Reproductive traits affect the rescue of valuable and endangered multipurpose tropical trees

AoB Plants, Jan 2016

Conservation strategies are urgently needed in Tropical areas for widely used tree species. Increasing numbers of species are threatened by overexploitation and their recovery might be poor due to low reproductive success and poor regeneration rates. One of the first steps in developing any conservation policy should be an assessment of the reproductive biology of species that are threatened by overexploitation. This work aimed to study the flowering biology, pollination and breeding system of V. doniana, a multipurpose threatened African tree, as one step in assessing the development of successful conservation strategies. To this end, we studied (1) traits directly involved in pollinator attraction like flowering phenology, flower numbers and morphology, and floral rewards; (2) abundance, diversity and efficiency of flower visitors; (3) breeding system, through controlled hand-pollination experiments involving exclusion of pollinators and pollen from different sources; and (4) optimal conditions for seed germination. The flowering phenology was asynchronous among inflorescences, trees and sites. The flowers produced a large quantity of pollen and nectar with high sugar content. Flowers attracted diverse and abundant visitors, counting both insects and birds, and efficient pollinators included several Hymenoptera species. We detected no spontaneous self-pollination, indicating a total dependence on pollen vectors. Vitex doniana is self-compatible and no inbreeding depression occurred in the first developmental stages. After extraction of the seed from the fruit, seed germination did not require any particular conditions or pre-treatments and the seeds showed high germination rates. These pollination and breeding characteristics as well as germination potential offer the required conditions to develop successful conservation strategies. Protection, cultivation and integration in agroforestry systems are required to improve the regeneration of the tree.

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Reproductive traits affect the rescue of valuable and endangered multipurpose tropical trees

AoB PLANTS www.aobplants.oxfordjournals.org Reproductive traits affect the rescue of valuable and endangered multipurpose tropical trees Viviane Sine´ bou 0 1 Muriel Quinet 1 Bonaventure C. Ahohuendo 0 Anne-Laure Jacquemart 1 Associate Editor: Dennis F. Whigham 0 De ́partement de Productions Ve ́ge ́tales, Faculte ́ des Sciences Agronomiques, Universite ́ Abomey-Calavi , Cotonou 01 BP 526 , Benin 1 Research Group Genetics , Reproduction, Populations , Earth and Life Institute - Agronomy, Universite ́ Catholique de Louvain , Croix du Sud 2 Box L7.05.14, B-1348 Louvain-la-Neuve , Belgium Conservation strategies are urgently needed in Tropical areas for widely used tree species. Increasing numbers of species are threatened by overexploitation and their recovery might be poor due to low reproductive success and poor regeneration rates. One of the first steps in developing any conservation policy should be an assessment of the reproductive biology of species that are threatened by overexploitation. This work aimed to study the flowering biology, pollination and breeding system of V. doniana, a multipurpose threatened African tree, as one step in assessing the development of successful conservation strategies. To this end, we studied (1) traits directly involved in pollinator attraction like flowering phenology, flower numbers and morphology, and floral rewards; (2) abundance, diversity and efficiency of flower visitors; (3) breeding system, through controlled hand-pollination experiments involving exclusion of pollinators and pollen from different sources; and (4) optimal conditions for seed germination. The flowering phenology was asynchronous among inflorescences, trees and sites. The flowers produced a large quantity of pollen and nectar with high sugar content. Flowers attracted diverse and abundant visitors, counting both insects and birds, and efficient pollinators included several Hymenoptera species. We detected no spontaneous self-pollination, indicating a total dependence on pollen vectors. Vitex doniana is self-compatible and no inbreeding depression occurred in the first developmental stages. After extraction of the seed from the fruit, seed germination did not require any particular conditions or pre-treatments and the seeds showed high germination rates. These pollination and breeding characteristics as well as germination potential offer the required conditions to develop successful conservation strategies. Protection, cultivation and integration in agroforestry systems are required to improve the regeneration of the tree. Bees; breeding system; conservation biology; mating system; pollinator efficiency; seed germination Introduction Global biodiversity is decreasing at an unprecedented rate as a complex response to several human-induced changes (Sala et al. 2000) . Land use change is the driver that has the largest global impact on biodiversity, mostly due to habitat destruction and fragmentation. Land use change is particularly the most important driver in tropical forests (Sala et al. 2000) . The African forests are subject of haphazard modification following anthropogenic pressures including tree cutting and clearing for agriculture. In West Africa, logging and seasonal fires set by farmers and hunters have increased deforestation, destroying an average of 870 000 ha/year between 2000 and 2010 (FAO 2011) . Consequently, several food and medicinal tree species have been declared locally endangered and are priorities for conservation (Eyog-Matig et al. 2002; FAO 2011) . Forest harvesting directly decreases the rates of survival, growth and reproduction of individual trees, affecting the structure and dynamics of harvested populations (Oumorou et al. 2010). In harvested stands, only large, old trees and a few seedlings and saplings generally survive (Oumorou et al. 2010) . Maintaining these local remnant populations will require informed management and conservation practices. Vitex doniana, commonly called black plum, is one of the most important wild-harvested, multipurpose trees in tropical Africa (Akoe`gninou et al. 2006; N’Danikou et al. 2015) . The tree is widely used for food, medicinal purposes and as firewood (Achigan-Dako et al. 2011) . The species also has a great socio-cultural and mythological importance for local people (Dadjo et al. 2012; N’Danikou et al. 2015) . Despite its high value for local populations, there is no evidence of any conservation initiatives from harvesters (N’Danikou et al. 2011) . People usually harvest the desired resources without considering regeneration and management or attempting silvicultural practices (e.g. planting and sowing) (Dadjo et al. 2012; N’Danikou et al. 2015) . Mainly due to overexploitation, V. doniana is one of the most-threatened food tree species with high priority for conservation in Benin, Kenya, Niger and Burkina Faso (Eyog-Matig et al. 2002; Oumorou et al. 2010; N’Danikou et al. 2015) . The threats to the (...truncated)


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Viviane Sinébou, Muriel Quinet, Bonaventure C. Ahohuendo, Anne-Laure Jacquemart. Reproductive traits affect the rescue of valuable and endangered multipurpose tropical trees, AoB Plants, 2016, 8, DOI: 10.1093/aobpla/plw051