Trees returning to farms already storing carbon
Wednesday 03 August 2016 Around the world, tropical forests continue to decline: a pattern which, though it has slowed in recent years, remains one of the most pressing environmental issues of our time. Elsewhere though, a remarkable change is happening: tree cover on agricultural land has increased across the globe, capturing nearly 0.75 Gigatonnes carbon dioxide every year.
That’s according to a new study from the World Agroforestry Centre (ICRAF), which sees the return of trees to farmed landscapes as being of significant environmental benefit, and potentially also carrying benefits for farmers through providing natural pest protection, nutrient cycling, flood protection and in some cases a new income stream.According to the International Panel on Climate Change (IPCC), agriculture and land-use change account for about 24% of the world's greenhouse gas emissions. Climate change will also have strong impacts on food security in the long-term. Therefore agriculture needs to reduce its climate footprint. However, experts in the various farm sectors claim that there is only limited scope to reduce emissions from agriculture on the scale that climate scientists say is needed. At the same time, large forest areas, primarily in the tropics, are still being converted into agricultural land to feed the world's growing population. One method of greening agriculture, whilst maintaining production is agroforestry - returning trees to agricultural lands - which proponents say carries benefits across a range of different climates and on both cropland and pasture. The World Bank estimates that 1.2 billion people around the world already depend on agroforestry farming systems, especially in developing countries. In France, state research agency INRA has ongoing agroforestry programmes and the approach has taken more of a foothold, though in the UK too some landowners have replanted trees on farmed land, most prominently in Mid-Wales and Shropshire, to provide natural flood defences. In some cases, the high set-up cost of agroforestry has slowed uptake, as have some policy barriers. The UN Food and Agriculture Organisation has said the approach can effectively tackle environmental, economic and social problems we face, and recognises that a growing body of scientific literature points to agroforestry as a positive force within farming. Even so, trees on agricultural lands are currently not considered in the greenhouse gas accounting framework of the IPCC.Research into carbon savings from agroforestryBecause of this, a team of researchers from various institutions in Africa, Asia and Europe carried out a study to assess the role of trees on agricultural land and the amount of carbon they have sequestered from the atmosphere over the past decade. They said the amount of tree cover on farmed land varied widely from region to region: South East Asia, Central America, eastern South America, and coastal West Africa all had good levels of tree cover on farmland, with eastern China, Western Australia, the North American prairies and northern India having the least trees. Western Europe, the American midwest and Amazonia, South America all had ‘moderate’ tree cover. Over time, tree cover on farmed land has changed (China has seen increases, as has Indonesia and Brazil, though Argentina, Myanmar, and Sierra Leone have seen large decreases).Discussing the return of trees to farmed land, the study’s lead author, Robert Zomer of the World Agroforestry Centre said, "Remote sensing data show that in 2010, 43% of all agricultural land globally had at least 10% tree cover, up from eight percent in the preceding decade. Given the vast amount of land under agriculture, agroforestry may already significantly contribute to global carbon budgets.”Zomer’s study also reported that, given the large amount of agricultural land where tree cover is below its potential, there is a huge emissions mitigation potential in returning trees to farmed land, which the report recommends should be explored more systematically.Going into the results, Henry Neufeldt, Head of Climate Change research at the World Agroforestry Centre said, ”The results of our spatial analysis show that trees on agricultural land sequestered close to 0.75 Gigatonnes of carbon dioxide globally per year over the past decade. If we can harness good policies to enhance positive examples and stop negative trends, trees in agricultural landscapes can play a major role in greenhouse gas mitigation. But no one should say that this is already solving the problem for agricultural emissions as long as we do not know what is actually happening on the ground."