Restoring land for and with Kenyan pastoralists
Mike Harrison’s tee-shirt reads “Prairies, Plains, Pampas, Cerrado, Steppe, Savanna, Veldt”, some of the many terms used around the world to describe the same thing: grasslands. Grasslands represent the majority of the world’s agricultural land and hold 20% of the world’s soil carbon stock, according to the FAO’s Grasslands Carbon Working Group.
About 30% of the globe’s grasslands are severely degraded, however. Deeply worrying for the animals and people that depend on them as well as for carbon sequestration, this includes vast swathes of Kenya where Harrison is CEO of the Northern Rangelands Trust. NRT works with 27 communities – an estimated 250 000 people, many of them pastoralists, on 32 000 km2 — using a conservancy approach.
A light but significant presence of trees is integral to grasslands. But that was not what drew Harrison to the work of Tor Vågen at the World Agroforestry Centre (ICRAF). It was the need for a baseline. “We had received funds from Danida for rangelands work, and our main motivation was to learn what the starting point was so that as we improve the rangelands, we have a baseline to compare it to.”
NRT asked ICRAF to assess current levels of degradation of grass, erosion of soil and depletion of soil carbon and conduct historical analysis. “Tor and his team can go back to satellite records from the 1980s,” says the NGO chief. “It’s fantastic to paint the timeline of decline of those three factors, and then to look at the dynamics of what is going on and how that can help us with the rehabilitation.”
For Vågen and colleague Leigh Winowiecki, the collaboration was an opportunity to utilize their innovative methodology, which measures carbon and vegetation on the ground and aligns it with images from remote sensing. “The most exciting part is the synergies between our way of assessing ecosystem health and the community-based rangeland management implemented by NRT,” says Vågen.
Their findings showed shockingdegradation: 70% of the rangelands in NRT conservancies are highly degraded and 50% heavily eroded; erosion rates have increased in recent decades; and soil organic carbon, a key indicator of regeneration potential, is critically low: below 3.5 kg m-3 or 5 g kg-1, the United Nations Convention to Combat Desertification threshold for healthy plant growth.
The scientists, who had been conducting research in the region for several years, were not surprised. “But what did surprise us,” says GeoScience Lab leader Vågen, “was the accuracy at which we were able to predict different indicators of rangeland health, allowing us to map hotspots at very fine spatial resolution and provide spatially explicit recommendations to NRT.”
Harrison was not surprised either. Without any research, he could see that some rangelands lacked grass entirely. But his desire was to have the crisis quantified, and this was met. Among its other findings, the ICRAF team determined that density and diversity of grasses is strongly related to soil carbon. Also, where the invasive Acacia recifiens grows in high densities, soil erosion is very severe.
At the heart of the problem is overgrazing. “Not in the sense of too much livestock,” stresses Harrison, “But rather the poor management of livestock, heavy concentrations which do not allow grass to recover. Having been repeatedly eaten down to its roots, much of the perennial grass has gone. Yet it is the perennial grasswhich locks up the carbon and represents the resilience of the ecosystem.”
The spread of the indigenous Acacia reficiens is a further disaster. “It loves highly degraded soil and, as soils become more degraded, nothing else will grow. Even worse, it suppresses the growth of pasture underneath.”
However, NRT is now in action with Vågen and Winowiecki’s results. Conservancies, with funds from Danida for land rehabilitation and revenues from ecotourism, are paying morans, unmarried warriors, to fell the Acacia reficiens. Laid on the ground, the cut trees protect the soil. Perennial grass, seeded by the community, sprouts through them. Other remedies also require fundamental community buy in.
“One approach,” says Harrison, “is getting cattle owners to agree to bunch their cattle in bigger herds so the hoof action breaks up the hardpan and rain can penetrate. Another is the concentrated kraals in heavily overgrazed areas to enrich the soil. A third is forage assessment. You determine that a hillside has enough grass for, say, 500 cattle for 11 days. They only eat a certain amount and then move on.”
“The aim,” says the NRT CEO, “is to always have a planned system of letting the grassland rest. You never leave the land bare, you do not deplete the roots, and you leave some grass behind for wildlife.”
The NRT-ICRAF collaboration is a happy case of scientists meeting managers’ needs. It has resonated with the people. “When we talk about planned grazing,” says Harrison, “the elders say ‘We used to do this!’ So it appears that the work is helping them re-find the traditional grazing systems that they used to practice before insecurity, the erosion of authority and marginalization took their toll.”
From the Amazon, where he and Winowiecki are taking more soil cores to map to satellite images, Vågen agrees on the importance of indigenous wisdom and know how. Asked what he would do to rehabilitate the rangelands, he says, “With local communities, I would use the very detailed maps developed to target interventions. I would also use the mapping techniques to monitor change.”