International Journal of Agriculture and Forestry 2016, 6(1): 1-7 DOI: 10.5923/j.ijaf.20160601.01

A Concept of Wild Flora and Biodiversity Based on Tree Resource Domestication in Agriculture

Benjamin E. Uchola

Faculty of Agriculture, Federal University, Dutsin-ma, Nigeria

Abstract Tree Resource Domestication (TRD) is an influential process in the development of a tree crop and its large scale cultivation. But TRD have a minimal impact on the meaning of concepts such as wild flora and biodiversity as they are popular with conservation interests and Natural Resource Management. Tree Resource Domestication (TRD) as a development process of tree crops involves the relocation of valued parts of a tree or whole seedlings from forest to artificial environments, the adaptation of successive generations of relocated trees to human-controlled environments and the selection of desired production traits in plantation-grown populations of trees. A close association exist between TRD and tree species of wild origin, established populations of cultivated trees as well as their cultivars/clones. These relationships were explored so that the unique experiences of TRD in agriculture would be reflected in concepts that are closely associated with the domestication process. The derivatives are more specific concepts of wild flora, tree crop diversity and biodiversity. Keywords Agricultural biodiversity, Tree crop diversity, TRD-Based concepts

1. Introduction of controlled breeding programmes. These two main phases in TRD are demonstrated in a number of valued trees Tree is a distinct category of plants. The presence of trees, including the macadamia [12-14], the oil palm [15-19], the their composition and number per hectare are important rubber [20-22] and in the ongoing domestication of the features of major ecological zones. A landscape of trees and African bush mango [23-29]. Indeed, the progressions of other associated woody plants, the size of land area with tree wild trees from natural resource that were exploited to crops crown or the average height of trees at maturity are among that are cultivated in plantations characterize the the criteria that have been employed in defining what development of all known tree crops [30, 31]. As a result, constitutes a forest [1, 2]. The composition of tree species Tree Resource Domestication (TRD) becomes the that constitute a forest are most diverse in the rainforest transformation-based process that extends across successive which extends from South America through Africa to parts generations of a tree and results in its domestic form whose of Asia [3, 4]. Some native trees in natural forest have be production traits are better expressed. discovered by indigenous peoples to be of value leading to Tree Resource Domestication (TRD) as a process of their continuous exploitation but also to their protection and transforming wild trees into their cultured equivalent may be conservation [5-7]. employed in understanding the concept of wild flora and An important sphere in the rational use of forest resources biodiversity. Although these terms have also been applied in is the domestication of wild trees. Generally, the crop improvement programmes [32-34], their meanings is domestication of food resource is believed to be a human yet to be clearly differentiated from similar concepts in response to the threat of unsustainable supply from the wild Natural Resource Conservation as evident in the documents due to changes in climatic conditions [8-11]. Nevertheless, of the International Union for the Conservation of Nature Tree Resource Domestication (TRD) comprises an initial (IUCN), Flora and Fauna International (FFI) and other phase that involves the relocation of valued parts of a tree or Conservation-based Organisations [5, 35]. The use of both whole seedlings to human-controlled environments as well terms may be enhanced when the fundamental process of as a final phase which comprise selection of faster growth Tree Resource Domestication (TRD) is emphasized. An rate, larger fruit size and other desired traits through series enhanced concept of wild flora and biodiversity based on TRD would distinguish them from those used in Natural * Corresponding author: [email protected] (Benjamin E. Uchola) Resource Conservation. For this reason, the study focuses on Published online at http://journal.sapub.org/ijaf developing these terms so that they could reflect and express Copyright © 2016 Scientific & Academic Publishing. All Rights Reserved the unique experience of TRD in agriculture.

2 Benjamin E. Uchola: A Concept of Wild Flora and Biodiversity Based on Tree Resource Domestication in Agriculture

2. Tree: A Natural Resource 21]. Even more, the extraction of tree products as a form of production is central to the development of the palm oil The importance of trees as a distinct category of plants industry in West Africa and the rubber industry in South includes those related to the environment and its value to America prior to the use of plantation-grown trees. humans. An extensive landscape of trees and other The continuous exploitation of tree resource threatens the associated woody plants or interspersed trees with grassland survival of natural populations and their capacity to meet is an important part of the environment and constitutes an human demands. As a result, there are on-going attempts ecological zone [1-3]. Furthermore, trees as an integral part aimed at preserving tree populations in their natural habitats of the environment are important source of food, latex and so as to prevent their loss especially those of rare species other valuable items to indigenous peoples in particular and [5-7]. These concerns find concrete expression in the human society in general [15, 20]. preservation of valuable trees on forest farmlands and the The role of trees as an integral part of an ecosystem can be establishment of Protected Areas/Forest Reserves [15, 18, 19, perceived from the differences in flora composition across 44, 45]. Some fruit-diverse forests in Asia and the wild broad ecological zones like the rainforest and savannah. coffee-rich forest in Ethiopia are among the Protected Areas Forest as vast area of tree-cover is an habitat for several acknowledged by the International Treaty on Plant Genetic groups of plants and animals but more importantly a centre Resource for Food and Agriculture (ITRGRFA). Conserved of diversity for many tree species. The oil palm (Elaeis spp), population of trees in natural habitats or on farmlands, as in cocoa (Theobroma spp) and gmelina (Gmelina spp) are few the case of oil palm and bush mango, are most often the of the several hundreds of tree species that are native to the founding stock for domestication purposes [15, 23, 44, 45]. rain forest zone which extends from the Amazon in South America through parts of Africa to parts of Asia while the locust bean (Parkia biglobosa), baobab (Adansonia digitata) 3. Tree Resource Domestication and marula (Sclerocarya birrea) are among the relatively few tree species that are endemic to the savannah region of Domestication of tree resource is a complex biological Africa [15, 36-39]. Many of these wild trees scarcely express process that entails the interaction between humans and trees. their full productive potentials due to the influence of wide This often involves the relocation of valued trees from their range of environmental factors and often manifest this natural habitat to artificial environment and selection of restriction in the form of prolong growth period, irregular desired production traits. But most importantly, it leads to fruiting patterns and low productivity [40-42]. A species of the development of trees that are well adapted to macadamia tree that is native to the Australian forest grows human-controlled environments and highly productive for up to two decades before the commencement of [30, 31]. flowering and fruiting activities which are often Introduction of valued trees into artificial environments is characterized by irregular patterns and low productivity [12, a major first step in the long process of domesticating wild 13]. Similarly, the oil palm of the humid lowland rainforest trees. The ecological aspects is pronounced in the of west and central Africa matures after growing for over domestication of a number of valuable wild trees such as the three years while the bush mango in the same region requires macadamia [12-14], the oil palm [15-18] and the rubber a growth period of not less than a decade to attain maturity [20, 21]. Relocation of native trees from their natural habitat [15, 17, 25]. Long juvenile period, late maturation and to artificial environment is a distinct phase in the process of inconsistent fruiting pattern as a result of environmental domestication but there may have been a transition phase in factors are generally associated with the primitive state of the form of preservation on forest farmlands. The avocado plants and trees [30, 31]. and cocoa of south America, figs and olives of the Wild trees are often subjected to evaluation in the course Mediterranean region, mango and apples of the Asian of human-tree interactions. Some species of trees such as continent were most likely preserved and monitored in their Elaeis guineensis, Mangifera indica and Theobroma cocoa, natural habitats prior to their relocation to human-controlled were identified as sources of valuable food items while environments [33, 43, 46]. Similarly, the oil-bearing African others like Hevea brasiliensis and Gmelina arborea proved palm were preserved on forest farmland before its to be good sources of latex and timber respectively [15, 20, introduction into artificial environments in Southeast Asia 21, 36, 37, 43]. Nevertheless, the yields from wild trees are just as rubber trees were tapped in the Amazonian forest by often low due to limited expression of their production native Indians prior to its introduction to a botanical garden potentials [40-42]. This fact is illustrated vividly in wild in England and Southeast Asia afterwards [15, 18, 20, 21]. macadamia, oil palm and rubber trees whose productivity are More recently, the bush mango is being preserved on new generally characterised by prolong growth periods. The yield forest farmlands and the breakthrough in vegetative estimate of some wild macadamia trees would be abysmally propagation of seedlings is facilitating the establishment of low and insignificant per hectare, fresh fruit bunch estimate nurseries and field banks [23, 25-29]. Interestingly, of wild/semi wild oil palm range between 2-5 tonnes while field-grown bush mango displays reduced age at maturity, the yield of the earliest rubber plantings is less than 450 better fruit qualities and higher yield which is an indication pounds of latex , that is, about 0.2 tonnes/ha/year [12, 13, 15, that the tree is responding to human selection and a potential

International Journal of Agriculture and Forestry 2016, 6(1): 1-7 3

tree crop. Another phase in the domestication of native trees shows stability in yield, which is, the hybrid RRII 105 [22]. is the selection of desired production traits. This aspect of Several other hybrid rubber clones, a number of olive domestication is clearly demonstrated in oil palm [16-18]. cultivars like the Spanish Gordal Sevillana and the Israeli Series of selection of plantation-grown oil palm enhance its Merhavia are results of selection pressures on tree crops in productivity which was further improved through plant human-controlled environments. breeding programmes involving two different fruit types. The unique characteristics of tree crops present a new Thick-shelled dura populations when crossed with selected relationship with their undomesticated relatives and cultivars. shell-less pisifera population results in a fruit type with The cultivated rubber, whose transition from the wild to the reduced shell thickness, increased mesocarp size and cultured state begins with a relocation of its wild progenitor improved oil yield [18, 47]. to human-controlled environments, is in the most developed Domestication therefore facilitates better expression of the form of rubber tree [30, 31]. Other species of rubber failed production capacity in native trees. Cultivated macadamia evaluation exercises due to inferior product quality or yields 0.25-0.5 tonnes per hectare 4-6 years after unsatisfactory response to selection pressures in artificial nursery-grown seedlings are transplanted onto fields which environments. As a result, the other species of rubber is an improvement when compared to some wild macadamia continue to be important only as plants within an ecosystem that still remains reproductively immature at the age of seven or a resource to indigenous people which indicates that they [12-14]. Cultivated oil palm produces fresh fruit bunch of are the less developed forms of the rubber tree [30, 31]. In 24-32 tonnes in well managed plantations which when other words, the other species of rubber are less developed in compared to the 2-5 tonnes yield from wild/semi-wild relation to their cultivated counterpart and accordingly populations is a monumental achievement [15, 18, 47]. constitute the wild form of cultivated rubber. Cultivated Likewise, a 5-year old plantation-grown rubber yields up to rubber further responds to selection for early maturity, 1.6 tonnes of latex/ha/year which is a better production higher yield and disease resistance resulting in the performance in relation to earlier plantings that produce development of clones (Table 1). The emergence of these about 0.2 tonnes of latex/ha/yr [20-22]. In other words, these clones of rubber is an expression of diversity inherent within patterns of yield and growth in domesticated trees are in cultivated rubber or further expression of cultivated rubber to contrast to those in their wild progenitors which have lower specific selection pressures in human-controlled productivity and longer growth period. environments. From this perspective, the sum of clones of cultivated rubber and the wild flora of rubber constitute the biodiversity of the rubber tree. 4. TRD-Derived Concepts of Wild Flora Cultivated cocoa and oil palm descended from wild and Biodiversity Theobroma cocoa and Elaeis guineensis respectively based Tree crops develop from the responsiveness of wild trees on the criteria of high utility value and positive response to to selection pressures in human-controlled environments. selection pressures. Other species in the genus Theobroma Plantation-grown oil palm is the domestic form of wild and Elaeis manifest inferior performance based on utility and Elaeis guineensis which shares the genus Elaeis with wild production-based evaluation criteria thereby restricting their Elaeis oleifera, cultivated cocoa is a derivative of wild further development. Put simply, the other species are less Theobroma cacao which shares the genus Theobroma with developed in relation to their cultured equivalent and they other species such as Theobroma angustifolium, T. bicolor, constitute the wild flora of their domestic forms which and T. canumanense while domestic mango is the always respond to artificial selection in controlled domesticated form of wild Mangifera indica one of the environments. Cultivated cocoa responds to further selection several wild species that includes Magnifera odorata, M. resulting in cultivars such as LLT EEN 46 and LLT EEM persiciformis, M. rubropetala (Table 1). Furthermore, series 127 in the same way as cultivated oil palm generates clone of artificial selections of desired traits result in diversity like TARS 225 and MIA 29290 (Table 1). The different within populations of a particular tree crop. This has been the expressions of a particular trait that characterize cultivars or case for plantation-grown rubber, olive and coffee. Different clones of cocoa and oil palm suggest a diversity that is populations of plantation-grown rubber are often good but inherent within the cultivated trees. In this way, the broad may not necessarily be excellent in terms of yield range which comprises clones of cocoa as well as its wild performance, latex tapping age, drought tolerance and flora represents the biodiversity of cocoa just as the wild disease resistance. Selection of these traits from two rubber flora of oil palm and its clones constitutes the biodiversity of clones Tjir and GI 1 results in the highest yielding clone that the oil palm tree.

4 Benjamin E. Uchola: A Concept of Wild Flora and Biodiversity Based on Tree Resource Domestication in Agriculture

Table 1. Wild flora and Tree Crop Diversity of selected commercial tree crops

WILD PRO- TREE CROP DIVERSITY TREE CROPS WILDFLORA GENITOR (CULTIVARS/CLONES) Minimum estimate: 54 species* [48, 49] Malus angustifolia, M. asiatica, M. baccata, M. bracteata, M. brevipes, M. chitralensis , M. coronaria, M. daochengensis, M. dasyphylla, M. domestica, M. doumeri, M. florentina, M. Several hundred cultivars* [50] floribunda, M. fusca, M. glabrata, M. glaucescens, M. halliana, M. Malus domestica Brown, honanensis, M. hupehensis, M. ioensis, M. jinxianensis, M. Circassian, Coast, Gala, Lady, APPLE kansuensis, M. kirghisorum, M. lancifolia, M. leiocalyca, M. Red , Landsberger Reinette, Malus domestica Malus sieversii mandshurica, M. melliana , M. micromalus, M. montana, M. Paide's Winter, muliensis, M. niedzwetzkyana, M. ombrophila , M. pallasiana, M. Toko, Wealthy. platycarpa, M. praecox, M. prattii, M. prunifolia, M. pumila, M. sachalinensis, M. rockii, M. sargentii, M. sieboldii, M. sieversii, M. sikkimensis, M. soulardii , M. spontanea, M. sylvestris, M. transitoria, M. toringoides, M. trilobata, M. tschonoskii, M. turkmenorum, M. yunnanensis, M. zumi Minimum estimate: 22 species* [48, 51] Several cultivar/ Theobroma angustifolium, T. bernoullii, T.bicolor, T.cacao, clones * [50] COCOA T.canumanense , T. cirmolinae , T. duckei, T. gileri, T. glaucum, Theobroma Theobroma T.grandiflorum, T. hylaeum , T. mammosum, T.microcarpum, T. LCT EEN 46; LCT EEN 86; LCT cacao cacao nemorale, T. obovatum, T.simiarum, T. sinuosum , T. speciosum, EEN 127; RIM13 [MEX]; RIM T.stipulatum, T. subincanum, T.sylvestre T.velutinum 105[MEX]; PB 43[MEX] Several cultivar* [54] Over 100 species globally. 10 of the accepted species * [48, 51, 53] Coffea arabica Ethiopian Harar, COFFEE Coffea arabica, C. ambongensis,C. anthonyi, C. bissetiae, C. Sidamo, Yirgacheffe,Geisha Coffea arabica boinensis, C. canephora, C. charrieriana, C. labatii, C. T.2722; Java; Mocha; Ruiru 11; Coffea arabica namorokensis, C. pterocarpa. Timor Arabusta ; Typica Minimum estimate: 31 species* [48, 55] Gmelina annamensis , G.arborea, G.asiatica, G. basifilum, G. chinensis, G. dalrympleana, G. delavayana, G. elliptica, G.evoluta, G. fasciculiflora, G.hollrungii, G. lecomtei, G. ledermannii, G. GMELINA Several yet to be properly Gmelina arborea leichhardtii, G. lepidota, G. lignum-vitreum, G. magnifica, G. Gmelina arborea identified* [56] moluccana, G. neocaledonica, G. palawensis, G. papuana, G. peltata, G. philippinensis, G. racemosa, G.salomonensis, G. schlechteri, G. sessilis,G. smithii, G. szechwanensis G. tholicola, G. uniflora, G. vitiensis hundreds of cultivars* [50] Minimum estimate: 10 species* [48] Mangifera indica Alfonso, MANGO Mangifera caesia, M. casturi, M. indica, M. laurina, M. lineariflia, Ameeri, Amini, Fajri, Mangifera Mangifera indica M. odorata, M. persiciformis, M. rubropetala, M. siamensis, M. Cambodiana, Carabao, Peach, indica sylvatica Sufaida, Suwon Tip, Tommy Atkins. OIL PALM Relatively few clones* [50] Minimum estimate: 2 species* [48] Elaeis TARS 225, TARS 1074, TAR Elaeis guineensis Elaeis guineensis, E. oleifera guineensis 1614, PI 78538, PI156642. Minimum estimate: 36 species* [48] Olea ambrensis, O. borneensis, O.brachiata, O.capensis, O. capitellata, O.caudatilimba, O. chimanimani, O.cordatula, O. Several cultivars* [50] dioica, O. europaea, O.exasperata, O. gagnepainii, O.gamblei, O. Olea europaea Gordal Sevillana, OLIVE hainanensis, O. hoschstetteri, O.javanica, O. lancea, O. laxiflora, Ascolana Tenera, Meski , Souri , Olea europaea Olea oleaster O. moluccensis, O. neriifolia, O. oleaster, O. palawanensis, O. Chalkidiki , Merhavia , Oblonga, paniculata, O. parvilimba, O. polygama, O. puberula, O. rosea, O. Nabali , Massabi Adrouppa rubrovenia, O. salicifolia, O. schliebenii, O.tetragonoclada, O. tsoongii O. welwitschii, O. wightiana, O.woodiana, O.yuennanensis. Minimum estimate: 10 species* [48, 57] Several clones* [22] Hevea benthamiana, H.brasiliensis, H. camargoana, H. camporum, GT l, Tjir, PB 86, PB 260, PB RUBBER H. guianensis, H. microphylla, H. nitida, H. pauciflora, H. 280, PB 312, Hevea Hevea rigidifolia, H. spruceana RRII 105, RRII 430 brasiliensis brasiliensis RRIM 600, RRIM 712, RRIC 100, RRIC 130.

International Journal of Agriculture and Forestry 2016, 6(1): 1-7 5

The description of TRD-based concept of wild flora in agriculture indicates that it is a synonym for wild relatives of tree crops. However, a TRD-based concept of biodiversity in agriculture confines the term to wild flora of a tree crop and REFERENCES its cultivars since TRD involves the transformation of a wild tree into a tree crop as well as the development of its cultivars. [1] FAO. On definitions of forest and forest change. Food and A concept of biodiversity which is derived from TRD would Agriculture Organisation. FAO, Rome. Tree resource Assessment Programme Working Paper 33. 15p. 2000. therefore exclude tree species that are unrelated to tree crops. Accordingly, the biodiversity of rubber comprise wild flora [2] FAO, FLD, IPGRI. Forest genetic resource conservation and of rubber but not other undomesticated latex-producing management. Overview, concepts and some systematic plants such as the Gutta-percha (Palaquium gutta) and approaches. International Plant Genetic Resource Institute, Rome, Italy. Vol. 1. p 1-4. 2004. Indian rubber plant (Ficus castillas). In like manner, the wild flora of rubber includes all species of Hevea that are related [3] FRA 2001. Global ecological zoning for the Global Forest to cultivated rubber but not those of Landolphia (Congo Resource Assessment 2000. Final Report. Forest Resource rubber) whose cultivation in human-controlled environments Assessment Programme Working Paper 56. is greatly hampered. These undomesticated trees and other [4] LET. 2000. Ecofloristic zones and global ecological zoning of heavily exploited or threatened trees like Pinabete (Abies Africa, South America and Tropical Asia. Toulouse, France. guatemalensis) are termed “wild flora” and by extension Prepared for FAO-FRA2000 by M.F. Bellan. 199 pp + maps. “biodiversity” by the international Union for the [5] Fauna and Flora International. The Red List of Trees of Conservation of Nature (IUCN) and other Natural Resource Guatemala. Compiled by Vivero J.L., Szejner M., Gordon J. Conservation-based organisations [5, 35]. Put differently, and Magin G. Published by Fauna and Flora International, concepts of wild flora and biodiversity that are borne out of Cambridge, UK. 48p+. 2006. the domestication experience gives specific meaning to the [6] G. Namkoong, 1998. Genetic diversity for forest policy and generalised forms as used by international conventions management. Pp. 30–44 in The living dance: policy and including the Convention on International Trade in practices for biodiversity in managed forests (F.L. Bunnel and Endangered Species (CITES) and Convention on Biological J.F. Johnson, eds.). UBC Press, Vancouver, Canada. Diversity (CBD). In this way, TRD-derived concept of wild [7] Namkoong, G. 2001. Forest genetics: pattern and complexity. flora transforms the general view of wild flora into a Can. J. For. Res. 31(4):623–632. particular one, that is, a less developed form of a specified [8] Blumler MA.1992. Independent inventionism and recent domesticated tree. In like manner, TRD-based concept of genetic evidence on plant domestication. Economic Botany biodiversity redefines biodiversity from a general category 46:98111 of organisms to a specific category that comprise the wild progenitor of a domesticated tree, undomesticated species in [9] Sherratt A. (1997) Climatic cycles and behavioural revolutions: the emergence of modern humans and the the genus of the wild progenitor, the domesticated tree and beginning of farming. Antiquity 71. 271–287. its cultivars only. [10] Diamond, J. (2002) Evolution, consequences and future of plant and animal domestication. Nature 418: 700–707. 5. Conclusions [11] Salamini F., Özkan H., Brandolini A. , Schäfer-Pregl R. Martin W. (2002) Genetics and geography of wild cereal Tree Resource Domestication (TRD) has facilitated the domestication in the near east. Nature Review Genetics 3. use of new terms in the course of the continuous interactions 429–441. between humans and trees. Tree crops, tree crop cultivars and plantations are among the terms that have emerged from [12] Hardner, C. M., C. Peace, A. J. Lowe, J. Neal, P. Pisanu, M. Powell, A. Schmidt, C. Spain, and K. Williams. 2009. Genetic the domestication of trees. Tree crops are borne out of Resource and Domestication of Macadamia. Horticultural changes in the form and function of wild tree species after Reviews 35:1–125. their adaptation to human-controlled environments. Tree crop diversity develops as responses to further selections [13] Neal, J.M., C. M. Hardner, and C. L. Gross. 2010. Population demography and fecundity do not decline with habitat intended at better production performance and are usually fragmentation in the rainforest tree Macadamia integrifolia the main planting materials that are cultivated on large areas (Proteaceae). Biological Conservation. 143:2591–2600. (plantations). However, the links between the different levels [14] Quinlan, K and Wilk, P. 2005. Macadamia culture in of tree development as a result of TRD are best expressed by NSW. Primefact 5. www.dpi.nsw.gov.au. phrases such as wild flora of a tree crop (eg. wild flora of gmelina), tree crop diversity (eg. rubber crop diversity), or [15] A.C. Zeven, The semi-wild oil palm and its industry in Africa. the biodiversity of a tree crop (eg. biodiversity of apple). Agricultural Research Report, No. 687,178p. 1967. Unlike in Natural Resource Conservation, wild flora and [16] Corley, R.H.V; Gary, B.S and Ng, S.K.1971a. Productivity of biodiversity as TRD-based concepts are most expressive the oil palm (Elaeis guineensis Jacq.) in Malaysia. when directed at a specified domesticated tree. Experimental Agriculture 7:129-136.

6 Benjamin E. Uchola: A Concept of Wild Flora and Biodiversity Based on Tree Resource Domestication in Agriculture

[17] Corley, R.H.V; Hardon J.J and Tan, G.Y. 1971b. Analysis of [32] Hawkes, J.G., (1958). Significance of wild species and growth of the oil palm (Elaeis guineesis Jacq) I. Estimation of primitive forms for potato breeding. Euphytica, 7:257–270. growth parameters and applicaton in breeding. Euphytica 20: 304-315. [33] Brar D.S., Dalmacio R., Elloran R., Aggarwal R., Angeles R. and Khush G.S. Gene transfer and molecular characterization [18] Zeven, A.C. 1972. The partial and complete domestication of of introgression from wild Oryza species into rice. Khush G.S oil palm (Elaeis guineensis). Economic Botany 26:274– 279. (Ed.) Rice Genetics Ill. Proceedings of the Third International Economic Botany 1972. 26(3):274-279. Rice Genetics Symposium. Manila, Philipines. International Rice Research Institute, Manila-Philippines. 477-486. 1996. [19] J.J Hardon; R.H.V Corley and C.H. Lee. Breeding and selecting the oil palm. In: Abott, A.J and Atkin, R.K (Eds). [34] Hajjar, R. and Hodgkin, T., (2007). The use of wild relatives Improving Vegetatively Propagated Crops. Academic Press in crop improvement: a survey of developments over the last Ltd, London. Pp 63-68. 1987. 20 years. Euphytica, 156: 1–13. [20] Schultes, R.E. 1984. The tree that changed the world in one [35] IUCN-WWF. 1988. Biodiversity: the key role of plants. Joint century. Arnoldia 14(2): 2-16. IUCN-WWF Plants Conservation Programme. 13p +. [21] Schultes, R. E. 1993. The Domestication of the Rubber Tree: [36] Clement C.R., de Cristo-Araújo M., d’Eeckenbrugge G.C., Economic and Sociological Implications. The American Pereira A. A. and Picanço-Rodrigues D. 2010. Origin and Journal of Economics and Sociology, 52 (4): 479-485. domestication of native Amazonian crops. Diversity 2:72-106. doi:10.3390/d2010072. [22] Rubber Board 2002. Rubber clones. http://rubberboard.org. [37] Sulaiman A. and Lim S.C. 1989. Some timber characteristics [23] Ayuk E.T, Duguma B, Franzel, S., Kengue, J., Mollet, M., of Gmelina arborea grown in a plantation in peninsular Tiki-Manga, T., Zenkeng. P. 1999. Uses, management and Malaysia. Journal of Tropical Forest Science. 2(2):135-141. economic potential of Irvingia gabonensis in the humid lowlands of Cameroon. Forest Ecology and Management, [38] National Research Council. 2006. Lost Crops of Africa. 113, 1–9. Volume II: Vegetables. The National Academies Press, Washington, D.C. [24] Leakey, R. R. B., MeseÂn, J. F., Tchoundjeu, Z., Longman, K. A., Dick, J. McP., Newton, A. C., Matin, A., Grace, J., Munro, [39] National Research Council. 2008. Lost Crops of Africa. R. C. and Muthoka, P. N. 1990. Low-technology techniques Volume II1: Fruits. The National Academies Press, for the vegetative propagation of tropical trees. Washington. Commonwealth Forestry Review 69:247-257. [40] Herrera, C. M., Jordano, P., Guitian, J. and Traveset, A. 1988. [25] D.O. Ladipo, J-M. Fondoun, N. Ganga. Domestication of the Annual variability in seed production by woody plants and the bush mango (Irvingia spp.): some exploitable intraspecific masting concept: Reassessment of principles and relationship variations variations in west and central Africa. In: In: FAO to pollination and seed dispersal. American Naturalist Technical Paper. Domestication and Commercialization of 154:576– 594. Non-Timber Tree products for Agroforestry FAO, Rome. 1996. Non-Wood Tree products No. 9. Pp. 193–205. [41] Kelly, D. and Sork, V. L. 2002. Mast seeding in perennial plants: Why, how, where. Annual Review of Ecology and [26] Shiembo, P. N., Newton, A. C. and Leakey, R. R. B. 1996. Systematics 33:427–447. Vegetative propagation of Irvingia gabonensis, a West African fruit tree. Forest Ecology and Management 87: [42] Goldschmidt, E. E. 2013. The evolution of fruit tree 185-192. productivity: A review. Economic Botany, 67(1), 51–62. [27] Leakey, R. R. B. and Simons, A. J. 1998. The domestication [43] Janick, J. 2005. The origin of fruits, fruit growing and fruit and commercialization of indigenous trees in agroforestry for breeding. Plant Breeding Reviews 25:255–320. the alleviation of poverty. Agroforestry Systems 38:165-176. [44] K.F. Wiersum. Domestication of valuable tree species in [28] Tchoundjeu, Z., Duguma, B., Fondoun, J-M. and Kengue, J. agroforestry systems: evolutionary stages from gathering to 1998. Strategy for the domestication of indigenous fruit trees breeding. In: FAO Technical Paper., Domestication and of West Africa: case of Irvingia gabonensis in southern Commercialization of Non-Timber Tree products for Cameroon. Cameroon Journal of Biology and Biochemical Agroforestry FAO, Rome. 1996. Non-Wood Tree products Sciences 4:21-28. No. 9. Pp. 147–158.

[29] Atangana, A. R., Tchoundjeu, Z., Fondoun, J-M., Asaah, E., [45] Wiersum, K. F. 1997. From natural forests to tree crops, Ndoumbe, M. and Leakey, R. R. B. 2001. Domestication of co–domestication of forests and tree species, an overview. Irvingia gabonensis: I. Phenotypic variation in fruit and Netherlands. Journal of Agricultural Science 45:425–438. kernel traits in two populations from the humid lowlands of Cameroon. Agroforestry Systems. 53:55-64. [46] Zohary, D. and Spiegel-Roy, P. 1975. Beginning of fruit growing in the Old World. Science 187:319–32. [30] Uchola B.E. 2014. A development perspective to Tree Resource Domestication in Agriculture. International Journal [47] C.D. Ataga, and H.A.M. van der Vossen, Elaeis guineensis of Agriculture and Forestry. 4(6):459-464. Jacq. In: van der Vossen, H.A.M. & Mkamilo, G.S. (Editors). Vegetable oils / Oléagineux. [CD-Rom]. PROTA, [31] Uchola B.E. 2015. Agriculture: From a development Wageningen, Netherlands. PROTA 14: 2007. perspective to Plant Resource Domestication. American Journal of Agriculture and Forestry 3(4):127-134. [48] The plant list 2013, www.theplantlist.org.

International Journal of Agriculture and Forestry 2016, 6(1): 1-7 7

[49] Phipps JB, Robertson KR, Smith PG, Rohrer JR 1990. A "A new caffeine-free coffee from Cameroon.". Botanical checklist of the subfamily Maloideae (Rosaceae). Can. J. Bot. Journal of the Linnean Society 158 (1): 67–72. 68, 2209–2269. [54] Anthony F. , Combes M. C., Astorga C., Bertrand B., [50] Germplasm Resources Information Network, United States Graziosi G., Lashermes P. 2002. The origin of cultivated Department of Agriculture. http://www.ars-grin.gov coffee Arabica L. Varieties revealed by AFLP and SSR Retrieved 2015-11-01. markers. Theoretical and Applied Genetics. 104:894–900. [51] Cuatrecasas, J. 1964. Cacao and its allies: A taxonomic [55] de Kok, R. 2012. A revision of the genus Gmelina revision of the genus Theobroma. Contrib. US Natl. Herb. (Lamiaceae). Kew Bulletin 67 (3): 293–329. 35:379- 614. [56] Kumar A. 2007.Growth Performance and Variability in [52] Davis A.P. and Rakotonasolo F. 2008. A taxonomic revision Different Clones of Gmelina arborea (ROXB.) Silvae of the baracoffea alliance: nine remarkable Coffea species Genetica. 56(1): 32-36. from western Madagascar. Botanical Journal of the Linnean Society 158: 355-390. [57] Schultes R.E. A brief taxonomic view of the genus Hevea. Malaysian Rubber Research and Development Board, Kuala [53] Stoffelen, P, Noirot M., Couturon E and Anthony F. (2008). Lumpur. Monograph no. 14, 1990.