Forest Genetic Resources Training Guide Tree seed supply chains Tree planting on farms in East Africa: how to ensure genetic diversity? David Boshier, Ian Dawson & Ard Lengkeek
Forest Genetic Resources Training Guide Location of the countries and survey areas Kenya Uganda Tanzania Kabale Mabira Arusha Meru Nairobi Location of nursery survey sites
Forest Genetic Resources Training Guide
Nursery sites
Forest Genetic Resources Training Guide Why bother about genetic diversity? adaptation to changing environments direct use of genetic resources viability of populations in short term - seed production - inbreeding depression
Forest Genetic Resources Training Guide Inbreeding depression in Acacia mangium in Sabah Seed source 1st generation 2nd generation 3rd generation Seedling height (cm) Sim, 1984
Forest Genetic Resources Training Guide Theory direct impacts decrease population size increase spatial isolation decrease densities change local environment genetic processes genetic drift gene flow mating - inbreeding selection
Forest Genetic Resources Training Guide Bottleneck genetic drift
Forest Genetic Resources Training Guide Isolated trees – mating patterns?
Forest Genetic Resources Training Guide Altered mating patterns in farm trees? Predictions: increased inbreeding greater pollen dispersal fewer sires Isolated farm tree Continuous forest inbreeding dispersal sires
Forest Genetic Resources Training Guide How many trees to collect from?
Forest Genetic Resources Training Guide Data collected in a survey of seed-propagated tree species in tree nurseries from five areas in East Africa Survey area (country)All areas Kabale (Uganda) Mabira (Uganda) Nairobi (Kenya) Meru (Kenya) Arusha (Tanzania) Nurseries [client data*]7 [6]9 [7]21 [16]12 [8]22 [22]71 [59] Cases [client data]15 [8]26 [16]31 [25]17 [10]54 [54]143 [113] All species Indigenous species Cases indigenous species Cases five most common species Cases of unique species occurrence Single tree collections all species Single tree collections indigenous species Seed trees per nursery lot, N m : mean (SD) 3.7 1.8 (3.6) 5.1 2.3 (6.0) 5.8 3.1 (8.9) 5.7 3.1 (6.5) 8.2 3.8 (14.1) 6.4 1.7 (10.3) Seedlings per nursery lot, N s : mean (SD) 871 712 (1408) 2060 1408 (3661) 787 432 (1228) 1339 1011 (2127) 1543 676 (2535) 1378 401 (2446) Clients per nursery lot, N c : mean (SD) 12 14 (20) 41 27 (55)17 9 (22)81 92 (149) 22 5 (20)28 10 (53)
Forest Genetic Resources Training Guide
Cupressus lusitanica Wind pollinated Hermaphrodite, self compatible 100,000 seed produced per tree
Forest Genetic Resources Training Guide Calliandra calothyrsus Bat/moth pollinated Hermaphrodite and male flowers, Mainly outcrossing 1,000 seed produced per tree
Forest Genetic Resources Training Guide Dovyalis caffra Bird?/insect pollinated Dioecious seed produced per tree
Forest Genetic Resources Training Guide Sclerocarya birrea – male tree being cut as not producing fruits
Forest Genetic Resources Training Guide Grevillea robusta Self incompatible with protandry Fruit set cross-pollination ( %) >open-pollination on farms (0.1%-3.3%) Open-pollinated flower stigmas – most no pollen or only self-pollen Lack of cross-pollen may limit seed production
Forest Genetic Resources Training Guide Senna siamea Insect pollinated Hermaphrodite Self–compatible? High seed production per tree
Forest Genetic Resources Training Guide Procurement pathways NGOs compared withCBOs
Forest Genetic Resources Training Guide Distribution pathways
Forest Genetic Resources Training Guide Think about and discuss Where are bottlenecks to genetic diversity? How to overcome these? In 5 main species, how does seed production per tree influence number of trees seed collected from? How species biology affects genetic diversity in seed collections? How can mixing seed ensure use and maintenance of existing genetic diversity? mean N s /N c vs mean N s /N m. Advice/training to improve situation? Figs 2-4; to NGOs and/or directly to communities? What specific advice/training? How does seed collection and plant production occur? Are seeds and plants transferred and if so how? Does this provide limitations or opportunities?
Forest Genetic Resources Training Guide Plan objective: ensure maintenance of genetic diversity in the collection & supply of seed, & improved nursery practice Plan should identify: influences on genetic diversity(bottlenecks, selection, genetic drift) associated with current seed collection and distribution paths key actors (individuals, institutions), processes (what actors do), social limits in seed supply chain (policy, trade, institutional, capacity). Communication/training needs related to key actors. Specific actions to improve situation, addressing diversity issues in seed system (e.g. practical ways to collect & distribute seed/seedlings to ensure genetic diversity in nurseries & material planted in field)