Overstory #233 - Agroforestry in coping with meteorological and climatological risks
Combating disasters by using agroforestry
Trees outside forests and agroforestry are defined in BOX I. It is recognized (Stolton et al. 2008) that there have been many international agreements and declarations linking the preservation of ecosystem services with the mitigation of disasters. But it must be noted that in many cases it is only the permanent and well-managed setting aside of land and sea as protected areas which can provide the stability and protection so often called for. Protected areas can play three direct roles in preventing or mitigating disasters arising out of natural hazards (Stolton et al. 2008; WWF 2008):
- Maintaining natural ecosystems, such as coastal mangroves, coral reefs, floodplains and forests that may help buffer against natural hazards.
- Maintaining traditional cultural ecosystems that have an important role in mitigating (the consequences of) extreme weather events, such as agroforestry systems, terraced crop-growing and fruit tree forests in arid lands.
- Providing an opportunity for active or passive restoration of such systems where they have been degraded or lost.
Of the functions listed by Stolton et al. (2008), agroforestry systems come mainly in at the observation that protected areas can provide barriers against the impacts of drought and desertification by:
- Reducing pressure (particularly grazing pressure) on land and thus reducing desert formation.
- Maintaining populations of drought resistant plants to serve as emergency food during drought or for restoration.
As an example, in Portugal different high conservation value landscapes have been maintained due to agrosilvopastoral activities. Most of southern Portugal, for instance, is included in the WWF Mediterranean Ecoregion and is considered a significant biodiversity hotspot particularly due to the presence of evergreen oak savannas, i.e. silvopastoral systems of cork oak and holm oak. Such systems have considerable within habitat and inter-habitat diversity maintained through centuries of human use (Stolton et al. 2008).
Wildfires, particularly those induced by the heat waves of 2003 and 2005, affected Portuguese protected areas mainly through total burned areas. Main cover affected was shrub land, a land use resulting from land abandonment, which points to the socio-economic root of the wildfire problem. Otherwise, the interaction between predicted increasing heat wave frequency through climatic changes and land use changes leading to higher fuel loads on the field will continue to aggravate the fire problem in Portugal (Stolton et al. 2008).
However, also in flood protection, agroforestry is expected to play a role, as shown by implementation of pilot projects along with awareness building activities in the field of agroforestry and energy, in order to protect the watershed above Muminabad town, Tajikistan (Anonymous 2004). In the context of Hurricane Mitch in Central America, smallholder subsistence agriculturalists would be the greatest beneficiary of Vetiver Grass Technology. Damage surveys noted that virtually all the farms using recommended soil and water conservation techniques, especially vetiver grass contour barriers, rock terraces, green mulch and crop residue management, and an indigenous agroforestry system, survived Hurricane Mitch with little damage, while neighboring farms using conventional practices suffered devastating landslides that destroyed homes and degraded fields (Smyle 2000).
The traditional agroforestry system concerned was the Quesungual system, indigenous to the sloping lands in the humid subtropics of southern Honduras: small holder system (2 ha); natural regeneration (150 to 500 trees/ha); pruning of trees at 1.5 to 2 m; residues and weeds slashed and left as mulch; associated with bean, corn, sorghum; use o 65 kg urea/ha with grain crops, beans climb or are hung on pruned trees; fields are not burned to promote regeneration of trees for next year. From farmer's perspective: reduced labor and costs; conserves soil moisture; fuelwood and mulch from tree prunings; trees provide support to bean crop and for harvested corn.
Trees grow outside forests in a variety of ways and uses. They cover a wide range of shrub and tree formations with very many species. Applied fields go from agronomy to urban planning, sociology and biology, with practices in agriculture, the environment and livestock production. Studies on “trees outside forests” have come out of numerous domains such as fruit tree cropping, farming systems and apiculture. They are a crucial and core element of agroforestry systems, silvopastoral systems, and urban, rural and community forestry. Trees outside forests are found in most rural landscapes and many agroforestry systems. The International Council for Research in Agroforestry (ICRAF, now World Agroforestry Center) defined agroforestry as a dynamic, ecologically based, natural resource management system that, through the integration of trees on farms and in the agricultural landscape, diversifies and sustains production, enhancing social, economic and environmental benefits for land users at all levels.
Much research on the tree/crop/livestock association was produced in almost every developing country and also in some industrialized countries. Despite some of the failures, particularly in large scale actual adoption in developing countries, agroforestry systems were often proposed to promote agricultural development in the tropics. Recent work on the valorization of multipurpose trees and the domestication of trees for products other than wood, have made it easier to measure and promote the potential use of trees in non-forest situations. Even granting that agroforestry is an ancient art, the current interest in trees and their development is unquestionably responsible for some of the newly enhanced awareness of “trees outside forests” (Bellefontaine et al. 2002). A very good introduction to the core aspects of agroforestry was recently given by Cornell and Miller (2007). FAO (2008) lists agroforestry as an agricultural measure in its role in Disaster Risk Reduction.
II. Designing and communicating improvements in farm applications of risk information products in agroforestry
The concept of “optimization” of the production of various products and services, with minimum risk, from a unit of land, as opposed to “maximization” of a single commodity in monocultural production systems, may be considered new in agroforestry since about twenty years (Lundgren 1897; Nair 1989). For the time being, methods that are low-cost and affordable by farmers must be found to redress the degradation of the natural resources base, particularly soils and forests, while farmers and rural communities need institutional mechanisms that can begin to place pressure and build leverage so that their voices and concerns can be acted upon and implemented (Scott 1996).
The most thorough discussion of risk, uncertainty and agroforestry has been given by Senkondo (2000). He argued among others that interrelationship between an agricultural crop and a tree crop on a single piece of land may be supplementary, complementary or competitive. In the former two cases agroforestry is always an attractive option (see also Nair 1993; Boffa 1999). Examples of instances where agroforestry can increase risk are (Senkondo 2000):
- Tree products are mainly sold in an uncertain future, where prices are not known with certainty during the planting period. The long time taken by trees to realize output as compared to annual crops may act as an impediment to adoption;
- A combination of trees and crops may promote diseases and pests. For example, agroforestry technology versus tsetse re-invasion. The question whether experiences with tsetse flies in Tanzania would limit adoption of agroforestry or not is yet to be answered;
- Tree product markets in developing countries are still underdeveloped thus acting as a potential source of risk in agroforestry income.
Because of the above three instances, an agroforestry strategy needs to be based on the bottom line question: “How and to what extent can one prove that agroforestry systems (including those resulting from current research) enhance the farmer’s capability and options to improve or reduce risk and uncertainty in his/her production system?” If we can show that an agroforestry system does reduce risk, it will have great economic value to agriculture (Senkondo 2000). This includes risks from weather and climate.
Senkondo (2000) drew among others the following conclusions relevant for our subject here:
- Farmers’ actual choices of cropping systems are generally consistent to their risk attitude, risk perception and preference ranking of cropping systems;
- Risk aversion emanating with farmers in Tanzania is more or less similar to that of farmers from other parts of the world;
- Farmers use agroforestry as part of their coping strategies with risk, and the combination of trees (timber/fuelwood combination) + mixed crops had a high preference even when perceived as moderately risky.
Risk information products as exemplified above can be improved for farm applications by taking such results and approaches into account. They should always be applied in the context of farmer preparedness strategies (BOX II). It is important to consider different time frames in risk analyses, to simultaneously consider chances for improvements of infrastructure such as roads, and socioeconomic factors such as extension and land and tree tenure (Senkondo 2000).
Rathore and Stigter (2007) recommended that preparedness strategies are taken serious because local, federal and international support can be better absorbed and used when more challenges to coping strategies are met within the local possibilities of communities, families and individuals. We reported earlier that Olufayo et al. (1998) concluded that third world scientists should concentrate on problems that have jointly been identified with local farmers. The same of course applies to western scientists working in the third world. Olufayo et al. (1998) also recommended that participatory on-farm validation of new approaches and technologies that take traditional and more recent local expertise into account should particularly be undertaken more frequently.
An example of this in agroforestry was given by Roothaert (2000). He studied indigenous and naturalized fodder trees and fodder shrubs (IFTSs) in central Kenya. It appeared that farmers had specific knowledge about pests which affected IFTSs. Acknowledging that these pests occur is important for the final selection of IFTSs. He indicates that Trema orientalis is a clear example of a tree which has almost all the desired characterisitics of an ideal fodder tree, apart from the fact that its leaves are badly eaten by caterpillars during the time when it is needed most as livestock feed. This local knowledge means that its adoption might be hindered.
Other knowledge with important implications for IFTS is toxicity. Two Acacia species were associated with toxicity by farmers and did therefore not rank high in preference. Lantana camara remains a controversial species since it was sometimes mentioned as causing digestive problems and in other parts of the world it causes death of livestock. But in the study area of Roothaert (2000) it ranked high in preference, and adverse effects were hardly mentioned by farmers. Roothaert (2000) also confirms a positive correlation for farming systems with IFTSs between population density and increased production per animal, the way this was earlier suggested for Kenya for production per unit of land (e.g. Tiffen et al. 1994).
III. Improving coping strategies with weather and climate related risks in agroforestry including the improved use of insurance approaches
Tree planting may among others reduce salinity, improve soil fertility, control and prevent erosion, control water logging, reduce the greenhouse effect, reduce catchment eutrophication, possibly check acidification and probably increase local biodiversity (e.g. Prinsley 1993). Woody plants can play a significant role in the transition phase of agrosilvopastoral systems in semi-arid regions from extensive systems to intensified systems. Woody plants provide buffering functions, stabilizing ecosystem dynamics, and allowing effective use of additional nutrient an water inputs, or allowing effective use of these resources where they occur naturally. So far woody plants have been predominantly used for productive purposes. Substantial changes are required to change the focus to protective and supportive functions (Breman and Kessler 1995). See also Stigter and Baldy (1993) and BOX III.
All over the world, there are ample examples of permanent, slow and fast traditional adaptations to seasonal variability for coping strategies and food security. The return of intercropping, sequential cropping and agroforestry to parts of Asia and the Pacific is an example (Stigter 2007). In fact these adaptations may be seen as the oldest examples of response farming. However, there are no expectations of improvement of these traditional "fitting" methods per se under the presently fastly changing conditions. Their blending with more scientific meteorological/climatological approaches into actual services for farmers appears the only way forwards (Stigter 2007).
Tanzania is listed among the thirteen African countries worst affected by climate change impacts and vulnerability, and having the least adaptive capacities (Thornton et al. 2002). Tanzania is home to several traditional agroforestry systems that have been in practice for hundreds of years. Some have been documented: the Chagga homegardens, the related Mara region homegardens and the traditional Wasukuma silvopastoral system (WAC 2009). Incorporating agroforestry systems into national agricultural development programmes offers more affordable and sustainable sources of soil nutrients through deep soil extraction and nitrogen fixation, as we have seen throughout this sub-Chapter. The technologies concerned have indeed been proven to increase the resilience of farming systems by improving agricultural productivity and enhancing the productive use of rainfall in drylands. The intensification and diversification functions of agroforestry practices strengthen the socio-economic resilience of rural populations to climate change (WAC 2009). See also Muhwezi-Bonge (2009).
SCC & Vi Agroforestry (2008a) is the first organization to trade certified carbon dioxide from agroforestry/land use in Africa. Farmers are going to get paid for different types of farming activities. The methods will reduce the leakage of carbon dioxide from the earth and accumulate the absorption of carbon dioxide from the air. A new initiative shows that sustainable land use management practices on small-holder farms in Western Kenya will both increase staple food production and generate carbon revenues (SCC & Vi Agroforestry 2008b).
The initiative gives advisory services to farmers about agroforestry and sustainable land use management who are at the same time, if implementing, participating in climate change mitigation and thereby deriving additional revenues for the environmental mitigation service. The practices include agroforestry, conservation agriculture, nutrient management, tillage/residue management, soil and water management, restoration/rehabilitation of degraded lands and livestock management. More households can be reached. This should also be considered a form of insurance in years that the annual crops fail.
For agrosilvicultural systems in Africa, three situations have been described where the integration of woody plants with cropping has a synergistic insurance effect (Breman and Kessler 1995):
- On sandy soils, in the driest parts of sub-humid zones, or at run-on sites in drier situations where nutrients have become the limiting factor for plant production, woody plants oriented as windbreaks improve germination and establishment of crops by reducing the impact of wind. [We now know that this is particularly a protection from hot dry air (Onyewotu et al. 2004).] One condition is that the woody plants can effectively use sub-soil groundwater reserves. [An example are the sandy soils in northern Nigeria (Onyewotu et al. 2003a).] For maximum benefits of windbreaks for crop production, selection and management of woody plants should be oriented at minimizing shallow rooting, and maximum protective biomass with low growth rates. [The same Nigerian example applies (Onyewotu et al. 2003b).]
- In the more humid parts of sub-humid zones, where run-off and leaching are significant processes, evenly distributed woody plants can lead to improved nutrient availability for crops. [See also Boffa (1999).] Selection of woody species and management of the woody plants should be oriented at the combination of minimum light reduction and maximum woody plant production. [See also Baldy and Stigter (1997).]
- Woody plants can lead to a prolonged growing season for crops. Most suitable are relatively humid conditions, and the presence of fertile and deep soils.
Anonymous (2004) Natural disaster risk management in Muminabad. Swiss Cooperation Office, Bern. http://www.deza.admin.ch/ressources/resource_en_169148.pdf
Baldy C, Stigter CJ (1997) Agrometeorology of multiple cropping in warm climates. Translated from the French (with an Epilogue for the English version). INRA, Paris, France + Oxford & IBH Publ. Co., New Delhi, India + Science Publ. Inc., Enfield, USA, 237 pp
Bellefontaine R, Petit S, Pain-Orcet M, Deleporte P, Bertault J-C (2002). Trees outside forests. Towards better awareness. FAO Conservation Guides 35, Rome, 216 pp
Boffa J-M (1999) Agroforestry parklands in Sub-Saharan Africa. FAO Conservation Guide 34, Rome, 230 pp
Breman H, Kessler J.-J. (1995) Woody plants in agro-ecosytems of semi-arid regions (with an emphasis on the Sahelian countries). Springer, Berlin etc, 340 pp
Cornell, J, Miller M (2007) Agroforestry. In: Cutler J (ed) Encyclopedia of Earth. Environmental Information Coalition, National Council for Science and the Environment, Cleveland, Washington DC http://www.eoearth.org/article/Agroforestry
FAO (2008) FAO's role in Disaster Risk Reduction. FAO, Rome http://www.fao.org/fileadmin/templates/tc/tce/pdf/faoroledisasterriskreduction. pdf
Lundgren BO (1987) Institutional aspects of agroforestry research and development. In: Steppler HA, Nair PKR (eds), Agroforestry: A decade of development. ICRAF, Nairobi, 150 pp
Muhwezi-Bonge G (2009) Tanzania at risk of failing to feed itself. Africa News. Posted Friday 13 March 2009 http://www.africanews.com/site/Tanzania_at_risk_of_failing_to_feed_herself/ list_messages/23719
Nair PKR (1989) Agroforestry systems in the tropics. Kluwer Academic Publ, Dordrecht etc, 664 pp
Nair PKR (1993) An introduction to agroforestry. Kluwer Academic Publ, Dordrecht etc, 499 pp
Olufayo AA, Stigter CJ, Baldy C (1998) On needs and deeds in agrometeorology in tropical Africa. Agric For Meteorol 92:227-240
Onyewotu L, Stigter K, Abdullahi Y, Ariyo J (2003a) Shelterbelts and farmers' needs. LEISA Mag Low Ext Input Sust Agric 19(4):28-29
Onyewotu LOZ, Stigter CJ, Abdullahi AM, Ariyo JA, Oladipo EO, Owonubi JJ (2003b) Reclamation of desertified farmlands and consequences for its farmers in semiarid northern Nigeria: a case study of Yambawa rehabilitation scheme. Arid Land Res Managem 17:85-101
Onyewotu LOZ, Stigter CJ, Oladipo EO, Owonubi JJ (2004) Air movement and its consequences around a multiple shelterbelt system under advective conditions in semi-arid northern Nigeria. Theor Appl Climatol 79:255-262
Prinsley RT (1993, ed) The role of trees in sustainable agriculture. Kluwer, Dordrecht etc, 186 pp
Rathore LS, Stigter CJ (2007) Challenges to coping strategies with agrometeorological risks and uncertainties-Regional Perspectives: Asia. In: Sivakumar MVK, Motha R (eds), Managing weather and climate risks in agriculture. Springer, Berlin/Heidelberg, pp 53-69
Roothaert RL (2000) The potential of indigenous and naturalized fodder trees and shrubs for intensive use in central Kenya. Doctoral thesis. Department of Agronomy, Wageningen University, 172 pp
SCC & Vi Agroforestry (2008a) A ground breaking initiative at the United Nations Climate Change Conference in Poznan in Poland this week. A film showing sustainable agriculture land management resulting in both economic development and generation of carbon revenues for small-scale farmers in the Lake Victoria basin. http://www.sccportal.org/Default.aspx?ID=827&M=News&PID=1534&NewsID=1854
SCC & Vi Agroforestry (2008b) Swedish Cooperative Centre and Vi Agroforestry introduces certified carbon from Africa. http://www.sccportal.org/Default.aspx?ID=827&M=News&PID=1534&NewsID=1278
Scott RB (1996) Land-use transformation in Africa: the role of agroforestry. In: Mugah JO (ed) People and institutional participation in agroforestry for sustainable development. Proceedings of a conference, KEFRI, Nairobi, pp 7-16
Senkondo EMM (2000) Risk attitude and risk perception in agroforestry decisions: the case of Babati, Tanzania. Mansholt Studies 17. Mansholt Institue, Wageningen University, 213 pp
Smyle J (2000) Disaster mitigation and vulnerability reduction: Perspectives on the prospects for Vetiver Grass Technology (VGT). http://www.vetiver.org/LAVN_disaster.htm
Stigter K (2007) Addressing climate change in agriculture. Opinion and Editorial - Jakarta Post, October 15. http://www.thejakartapost.com/yesterdaydetail.asp?fileid=20071015.
Stigter CJ, Baldy CM (1993) Manipulation of the microclimate by intercropping: making the best of services rendered. In: Sinoquet H, Cruz P (eds) Ecophysiology of tropical intercropping, INRA, Paris/Guadeloupe pp 29-44
Stolton S, Dudley N, Randall J (2008) Natural Security. Protected areas and hazard mitigation. Arguments for Protection Series. World Wide Fund for Nature (WWF) and Equilibrium, The Hague, Netherlands. http://assets.panda.org/downloads/natural_security_final.pdf
Thornton PK, Kruska RL, Henninger N, Kristjanson PM, Reid RS, Atieno F, Odero AN, Ndegwa T (2002). Mapping poverty and livestock in the developing world. International Livestock Research Institute, Nairobi. http://www.ilri.org/InfoServ/Webpub/Fulldocs/Mappoverty/media/index.htm
Tiffen M, Mortimore M, Gichuki F (1994) More people, less erosion. Environmental recovery in Kenya. Wiley & Sons, New York, 311 pp
WAC (2009) Agroforestry options for Tanzania. World Agroforestry Centre Policy Brief 03. http://www.worldagroforestry.org/af1/downloads/publications/PDFs/BR09007.
WWF (2008) Environmental protection vital to reducing natural disaster impact: WWF. A News Item. http://www.panda.org/index.cfm?uNewsID=133981
This article was excerpted with permission of the editor and publisher from:
Kees Stigter (Ed.). 2010. Applied Agrometeorology. Springer (Berlin/Heidelberg etc.). xxxviii + 1101 pp. ISBN: 978-3-540-74697-3
Springer Distribution Center GmbH
HaberStr. 7, 69126
URL INSAM (with Table of Contents Link):
About the Author
Prof. Kees Stigter, Agromet Vision (Bruchem, The Netherlands and Bondowoso, Indonesia), is the founding president of the International Society for Agricultural Meteorology (INSAM, www.agrometeorology.org)
Related Editions of The Overstory
- The Overstory #220: Adapting to climate change
- The Overstory #205--Smallholder agroforestry carbon storage
- The Overstory #186--Introduction to tropical homegardens
- The Overstory #149--Live Fences, Isolated Trees, and Windbreaks: Tools for Conserving Biodiversity
- The Overstory #147--Major Themes of Tropical Homegardens
- The Overstory #111--Land Husbandry
- The Overstory #109--Cultural Landscapes
- The Overstory #105--Complex Agroforests
- The Overstory #104--Soil and Water Conservation
- The Overstory #103--Land Management
- The Overstory #98--Integrating Forestry into Farms
- The Overstory #73--Buffers, Common-Sense Conservation
- The Overstory #66--Carbon Sequestration
- The Overstory #64--Tropical Homegardens
- The Overstory #61--Effects of Trees on Soils