What do we really mean by land degradation?
“Land has been perceived as a resource that can be freely degraded,” said Luc Gnacadja, Executive Secretary of the United Nations Convention to Combat Desertification (UNCCD) . “We need to move towards an understanding of land as natural capita and an important foundation for poverty alleviation.”
Gnacadja was speaking at a side event held on the margins of the Eleventh Conference of the Parties to the UNCCD in Namibia 16-27 September. A number of speakers discussed issues relating to the scientific understanding of land degradation and how to incorporate land degradation into a Sustainable Development Goal (SDG).
The event was organized by staff from the World Agroforestry Centre (ICRAF), in collaboration with UNCCD, to make progress towards developing a Sustainable Development Goal that includes land degradation. “The importance of the issue was recognized at Rio+20 and a shift to strive to achieve a land-degradation neutral world was called for,” said Gnacadja.
Phil Dobie, a senior advisor to ICRAF said, “Getting to a common understanding of what land degradation is, and what the definitions are, is still a huge challenge.”
Meine van Noordwijk, Chief Scientist of ICRAF, agreed. “Land degradation is as fuzzy a term as deforestation,” he said. He also questioned the phrase ‘zero net land degradation,’ which is itself vague. For example, does that mean quantifying changes across the world, or between countries, implying that degradation could proceed unchecked in some countries if it were being reduced in others, or would there be within-country measurement?
Land degradation needs to be looked at in terms of principles, criteria, indicators and metrics. What should be uniform across countries and regions and what could be locally defined. The metrics are complex as they would include the effects of human population and sociological factors. Healthy landscapes imply a sociological systems approach, balancing ecological and social interactions.
Looking at the landscape and its complex interactions, it is clear that there were steps in the process of land degradation, some of which are easy to reduce, such as restoring tree biomass, and others that are much harder to recover from, such as loss of fertility and erosion of the soil. Another question demanding an answer is how far can soil be degraded before all of its environmental services are lost, such as terrestrial soil carbon storage.
“Can we stop land degradation unless we have a healthy landscape?” asked van Noordwijk, talking about the contributions that agroforestry could make to minimize or avoid land degradation, and even recover from it. Trees are an essential part of a multifunctional landscape and can have a major influence on land and soil conditions, and hence land degradation. For example, tree roots can lift water from deep within the soil and distribute it across the surface, making it available to agricultural crops while strengthening soil quality. Groups of trees can also lower temperatures by up to 5 deg C under their canopies, reducing the effects of drought and even climate change. In fact, on a large scale these localized effects are probably larger that those from climate change.
Miyuki Iiyama, a scientist at ICRAF, used the case of the charcoal trade in Kenya as an illustration of the degradation of dryland forest. With the growth in income and urbanization in Kenya, there has been a shift from firewood to charcoal consumption for cooking. This has had a significant and unsustainable impact on land use. Charcoal production is a major consumer of trees; every tonne of charcoal requires from 3 to 10 tonnes of raw wood. In SubSaharan Africa, producing charcoal for sale is the major use of trees on farms and in the landscape, and so a major potential driver of land degradation. Unsustainable collection undermines ecosystem and agriculture. Assuming that the charcoal that is sold in urban areas is coming from dryland landscapes (forest or woodlands with 40 t/ha of biomass stock), about 1% of Kenyan land would be degraded annually. Echoing Meine van Noordwijk’s sentiments, Iiyama said, “There is a need to identify the best strategies to prevent land degradation, but we require accurate data for that.”
Jon Davis of IUCN asserted that any targets for land degradation should take into account pastoralism, a way of life that depends on the herding of livestock. In some West African countries, pastoralism contributes 80% of the agricultural budget, so it has a high development potential in the drylands. Despite a mistakenly negative image of rangeland degradation, pastoralism contributes highly valuable environmental services. It is the most economically viable option for land use in many rangelands and a way of preventing land degradation, as most are sustainably managed. It is cheaper to manage land sustainably than to recover degraded lands, but there is an general emphasis on funding restoration.
Political consensus is building towards including land degradation in the Sustainable Development Goals. “We are a long way from defining land degradation, and it is these definitions that will allow us to develop the mechanisms to start reversing the trend of land loss,” said Phil Dobie.