Since the poor are simultaneously dependent on, yet vulnerable to events that change the quality of their land resources, approaches to improving their livelihoods must pay close attention to integrated ecosystem management. There is an increasing appreciation that agricultural components of the ecosystem are dependent on a large suite of ecosystem goods and services taken for granted too often in the past.

Goods and services from natural ecosystems that are crucial for the livelihoods of the rural poor include wild foods, timber, fuel, fiber, medicines, pollination services to crops, soil fertility regeneration, water storage and supply (drought and flood control), carbon storage, air and water purification, climate moderation, tourism potential, and cultural values, among others. Many of these also have global value, for example the carbon storage potential of the vast dry areas, and the role of ground cover in preventing massive dust storms that cross oceans.

If the true value of ecosystem goods and services were recognized, it is possible that society would make greater efforts to protect them. Worldwide, according to the Smithsonian Institution and the US President's Committee of Advisors on Science and Technology (Alonso et al. 2001), ecosystems provide goods and services that would cost an astonishing US$33 trillion annually to replace, almost twice the value of all goods and services produced by people.

This Theme will build an understanding of the role and value of natural resources in both natural and agricultural components of dryland ecosystems, especially in the provision of vital environmental goods and services. This understanding is critical for rational decisions to balance better livelihoods with the maintenance of healthy lands.

Livelihoods in the drylands have always had to adapt to the ever-present risk of drought and desertification. Traditionally, land users mitigated risk through the mobility of pastoralism (Behnke et al., 1993), seeking less drought-affected areas for grazing. As populations increase, pastoralism gradually gives way to settled farming. Farmers learn techniques such as water harvesting and 'soil fertility borrowing' to reduce farming risk. Land users also mitigate risk by diversifying their enterprises, including off-farm employment (Mortimore, 1998).

Drylands are often characterized as ecologically 'fragile'. The loss of scarce vegetation and soil carbon, for example increases vulnerability to soil erosion. As populations increase and as droughts set in, the soils and biodiversity of these areas can be quickly degraded, as observed in the Sahel (Breman 1992; Norton-Griffiths and Rydén 1989) and in the Horn of Africa (Akhtar 1998; Ndikumana et al. 2002).

'Carrying capacity' is an intuitive concept for estimating ecosystem fragility (Wood and Rydén 1992). Agriculture is the dominant human use of the the drylands in the developing world, and carrying capacity limitations are major concerns. Apparent limits, however might be increased through inflows of critical limiting resources such as soil fertility and water (Breman 1992).

Such changes can trigger undesirable follow-on effects in neighboring ecosystems, however such as soil erosion from excessive tillage and the dessication of wetlands when water supplies are diverted for agriculture. In the long term, such degradation will reduce carrying capacity even further. Research is needed to understand and predict these potentials and risks, and find sustainable ways to increase dryland carrying capacity.

The relationships between ecosystem degradation and recovery need to be better understood because the drylands are coming under increasing pressure from agricultural and other human activity. What is the tipping point beyond which degradation becomes effectively irreversible, what parameters trigger it, and how can it be averted? How can we help farmers and rural communities become aware when they are on the brink of losing their crops, livestock, and wild harvests - and know what to do about it?

Little is known, for example about the relationships between losses of ecosystem functions and their above and below-ground biodiversity, or of the requirements to initiate successional processes that will lead to the re-establishment of key functions that regulate and deliver valuable ecosystem goods and services. 'Keystone species' are crucial for the health and survival of many other species in ecosystems; they need to be identified and their dynamics understood.

Expected outputs for impact include: tradeoffs and win-win opportunities identified and understood for sustaining healthy ecosystem functions and resources (particularly biodiversity-related) in both managed and un-managed areas in the landscape; ecosystem restoration dynamics understood and strategies developed and implemented; new and better integrated soil and water management strategies for soil surface management, water harvesting, integrated soil fertility management and cropping strategies; economic as well as non-monetary evaluations of outputs from managed and unmanaged land uses to aid policy-making and research planning; integrated ecosystem degradation monitoring tools and manuals developed and validated with land users; and training and knowledge-sharing resources.

Initial core partners

This Theme will bring together an innovative partnership of agricultural and ecological organizations by including the Commission on Ecosystem Management of IUCN - The World Conservation Union. IUCN will advise and assist in the design and implementation of assessments and monitoring of the natural components of landscape-level ecosystems, and in developing ecosystem restoration methods. ILRI will contribute in sustainable rangeland management. The Agroforestry and Novel Crops Unit of the School of Tropical Biology at James Cook University will explore opportunities to increase agro-biodiversity by tapping natural species components of ecosystems. Desert*Net (the German Competence Network for Research to Combat Desertification) will help assess natural biodiversity trends and indicators in ecosystems under pressure.

References

Alonso, A., Dallmeier, F., Granek, E. and Raven, P. 2001. Biodiversity: Connecting with the Tapestry of Life. Smithsonian Institution/Monitoring and Assessment of Biodiversity Program and President's Committee of Advisors on Science and Technology. Washington, D.C. USA.

Behnke, R. H., Scoones, I. and Kerven, C. (eds.) 1993. Range ecology at disequilibrium: New models of natural variability and pastoral adaptation in African savannas. London: Overseas Development Institute.

Breman, H. 1992. Desertification control, the West African case: prevention is better than cure. Biotropica 24:328 - 334.

Mortimore, M. 1998. Roots in the African Dust: Sustaining the Drylands. Cambridge University Press.

Ndikumana, J., Kamidi, R., Desta, S., Marambii, R., Abdi, A. I., and Shori, R. 2002. Assessment of possible USAID/OFDA-led activities for increasing resilience of pastoral communities in the Greater Horn of Africa. Addis Ababa: International Livestock Research Institute and ASARECA Animal Agriculture Research Network.

Norton-Griffiths, M. and Rydén, P. 1989 (eds.) The IUCN Sahel Studies 1989. Gland, Switzerland: IUCN-The World Conservation Union.

Wood, A. P. and Rydén, P. 1992 (eds.) The IUCN Sahel Studies 1991. Gland, Switzerland: IUCN-The World Conservation Union.