On the one hand, parklands have been referred to as a vegetation type. In Cole's analysis, savanna parklands occur in Australia and in Africa, mostly in Central and Southern Africa, but not in South America, with the exception of the region of the High Pantanal.
Forests with a very open canopy and a history of frequent fire in Western Canada and northwestern United States are also called parklands British Columbia Ministry of Forests, In parklands the composition and density of the woody vegetation is altered in order to facilitate its use. Most often parklands are not the product of a single agricultural season, but reflect a slow process of species selection, density management, and tree growth over one or several decades.
Parklands, in the strict sense of the word, are specific to permanently cultivated fields or fields where fallow duration is shorter than necessary for the regeneration of a second-growth forest Seignobos, ; Raison, Parkland trees stand out as an important component of the spatial structure of the landscape Sautter, , cited in Raison, ; Seignobos, Parkland attributes include a regular distribution of relatively even-aged trees or shrubs and a low tree density so that tree cover is never continuous.
Their name derives from their resemblance to urban or rural recreational parks with large scattered trees in expanses of grass. Examples of parklands are more common in the semi-arid or subhumid tropics, and particularly in West Africa which will be the main subject of this report as it is of most of the literature reviewed in it.
Parklands are not, however, limited to the Sahel and Sudan zones of Africa. While they may not generally be called parklands, systems with scattered trees in fields with similar appearance and purpose are also widespread in Zimbabwe Campbell et al.
Several systems in Asia, Oceania, and Latin America would qualify as agroforestry parklands by definition. Information on practices in these areas is more limited, however Baumer, ; Raison, In India, the well-known Prosopis cineraria is commonly protected in fields planted with millet and legumes, and occurs on fallows and grazing lands in the semi-arid zone of Rajasthan Mann and Saxena, Farmers value its high ecological combining ability and suitability for pruning and fodder as well as its socio-cultural significance.
Other species found in these systems include Ziziphus nummularia, Acacia nilotica var. In the state of Tamil Nadu, several tens of multipurpose tree species are naturally regenerated or planted on farmlands Jambulingam and Fernandes, To cite only a few, Borassus flabellifer is grown with cereals and pulses, A.
Parkland or related systems also exist in temperate regions. Dehesa Spanish or montado Portuguese systems are centuries old, mainly silvipastoral systems in southwestern Spain and southeastern Portugal where holm oak Quercus rotundifolia , syn. Quercus ilex and cork oak Quercus suber are scattered in pastures or cereal oats, barley, wheat fields Joffre et al. Trees are sometimes seeded and systematically pruned for better fruit and wood production.
They provide highly nutritious acorns for fodder and timber, charcoal, tannin, cork Q.
With a density of 20 to 40 trees per hectare, the tree cover may be 5 to 20 percent. This system extends over an estimated 5 million ha in Spain and more than ha in Portugal.
Similar systems with the same or different species olive, carob, etc. Moreover, the Acacia caven silvipastoral system is widespread in the semi-arid and subhumid Mediterranean climate zone of Chile, covering 1. Walnut plantations in the Touraine and Berry regions of France may be included in the parkland family Raison, The oak savannas of the eastern United States New York State may also be a case of parklands with a silvipastoral focus.
These trees usually have a positive ecological role soil fertility or wind reduction and a strong economic significance. Examples of such vegetation types include cattle-raising areas in Brazil, such as the open forests of the Sao Paulo and central-east regions, highly forested grasslands of southeastern Queensland in Australia, Miscanthus grasslands under forest relics in Indonesia, and the Daniellia oliveri open dry forests of East Africa.
Sometimes, however, it is used to describe lands in parks, which bear no relation to the agroforestry parklands considered in this report. It was chosen for this study because it emphasizes the multiple forms and purposes of these systems, and thus includes various schools of thought. As defined by Bonkoungou et al.
Table 1. As mentioned in the introduction, agroforestry is an ancient practice but a relatively new science. In order to assess the significance of the parkland system, it is important to characterize it physically, determine its zone of occurrence, and identify and describe existing parkland types.
The next section sets the geographical stage, beginning with a review of the main historical studies of parklands. This is followed by a presentation of the main modes of investigation and existing data, on the basis of which a tentative picture of the wide spatial extension of agroforestry parklands and the distribution and density of prominent parkland species see Table 1.
Being linked to human activities, parklands occur in various latitudes and are not confined to specific agroecological zones. We are indebted to the early explorers for the first references to African parklands Pullan, On his travels to Hausaland in Nigeria, Clapperton described well-maintained Vitellaria , Parkia and Tamarindus trees located in agricultural lands.
The early reports also focused on how products from these species were prepared for various human and animal uses. In the late s, scientific and commercial interest in savanna and parkland species grew. Plant collections were undertaken and tropical African floras prepared, while tree products were sampled and investigated for commercial use in colonial countries of the North.
Their origin in people's agricultural activities has given parklands a peculiar scientific status amongst plant communities. Pullan noted that plant ecologists have generally neglected the study of vegetation in cultivated zones. Thus the degree to which parklands were recognized as distinctive vegetation types, or had their importance in successional stages of vegetation regrowth acknowledged, was variable among early plant scientists.
Recognizing the widespread occurrence of Faidherbia albida 1 in the vegetation of southwestern Senegal, Trochain characterized it as a climax association or, more specifically, a stable plant community of anthropogenic origin, which replaces the climax vegetation, including various forms of open forest found in the Sudan zone, on silica and clay-rich soils , developed after the species was introduced by nomadic people and their livestock.
Roberty established distribution maps of parkland types in western Senegal Fig.
The species was first named Acacia albida by Delille in Baillon observed in that its staminal characteristics departed from the pattern usually found in the Acaciae tribe. This distinction which relates it more closely to the Ingeae tribe, as well as variations in phenology, leaf, cotyledon, pollen and wood anatomy reviewed in CTFT , led Chevalier in to propose a new monospecific genus Faidherbia located between the Acaciae and the Ingeae tribes.
This name has been adopted by many authors since, but not unanimously. In order to emphasize its divergence from members of the Acacia genus, the use of Faidherbia albida has been recommended until its taxonomic position is clearly established CTFT, Faidherbia albida is therefore used in this report. Lely recognized a parkland type dominated by Parkia, Vitellaria, Afzelia, Tamarindus and Acacia species in Nigeria.
Vegetation maps for northern Nigeria Clayton, , took into account Keay's contribution to the recognition of local parkland types.
Three types of parklands, dominated by F. In the northeastern part of the country, Leeuw and Tuley mapped F. In northern Ghana, Taylor identified Vitellaria-Parkia-Tamarindus and Adansonia-Tamarindus parkland associations, with small parkland patches of F.
Irvine also referred to mature F.
Wills also referred to farmed parklands in this area. Early citations for Niger include Dundas and Fairburn , yet the relationship of the described vegetation to parklands was not clearly made Pullan, Parkland communities dominated by Vitellaria, Parkia, F. Parklands did not become a major object of study until fairly recently, perhaps because their definition did not fit squarely into any single discipline.
Similarly, in the early days there were only isolated scientific investigations of parklands by agronomists or foresters, the latter having focused on natural forests and industrial or village plantations. It was only the emergence of agroforestry as a scientific discipline in the s that finally established the study of parklands in their own right.
The Macro- and Micro-Diagnostic and Design exercises conducted in the first half of the s advanced the identification, description and general analysis of the various agroforestry land-use systems on a national basis see for instance ICRAF, Parklands constitute the predominant agroforestry system in semi-arid West Africa. Parklands occupy a vast land area, representing a large part of the agricultural landscape under subsistence farming in the tropics and constituting the predominant agroforestry system in semi-arid West Africa Nair, ; Bonkoungou et al.
In Burkina Faso, parklands are found throughout settled zones where agriculture is practised, i. The parkland system is also recognized as the most common production system in Katsina State in northern Nigeria Otegbeye and Olukosi, A discontinuous cover of scattered trees in crop fields is traditional in northern Ghana Rudat et al.
These references highlight the local or national significance of parklands but also serve to illustrate the lack of a coordinated quantitative assessment of this land-use system at the regional level. Nowadays, agroforestry parklands are most often characterized by the dominance of one or a few species.
Species composition is generally more diverse and variable, however, in areas located farther away from villages and only occasionally cultivated. In parklands, one or a few dominant species may prevail on a local scale or across large land areas with substantial variations in relative abundance, frequency and overall species composition.
Thus, parklands are often described by their dominant species Pullan, ; Weber and Hoskins, Otegbeye and Olukosi also report that parklands with a species mix without specific dominance are the most common types in Katsina State, northern Nigeria. Whether or not there is a dominant species, parklands usually host a wide variety of tree and shrub species.
For instance, 22 and 39 species were recorded in cultivated fields in two sites around Kano, northern Nigeria Cline-Cole et al. Species diversity increases when fallows are included.
There is very little quantitative information regarding the relative representation of major species throughout the parkland range which could help to prioritize conservation and development efforts in a rigorous way.
Faiderbia albida parklands have received considerable attention because of the generally observed positive effects of the tree on soil fertility and crop production. It is likely, however, that V.
Agroforestry parklands in sub-saharan africa pdf latitude
Breman and Kessler indicate that V. There is a definite need for more quantitative data on the main parkland species at the regional level, including their distribution, stocking rates and dynamics, to improve the formulation of parkland research and development activities.
Some methods for assessing parkland resources are reviewed in Box 1. The rest of this section reviews recent information on individual parkland species throughout their zone of occurrence. Species are reviewed in order of their importance in the literature. Where parkland studies included information on tree densities, these are listed in Tables 1. Other species mentioned may seem less widespread but are equally important to farmers.
Reports of particular species in agroforestry parklands are generally localized, but their wider distribution is by no means limited to these few geographical references.
Faidherbia albida parklands occur throughout the Sahel and Sudan zones of West Africa, as well as in eastern and southern Africa where it is strongly associated with alluvial soils along perennial or seasonal watercourses. In West Africa, F. The African distribution of the species and the two geographical races identified by Brenan are shown in Figure 1.
Because of its unusual characteristic of reverse foliation i.