The Green Tau: issue 20

Biodiversity and food production 

Last week’s Green Tau weekly began a mini series looking at biodiversity. We noted that despite the relative smallness of humanity in terms of global biomass, we humans are dramatically and drastically altering the planet’s biodiversity. This week I want to look at the impact food production has on biodiversity. 

Over the millennia humans have domesticated both animals and plants, selecting and breeding species, and developed farming practices that would best provide food. In the process, humans extended their control over land that had previously been wild, which in turn has limited the land available for wild animals and plants. 1000 years ago, less than 4% of habitable land was farmed. This increased over the centuries, and particularly so from the mid 1800, when the area of farmed increased from under 25%  to the current 50%. (Habitable land is land not covered by glaciers, 10%, nor barren land such as deserts, sand dunes, bare rock, salt flats etc, 19%). In Europe the area of farmed land is now declining slightly, whereas it is continuing to expand in Africa, Asia, China and parts of South America.

Currently there is much media coverage about the clearance of the rain forests in Brazil to create new agricultural land plus accompanying access roads. This process destroys unique habitats with the loss of many plants, animals, birds and insects etc. It also destroys the millennia old way of life of indigenous people.  It is easy to see how such expansion of farming land exacerbates biodiversity loss. The same problem also arises in Africa, Asia and China. Mangroves have also been cleared to make way for shrimp farms, palm oil plantations and rice fields. 

A perhaps previously ignored consequence of expanding farming into previous areas of wilderness, is the increased contact between wild and domesticated animals. This allows diseases to spread more rapidly between the different species. What might be an insignificant virus infecting a wild animal can become a highly infectious virus in domestic animals. These virus can then spread to humans. Such zoonotic diseases include the Ebola virus, SARS and the current Covid 19.

Over the millennia, much of the UK has also been deforested to make way for farm land. Tree coverage  in the UK stands at about 12% which is much lower than most other countries in Europe. Top of the league is Finland with over 50% tree cover; Spain and Portugal are around 35%; France, Germany and Switzerland around 30%. As trees provide a great many habitats for other plants, birds, animals and insects, as well being good stores of carbon, the government’s climate advisers now recommend  tree cover should be increased to 17-19%. As well as planting new trees, it is also important that existing trees are protected: it takes many years for a tree to reach maturity and whilst they are still saplings they do not provide much habitat for other wild life. 

It is not only trees that have been cleared to make way for farming in the UK. Wetland areas such as marshes and bogs, have been drained. This destroyed the unique habitats of many different plants, insects and animals. In the same way, clearing hedgerows has had a detrimental affect on biodiversity. There is now a growing awareness of the importance of restoring and maintaining a diverse range of habitats to support different plants and creatures. Where the area of a particular habitat becomes too small, it may fail to maintain populations of plants and creatures at a viable level. However creating a corridors between habitats enables larger populations to be supported. Hedgerows perform this task on a small scale, as can railway lines and road verges.

Not only has farmland been expanding over the centuries, but what is farmed has changed. Increasing global trade, colonialism and the intensification of farming, has produced a agricultural system that now grows a very limited number of plant species. Two thirds of the world’s food comes from just nine plants: sugar cane, maize, rice, wheat, potatoes, soybeans, oil-palm fruit, sugar beet and cassava. 

Such a concentration makes our food supply vulnerable to the effects of climate change and diseases. This year’s durum wheat crop has been much reduced because of  exceptionally dry conditions in Canada (the harvest is down by a third) and wet ones in Europe. Nearly half of all the bananas grown in the world are one variety, Cavendish, even though there are approximately 999 other varieties. The Cavendish banana is now threatened by a fungus which could wipe it out.  

This over concentration on a limited number of species has meant that many local and older plant varieties have been marginalised – another form of biodiversity loss. However the value of such plants is now being recognised. They can provide alternative crops better suited to local growing conditions and/or changing climatic conditions. Such species include quinoa, which  can be grown at high altitudes, teff which like quinoa can be grown at high altitudes and where water supplies are limited, millet which can tolerate high temperatures, and einkorn which needs less nitrogen – ie can grow in less fertile soils – than wheat.

The same pattern of concentration occurs in animal farming too. Nearly all the world’s diary cows are based on one single breed, the Holstein. As with arable crops, there are advantages of protecting and promoting rare and ancients breeds of farm animals. But in terms of biodiversity what is more incredible is the sheer biomass of farm animals. They account for 60% of all mammals on the planet (of which cattle and buffalo  account for 40%); we humans account for 36% whilst the remaining wild mammals a mere 4%.

Globally 77% of agricultural land is used to raise livestock. This includes land used to grow animal feed. Yet this 77% produces less than  20% of the world’s calories. Land used for livestock could be better used to produce plant based food that would feed a greater number of people and/ or rewilded to increase biodiversity. Factoring in the carbon footprint of livestock, especially cattle, there are even more benefits to be gained from reducing livestock levels.