in Rio resulted in 193 nations supporting the Convention on Biological Diversity’s goals of biodiversity conservation and the sustainable use of natural resources.

The summit spurred a flood of research into ecosystems and biodiversity. From that work, the authors say, strong scientific evidence has emerged showing that loss of the world’s biological diversity reduces the productivity and sustainability of natural ecosystems.

“Twenty years and a thousand studies later, what the world thought was true in Rio in 1992 has finally been proven: Biodiversity underpins our ability to achieve sustainable development,” said Naeem, who is chairman of the Department of Ecology, Evolution and Environmental Biology at Columbia and director of science for the Earth institute’s Center for Environmental Research and Conservation.

In just two weeks, representatives from national governments, civil society groups, businesses and other organizations from around the world will gather in Rio again, for Rio+20, the United Nations Conference on Sustainable Development, to try to hammer out new goals for economic development, the eradication of extreme poverty and environmental protection. The Nature paper’s authors say biodiversity should be high up on the agenda.

“Much as the consensus statements by doctors led to public warnings that tobacco use is harmful to your health, this [paper] is a consensus statement by experts who agree that loss of Earth’s wild species will be harmful to the world’s ecosystems and may harm society by reducing ecosystem services that are essential to human health and prosperity,” said, Bradley Cardinale, an associate professor at the University of Michigan who led the review.

“We need to take biodiversity loss far more seriously – from individuals to international governing bodies – and take greater action to prevent further losses of species,” said Cardinale.

Human actions — such as deforestation, overfishing, industrial-scale agriculture and urban development — are dismantling Earth’s natural ecosystems, resulting in species extinctions at rates several orders of magnitude faster than observed in the fossil record.

Even so, there’s still time – if the nations of the world make biodiversity preservation an international priority – to conserve much of the remaining variety of life and to restore much of what’s been lost,

Biodiversity and farming go head to head in two R&D projects that I have a hand in. The struggles to both feed the swelling ranks of humanity and save our continent’s natural splendour are so often at odds, but we need to find a way to marry the two. The projects I’m involved in are:

1) a bid for a Cooperative Research Centre (CRC) for Safeguarding Biodiversity (twitter #safeguardingbiodiversity), a national program designed to prevent the extinction of Australian native vertebrate animals

2) UWA Future Farm 2050, for which the vision is “Imagine the ideal farming system for 2050, and do it now” (the year 2050 has been chosen because, by then, we will need to feed 50% more people globally without destroying the planet).

These two projects collide head-on because biodiversity can be lost when we change the landscape, and the farmers of Australia are the custodians for as much as 80% of the landscape. We cannot do without agriculture, but the industry must be profitable. By contrast, protecting biodiversity is unlikely to be profit-driven. Can the two ventures be compatible? One aspect of the UWA Future Farm project aims to show that they can be.

The Future Farm project might look like academic idealism but, in fact, its major indicator of success will be a normal level of profitability. The crop (wheat, canola) and animal (primarily sheep) enterprises will fit the 2050 vision but they must be profitable so the farm can pay salaries and have money for maintenance and development.

However, about 35% of the 1600 hectares is not profitable for cropping or pastures because it is rocky or otherwise unsuitable. Arguably, this land should never have been cleared of native bush. This situation is typical of farms in the WA wheat/sheep zone, and probably typical for much of the Australian agricultural landscape.

This land, however, is not a waste but an opportunity. In the Future Farm project, we are re-establishing the native ecosystem on the non-profitable parts of the farm. This is no simple matter – one does not simply go out and plant a few favourite native bushes. We need professional expertise: people who can measure the local ecosystem, make informed estimates of its likely structure before colonisation, and then formulate a feasible mix of plants for restoration.

We began by planting 14,000 plants comprising a mix of native tree and shrub species belonging to functional groups that differ in the way they acquire nutrients. The planted area links two remnants of native bush and it is our first step towards the creation of a mosaic and corridors that we hope will include neighbouring farms and public roadside verges and nature reserves.

Clearly, we have high expectations that restored ecosystems will be colonised by other Australian plants and, of course, by native Australian animals. This brings us back to the bid for a CRC for Safeguarding Biodiversity and its three elements of research and development: i) gauge the urgency with which we need to tackle a given problem; ii) provide proven responses that solve the problem; and iii) future-proofing to prevent the problem recurring.

Part of CRC’s remit will be restoring and managing ecosystems restoration and management. We also have to grapple with the socio-political issues that get in the way of saving biodiversity. This type of problem is seen, for example, in cockatoos that are endangered yet are seen as pests by horticulturalists. At the other extreme, over-abundant animals are difficult to control in peri-urban areas.

Both the CRC and the Future Farm grapple with core elements of Australia’s self-image. We cannot imagine an Australia without our iconic animals such as the bilby or the black cockatoo, and we cannot imagine an Australia that does not produce food.

So what is needed to marry these two identities? Probably the highest priority will be creating a socio-political system that encourages the custodians of our landscape to both produce food and participate in safeguarding biodiversity. The policies and laws of the land need to be compatible rather than contradictory. We currently punish industries that cause environmental damage but we should also financially reward them if they invest in ecosystem restoration.

On the Future Farm, we are certain that ecosystem restoration will have little effect on our long-term profitability because we are only using non-profitable parts of the farm. But the initial cost is significant, certainly tens of thousands of dollars, and it would be unwise to expect all farmers to do this simply out of the goodness of their hearts. On the other hand, it seems feasible to ensure a commitment from the farmers if they were rewarded financially for their efforts – via carbon sequestration, for example.

Importantly, neither the CRC nor the Future Farm deal with a critical issue in modern Australia: the role of indigenous people, their history, their culture, and their relationship with the landscapes that we share.

It is critical that all Australians see farmers as part of the solution, not the problem.

Silicon Valley, Bangalore, Shanghai. At one time or another, each of these locations, among others, has become home to a successful ‘business cluster’ of industries. Although the term was coined as recently as 1990, clustering of businesses in the same geographical locality has taken place for centuries, driving productivity, innovation and expertise.

A comparatively new phenomenon is the co-location of institutions whose goal is to protect and manage biodiversity worldwide. Whereas business clusters are built on inter-firm competition resulting in enhanced economic growth, conservation clusters are built on inter-organisation collaboration resulting in innovative solutions to a global threat.

Collaboration between organisations linked by a common cause has the potential to unleash synergies and spur innovation that can positively impact the world

Now, a study by Vena Kapoor, a student on the MPhil in Conservation Leadership Programme in the Department of Geography, has explored how conservation clusters function optimally, highlighting best practices and lessons learnt for current and future conservation clusters.

“Probably the most important aspect for success is for a cluster to be based on a social network that initiates and facilitates a trusted collaboration,” she said. “Those clusters that began with an injection of funds but no underlying social network have been less successful.”

Kapoor identified 17 conservation clusters currently in existence globally. Clustering, as she explained, brings advantages: “Like their business counterparts, conservation clusters benefit from the physical proximity of similar organisations in terms of the potential for knowledge spill-over and a growing pool of skilled employees.”

Cambridge is home to the largest conservation cluster in the world. Comprising eight conservation organisations, a conservation network and departments of the University, the cluster has been co-ordinated as the Cambridge Conservation Initiative (CCI) since 2007, and is also a Strategic Initiative of the University.

“In Cambridge’s case, the network took the form of the Cambridge Conservation Forum (CCF),” explained Dr Mike Rands, Executive Director of CCI. “Out of CCF bubbled a series of programmes that people wanted to do together. Then came the process of co-ordinating these collaborative programmes and raising the funds to deliver them.”

A representative and democratic governance mechanism and a neutral facilitator to guide the collaboration were also identified as key features of successful clusters. The study concludes that ideally these features should take the form of a ‘cluster initiative’ that improves the collaborative potential of the cluster and raises independent funds for it. Although rare in conservation, cluster initiatives have become a popular feature in business, often with government support.

“Collaboration between organisations linked by a common cause has the potential to unleash synergies and spur innovation that can positively impact the world,” added Rands. “But even the best initiatives can be derailed. At this early stage in the creation of conservation clusters, it’s important to be aware of the challenges as well as the rewards.”

For a cluster to be successful, the advantages of being part of the collaboration must continue to outweigh the disadvantages, as Kapoor explained: “In the beginning, members get something from each other – they all learn about each other’s practices, research agendas and tools. But tension can develop when a member perceives a growing competitive overlap with another member, a feeling of dominance by a single or few members, or a lessening of their branding or niche position.”

“This is where a neutral facilitator can continually bring value,” said Dr Stelios Zyglidopoulos, from the Cambridge Judge Business School, who co-supervised the study with Dr Rands. “The purpose is to bring oil and water together – to forge links between different organisations. It’s through bringing together different kinds of people and organisations that innovation happens.”

Dr Rands agrees: “If there is a lesson that I’ve learned it’s to keep fostering the mixing of researchers and practitioners across disciplines. Only then can we demonstrate that together the members are able to do things that they could never have done on their own, and yet still progress their own individual organisation’s mandate and interests. This study makes a strong case for the global conservation community to harness the concept of clusters to deliver stronger and better conservation solutions for the world’s biodiversity and the natural capital it provides.”

Botswana produces some of the highest quality, organic, free range beef in the world. Until early last year, the EU was an important destination for this high value product. Then, following a visit by EU veterinary inspectors, new requirements were imposed requiring that all beef exports be traceable to fenced ranches or territories. After over a million USD in expenditures, and a six month self-imposed export moratorium to the EU, the Government of Botswana has met these requirements. Unfortunately, these new regulations will almost certainly hasten rangeland degradation in this semi-arid country.

Botswana is an African development success story. It was one of the poorest African countries at independence in 1966 with only five kilometers of paved roads and 23 college graduates. The discovery of diamonds a few years after independence, and the astute management of this resource, allowed the country to invest heavily in education, infrastructure and health care. These investments, combined with a relatively small national population of about two million people, allowed the country to become one of Africa’s most well-to-do.

The country has had one of the fastest growing economies in the world over the past 40 years. This rate of growth is comparable to that of the Newly Industrialized Countries (NICs) of East Asia, yet Botswana did this under democratic governance. Today Botswana has a per capita GDP of $13,100 and eight billion USD in reserves, enough to cover imports for 20 months. The three pillars of its economy are: gem diamond exports (for which it is the world’s largest producer), high end ecotourism, and high quality, grass fed beef production.

European eco-imperialism

Animal husbandry in the semi-arid regions of Africa has long been organized differently than that of the temperate zones for sound ecological reasons. Herders traditionally ranged widely across the landscape in search of better pasture, focusing on different areas depending on meteorological conditions. The approach worked because, unlike fenced pastures in Europe or North America, it was incredibly flexible and well adapted to variable rainfall conditions. Fenced ranches in semi-arid Africa are problematic because livestock become more concentrated, more vulnerable to drought, and more detrimental to the landscape.

The Botswana Meat Commission (BMC), a government parastatal, has played a central role in Botswana’s developmental success. By ensuring proper veterinary care, appropriate controls on the spread of foot and mouth disease, fair prices for producers, and sophisticated international marketing, the BMC has ensured that this traditional element of the rural Botswana economy has grown and prospered over time.

While Botswana has experienced periodic outbreaks of food and mouth disease (which often reaches cattle via wildlife populations), the BMC is incredibly meticulous about insuring that beef exports only originate from areas of the country that are completely disease free.

While the fencing of ranches is not a new phenomenon in Botswana, the latest EU regulations mean that cattle must be traceable to smaller and smaller areas. This implies that growing quantities of fencing are required and cattle movement is increasingly restricted. The desirability of traceability to such small areas may make sense in the temperate zone, but it is extremely problematic in semi-arid, tropical regions where rainfall and pasture conditions are more variable.

Ecological impact?

Skeptics wonder if the new EU regulations were really about disease prevention, and quality control, rather than protecting European beef producers. If the latter was the intent, Botswana has shown the EU that it could overcome this latest trade barrier in a relatively short amount of time.

The real tragedy is that EU regulations are now hastening rangeland degradation in an ecologically fragile part of the world. While EU consumers may think that organic, free range beef implies a product which is better for the environment, they should know that European eco-imperialism, in the form of trade regulations, is incredibly dogmatic, destructive and ignorant of tropical grassland ecology.

In this instance, the EU should look anew at the ecological impact of its regulations abroad. A failure to do so is particularly ironic given European concern for sustainable environmental management in this part of the world.

Botswana, for its part, should continue to explore and expand other markets for its beef exports, such as it is doing with South Africa and China. It must also push back against the EU and assert the importance of understanding semi-arid rangeland ecology in the tropics. Botswana has historically prospered when it carefully considers it options, pushes back when it needs to, and does what is best for the long term, sustainable development of the country. This time is no different.

William G. Moseley is a human-environment and development geographer. He is a professor at Macalester College in Saint Paul, MN USA and, currently, visiting scholar in the Department of Environmental Science at the University of Botswana, Gaborone.

We know very little about the world’s biodiversity. A recent study suggests that, despite 250 years of taxonomic effort, a mere 14% of the world’s species are recognised by scientists.

Worryingly, anthropogenic effects, including habitat loss, climate change, and invasive species, threaten to exterminate thousands of species before they are even described. In this race against time, scientists are working to describe new species and characterise the extinction risk of known species so they can plan actions to reduce extinctions.

The International Union for the Conservation of Nature (IUCN) has been working since 1994 to identify which species are at greatest risk of immediate extinction and place them on the Red List of threatened species.

The IUCN uses quantitative and objective criteria (such as population size, rate of decline, and range size) to classify species as imperilled (Vulnerable, Endangered, or Critically Endangered), Near Threatened, or Least Concern. Through the collaboration of many scientists, and regular refinement of the categories and criteria, the IUCN Red List has emerged as the leading global threatened species list.

Many countries use national “red lists” to protect locally threatened species and evaluate species at the local level where they are managed. One of the best known national lists is the United States Endangered Species Act (ESA), which legally protects species. It is arguably the world’s most effective conservation law.

The ESA classifies a species as endangered if it is “in danger of extinction throughout all or a significant portion of its range”. It is threatened if it is “likely to become endangered in the foreseeable future”. If sufficient information is available to warrant listing but listing is “precluded by higher listing actions”, species are considered “warranted but precluded” and not listed. This means that species deemed to be at greater risk of extinction are often listed before “warranted but precluded” species.

ESA listing decisions often become political because listings have the power to stop development projects that impact listed species.

The ESA has succeeded in improving the conservation status of most listed species over time and may have prevented 227 extinctions. Nonetheless, the US government’s implementation of the ESA has been problematic, including political intervention and protracted listing times.

For example, the listing rate varies greatly depending on who is president. The mean listing time from 1974–2003 was greater than 10 years (in contrast to stated maximum of one year). Partly as a result of these shortcomings, at least 42 species or subspecies have gone extinct while awaiting ESA listing.

Given the ESA’s status as one of the world’s most prominent national lists, its track record at conserving species is of international interest. A previous study found that the ESA does not recognise at least 90% of the United States’ imperilled species listed by NatureServe. But no studies have analysed the ESA’s coverage of species listed as globally imperiled by the IUCN.

We undertook the first comparison of IUCN and ESA listings of US birds, mammals, amphibians, gastropods, crustaceans, and insects. We studied the listing histories of three bird species and Pacific salmon in more detail. We found that 40% of IUCN-listed birds, 50% of mammals, and 80–95% of species in the other groups were not recognised by the ESA as imperilled.

Our research suggests that a nearly 10-fold increase in listing would be required if the ESA were to protect the gamut of IUCN-listed species. Our data indicate that less imperilled (but at-risk) species are most likely to be overlooked. This does not bode well for the ESA’s ability to mitigate declines before species become critically imperilled.

The bird case studies exemplify how rapidly declining species can be carefully evaluated by the ESA but still not listed. By contrast, the salmon example shows an alternative situation: agencies were effective in evaluating and listing multiple (closely-related) species.

Lack of funding, vague definitions of the ESA’s threatened and endangered categories, and the existence of the “warranted but precluded” category likely contribute to the ESA’s under-recognition of imperiled species.

The ESA is a powerful environmental law, but its impact is limited because most imperilled species (measured by the IUCN Red List) are not ESA-listed. The case of the ESA illustrates a tradeoff between strong species protection and poor coverage of threatened species caused by the substantial implications of listing. The successes and failures of the ESA provide rich lessons in threatened species conservation stategies that should inform managers in other countries.

Researchers develop a unified theory of ecosystem change by combining spatial modelling and food web analysis.

Animals like foxes and raccoons are highly adaptable. They move around and eat everything from insects to eggs. They and other “generalist feeders” like them may also be crucial to sustaining biological diversity, according to a new study published this week in the Proceedings of the National Academy of Sciences (PNAS).

McGill biology researchers have developed a unified, spatially based understanding of biodiversity that takes into account the complex food webs of predators and prey. “Biodiversity exists within a landscape. Predators and prey are continuously on the move as their habitats change – it’s a complex dynamic system,” says lead author Pradeep Pillai, a former doctoral candidate at McGill, now a research associate at the University of Oregon.

Previous theories of biodiversity have either concentrated on the complex network of feeding interactions that connects all species into food webs or have focused on the way that species are connected in space. “A unified theory of ecological diversity requires understanding how species interact both in space and time, and this is what is different about our work,” explains co-author Michel Loreau, who holds the Canada Research Chair in Theoretical Community and Ecosystem Ecology.

What they discovered was that a “branching network” maintained by generalist species, like foxes or coyotes, that are able to move around and prey on different species in different locations, have an important role in promoting complex food webs and thereby in maintaining biodiversity. The researchers concluded that these generalist species have the advantage of being able to find prey no matter where they are as they move from one place to another, and this sustains the network.

This theory also lays a foundation for understanding the effects human activities – like deforestation – are likely to have not simply on a single species but on whole food webs. The researchers show how food webs are eroded by species extinction when disturbed by habitat destruction. “The theory is useful because it helps us understand how biodiversity is maintained, but also the impacts humans have when they disrupt ecological networks by destroying and fragmenting habitat,” concludes co-author Andrew Gonzalez, Canada Research Chair in Biodiversity Science and Director of the Quebec Centre for Biodiversity Science.

When my children are my age they will be living in a country with an economy that’s three times larger, and a population that’s twice as large as today.

And, on current trends, my children will be living in a country with around 10 million hectares less of native bushland.

So, how can we stem the loss of our distinctive natural heritage in the face of continuing economic growth?

The Federal Government is currently seeking public comment on a controversial solution to this problem.

Their plan is to nationalise “biodiversity offsets” to halt the loss of our significant biodiversity. Biodiversity offsets are actions at one site that compensate for losses at another.

For example, a company might destroy native habitat to create an open cut mine and offset this impact by planting vegetation in another area.

On face value this seems to be a win-win outcome, which probably explains why governments around the world are embracing biodiversity offsets.

But will biodiversity offsets halt the loss of biodiversity?

Not according to most ecologists.

The key criticism of biodiversity offsets is that there is only a narrow range of circumstances in which impacts on biodiversity can be offset with any kind of certainty.

An ecologist named Keith Bradby put it nicely in a documentary called “A Million Acres a Year” when he said, while looking over a piece of Western Australian bushland: “We can put a man on the moon, but we can’t recreate that.”

Another problem with the policy proposed by the Australian Government is that biodiversity offsets are not established before the impacts occur.

It can take 200 years before an offset will replace a nest tree for Carnaby’s Black-Cockatoo, a species threatened by urban development. We should be establishing offsets well in advance of impacts on our biodiversity.

The fault with many offset programs, including the Australian Government’s recent offering, is they promote the protection of high quality habitats as suitable offsets. If you think about it, a site that is already in good condition has little scope for improvement. So, this strategy actually results in a net loss of bushland.

Despite these issues, I offer guarded support for biodiversity offsets for the same reason I believe we should place a price on carbon to reduce greenhouse gas emissions.

Biodiversity offsets effectively place an economic value on biodiversity, thus discouraging its destruction in the first place. This is because offsets represent an economic impost to developers: it takes considerable resources to identify, establish and manage an offset.

This was demonstrated in New South Wales where the number of approvals to clear native vegetation dropped by about 80% after the introduction of offsets.

So, while offsets will not stop the loss of biodiversity, they might reduce the rate of loss.

That said, the Australian Government’s proposed policy will subvert this market effect. This is because the policy is riddled with exemptions. “Minor” losses, “non-signficant impacts”, and “economic and social factors” are all reasons a project can proceed without offsets under the current proposal.

At at time when mining industries have significant clout, when governments are doing everything in their power to maintain economic growth and when we have a rapidly growing population coupled with a housing shortage, you can bet these exemptions will be like cracks in a dam wall.

This was demonstrated recently in New South Wales. While the number of approvals to clear native vegetation dropped by about 80% after the introduction of biodiversity offsets, the area of clearing only decreased by 30%.

Exemptions in the legislation discouraged developers from finding alternatives to clearing.

And this takes us to the nub of the problem with land clearing policy. The current proposal from the Australian Government, like others before it, seeks to minimise the impacts of development on biodiversity, while making no attempt to address the causes.

We keep trying to plug the cracks in the dam rather than drain the water.

If we really want to stem the erosion of our natural heritage we must divorce economic growth from its attendant impacts on biodiversity.

That is, we need to de-couple food security from land clearing, achieve population growth without urban expansion, find transport solutions without widening roads and supply utilities without clearing easements.

Only then can we pursue economic growth without continuing to erode Australia’s distinctive natural heritage.

And only then are our children likely to enjoy the same natural heritage that we did.

We live in an age of vanishing rainforests. Half of the world’s tropical forests have disappeared since World War II and roughly another 10 million hectares are being felled each year — the equivalent of 40 football fields every minute.

It’s a bit of a no-brainer to say this is bad for biodiversity. After all, rainforests are the biologically richest real estate on the planet, sustaining at least half of all known species of plants and animals in just 7% of the Earth’s land area.

Despite these facts, biologists are far from certain about how many species are imperiled by rainforest destruction. Some believe as many as two-thirds of all species could disappear in the coming century, largely because of tropical deforestation.

Others reckon the figure will be a lot lower — perhaps just 5-10% of all species will eventually disappear.

Why the big difference in these numbers? A key reason is that we’re still unsure about how many species can survive in degraded forests.

Degraded forests come in lots of flavours.

There are selectively logged forests, fragmented forests, forests that are scorched by ground fires, and forests that are overhunted.

In many areas, forests are regenerating after being completely felled or burned. In other areas plantations of exotic species, such as acacia or oil palm trees, are spreading across the landscape.

Degraded forests are the future. All across the tropical world, old-growth rainforests are vanishing and being transformed into human-dominated landscapes. These landscapes might sustain a few isolated patches of old-growth rainforest surrounded by expanses of farmland, human settlements, plantations and degraded forests.

So will most species survive in these wounded landscapes, or just a few?

The debate about species extinctions and degraded forests has polarised the scientific community. A leader of the extinctions-won’t-really-be-that-bad-camp, Joe Wright of the Smithsonian Institution in Panama, has upset a lot of people by arguing that most species will be able to survive in regenerating rainforests.

Some biologists think this is bunk.

At a large international meeting in Darwin a few years ago, one well-known scientist got so upset with Joe that he told him to perform a rude physical act that is technically impossible. Joe was mortified but the audience loved it. They felt Joe wasn’t taking the extinction crisis seriously enough.

This week my colleagues and I jumped into the middle of this debate. We did so by publishing a research paper in the journal Nature today, synthesising 138 different studies around the tropics.

These studies were used to contrast the biodiversity in old-growth forests with that in many different kinds of degraded forests.

In broad terms we found that the old-growth forests won, hands down. For the species we are most concerned about —those most vulnerable to extinction — you just can’t beat an undisturbed rainforest.

There was, however, one kind of degraded forest that fared better than the others: those that have been selectively logged.

In logged forests, bulldozers are used to extract a few large logs per hectare of forest. The bulldozers do quite a lot of damage, but the forest itself largely remains. In logged forests, some disturbance-sensitive species decline in abundance, but only a few vanish altogether.

This means we shouldn’t write off logged rainforests as being unimportant. They’re not pristine, but from a biodiversity perspective they’re a heck of a lot better than farmland, regenerating forest or plantations.

This conclusion has some vital implications.

Earlier this year, the Indonesian government designated a vast area of logged forest – around 35 million hectares, a dozen times the size of Belgium — to be cleared for farmland or exotic tree plantations. They’ve done so because logged forests, they argue, are too badly degraded to be of much importance.

Our findings suggest the Indonesian government is flatly wrong: logged forests have a great deal of biological value. Instead of clearing logged forests, they should be expanding agriculture onto degraded grasslands and abandoned farmlands, which exist in abundance in the country.

Biologists like myself are not anti-development. But we are anti-foolish development. The thing that irks me and others is to see biological travesties still occurring in an era when we should (and do) know better.

The bottom line is that old-growth rainforests are the greatest celebration of life on earth. We should do everything we can to preserve them.

But if we can’t save enough old-growth forest to sustain nature, then selectively logged forests are pretty good as well.

So, we have to feed an extra 2.5 billion people by 2050. For those of us interested in the future of biodiversity on this planet, this poses an uncomfortable challenge. It is also the topic of a recent paper in Science by Ben Phalan and colleagues at Cambridge University.

Clearly, we need to ramp up food production considerably but how will we do this?

Simply put, there are two options:

1) convert more land for agriculture;
2) increase yields from existing agricultural land.

Of course we will end up doing a bit of both (it will be interesting to see whether we can actually reach our food production target either way – but that is another story).

But is one or the other approach better from the perspective of biodiversity conservation?

Should we be encouraging intensification of agriculture, to get the most out of every farmed hectare, and spare as much “natural” habitat as possible (known as “land sparing”)?

Or should we be encouraging “land sharing”: using “wildlife-friendly” farming, despite such methods generally producing smaller yields? (Of course, smaller yields mean more land conversion is needed to produce the same amount of food.)

The “land sparing vs. land sharing” debate is not new, but Phalan’s study is a neat analysis using data on birds and trees from Ghana and India.

Phalan and colleagues tackled the question: as food production (measured in both energy value and profit) is ramped up, do more species win from land sparing, or from land sharing?

This debate is something we all partake in every time we buy (or choose not to buy) a product such as chocolate from shade-grown plantations.

Many studies have shown that intensive agricultural methods generally result in poorer outcomes for wildlife, compared to less-intensive approaches.

Also, production systems such as shade-grown cacao tend to provide much better habitat than conventional monocultures (agriculture where just one species is grown).

What this research should prompt us to think about, though, is the impact beyond the operation in question.

If yields are lower in such wildlife-friendly systems, then, given rising global demand, such low-yield operations might simply increase pressure to convert more land elsewhere.

Phalan and colleagues estimated the yields from low- and high-intensity farming, and worked out how much more land would need to be cleared to make up for lower yields in low-intensity systems.

They used information on birds and trees in landscapes with different levels of production output to project how different species’ population sizes would respond to different ways of using the land.

While shifting from low- to high-intensity farming is generally bad for wildlife, shifting from forest to even low-intensity farming is generally disastrous.

As agricultural output increases, there are two possible scenarios. If production intensity is ramped up but forest conversion is minimised, far fewer species decline dramatically. If land is shared, species decline more rapidly.

So, for birds and trees in Ghana and India, the answer was clear – there are simply far more species which stand to lose from land sharing than land sparing.

Despite some of the media reaction, there are two things the study does not do. It does not trash organic agriculture, nor does it shed much light on whether agri-environment schemes, such as those mandated by the European Union, are a waste of money.

European agro-ecosystems are fundamentally different from recently converted forests. In Europe, traditional agricultural practices have operated for millennia, and modern conservation goals in Europe are generally entwined with those agroecosystems.

On the other side of the equation, there is far greater potential for increased yields in Ghanaian farming systems than those in Europe (or Australia).

So it seems likely there would be more “winners” from wildlife-friendly farming in Europe than in a region from which most of the forest system has been cleared within the past hundred years.

Nevertheless, it remains important to explore not only the benefits of such schemes for particular species within Europe, but also the possible “land leakage”. Does wildlife-friendly farming in Europe add to pressure for land conversion (and potentially species loss) elsewhere in the world? And which path should we follow in Australia?

Just as conservation action in one place might simply move development pressure to another place, intensification has its own effects on the environment. These were not accounted for by Phalan and colleagues.

Intensive agriculture often relies on significant fertiliser use (especially in Australia), increased fuel use, and chemicals (although some of the “low-intensity” systems they studied involved high chemical use, too).

All of these things affect biodiversity well beyond the tilled field, but their impacts are difficult to quantify.

And what of the long-term sustainability of the production systems themselves?

If we choose intensive farming, will the less-biodiverse system be less resilient and decline in productivity, requiring us to clear more land anyway?

Finally, if we take Australia as an example, there are many species (such as the superb parrot or south-eastern red-tailed black-cockatoo) we could lose entirely if we don’t invest in their conservation on farmed land.

There can never be a single, simple answer to the “land sharing vs. land sparing” debate. In fact, we still have more questions than answers.

But they are important questions – and we need to keep trying to answer them if we are to have our biodiversity and eat, too.