Managing genetic variation in tropical trees: linking knowledge with action in agroforestry ecosystems for improved conservation and enhanced livelihoods

  • Ian K. Dawson
  • Ard Lengkeek
  • John C. Weber
  • Ramni Jamnadass
Original Paper

Abstract

Tree species in agroforestry ecosystems contribute to the livelihoods of rural communities and play an important role in the conservation of biodiversity. Unless agroforestry landscapes are productive, however, farmers will not maintain or enhance the range and quality of tree species in them, and both income opportunities and biodiversity will be lost. Productivity depends on both tree species diversity and genetic (intra-specific) variation, but research on the latter has until recently not received the recognition it deserves. Worse, when knowledge on tree genetic variation in agroforestry systems has become available, it has not generally been linked in any systematic way with management, indicating a disjunction between research and field-level practice. In this essay, we attempt to bridge this gap by considering three questions: why is genetic diversity important in tree species? What is our current state of knowledge about intra-specific variation in trees in agroforestry systems? And, finally, what practical interventions are possible to support the conservation of this diversity in agricultural landscapes, while enhancing farmers’ livelihoods? A wide genetic base in agroforestry trees is essential to prevent inbreeding depression and allow adaptation to changing environmental conditions and to altering markets for tree products. Recent evidence shows, however, that many species are subject to poor germplasm collection practice, occur at low densities in farmland, and are found in highly aggregated distributions, all of which observations raise concerns about productivity and sustainability. A range of germplasm-access based interventions is necessary to improve current management, including the enhancement of community seed- and seedling-exchange networks, and the development of locally based tree domestication activities. Equally necessary, but more difficult to address, is the development of markets that support genetic diversity in tropical tree species; we discuss approaches by which this may be undertaken.

Keywords

Agroforestry ecosystems Biodiversity management Genetic variation Tropical trees 

References

  1. Acharya KP (2006) Linking trees on farms with biodiversity conservation in subsistence farming systems in Nepal. Biodivers Conserv 15:631–646. doi:10.1007/s10531-005-2091-7 CrossRefGoogle Scholar
  2. Aitken SN, Yeaman S, Holliday JA, Wang T, Curtis-McLane S (2008) Adaptation, migration or extirpation: climate change outcomes for tree populations. Evol Appl 1:95–111. doi:10.1111/j.1752-4571.2007.00013.x CrossRefGoogle Scholar
  3. Akinnifesi FK, Kwesiga F, Mhango J, Chilanga T, Mkonda A, Kadu CAC, Kadzere I, Mithofer D, Saka JDK, Sileshi G, Ramadhani T, Dhliwayo P (2006) Towards the development of miombo fruit trees as commercial tree crops in southern Africa. For Trees Livelihoods 16:103–121Google Scholar
  4. Assogbadjo AE, Kyndt T, Sinsin B, Gheysen G, Van Damme P (2006) Patterns of genetic and morphometric diversity in baobab (Adansonia digitata) populations across different climatic zones of Benin (West Africa). Ann Bot (Lond) 97:819–830. doi:10.1093/aob/mcl043 CrossRefGoogle Scholar
  5. Atta-Krah K, Kindt R, Skilton JN, Amaral W (2004) Managing biological and genetic diversity in tropical agroforestry. Agrofor Syst 61:183–194. doi:10.1023/B:AGFO.0000028998.32732.65 CrossRefGoogle Scholar
  6. Bawa KS, Dayanandan S (1998) Global climate change and tropical forest genetic resources. Clim Change 39:473–485. doi:10.1023/A:1005360223639 CrossRefGoogle Scholar
  7. Boivin-Chabot S, Margolis HA, Weber JC (2004) Variation in coppice-shoot growth among provenances of Calycophyllum spruceanum Benth. in the Peruvian Amazon Basin. For Ecol Manag 198:249–260. doi:10.1016/j.foreco.2004.04.009 CrossRefGoogle Scholar
  8. Boshier DH (2000) Mating systems. In: Young A, Boshier D, Boyle T (eds) Forest conservation genetics: principles and practice. CSIRO Publishing/CABI Publishing, Melbourne/Wallingford, pp 63–79Google Scholar
  9. Boshier DH (2004) Agroforestry systems: important components in conserving the genetic viability of native tropical tree species? In: Schroth G, da Fonseca GAB, Harvey CA, Gascon C, Vasconcelos HL, Izac A-MN (eds) Agroforestry and biodiversity conservation in tropical landscapes. Island Press, Washington, pp 290–313Google Scholar
  10. Bouvet J-M, Kelly B, Sanou H, Allal F (2008) Comparison of marker- and pedigree-based methods for estimating heritability in an agroforestry population of Vitellaria paradoxa C.F. Gaertn (shea tree). Genet Resour Crop Evol (in press)Google Scholar
  11. Brodie AW, Labarta-Chávarri RA, Weber JC (1997) Tree germplasm management and use on-farm in the Peruvian Amazon: a case study from the Ucayali region, Peru. Research Report, Overseas Development Institute (ODI), London and the World Agroforestry Centre (ICRAF), NairobiGoogle Scholar
  12. Charlesworth D, Charlesworth B (1987) Inbreeding depression and its evolutionary consequences. Annu Rev Ecol Syst 18:237–268. doi:10.1146/annurev.es.18.110187.001321 CrossRefGoogle Scholar
  13. Cornelius JP, Clement CR, Weber JC, Sotelo-Montes C, van Leeuwen J, Ugarte-Guerra LJ, Ricse-Tembladera A, Arevalo-Lopez L (2006) The trade-off between genetic gain and conservation in a participatory improvement programme: the case of peach palm (Bactris gasipaes Kunth). For Trees Livelihoods 16:17–34Google Scholar
  14. Crutsinger GM, Collins MD, Fordyce JA, Gompert Z, Nice CC, Sanders NJ (2006) Plant genotypic diversity predicts community structure and governs an ecosystem process. Science 313:966–968. doi:10.1126/science.1128326 PubMedCrossRefGoogle Scholar
  15. Dawson I, Were J (1998) Multiplication, that’s the name of the game guidelines for seed production of agroforestry trees. Agrofor Today 10:19–22Google Scholar
  16. Dawson IK, Guarino L, Jaenicke H (2007) Underutilised plant species: impacts of promotion on biodiversity. ICUC Position Paper No. 2. The International Centre for Underutilised Crops, ColomboGoogle Scholar
  17. Dawson IK, Hedley PE, Guarino L, Jaenicke H (2008a) Does biotechnology have a role in the promotion of underutilised crops? Food Policy (in press)Google Scholar
  18. Dawson IK, Hollingsworth PM, Doyle JJ, Kresovich S, Weber JC, Sotelo-Montes C, Pennington TD, Pennington RT (2008b) Origin and genetic conservation of tropical trees in agroforestry systems: a case study from the Peruvian Amazon. Conserv Genet 9:361–372. doi:10.1007/s10592-007-9348-5 CrossRefGoogle Scholar
  19. Degrande A, Schreckenberg K, Mbosso C, Anegbeh P, Okafor V, Kanmegne J (2006) Farmers’ fruit tree-growing strategies in the humid forest zone of Cameroon and Nigeria. Agrofor Syst 67:159–175. doi:10.1007/s10457-005-2649-0 CrossRefGoogle Scholar
  20. Donald PF (2004) Biodiversity impacts of some agricultural commodity production systems. Conserv Biol 18:17–37. doi:10.1111/j.1523-1739.2004.01803.x CrossRefGoogle Scholar
  21. Edwards D, Schreckenberg K (1997) Demand from smallholder farmers for multipurpose tree germplasm: implications for policy, research and development. In: Simons AJ, Kindt R, Place F (eds) Policy aspects of tree germplasm demand and supply. Proceedings of an international workshop. The World Agroforestry Centre (ICRAF), Nairobi, pp 9–26Google Scholar
  22. El-Kassaby YA, Cook C (1994) Female reproductive energy and reproductive success in a Douglas-fir seed orchard and its impact on genetic diversity. Silvae Genet 43:243–246Google Scholar
  23. El-Kassaby YA, Fashler AMK, Crown M (1989) Variation in fruitfulness in a Douglas-fir seed orchard and its effect on crop-management decisions. Silvae Genet 38:113–121Google Scholar
  24. FAO (2004) Preliminary review of biotechnology in forestry, including genetic modification. Forest genetic resources working paper FGR/59E. Food and Agriculture Organization of the United Nations, RomeGoogle Scholar
  25. FAO (2006) Global forest resources assessment 2005. Main report, FAO Forestry Paper 147. Food and Agriculture Organization of the United Nations, RomeGoogle Scholar
  26. Friis-Hansen E, Sthapit B (eds) (2000) Participatory approaches to the conservation and use of plant genetic resources. Bioversity International (formerly the International Plant Genetic Resources Institute), RomeGoogle Scholar
  27. Garrity DP (2004) Agroforestry and the achievement of the millennium development goals. Agrofor Syst 61:5–17. doi:10.1023/B:AGFO.0000028986.37502.7c CrossRefGoogle Scholar
  28. Geburek T (2005) Genetic diversity in forest trees—its importance and potential human impact. In: Geburek T, Turok J (eds) Conservation and management of forest genetic resources in Europe. Arbora Publishers, Zvolen, pp 437–463Google Scholar
  29. Geburek T, Konrad H (2008) Why the conservation of forest genetic resources has not worked. Conserv Biol 22:267–274. doi:10.1111/j.1523-1739.2008.00900.x PubMedCrossRefGoogle Scholar
  30. Gentry AH, Vasquez R (1988) Where have all the Ceibas gone? A case history of mismanagement of a tropical forest resource. For Ecol Manag 23:73–76. doi:10.1016/0378-1127(88)90015-1 CrossRefGoogle Scholar
  31. Gigord L, Lavigne C, Shykoff JA (1998) Partial self-incompatibility and inbreeding depression in a native tree species of La Reunion (Indian Ocean). Oecologia 117:342–352. doi:10.1007/s004420050667 CrossRefGoogle Scholar
  32. Gil L, Fuentes-Utrilla P, Soto A, Teresa Cervera M, Collada C (2004) English elm is a 2,000-year-old Roman clone. Nature 431:1053PubMedCrossRefGoogle Scholar
  33. Graudal L, Lillesø J-PB (2007) Experiences and future prospects for tree seed supply in agricultural development support—based on lessons learnt in Danida supported programmes, 1965–2005. The Ministry of Foreign Affairs of Demark, CopenhagenGoogle Scholar
  34. Hajjar R, Jarvis DI, Gemmill-Herren B (2008) The utility of crop genetic diversity in maintaining ecosystem services. Agric Ecosyst Environ 123:261–270. doi:10.1016/j.agee.2007.08.003 CrossRefGoogle Scholar
  35. Hamrick JL, Godt MJW, Sherman-Broyles SL (1992) Factors influencing levels of genetic diversity in woody plant species. New For 6:95–124. doi:10.1007/BF00120641 Google Scholar
  36. Hansson B, Westerberg L (2002) On the correlation between heterozygosity and fitness in natural populations. Mol Ecol 11:2467–2474. doi:10.1046/j.1365-294X.2002.01644.x PubMedCrossRefGoogle Scholar
  37. Hardner CM, Potts BM (1997) Post-dispersal selection following mixed mating in Eucalyptus regnans. Evol Int J Org Evol 51:103–111. doi:10.2307/2410964 Google Scholar
  38. Harlan JR (1975) Crops and man. The American Society of Agronomy and the Crop Science Society of America, MadisonGoogle Scholar
  39. Hellin J, Higman S (2005) Crop diversity and livelihood security in the Andes. Dev Pract 15:165–174. doi:10.1080/09614520500041344 CrossRefGoogle Scholar
  40. Hodge GR, Dvorak WS, Urueña H, Rosales L (2002) Growth, provenance effects and genetic variation of Bombacopsis quinata in field tests in Venezuela and Colombia. For Ecol Manag 158:273–289. doi:10.1016/S0378-1127(00)00720-9 CrossRefGoogle Scholar
  41. Holding C, Omondi W (eds) (1998) Evolution of provision of tree seed in extension programmes: case studies from Kenya and Uganda. SIDA Technical Report No. 19. Regional Land Management Unit, Swedish International Development Cooperation Agency, NairobiGoogle Scholar
  42. Hollingsworth PM, Dawson IK, Goodall-Copestake WP, Richardson JE, Weber JC, Sotelo-Montes C, Pennington RT (2005) Do farmers reduce genetic diversity when they domesticate tropical trees? A case study from Amazonia. Mol Ecol 14:497–501. doi:10.1111/j.1365-294X.2005.02431.x PubMedCrossRefGoogle Scholar
  43. Jamnadass R, Hanson J, Poole J, Hanotte O, Simons TJ, Dawson IK (2005) High differentiation among populations of the woody legume Sesbania sesban in sub-Saharan Africa: implications for conservation and cultivation during germplasm introduction into agroforestry systems. For Ecol Manag 210:225–238. doi:10.1016/j.foreco.2005.02.033 CrossRefGoogle Scholar
  44. Jamnadass R, Lowe AJ, Dawson IK (2008) Genetic variation in tropical indigenous fruit trees: information from molecular markers and lessons for practical application. Trop Plant Biol (submitted)Google Scholar
  45. Janzen DH (1986) Blurry catastrophes. Oikos 47:1–2. doi:10.2307/3565912 CrossRefGoogle Scholar
  46. Jennings SB, Brown ND, Boshier DH, Whitmore TC, Lopes J do CA (2001) Ecology provides a pragmatic solution to the maintenance of genetic diversity in sustainable managed tropical rain forests. For Ecol Manag 154:1–10. doi:10.1016/S0378-1127(00)00637-X CrossRefGoogle Scholar
  47. Kelly BA, Hardy OJ, Bouvet J-M (2004) Temporal and spatial genetic structure in Vitellaria paradoxa (shea tree) in an agroforestry system in southern Mali. Mol Ecol 13:1231–1240. doi:10.1111/j.1365-294X.2004.02144.x PubMedCrossRefGoogle Scholar
  48. Kindt R (2002) Methodology for tree species diversification planning in African agroecosystems. PhD thesis, University of Gent, GentGoogle Scholar
  49. Kindt R, Lengkeek AG (1999) Tree diversity on farm—use it or lose it. In: agricultural biodiversity conservation. Proceedings of a workshop held in Nairobi, Kenya. Intermediate Technology Development Group East Africa, Nairobi, pp 75–85Google Scholar
  50. Kindt R, Lillesø J-PB, Mbora A, Muriuki J, Wambugu C, Frost W, Beniest J, Aithal A, Awimbo J, Rao S, Holding-Anyonge C (2006a) Tree seed for farmers: a toolkit and reference source. The World Agroforestry Centre (ICRAF), NairobiGoogle Scholar
  51. Kindt R, Van Damme P, Simons AJ, Beeckman H (2006b) Planning tree species diversification in Kenya based on differences in tree species composition between farms. I. Analysis of tree uses. Agrofor Syst 67:215–228. doi:10.1007/s10457-005-1703-2 CrossRefGoogle Scholar
  52. Kindt R, Van Damme P, Simons AJ, Beeckman H (2006c) Planning tree species diversification in Kenya based on differences in tree species composition between farms. II. Analysis of tree niches. Agrofor Syst 67:229–241. doi:10.1007/s10457-005-3824-z CrossRefGoogle Scholar
  53. Kindt R, Van Damme P, Simons AJ (2006d) Tree diversity in western Kenya: using profiles to characterise richness and evenness. Biodivers Conserv 15:1253–1270. doi:10.1007/s10531-005-0772-x CrossRefGoogle Scholar
  54. Kirschenmann FL (2007) Potential for a new generation of biodiversity in agroecosystems of the future. Agron J 99:373–376. doi:10.2134/agronj2006.0104 CrossRefGoogle Scholar
  55. Koelewijn HP, Koski V, Savolainen O (1999) Magnitude and timing of inbreeding depression in Scots pine (Pinus sylvestris L.). Evol Int J Org Evol 53:758–768. doi:10.2307/2640716 Google Scholar
  56. Leakey RRB (2007) Domestication and marketing of novel crops. In: Scherr SJ, McNeely JA (eds) Farming with nature: the science and practice of ecoagriculture. Island Press, Washington DC, pp 83–102Google Scholar
  57. Leakey RRB, Page T (2006) The ‘ideotype concept’ and its application to the selection of ‘AFTP’ cultivars. For Trees Livelihoods 16:5–16Google Scholar
  58. Leakey RRB, Schreckenberg K, Tchoundjeu Z (2003) The participatory domestication of West African indigenous fruits. Int For Rev 5:338–347Google Scholar
  59. Leakey RRB, Tchoundjeu Z, Smith RI, Munro RC, Fondoun J-M, Kengue J, Anegbeh PO, Atangana AR, Waruhiu AN, Asaah E, Usoro C, Ukafor V (2004) Evidence that subsistence farmers have domesticated indigenous fruits (Dacryodes edulis and Irvingia gabonensis) in Cameroon and Nigeria. Agrofor Syst 60:101–111. doi:10.1023/B:AGFO.0000013259.95628.22 CrossRefGoogle Scholar
  60. Leakey RRB, Tchoundjeu Z, Schreckenberg K, Shackleton SE, Shackleton CM (2005) Agroforestry tree products (AFTPs): targeting poverty reduction and enhanced livelihoods. Int J Agric Sustain 3:1–23Google Scholar
  61. Leakey RRB, Tchoundjeu Z, Schreckenberg K, Simons AJ, Shackleton S, Mander M, Wynberg R, Shackleton C, Sullivan C (2007) Trees and markets for agroforestry tree products: targeting poverty reduction and enhanced livelihoods. In: Garrity D, Okono A, Parrott M, Parrott S (eds) World agroforestry into the future. The World Agroforestry Centre (ICRAF), Nairobi, pp 11–22Google Scholar
  62. Ledig FT (1992) Human impacts on genetic diversity on forest ecosystems. Oikos 63:87–108. doi:10.2307/3545518 CrossRefGoogle Scholar
  63. Lengkeek AG (2003) Diversity makes a difference: farmers managing inter- and intra- specific tree species diversity in Meru, Kenya. PhD thesis, Wageningen University, WageningenGoogle Scholar
  64. Lengkeek AG, Carsan S (2004) The process of a participatory tree domestication project in Meru, Kenya. Dev Pract 14:445–451Google Scholar
  65. Lengkeek AG, Jaenicke H, Dawson IK (2005a) Genetic bottlenecks in agroforestry systems: results of tree nursery surveys in East Africa. Agrofor Syst 63:149–155. doi:10.1007/s10457-004-9155-7 CrossRefGoogle Scholar
  66. Lengkeek AG, Kindt R, van der Maesen LJG, Simons AJ, van Oijen DCC (2005b) Tree density and germplasm source in agroforestry ecosystems in Meru, Mount Kenya. Genet Resour Crop Evol 52:709–721. doi:10.1007/s10722-003-6021-9 CrossRefGoogle Scholar
  67. Lengkeek AG, Muchugi Mwangi AM, Agufa CAC, Ahenda JO, Dawson IK (2006) Comparing genetic diversity in agroforestry systems with natural forest: a case study of the important timber tree Vitex fischeri in central Kenya. Agrofor Syst 67:293–300. doi:10.1007/s10457-005-5830-6 CrossRefGoogle Scholar
  68. Lowe AJ, Boshier D, Ward M, Bacles CFE, Navarro C (2005) Genetic resource impacts of habitat loss and degradation; reconciling empirical evidence and predicted theory for neotropical trees. Heredity 95:255–273. doi:10.1038/sj.hdy.6800725 PubMedCrossRefGoogle Scholar
  69. Maranz S, Wiesman Z (2003) Evidence for indigenous selection and distribution of the shea tree, Vitellaria paradoxa, and its potential significance to prevailing parkland savanna tree patterns in sub-Saharan Africa north of the equator. J Biogeogr 30:1505–1516. doi:10.1046/j.1365-2699.2003.00892.x CrossRefGoogle Scholar
  70. McNeely JA (2004) Nature vs. nurture: managing relationships between forests, agroforests and wild biodiversity. Agrofor Syst 61:155–165. doi:10.1023/B:AGFO.0000028996.92553.ea CrossRefGoogle Scholar
  71. McNeely JA, Scherr SJ (2001) Common ground, common future: how ecoagriculture can help feed the world and save wild biodiversity. The World Conservation Union (IUCN), Gland, Switzerland and Future Harvest, WashingtonGoogle Scholar
  72. Miller RP, Nair PKR (2006) Indigenous agroforestry systems in Amazonia: from prehistory to today. Agrofor Syst 66:151–164. doi:10.1007/s10457-005-6074-1 CrossRefGoogle Scholar
  73. Miller AJ, Schaal BA (2005) Domestication of a Mesoamerican cultivated fruit tree, Spondias purpurea. Proc Natl Acad Sci USA 102:12801–12806. doi:10.1073/pnas.0505447102 PubMedCrossRefGoogle Scholar
  74. Miller AJ, Schaal BA (2006) Domestication and the distribution of genetic variation in wild and cultivated populations of the Mesoamerican fruit tree Spondias purpurea L. (Anacardiaceae). Mol Ecol 15:1467–1480. doi:10.1111/j.1365-294X.2006.02834.x PubMedCrossRefGoogle Scholar
  75. Nason JD, Hamrick JL (1997) Reproductive and genetic consequences of forest fragmentation: two case studies of neotropical canopy trees. J Hered 88:264–276Google Scholar
  76. Nathan I, Shrestha KB, Jha PK, Suvedi S (2005) Commercial distribution of tree seed in small bags—results from a pilot and action research project in Nepal. Working Paper No. 9, Development and Environment, Forest and Landscape Denmark, HørsholmGoogle Scholar
  77. Nill D, Böhnert E (2006) Value chains for the conservation of biological diversity for food and agriculture. Potatoes in the Andes, Ethiopian coffee, Argan oil from Morocco and grasscutters in West Africa. Deutsche Gesellschaft für Technische Zusammenarbeit, Eschborn. Germany and the Global Facilitation Unit for Underutilized Species, RomeGoogle Scholar
  78. O’Neill GA, Dawson IK, Sotelo-Montes C, Guarino L, Guariguata M, Current D, Weber JC (2001) Strategies for genetic conservation of trees in the Peruvian Amazon. Biodivers Conserv 10:837–850. doi:10.1023/A:1016644706237 CrossRefGoogle Scholar
  79. Reed DH, Frankham R (2003) Correlation between fitness and genetic diversity. Conserv Biol 17:230–237. doi:10.1046/j.1523-1739.2003.01236.x CrossRefGoogle Scholar
  80. Reusch TBH, Ehlers A, Hämmerli A, Worm B (2005) Ecosystem recovery after climatic extremes enhanced by genotypic diversity. Proc Natl Acad Sci USA 102:2826–2831. doi:10.1073/pnas.0500008102 PubMedCrossRefGoogle Scholar
  81. Rochon C, Margolis HA, Weber JC (2007) Genetic variation in growth of Guazuma crinita (Mart.) trees at an early age in the Peruvian Amazon. For Ecol Manag 243:291–298. doi:10.1016/j.foreco.2007.03.025 CrossRefGoogle Scholar
  82. Rodan BD, Newton AC, Verissimo A (1992) Mahogany conservation: status and policy initiatives. Environ Conserv 19:331–342CrossRefGoogle Scholar
  83. Rowe R, Cronk Q (1995) Applying molecular techniques to plant conservation: screening genes for survival. Plant Talk 1:18–19Google Scholar
  84. Sanou H, Lovett PN, Bouvet J-M (2005) Comparison of quantitative and molecular variation in agroforestry populations of the shea tree (Vitellaria paradoxa C.F. Gaertn) in Mali. Mol Ecol 14:2601–2610. doi:10.1111/j.1365-294X.2005.02601.x PubMedCrossRefGoogle Scholar
  85. Schroth G, da Mota MSS (2004) The role of agroforestry in biodiversity conservation in the tropics: a synthesis of evidence. Paper presented at the International Ecoagriculture Conference and Practitioners’ Fair, held in Nairobi, Kenya. The World Agroforestry Centre (ICRAF), Nairobi, September–October 2004Google Scholar
  86. Scott JC (1998) Seeing like a state—how certain schemes to improve the human condition have failed. Yale University Press, New HavenGoogle Scholar
  87. Simons AJ, Jaenicke H, Tchoundjeu Z, Dawson I, Kindt R, Oginosako Z, Lengkeek A, De Grande A (2000) The future of trees is on farm: tree domestication in Africa. In: Krishnapillay B, Soepadmo E, Lotfy Arshad N, Wong A, Appanah S, Wan Chik S, Manokaran N, Lay Tong H, Kean Choon K (eds) Forests and society: the role of research. Proceedings of the XXIst IUFRO World Congress, held in Kuala Lumpur, Malaysia, Sub-plenary Sessions vol 1, IUFRO Secretariat, Vienna and the Forest Research Institute Malaysia, Malaysia, pp 752–760, August 2000Google Scholar
  88. Smale M, Mar I, Jarvis DI (eds) (2002) The economics of conserving agricultural biodiversity on-farm: research methods developed from IPGRI’s global project ‘strengthening the scientific basis of in situ conservation of agricultural biodiversity’. Bioversity International (formerly the International Plant Genetic Resources Institute), RomeGoogle Scholar
  89. Sokol KA, Greenwood MS, Livingston WH (2004) Impacts of long-term diameter-limit harvesting on residual stands of Red Spruce in Maine. North J Appl For 21:69–73Google Scholar
  90. Sotelo-Montes C, Vidaurre H, Weber JC (2003) Variation in stem-growth and branch-wood traits among provenances of Calycophyllum spruceanum Benth. from the Peruvian Amazon. New For 26:1–16. doi:10.1023/A:1024425519480 Google Scholar
  91. Sotelo-Montes C, Hernández R, Beaulieu J, Weber JC (2006) Genetic variation and correlations between growth and wood density of Calycophyllum spruceanum Benth. at an early age in the Peruvian Amazon. Silvae Genet 55:217–228Google Scholar
  92. Stacy EA (2001) Cross-fertility in two tropical tree species: evidence of inbreeding depression within populations and genetic divergence among populations. Am J Bot 88:1041–1051. doi:10.2307/2657086 PubMedCrossRefGoogle Scholar
  93. Steffan-Dewenter I, Kessler M, Barkmann J, Bos MM, Buchori D, Erasmi S, Faust H, Gerold G, Glenk K, Gradstein SR, Guhardja E, Harteveld M, Hertel D, Hohn P, Kappas M, Kohler S, Leuschner C, Maertens M, Marggraf R, Migge-Kleian S, Mogea J, Pitopang R, Schaefer M, Schwarze S, Sporn SG, Steingrebe A, Tjitrosoedirdjo SS, Tjitrosoemito S, Twele A, Weber R, Woltmann L, Zeller M, Tscharntke T (2007) Tradeoffs between income, biodiversity, and ecosystem functioning during tropical rainforest conversion and agroforestry intensification. Proc Nat Acad Sci USA 104:4973–4978PubMedCrossRefGoogle Scholar
  94. Tata MHL, van Noordwijk M (2008) Trees, ectomycorrhizal dependence and regeneration strategies in rubber agroforests and other forest-derived vegetation in Jambi, Sumatra, Indonesia. For Ecol Manag (submitted)Google Scholar
  95. van der Steeg RP, Remington T, Grum M, Kemigisha E (2004) Seed vouchers and fairs and agrobiodiversity in Western Uganda. In: Sperling L, Remington T, Haugen JM, Nagoda S (eds) Addressing seed security in disaster response: linking relief with development. International Center for Tropical Agriculture, Cali, pp 29–44Google Scholar
  96. van Oijen DCC (2002) Will the spirit of nGai survive? A tree survey on ethnobotany, conservation potential and biomass on 35 farms in Meru, Kenya. MSc practical report, Wageningen University, WageningenGoogle Scholar
  97. Vaughan M, Hoffman Black S (2006) Enhancing nest sites for native bee crop pollinators. Agroforestry note 34. USDA National Agroforestry Center, LincolnGoogle Scholar
  98. Ward M, Dick CW, Lowe AJ (2005) To self, or not to self… A review of outcrossing and pollen-mediated gene flow in neotropical trees. Heredity 95:246–254. doi:10.1038/sj.hdy.6800712 PubMedCrossRefGoogle Scholar
  99. Weber JC, Sotelo-Montes C (2005) Variation and correlations among stem growth and wood traits of Calycophyllum spruceanum Benth. from the Peruvian Amazon. Silvae Genet 54:31–41Google Scholar
  100. Weber JC, Sotelo-Montes C (2008) Geographic variation in tree growth and wood density of Guazuma crinita Mart. in the Peruvian Amazon. New For (in press)Google Scholar
  101. Weber JC, Labarta Chávarri RL, Sotelo-Montes C, Brodie AW, Cromwell E, Schreckenberg K, Simons AJ (1997) Farmers’ use and management of tree germplasm: case studies from the Peruvian Amazon Basin. In: Simons AJ, Kindt R, Place F (eds) Policy aspects of tree germplasm demand and supply. Proceedings of an international workshop. The World Agroforestry Centre (ICRAF), Nairobi, pp 57–63Google Scholar
  102. Weber JC, Sotelo-Montes C, Vidaurre H, Dawson IK, Simons AJ (2001) Participatory domestication of agroforestry trees: an example from the Peruvian Amazon. Dev Pract 11:425–433. doi:10.1080/09614520120066710 CrossRefGoogle Scholar
  103. Weber JC, Larwanou M, Abasse TA, Kalinganire A (2008) Growth and survival of Prosopis africana provenances related to rainfall gradients in the West African Sahel. For Ecol Manag (submitted)Google Scholar
  104. Whitham TG, Bailey JK, Schweitzer JA, Shuster SM, Bangert RK, LeRoy CJ, Lonsdorf EV, Allan GJ, DiFazio SP, Potts BM, Fischer DG, Gehring CA, Lindroth RL, Marks JC, Hart SC, Wimp GM, Wooley SC (2006) A framework for community and ecosystem genetics: from genes to ecosystems. Nat Rev Genet 7:510–523. doi:10.1038/nrg1877 PubMedCrossRefGoogle Scholar
  105. Williams JW, Jackson ST, Kutzbach JE (2007) Projected distributions of novel and disappearing climates by 2100 AD. Proc Natl Acad Sci USA 104:5738–5742. doi:10.1073/pnas.0606292104 PubMedCrossRefGoogle Scholar
  106. Wily LA (2003) Participatory forest management in Africa: an overview of progress and issues. In: second international workshop on participatory forestry in Africa. Defining the way forward: sustainable livelihoods and sustainable forest management through participatory forestry, Arusha, United Republic of Tanzania, 18–22 February 2002, FAO, Rome, pp 31–58Google Scholar
  107. Wright S (1931) Evolution in Mendelian populations. Genetics 16:97–159PubMedGoogle Scholar
  108. Wu HK, Matheson AC, Spencer D (1998a) Inbreeding in Pinus radiata. I. The effects of inbreeding on growth, survival and variance. Theor Appl Genet 97:1256–1268. doi:10.1007/s001220051018 CrossRefGoogle Scholar
  109. Wu HK, Matheson AC, Spencer D (1998b) Inbreeding in Pinus radiata. II. Time course of inbreeding depression and effect on growth curve. N Z J For Sci 28:123–139Google Scholar

Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • Ian K. Dawson
    • 1
  • Ard Lengkeek
    • 1
    • 2
  • John C. Weber
    • 1
    • 3
  • Ramni Jamnadass
    • 1
  1. 1.The World Agroforestry Centre (ICRAF)NairobiKenya
  2. 2.The Tree Domestication TeamWageningenThe Netherlands
  3. 3.The World Agroforestry Centre (ICRAF)West and Central Africa Regional OfficeBamakoMali

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