Woody Species Conservation, Management, and Its Socioeconomic Importance of Agroforestry Practice in Ethiopia

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Introduction
Te preservation of biodiversity is not at all a luxury. Troughout millennia, a variety of cereals, fruits, vegetables, fne frewood, fne lumber, delectable fodders, domesticated animals, etc., have been culled from biodiversity. Tere are still plenty more in the abundant wild that may be benefcial as food or medications. Furthermore, biodiversity is essential to the health of an ecosystem because it drives the balance necessary for an ecosystem to function properly. Te natural order is a resilient phenomenon that tends to withstand stress and shield nature (humanity) from disturbances, even our own careless deeds [1]. In many developing countries today, the loss of biodiversity as a result of turning primary forests into unsustainable agricultural landscapes has grown. For instance, one of the most noticeable characteristics of the Ethiopian highlands is environmental deterioration, which manifests itself as deforestation, loss of biodiversity, and decreased soil fertility. In the highlands of Ethiopia, some 27 million hectares of land have been considerably degraded, of which 2 million hectares have been so severely damaged that they cannot support cereal production in the future [2]. Te well-known factors of forest clearing, exposing surface soil to erosion, and overgrazing, which typically results in a loss of biodiversity, are the fundamental causes of land degradation in Ethiopia.
It is vitally necessary to save the environment, or to plant the correct tree species in the right location for the right purpose [3], as well as to manage any remaining tree resources, such as trees on farms, other types of agroforestry trees in rangelands, and the like [4]. Tere is sufcient data to conclude that trees and shrubs, when properly maintained, can signifcantly contribute to preserving and enhancing soil fertility and overall productivity in agroecosystems [5]. Tere are countless instances of conventional land management techniques that involve cogrowing trees and livestock on the same plot of land throughout the world. When using these traditional land-management techniques, trees are purposefully kept on or near farmlands to support agriculture and other livelihood systems [6].
Agroforestry is a type of sustainable land use that combines farming or animal husbandry with planting trees to start an agroecological succession [7]. Agroforestry is a tool for diversifying and boosting productivity and is heavily pushed globally due to its economic, social, and environmental benefts [8,9]. Growing trees alongside annual crops also aids farmers in overcoming agricultural failure brought on by land degradation and climate change [10,11]. Despite all these benefts and uses, many local communities are seeing a sharp decline in the number of woody species on agriculture. Tis is because farmers' needs have not received enough scientifc attention. Tis research evaluates pertinent management approaches and focuses on the socioeconomic signifcance of Ethiopia's agroforestry practice for the protection of woody species.

Methods
For these reviews, systematic methods were used. Online search diferent published and local source of document that relate with the topic identifed between September 2021 and April 2022 used as source of information. Te author use web-based search for seeking of published research material from various regions of Ethiopia which was conducted on woody species management and its socioeconomics. By using the Google search engine, regional university websites, and international scientifc databases, the author specifcally included documents published 2000-present (primarily from 2015) from the southern, northern, eastern, southwestern, northwestern, mid-Rift Valley, and central highlands. A total of 89 published papers were chosen for this review based on the predetermined inclusion criteria; documents that lacked details regarding the study topics and aims were excluded. Te Natural Database for Africa (NDA), version 2.0, was used to identify tree species native to Ethiopia and their scientifc names [12]. Te review is to fulfll the information gap on woody species diversity management and socioeconomic importance.

Literature Review
3.1. Global Agroforestry Cover. Agroforestry, a traditional land-use practice found throughout the world, focuses on maximizing the benefts of biological interaction by intentionally linking trees, crops, and animals under agroecological systems [13]. According to a World Agroforestry Centre (ICRAF) working paper [14], agroforestry covers around one billion hectares or 43% of agricultural lands globally and involves more than 900 million people. In Asia, agroforestry is also prevalent and has played a critical role in local livelihoods since ancient times [15]. If defned as being more than 10% tree cover on agricultural land [14], then agroforestry covers 77.8% of all agricultural land in Southeast Asia, 50.5% in East Asia, 27.0% in South Asia, and 23.6% in Northern and Central Asia. Tirty-fve years ago, widespread concerns over land degradation and the lack of efective solutions in Africa led to the hope that international agroforestry research could contribute new solutions [16]. Despite local success stories [17], many parts of Africa have continued to experience food insecurity, declines in per capita farm income, and land and soil degradation, aggravated by biodiversity loss [18]. Troughout Africa, agroforestry systems come in a wide variety of shapes and forms. Many of these systems have little more in common than the coincidence of woody perennials with agricultural crops and/or livestock. Basic data collection by the FAO does not clearly stress the segregation between forests and agricultural landscapes with trees. Tis can be seen as an historical anomaly rather than a refection of incompatibility between annual and perennial plants within a farming system [16].

Agroforestry Practice and Human
Well-Being. AFS have the potential to serve in the restoration and rehabilitation of degraded ecosystems and could help to reinstate ecosystem services [19]. Food security, land tenure security, enhanced farm-based incomes, management of terrestrial and soil biodiversity, carbon sinks, hydrological functions, wildlife corridors, reduced soil erosion, biodiversity conservation, microclimate improvement, increased nutrient retention via root capture and cycling, etc., are some of the diverse benefts of AFS reported from the region [20]. Tere is considerable evidence that AFS support sustainable production, providing subsidiary household provisions with diversifed products, conservation of natural resources, aquifer recharge, etc. [21]. Agroforestry support is a sustainable intensifcation within a land use archetype that are based more on ecology than on chemistry and climate science [22]. Article 2 of the Paris Agreement proposed to strengthen global eforts to reduce climate impacts with reference to sustainable development and poverty alleviation. Hence, it is vital to recognize and acknowledge the role of agroforestry and to mainstream it at country level to address global climate targets. Leveraging the mitigation potential of land use sectors is crucial, in meeting emission reduction targets [23].

Agroforestry Practice in Ethiopia.
Parkland agroforestry (scattered trees on croplands), homegardens, hedge-row intercropping, riparian zone vegetation, enclosures, and natural regeneration of species in forests and pasture are the most prominent agroforestry practice activities in Ethiopia. Some examples of parklands agroforestry in Ethiopia include maize intercropping with Cordia africana in Bako and western Ethiopia, as well as Faidherbia albida-based agroforestry in the Hararghe Highlands and Bushoftu area [24,25]. In several places of southern and southwestern Ethiopia, multistorey homegardens are also prevalent. Te structural complexity of homegardens varies, ranging from complex and diversifed forms comprising several species, such as those found in Sidama, to simpler forms with one or two crop/tree mixes, such as those seen in Gurage [26][27][28][29][30]. As living fences, a variety of multipurpose tree and shrub species were utilized. Te majority of farmers' crops are grown in both homegardens and felds. Traditional agroforestry practices are compared to the homegarden complex [31].
In several areas of Ethiopia, hedgerow intercropping is used. In the hararghe highlands of eastern Ethiopia, one such example is the intercropping of sorghum/maize and chat (Catha edulis) hedgerows. Riparian vegetation can be found around rivers, streams, and other bodies of water. Tere are several perennial and intermittent rivers in Ethiopia, and some of these rivers and streams support huge populations of species with lush vegetation. Acacia tortilis, Acacia nilotica, Balanites aegyptiaca, Tamarindus indica, Tamarix spp., and Ziziphus spp. are examples of riparian zone vegetation in Ethiopia, which can be found along the Awash and Eliwoha waterways. During the dry season, riparian vegetation provides valuable feed for animals, as well as food, medicine, fre wood, farm implements, and timber for construction for utensils for humans.
It is also home to many plants and animals. Another agroforestry practice is enclosures and natural regeneration of species [32]. Te establishment of enclosures is a realistic and cheap approach to the improvement of pastoral and degraded woodlands. Te successful enclosure practices in Ethiopia include the enclosures of large inhospitable parts of Tigray Terrains, and enclosures established by Self Help International (SHI), Ireland, in the dry lands of the rift valley of southern Showa [33]. Te enclosures are managed for the advantage of local people, with cut-and-carry grass production, restricted harvesting of wood products and other minor forest products, and making them agroforestry practices in kinds of trees and shrubs [34]. Furthermore, household gardens in central, eastern, western, and southern Ethiopia have roughly 162 plant species, with 78 percent of them being food crops [35]. Te homegarden is a site where many indigenous taxa's crops have evolved and diversifed. Also seen in homegardens are crops introduced during the early stages of agricultural breakthroughs, as well as species planted at the experimental level. Homegarden has a lot of promise in Ethiopia, according to the fndings [36].
In agricultural lands, live fences, windbreaks, and isolated trees all help to conserve biodiversity. Floristic variety can be high in these agroforestry practices, and a large number of animal species may use these environments for eating, sheltering, and breeding in some circumstances. Live fences, windbreaks, and lone trees form natural habitat networks that can improve landscape connectivity and help conserve biodiversity at diferent scales. Tey do not, however, constitute whole biological units and cannot supply the same range of habitats or services as the original ecosystem. As a result, species in them are likely to seek refuge on live fences, windbreaks, and lone trees present in neighboring remnant habitats, at least to some extent [37].

Agroforestry for Biodiversity Conservation
As an in situ conservation strategy, agroforestry activities boost biodiversity on farmland. Te importance of agroforestry in conservation varies depending on the type and management of the crop (Table 1) [38].

Woody Species Conservation in Agroforestry
Managing multipurpose trees such as Cordia africana, Millettia ferruginea, Albizia gummifera, Croton macrostachyus, and Erythrina brucei as a major element of agricultural landscape are extensively accepted by Ethiopian farmers [39] (Table 2). Cordia africana, Ekebergia capensis, Olea capensis, Erythrina brucei, Millettia ferruginea, Citrus medica, and Annona senegalensis are also important in the south of the country, particularly in homegardens where they are managed using farmers' local knowledge [40]. Croton macrostachyus, Cordia africana, Vernonia amygdalina, and Erythrina abyssinica are other popular indigenous multipurpose tree species found in Ethiopia's west Hararge zone [41] (Table 2). In the southwestern areas of Ethiopia, Millettia ferruginea and Cordia africana are the most chosen woody plants for retention and planting in homegardens [42]. In contrast, in Tigray, the fruit tree Cordia africana is an indigenous fruit trees and fodder trees Faidherbia albida, Acacia nilotica, Acacia seyal, and Grewia bicolour are important in agroforestry practices [43] (Table 2). In addition to these, Albizia gummifera, Cordia africana, Croton macrostachyus, and Vernonia amygdalina are popular in smallholder cofee farms in Ethiopia for cofee shade [44].

Agroforestry Strata
Farmers intentionally maintained annual and perennial herbs, as well as woody species of several plant groups, to meet their subsistence and economic demands [48]. According to the fndings, 159 species were found in the homegarden, with 70.44 percent of those deemed helpful to the community. In agricultural environments, agroforestry is also an essential sanctuary for native and threatened species. For example, 85 percent of the 50 woody species identifed in traditional agroforestry in southeastern Ethiopia by [49] were sourced natively. As reported in various agroforestry practices in Ethiopia, agroforestry conserves endangered and national priority plant species such as Cordia Africana, Vicus vast, and Olea African (Figure 1). For example, cofee-based agroforestry in the southern region of Ethiopia [50] reported more than 59 percent native woody species, including 22 species of conservation signifcance out of 155 species.

Socioeconomic Benefit of Wood Species
Agroforestry ofers a signifcant potential for the protection of socioeconomically and environmentally important indigenous tree species utilized for a variety of services such as fodder, food, medicine, fuel wood, farm implements, and utensil wood [52]. Te majority of the inhabitants in the country rely on rain-fed agriculture, which includes agroforestry practices. Nontimber forest products and timber forest products such as fruit, frewood, honey, spices, lumber, pole, and charcoal are used to determine tree product income [53,54]. Even if the quantity of revenue obtained varies from place to place, that extra income is playing a signifcant role in improving farmers' livelihoods, particularly when crop production hazards arise as a result of climate change [55]. Furthermore, in Kafa and Wolaita Zone 800 to 1500 ETB in [56], and 1683 ETB where annual average income comes from homegarden agroforestry practice in Jimma Zone, southwest Ethiopia [55], the farmer earns 47 percent of his income from nontimber forest products. Various factors, however, determine the amount of money produced from tree products. According to some research, the age of the farmer, household wealth status, land   [57,58]. According to [59], the World Health Organization estimates that at least 80% of the inhabitants of most developing nations rely on traditional medicine for primary health care. Various works of literature [60][61][62] demonstrate the benefts of trees or shrubs for traditional medicine in various locations of Ethiopia. Croton macrostachyus, for example, is used to treat malaria, diarrhea, epilepsy, ringworm, and skin rush; Cordia africana is used to treat evil eyes; Euphorbia candelabrum is used to treat ringworm; Millettia ferruginea is used to treat fungal infection; and Vernonia amygdalina is used to treat diarrhea and stomach ache. Tus, in the Boosat district of central eastern Ethiopia [61], roughly 52 medicinal plant species were found; while in the Jimma zone of southwestern Ethiopia [62], 39 medicinal plants used to treat various diseases were identifed. Tree-based agroforestry land use practice provides a shade service. People are assembled under a shade tree for social issues and religious purpose (e.g., playing) in southwestern Ethiopia [63].

Management of Woody Species Diversity in Agroforestry
It is commonly accepted that agricultural conditions have a signifcant impact on how trees integrated into agricultural felds are maintained [64]. Trees have a unique role in a variety of management systems, whether they are predominantly subsistence or free enterprise operations and are consequently integrated into agricultural felds to varying degrees. Te main factor afecting the employment and management of trees is the management system [65]. Little or nothing is understood about current ground management practices, farmers' perceptions of the function of ground trees, and so the varied yields of ground trees in meeting their needs and their production, in contrast to what is celebrated regarding the plant and placental parts of agroforestry practices and practices unit celebrated goals and regarding the challenges farmers face that limit their capability to develop piece of ground tree resources in their farming systems. Te selection and management of the impacted species has an impact on the system's efectiveness as woody species management has the potential to be a tool for dominant agriculture competition in agricultural felds. Trough the use of heading, topping, and pruning techniques that should be used in the early summer or at the height of the season, it is important to manage the trees to ensure the sustained production of mulch or leaf feed and mild shade [56]. In order to try to improve coverage in a certain area, understanding tree care methods in a given location (forest), (woodland), (jungle), (tree-plant), and on private farm felds is absolutely essential. To do this, it is crucial to know management practices within the context of social unit keep ways and farmers' views on the values of trees [66].
Agroforestry piece of ground management procedures have a number of options, but the most common ones are pruning, facet branch cutting [67], pruning [68], watering, plant protection and fertilization [69], and root cutting [70]. By pruning, the mother trees should be able to grow taller without unduly shadowing the plants below [71]. Pollarding aids in reducing excessive shading. Although it is not a typical procedure, thinning was done in woody species when the canopy of two or more adjoining trees started to close and produce obtrusive shadows. To lessen the impact on crops, increase animal feed, and gather wood for fencing and frewood, agroforestry species in parklands that are still on arable ground are pruned [72]. Overall, maximizing the system's benefts is the main justifcation for managing woody species. Otherwise, woody species might impair agricultural productivity by competing with plants for resources like light, water, and nutrients, especially in areas International Journal of Forestry Research with high tree density and size [73,74]. Woody species must be managed in agroforestry in many regions of the nation for a variety of reasons, including home consumption and boosting household fnances. Te primary factor for choosing a tree and creating an efective management plan in agroforestry is the farmer's preference for particular tree species.

Summary
Ethiopia's oldest traditional practice is the agroforestry practice, which is currently viewed as a cutting-edge way to utilize land. Indigenous multipurpose agroforestry tree species are rapidly being incorporated into agroforestry practices in Ethiopia due to their signifcance in producing economic items for smallholder farmers while also serving crucial ecological roles. Te most signifcant indigenous multifunctional tree species in Ethiopia are Cordia africana, Millettia ferruginea, Ficus vasta, Albizia gummifera, Croton macrostachyus, Faidherbia albida, Vernonia amygdalina, Acacia nilotica, and Erythrina brucei. Homegardens, farmland, cofee plantations, and woodlots are a few examples of agroforestry approaches that farmers are more informed about. It makes a substantial contribution to the variety of products grown on a single plot of land. Terefore, from the perspective of farmers, it is better than monoculture. In addition, it ofers environmental services, socioeconomic advantages, and tree products (such as timber, frewood, food, and building materials) (reduce soil erosion, increase soil moisture and fertility, cofee shade, and keep microclimate balance). Once they are established as mature trees, numerous management techniques, including as pruning, pollarding, coppicing, thinning, and lopping, are employed to ensure the compatibility of trees with various crops in agroforestry practices.

Data Availability
Te data used to support the study are available from the corresponding author upon request.

Conflicts of Interest
Te author declares that there are no conficts of interest.