Issues Magazine

Biodiversity Conservation and Food Security

By Tony Gregson

Agricultural biodiversity is often seen simply as a source of interesting traits to improve crops and livestock. However, it can deliver far more than that if given the opportunities.

The United Nations has declared that 2010 will be the International Year of Biodiversity. The UN has three overarching goals for the year:

  • to increase awareness of the importance of biodiversity for our well-being;
  • to halt the loss of biodiversity, which is currently up to 100 times greater than the natural rate of extinction; and
  • to celebrate success stories.

You can bet that we’ll be hearing about the loss of rainforests and coral reefs, about the threat to what conservationists call “charismatic megavertebrates” – the Siberian tigers and blue whales and pandas – and about valiant efforts to save species such as Leadbeater’s possum.

These are all important causes, and I hope that the world does indeed wake up to the importance of conservation. But as a farmer there is an aspect of biodiversity conservation that is a lot closer to my heart, and a lot more important to human survival: food. Agricultural biodiversity is an aspect of biodiversity that is often neglected in discussions about conservation. Indeed, many conservationists treat farmers the world over as the enemy. And yet, in many respects, agricultural biodiversity is even more threatened than some aspects of “nature”, and its conservation is even more important.

Definitions of biodiversity in general are very difficult, and agricultural biodiversity is no exception. It can be thought of as the variability among living organisms associated with the cultivation of crops and rearing of animals, and the ecological complexes of which those species are part. This diversity occurs at three levels:

  • the different ecosystems in which people construct and operate farming systems;
  • the different species, including livestock and different crops and forages in those systems; and
  • the genetic diversity within a given species.

Furthermore, some aspects of agricultural biodiversity, most obviously breeding of new varieties, are purposefully managed by people while others, such as soil microbes and pollinators, may be managed indirectly through specific practices. Still others, such as ground cover upstream, can have a huge impact on water flows yet are not managed.

You can find a variety of expressions of the threat to agricultural biodiversity. A common one is the narrow dependence of the global food supply on just a few species. Depending on exactly how you measure it, somewhere between two-thirds and three-quarters of the energy in human diets is supplied by just three species: rice, maize and wheat. Given that there are scores of edible and often more nutritious cereals, this narrowing makes the global food system more vulnerable.

There is a reduction, too, in the amount of diversity within each species. These things are difficult to measure, not least because there are no widely agreed ways to express the degree of diversity at a genetic level.

Nevertheless, some salutary statistics are available. For example, an exhaustive catalogue of apples grown in the US, published in 1904, lists 7100 named varieties of apple. Of those, 6800 are now extinct. There’s a similar story from vegetables: 97% of varieties named in 19th-century seed catalogues in the US were no longer available 100 years later. And the best cereal varieties change every couple of years, it seems, with old ones impossible to find.

Of course, not all of those varieties would be worth growing today, but that isn’t the reason we need to conserve them. We need them for the genetic traits they contain, traits that we may not even know about today. The whole history of agriculture is based on selection by farmers each year of seeds they want to replant. What they want might vary – such as flavour, drought resistance, pretty colours or better nutrition – and by making their selections they created the amazing range of agricultural biodiversity in the world today.

The same is true of scientific breeders. They are selecting from the diversity that farmers and previous breeders have assembled for them.

But it is impossible to predict just what traits will be needed in the future. Climate change predictions say that in addition to changes in the averages, weather patterns will become more variable. Will farmers need drought resistance, or the ability to survive while submerged, or both?

New diseases keep emerging to challenge the status quo. For wheat farmers like me, the big unknown now is a form of rust called UG99, which emerged in Uganda in 1999. It has been making its way steadily eastwards, with spores blown on the wind, and is believed to be already in Iraq and Pakistan. No commercially available varieties are resistant, although a consortium of research organisations is scouring the world for the traits that breeders need, with some success.

I have no idea when the scientists will find what they’re looking for, or which scrawny forgotten wheat it will be in, but I am confident they will find it. History bears me out. Hessian fly, barley yellows, karnal bunt, stripe rust, powdery mildew and many others have all been brought under a measure of control using genetic diversity found originally in farmers’ fields.

This isn’t just a problem for poor farmers far away. In Queensland and the Northern Territory, banana farmers have come face to face with a new race of Panama disease, which almost wiped out the global banana industry in the 1950s. At that time almost every banana in international trade was one variety, Gros Michel, which was susceptible to Panama disease.

The global banana today is Cavendish, which survived because it was resistant to Panama disease (note: was). The new race of Panama disease has mutated and can now get past Cavendish’s defences, and it is poised to invade the really big banana-growing countries of the world. Salvation will come only from existing agricultural biodiversity.

The need for genetic resources as an input for breeding is the classical case for conservation, but there are other equally good reasons to preserve agricultural biodiversity. Diversity – of kingdoms, of species, of varieties or breeds – makes a huge contribution to the stability and resilience of farmers’ yields. That old English proverb about not putting all your eggs in one basket has counterparts in many, many languages and more than a grain of truth to it. The more diversity there is, the less chance a small upset will turn into a major catastrophe.

Before the Berlin Wall came down, East German barley farmers sowed their fields with a mixture of three or four different varieties, each with a different resistance profile to fungal diseases. They didn’t have to predict which races of disease would be most prevalent, and they didn’t have to spray fungicides, which they could not in any case afford. Yields were the same, or slightly higher, than the average of single plots of each of the three or four varieties, and they were more stable from year to year.

In China a couple of years ago I had the opportunity to visit Professor Zhu, a specialist in rice diseases at Yunnan Agricultural University, who uses a similar technique to protect better-tasting older varieties of rice, which people are happy to pay more for but which are disease-susceptible. He plants the susceptible variety among rows of modern disease-resistant varieties to slow the spread of the fungi. This idea of making use of genetic diversity to combat pests and diseases is one that has a great deal to offer and that is the subject of a major research initiative at Bioversity International, the international agricultural research centre whose board I chair.

Another vital aspect of agricultural biodiversity is that it is the basis of a diverse diet, which confers all sorts of health benefits. In the developed world we keep hearing about the Mediterranean diet, or the Okinawa diet, with an emphasis on eating a wide range of vegetables and fruits. We also hear about the alarming rise in so-called diseases of affluence, such as Type 2 diabetes, obesity, cardiovascular disease and cancers, which those diets can protect us against. The truth is, those plant-rich, diverse diets were also typical of poorer people in developing countries, but as their diet becomes simpler and shifts to refined carbohydrates and fats, so too are the diseases of “affluence” on the upswing.

Bioversity International has been working with farmers, food technicians, parliamentarians, supermarkets, non-government organisations and others to promote the benefits of traditional ingredients in a more diverse diet, with impressive results. In India, for example, snacks made from local cereals such as foxtail millet have revitalised farmers’ prospects, improved conservation in farming areas and delivered healthier food to nearby urban populations. In Kenya, after a concerted and multi-pronged campaign, supermarket sales of traditional African leafy vegetables shot up 1100% in just two years, admittedly from a very low base.

The world has made great strides in tackling acute hunger and famine. What remains is the hidden hunger of missing micronutrients, which afflicts some two billion people worldwide, most of them young women and children. The approach to date has been largely medical – supplements and fortified foods – with some attempts to breed more nutritious staples, which of course depends on genetic resources.

There are other options. Increasing the diversity of the diet using species and varieties and methods appropriate to local cultures can make a huge contribution to nutrition and, as a result, to health and productivity, but not if we don’t have the agricultural biodiversity available.

Then there is climate change, which is already putting pressure on agriculture. The models predict that in many parts of the world, including Australia, the coolest average temperatures in 2070 will be hotter than the hottest average temperatures now.

Think about that. It means that farmers in those regions will have absolutely no experience of that kind of climate. At the very least they will need new varieties of the crops they know. More likely they will need crops they have never grown before.

We’re already seeing that in parts of Africa. Maize, by far the dominant crop, is increasingly unpredictable and likely to fail. Farmers in Sub-Saharan Africa are having to reacquaint themselves with older cereals like millet and sorghum, which were widely grown before the introduction of maize less than 500 years ago.

As climate shifts, it puts pressure on agricultural biodiversity. Farmers are going to abandon their varieties as those varieties fail more often, and yet those varieties could be just the thing for a different climate emerging elsewhere. Crop wild relatives, so often the source of important traits, are also imperilled as climates change around them.

Good modelling studies that make the most of existing geographical information from gene bank samples and herbarium specimens can pinpoint the best areas to collect and conserve agricultural biodiversity. They can also suggest likely places to look for the kind of diversity that will enable farmers elsewhere to cope with changing climates. And diversity itself, because it confers adaptability and resilience, will be an essential ingredient in any strategy to cope with climate change.

Many have said that one of the primary reasons to conserve agricultural biodiversity is as insurance. I disagree. An insurance policy is an investment that protects you against the possibility that something might happen. Your house might be burgled, so you have insurance. If you aren’t burgled, your money has been in some sense wasted, although you bought some peace of mind.

Assurance is an investment in the inevitable. Not everyone will be burgled, but everyone will die. Life assurance pays out when you die. Although we don’t know exactly how and when agricultural biodiversity will be needed, we can guarantee that it will be.

I hope that we will look back on 2010 as the year in which the countries of the world decided that the policy was too cheap, and the benefits too great, to ignore for another moment; as the year in which the world finally agreed to support the use and conservation of agricultural biodiversity not simply as a source of useful traits for breeders but as the foundation of an intelligent and sustainable solution to the world’s need for food security.