This particular study was focused on providing scientific evidence for ethnobotanical assessment, identification and prioritization of high biomass energy producing plant species with short-rotation period at Boset District. This, in turn, evaluates their energy values at laboratory so as to solve the high demand of fuelwood problem and contributes to the sustainable management and use of resources through the application of silviculture.
Socio-demographic characteristics of informants
During ethnobotanical study, data were collected from three selected potential firewood and charcoal producing Kebeles at Boset District namely Borchota, Geri and Tedecha that consisting of 7 Kebele villages (Gots). These were Addis Ketema, Hadhecha, Hadhecha the Second, Harabona, Sogido, Bekebishan and Tedecha the Second. A total of 96 informants comprising 59 men and 37 women between the ages of 18 and 81 were sampled and participated (Table 1). Most of the informants (99%) were categorized under the medium wealth class, while the remaining were grouped under low income informants.
Out of sampled informants, the youth and adults comprised 90.6% (Table 2). Out of this, 86.4% contributed by men, while 97.3% shared by women. This indicated that most of the informants were under productive age and hence actively involved in firewood collection and/or charcoal making as well as management and utilization practices. Selected informants in the studied District indicated that 67.7% of the informants were engaged on this activity for more than 10 years, while 19.8% of them involved up to 10 years. At the same time, above 78% of the informants were married, while the remaining were single. The average family size of the sampled respondents was 4.63 children, with minimum and maximum family size of 0 and 12, respectively. Of these, over 43% of the informants were illiterate in their educational background, while 19.8% of them attended elementary school (Grade 1-6). This was followed by 17.7% of them, who attended secondary school (Grade 7-12) education or who completed adult education, each. On the other hand, 72.9% of the informants were lived for more than 20 years in the areas and most of them were familiar to forest and forest resources. Overall, the study result indicated that the socio-demographic factors were considerably contributed to for firewood collection and/or charcoal making at Boset District.
Socio-economic characteristics of the informants
Ethnobotanical study conducted in three Kebeles at Boset District revealed that informants diversify their income from different sources besides to provide their household consumption. These mainly included income from agricultural products; animal husbandry as well as income from firewood collection and charcoal production (Table 3). The study result indicated that among the studied Kebeles, Borchota Kebele had the highest annual cash income (35.89%) from different sources, followed by Geri Kebele, which accounted for 33.08%. The annual average informants’ cash income per household and its percentage contribution earned from different sectors is listed down in Table 3 as follows.
Cash income from agricultural products and livestock raising
Data analysis showed that nearly 99% of the informants were farmers and they generate income from different agricultural crops. In the same way, 12.5% of the informants also engaged on livestock husbandry side by side with farming activity. Therefore, most of the informants generated money by selling their agricultural products and livestock in addition to their household subsistence. They earned at least an average annual income of 275 and 142.71 Birr per household from agricultural crops and livestock sale, respectively. These agricultural products were agricultural crops (e.g. maize, teff (Eragrostis tef), sorghum, beans, barley, etc.) and vegetables and fruits (e.g. potato, sugar beet, carrot, onion, etc.). Source of income from livestock sale also included fattened ox, sheep, goat, cow, hen, horse, donkey and mule. Of the total informants, majority of them (64.6%) owned 1-13 ha of land for cultivation of different agricultural crops and raising livestock. In contrast, the remaining informants possessed less than 1 ha of land, while others didn’t have their own land and cultivate crops by renting the land (contract). However, the area was frequently affected by recurrent drought and characterized by erratic rainfall. For instance, some of the informants 7.3% showed that for the last three or four years cultivated crops were failed due to frequent drought occurrence and shortage of rain. As a result, they often faced a problem to subsidize their household income and live with Government funded and other supporting aid. Likewise, a similar trend was investigated in the study area by Moroda et al. [26], who found that 26.5% of respondents were most food insecure and thereby they subsidize their food by borrowing (9.7%) or through aid (17.9%). Consequently, they look for other alternative income generating activities including firewood collection and/or charcoal production from the surrounding woodland vegetation. Due this reason, source of income generated from cultivation of agricultural crops was the second in Borchota and Tedecha Kebeles. Income source from livestock raising also contributed almost the least across all Kebeles.
Income diversification from firewood collection and charcoal production
Analysis of field data indicated that informants in the study area engaged on various income generating activities hand in hand with farming activities. These were mainly on forest and forest products such as timber harvesting, firewood collection and/or charcoal making, beehive hanging and honey collection, harvesting medicinal plants for traditional remedies as well as collecting gum and resin products. However, source of income generated from charcoal making ranked first both in Borchota Kebele (33.35%) and Tedecha Kebele (29.17%). On the other hand, collection of firewood was the list income generating activity in Tedecha Kebele (29.17%), followed by Borchota Kebele (21.39%). Similarly, the same trend was observed for informants’ preference to charcoal production (2nd ranked) rather than firewood collection (least ranked) in Geri Kebele. This finding most probably suggests that informants in the studied Kebeles were mainly depending on charcoal production instead of firewood collection since they generate better income source. Furthermore, 97.9% of the informants in the studied Kebeles engaged on firewood collection and/or charcoal making. This figure showed that informants were directly relied on firewood and/or charcoal for cooking, heating and lighting purposes using traditional open fire or low efficiency traditional cooking stoves. This finding is in agreement with other previous study by Feyisa et al. [27], who reported that all of the sampled informants at Gechi District rely on fuelwood for cooking and lighting. Consequently, these authors further reported that 6529.9 tons/ha fuelwood on average is consumed by the community in the study area. Likewise, electric access in the rural setting is around 5% so that fuelwood has a significant contribution to rural population [2]. However, 54.2% of them used other sources of energy such as electric, fossil fuel, solar, crop and animal residues as main or alternative energy sources. As a result, income generated from these sources had significantly contributed to rural households to subsidize their livelihoods. Table 4 showed that 88.5% of the informants at Boset District involved in firewood collection, while 90% of them practiced charcoal making. Of this, more than half of the informants (55.2%) were men, who engaged by providing firewood and charcoal to the market. However, most of the time women and children spend most of their time to collect firewood from long distances and less accessible areas. But in this particular study higher contribution of men than women probably suggests the task requires more labour intensive under harsh environmental conditions. On the other hand, men participated in charcoal making since it requires a lot of traditional processes and labor intensive as well. Among the sampled Kebeles, more firewood collection and charcoal making was contributed in Geri and Tedecha Kebeles.
The average annual income from firewood collection and/or charcoal making, in turn, indicated that a total of 1,533.60 Ethiopian Birr per household was earned by providing to market areas including their village, along the Addis Ababa asphalt highway or Olenchit town (Table 5). Of these, 36.7% of firewood collection and 46.9% of charcoal making was contributed by women households. In line with this, the highest collection of firewood (41.5%) as well as charcoal production (41.2%) was supplied to the market to satisfied fuelwood demand by Borchota Kebele. On the contrary, the least annual income from both sources (26.7% of firewood collection and 27.7% of charcoal production) was generated by Geri Kebele.
Informants attitude and perception towards firewood collection and charcoal production at Boset District
The study result showed that local communities depend on various forest and forest products from the surrounding woodland vegetation. These were firewood collection and charcoal making; timber harvesting; beehive hanging and honey collection; traditional medicinal plants harvesting; harvesting of bamboo, wild fruits as well as gum and resin products. Among these, almost all of the informants (97.9%) engaged on firewood collection and/or charcoal making as compared to other forest and forest products. Findings from the study area corroborate this investigation and showed that charcoal sale is the main source of income for 83% of respondents [28]. With this, majority of the informants (72.9%) engaged on this activity for both household subsistence and to diversify their source of income. In contrast, 23.9% of them were required it only for household subsistence. Furthermore, collection of firewood contributed 55.3% of the average annual source of income at Boset District (Table 4). Similarly, an earlier study conducted in and around the semi-arid Awash National Park by Bahru et al. [20] revealed that firewood was the major source of energy, which accounted for 73% and an income generating activity in the livelihoods of many rural dwellers. In turn, about 30% of charcoal making is accountable for the forest degradation [28]. Hence, the majority of the local communities use fuelwood to cook their food, heat and light up their houses [20]. At the same time, contribution of charcoal production (86.9%) (Table 3) attributed to most probably due to higher potential of Acacia species in the studied Kebeles. A study conducted by Balemie et al. [29] in Fentalle area, in turn, found out that firewood collection and charcoal making contributed 17.9 and 18.5%, respectively. According to Zerihun and Mesfin [30], the Rift Valley vegetation is an important source of charcoal making for the nearby towns and Addis Ababa. As a whole, a study from 2015 reported that wood is harvested for the supply of 115 million m3 firewood and 5.4 million m3 charcoal [2]. In addition, traditional and low efficiency cooking stoves and open cooking fire in the rural areas further contributes for the high demand of fuelwood species and thereby depletion of forest resources. This is because open cooking fire and poorly designed cooking stoves may have 3-5% lower energy efficiency than high efficiency improved cooking stoves [9]. Therefore, a high efficiency improved cooking stoves instead of traditional low efficiency stoves and open cooking fire can save the loss of energy from fuelwood [9].
With this understanding, most of the documented fuelwood species were indigenous or native (76%) to the area, while the remaining species were introduced or exotic to the study area. More than 33% of the informants described that they used introduced species for fuelwood consumption, while 7.3% of them did not use it. Analyzed data further showed that 27% of the informants pointed out that they used these species so as to control their invasiveness and hence their spread to the area. Again, their easier availability, their importance for source of fuelwood species and shortage of preferred fuelwood species in the study area also made informants to use introduced species. According to various sources and informants suggestion, these exotic species were introduced to the study area due to various reasons at various time. For instance, Prosopis juliflora introduced to arid and semi-arid areas to rehabilitate the dryland areas. Parthenium hysterophorus also introduced through food aid with agricultural crops. Other introduced species, which are used for fuelwood species also comprised Azadirachta indica, Calotropis procera, Cryptostegia grandiflora, Lantana camara and Senna occidentalis. Out of these, P. juliflora is served as a good quality charcoal producing species. In the same way, A. indica and C. grandiflora often used as charcoal producing species, while the rest introduced specis were collected and used as firewood especially during dry season, when fuelwood was scarce. On the other hand, above 6% of the informants were further relied on other sources such as timber harvesting; honey collection; traditional medicinal plants harvesting as well as collecting gum and resin. During data collection, best quality parameters commonly practiced by the local communities to identify and prioritize species for firewood collection and/or charcoal making were listed. These included superior combustion characteristics (giving good energy, heat and light); higher amount of energy, heat and light produced per dry wood; lower pollution problems (little or no smoke or soot and ash contents); formation of little/no spark during heating and lighting; easier to cut and split the wood; production of high energy with longer time as well as heavy wood's dry weight per volume (density) with minimum moisture content; fuelwood species are easily accessible to the area and hence easier to collect firewood and make charcoal. This finding was corroborate with earlier study conducted by Bahru et al. [20], who indicated that selection of firewood mainly relies on availability, burning quality, little/no smoke/soot production and moisture content. Some of these fuelwood characteristics also reported by FAO [9-10] and ILO [11]. Overall, a total of 25 firewood and/or charcoal species were identified and listed at Boset District during this field study (Appendix 1).
Management and sustainable utilization of firewood and/or charcoal species at Boset District
Informants’ interview clearly showed that majority of them (83%) indicated that local communities widely collect firewood and produce charcoal from natural forests around the study area. Consequently, all informants (96 of them) agreed that the most preferred and selected firewood and/or charcoal species in the study area were declining in terms of their distribution and population size from time to time due to various anthropogenic factors. Of these, 78% of the informants mentioned two reasons as the main cause for species decline at Boset District. These were first local communities use these species as the only energy source and the demand for firewood and/or charcoal use becomes increased. Second, local communities commonly practiced the traditional open fire or poorly designed traditional cooking stoves for cooking, heating and lighting purposes. This is attributed to the loss of most of the fuelwood species due to the high fuelwood demand in the area. On the other hand, 26% of the informants stated that the population size of firewood and/or charcoal species was declined over time at alarming rate. This is because in the study area overexploitation of fuelwood species particularly Acacia species for charcoal production is commonly practiced. For instance, a study conducted by Bahru et al. [20] around the study area, showed that during both preference ranking and pairwise comparison for charcoal production, all species are classified under Acacia species. By contrast, according to Feyisa et al. [27] report at Gechi District, the most preferred and harvested fuelwood species are Syzygium guineense, Maesa lanceolata and Albizia gummifera. Others also listed that due to the high demand for firewood and/or charcoal, the supply was increased to satisfy the local communities need. However, other study showed that overgrazing/over browsing and deforestation for various uses are the major threats to fuelwood species [20].
Nevertheless, 29.2% of the informants explained that local communities manage and conserve the most preferred and selected firewood and/or charcoal species in the study area using various ways. Some of these were plant seedlings; protect species from cutting; replant the species around homesteads, farmlands and farm boundaries once cut/harvested for the required use; proper collection of the product as well as demarcating and protect/conserve the forest. For instance, some of the local communities satisfy their demand for firewood and/or charcoal products through planting Acacia tortilis, Eucalyptus species, Ziziphus mucronata, Acacia robusta and Azadirachta indica plant species, which is similarly reported for the conservation and management of some of the species by Bahru et al. [20], Balemie et al. [29] and Hunde et al. [31]. According to some informants this species can be harvested within 3-7 years after planted for firewood and/or charcoal use. Collected data as well as researcher observation during data collection indicated that local communities planted these species around homesteads and fences, farmlands and farm boundaries as well as other marginal lands. They selected these areas mainly due to the fact that it enhances soil fertility, soil and water conservation as well as easy for proper management of seedlings. Others also preferred to grow plants around homesteads and fences, farm boundaries and other marginal areas due to shortage of farmland or such tradition was commonly practiced by the local communities. In general, this trend revealed that local communities at Boset District have the traditional system to manage and conserve the natural resources, as also similarly reported by Hunde et al. [31]. Therefore, future plantation establishment and management through the application of suitable silvicultural practices (e.g. spacing, thinning, pruning and coppice management) will be helpful to address the high demand of short-rotation fuelwood species within three or four years.
Identification, prioritization and selection of the most popular firewood and/or charcoal species at Boset District
During ethnobotanical study, simple preference ranking followed by species pairwise comparison indicated that the best three most popular or commonly used firewood and/or charcoal producing species were selected. Accordingly, A. senegal was the most commonly used high biomass energy producing species, which ranked 1st with a total of 267 scores given by key informants (Table 6). This was followed by Acacia tortilis (244) and Acacia robusta, which was selected with 244 and 42 total scores.
Major opportunities and challenges for the plantation development, proper management and sustainable utilisation of firewood and/or charcoal species
In Boset District, there are many promising opportunities for small-scale plantation development, management and sustainable utilisation on most preferred and selected firewood and/or charcoal species. Some of these opportunities listed during informants’ interview were provision of alternative energy and income source; untapped fuelwood resource; fast growing and short-rotation fuel wood species as well as high demand and fair price of products. Of these, about 99% of the informants listed the first three opportunities for small-scale plantation development, proper management and sustainable utilisation on most preferred and selected firewood and/or charcoal species. Despite this fact there are major challenges and constraints for plantation development, management and sustainable utilisation on the most preferred and selected firewood and/or charcoal species in the study area. These major challenges were listed as follows: limited awareness on management and conservation of the resources (training, education, experts support and supervision, etc.); shortage of land to expand the resource; lack of market access and value chains for the product. Others included limited awareness on the use of the resource; shortage of quality and amount of seeds and seedlings; shortage of labor for quality and quantity product; lack of facilities and logistics to produce the product; government limited focus on the resource; high cost of labour and budget for resource management and conservation as well as various anthropogenic (agricultural and investment expansion, charcoal production, overgrazing/browsing, forest fire) and natural factors (drought). Some of the aforementioned threats to fuelwood species further reported by Bahru et al. [20] and Balemie et al. [29], in the semi-arid parts of the Rift Valley area. Of these challenges mentioned above, the first three were chosen by 96.9, 54.2 and 50% of the informants, respectively (Table 7).
Model development on selection of high biomass producing species at Boset District
Major predictor variables were identified and a GLM was developed to predict the correlation of various socio-economic and demographic features of informants’ with the selection of high biomass producing plant species at Boset District. A response variable and 13 major predictor variables were listed in Table 8 and described in detail as follows.
The developed GLM demonstrated that sampled Kebeles and informant’s source of income generated from firewood collection and/or charcoal making was positively and significantly (p<0.001) associated to identification, prioritization and selection of high biomass producing plant species (Table 8 & Fig. 2a&b). In the same way, informants’ main source of livelihoods also significantly (p<0.01) correlated but negatively (Table 8 & Fig. 2c). On the other hand, source of energy, informants’ age and experience were significantly related (p<0.05) although years of experience was negatively correlated (Table 8 & Fig. 2d-f).