Woody Species Composition, Vegetation Structure, and Regeneration Status of Majang Forest Biosphere Reserves in Southwestern Ethiopia

'e aim of this study was to analyse the species composition, structures, and regeneration of woody plant species and the impacts of site factors on the natural regeneration of tree species in four study sites of MFBR. 'e vegetation data were collected systematically in 140 plots with the size of 400m for trees; 25m for seedlings, saplings, shrubs, and lianas; and 1m for herbs. Individual tree and shrub DBH ≥ 5 cm were measured and counted. 'e diameter at breast height (DBH), frequency, basal area, importance value index (IVI), and density were used for vegetation structure description and regeneration. A total of 158 plant species belonging to 115 genera, 56 families, and 80 species (51%) trees, 26 (16%) shrubs, 19 (12%) herbs, and 33 (21%) lianas were identified and recorded. 'e most dominant families were Euphorbiaceae, Rubiaceae, and Moraceae, each represented by 13 species (7.4%), 12 species (6.8%), and 10 species (5.7%), respectively.'e tree densities varied from 1232 to 1478 stem ha, sapling density 176.8 to 708.7 stem ha, and seedling density 534.7 to 1657.5 stem ha, with an average basal area of 63.6m in the study sites.Dracaena afromontanawas the most frequent woody species in theMFBR occurring in 90% followed by Celtis zenkeri (65%) and Pouteria altissima (62.5%). 'e regeneration status of all the woody plant species was categorised as “not regenerate” (9.6%), “poor” (30.7%), “fair” (59.5%), and “good” (10.8%) in all sites. 'e correlation result between natural regeneration and site factors revealed both positive and negative relationships. However, the main threat to the biosphere reserve is illegal logging for different purposes. 'erefore, awareness creation on sustainable forest management, utilisation, conservation of priority species, and livelihood diversification to the local community and encouraging community and private woodlot plantation in the transitional zone of biosphere reserves are recommended.


Introduction
Ethiopia is the centre of biological diversity because of its wide range of geographical scale [1,2]. e various topographic factors with diverse climatic factors have created diversified vegetation types in the country. ese make Ethiopia have above 6000 higher plant species, of which about 10% are endemic [3]. e vegetation type at Majang forest biosphere reserves is part of the moist evergreen Afromontane forest and is found in the southwestern parts of Ethiopia. Most of these moist evergreen Afromontane forests are very crucial for the conservation of fauna and flora as well as water sources for the low land area [4,5]. However, moist evergreen Afromontane forest resources are being dwindled at an alarming rate because of anthropogenic disturbance [6,7].
Hence, studying plant population structure and regeneration status is significant to understanding the dynamics of vegetation and their disturbance factors [8]. Stand structure is displaying the distribution of an individual in each species and provides the general regeneration profile of the forest [9,10]. Population structure can show whether or not a continuous regeneration and stable population take place. Inspection of species population structure patterns could provide vital information about the recruitment status and the sustainability of population management. It is evidence for further planning and conservation strategies and helps recognise forest ecosystems and biodiversity [11].
Regeneration is a vital part of any forest ecosystem dynamics, as well as it regulates the existence of species and restoration of forest land degradation [12], and it could be playing a great role in planning, forest conservation, and sustainable management [13]. Sustainable forest management and utilisation could be possible if there is sufficient evidence available on the regeneration dynamics and factors influencing important canopy tree species [8]. e regeneration status of sample species can be accessed based on total seedling and sapling density dynamics in a given plant community [9,14]. As a result, the assessment of population structure and regeneration status is necessary to establish the effective conservation and management of forest resources base [15].
Population dynamics of seedlings, saplings, and tree plant species can demonstrate the regeneration profile of a given species. A population with a sufficient number of seedlings and saplings depicts satisfactory regeneration [16], but a scarce number of seedlings and saplings of the species show a poor regeneration state [17]. Furthermore, the regeneration status of a species is poor if the number of seedlings and saplings is much less than mature individuals [18]. e major causes for the destruction of natural forests are agricultural expansion and overexploitation for various purposes such as fuel wood, charcoal, construction material, and timber [19], which are responsible for the high degradation of regeneration status and population structure of the species in Majang forest biosphere reserves [20].
A biosphere reserve is an area established to conserve the biological and cultural diversity of a region while promoting sustainable economic and social development [21]. e requirements of biosphere reserves should, explicitly, fulfil three basic functions: conservation function, development function, and logistics function [22]. Nowadays, there are 699 biosphere reserves in 120 countries of the world. Out of the total biosphere reserves, 79 are found in 29 African countries, of which Ethiopia has five biosphere reserves such as Kafa besides Yayo, Sheka, Lake Tana, and Majang nominated in 2010, 2012, 2015, and 2017, respectively [23].
e Majang biosphere reserve is located in the Majang zone of the Gambella Peoples National Regional State. e Majang biosphere reserve is a newly established forest biosphere reserve; however, there is no first-hand information on vegetation ecology. For effective management and conservation of the biosphere reserves, detailed baseline information on species composition, population structure, and regeneration status is needed, which are crucial for the conservation and sustainable management of biosphere reserve tree species. e population structure of a tree species is indicative of its past distraction and environment. Moreover, it can be used to forecast its future status of Majang forest biosphere reserves [24]. erefore, the objectives of this study are (1) to assess species composition, structures, and regeneration of woody plant species and (2) to analyse the impacts of site factors on the natural regeneration of tree species of Majang forest biosphere reserves.

Description of Study Area.
is study was conducted in the Majang Forest Biosphere Reserve (MFBR), which is found in the Majang Zone, Gambella Peoples National Regional State of Ethiopia. It has unique biogeography and shares a border with the Illubabor zone of the Oromia regional state and Sheka and Bench-Maji zones of the Southern Nations, Nationalities, and Peoples (SNNP). It covers a total area of 233,254 ha of forest, woodland, agricultural and rural settlement, and towns ( Figure 1). e MFBR is located between 07°08′00″-07°50′00″ latitude and 34°50′00″-35°25′00″ longitude, and the area has an altitude of 562 m to 2444 m [1]. e climate of the zone is generally characterised by a hot and humid type, which is marked on most rainfall maps of Ethiopia as being the wettest part of the country. e annual average rainfall is 1774 mm, and means annual minimum and maximum monthly temperature ranges between 13.9 and 31.8°C in the Tinishu Meti metrological station. e annual average rainfall is 2053 mm, and means annual minimum and maximum monthly temperature ranges between 11.8 and 29.7°C in the Ermichi metrological station. e maximum average monthly temperature is in February (29.8°C and 31.8°C), while the minimum is in January (11.9°C and 13.9°C) in Ermichi and Tinishu Meti, respectively. e maximum rainfall is between April and October and low rainfall from November to March (NMSA, 2019) ( Figure 2). e pattern of land use is changing from time to time depending on cultural background and socioeconomic change. ere is a changing trend in the major land use/land cover types in Majang forest biosphere reserves [19] ( Table 1).
According to the vegetation classification of Ethiopia [25], the major vegetation types of the Majang biosphere are Montana evergreen forest, low-land semievergreen forest, and riparian vegetations [26]. Besides, the vegetation of this area has different categories in terms of life forms such as high natural forest, woodlands, bushlands, and grasslands. e dominant families were Euphorbiaceae, Asteraceae, Moraceae, Fabaceae, Poaceae, Solanaceae, Rubiaceae, and Sapotaceae.

Sampling Design.
A reconnaissance survey was conducted from 15 February up to 10 May 2020 in Majang biosphere reserves to inspect a local area. e forest cover and vegetation pattern related to topography and other apparent environmental conditions were recognised. Local variation of forest cover and management measures was assessed. Some geographical location of each forest was recorded to delineate the area. en, the measurement of forest cover (ha) was determined using Google Earth map and ground survey GPS coordinates (Figure 1).    International Journal of Forestry Research e systematic sampling design was adapted from [27] to collect vegetation. e studies were arranged in four sites considering altitudinal deference to represent Majang forest biosphere reserves: site I (Janje-Dope with an altitude of <1200 m.a.s.l.), site II (Newi-Kumi with an altitude between 1200 and 1500 m.a.s.l.), site III (Gelesha-Gubeti with an altitude between 1500 and 1800 m.a.s.l.), and site IV (Gumare-Kabo with an altitude of >1800 m.a.s.l.) ( Table 2).

Data Collection.
In this study, the shrub is defined as a woody plant that is multistemmed at the base of the plant, whereas a liana is any long-stemmed, woody vine that uses trees or other means for vertical support. Seedlings are defined as woody plants with a height less than 1.30 m and diameter of <2.5 cm; saplings as woody plants with a height of >1.30 m and diameter at breast height (DBH) of 2.5-5 cm; and adult trees as plants with a DBH of ≥5 cm [28].
e site factors such as elevation (m) and slope (%), harvesting index, and canopy openness were measured and documented. Elevation and slope were measured using the GPS and clinometer, respectively. Canopy openness was measured using the densitometer located at the centre of each plot, while harvesting index was measured by means counting the stumps individual which was an illegally logged tree inside the plot [30]. Stumps are a small part of a stem that remains after harvesting of trees reaching a minimum diameter of ≥5 cm.
Plants were identified in the field, and for those difficult to identify in the field, specimens were collected, pressed, and identified in the National Herbarium (ETH) of Ethiopia. e nomenclature of plants in this study follows those published in the Flora of Ethiopia as well as the Flora of Ethiopia and Eritrea [31,32].

Data Analysis.
e field data were compiled and arranged in an excel sheet, and the data such as stem density, relative density, frequency, relative frequency, dominance, relative dominance, important value index, and Jaccard's similarity coefficient (JSC) were analysed using the equations provided in Table 3.
For the sake of setting priority for conservation, all woody species encountered in the forest were grouped into five IVI classes based on their total IVI values according to the criteria developed by the Institute of Biodiversity Conservation and Research (IBCR). Species that receive lower IVI values need high conservation priority, while species that receive high IVI values need monitoring and management (Table 4) [38].
e regeneration pattern of woody species was assessed by employing a total count of seedlings (woody species of height ≤ 1.3 cm and DBH ≤ 2.5 cm) and saplings (woody species of height > 1.30 and DBH ≥ 2.5 cm) within the main quadrates [39]. Pattern 1 � If the regeneration results of woody species show seedlings > sapling > adults, "good regeneration". Pattern 2 � if seedlings > or ≤ saplings ≤ adults, "fair regeneration", and Pattern 3 � if the woody species survive only in the sapling stages, "poor regeneration". Pattern 4 � If a woody species is present only in the adult stage, it is considered as not regenerating ("not regenerated") [40].
Harvesting index was measured by means counting the stumps individual which was an illegally logged tree inside the plot and computed from the relative density of individual tree stump [30]. e stump relative density was computed as the sum of stump density divided by the total density (the sum of the logged stump and live individual tree). e variation of basal area and density of seedlings, saplings, and mature trees of all woody species in response to altitude along with study sites and sampling plots were computed using ANOVA (R statistical package). A correlation analysis was performed using the R statistical package to analyse the status of natural regeneration in response to site factors (elevation, slope, canopy openness, harvesting index, and herbaceous cover). Descriptive statistics such as tables and graphs were performed using the Microsoft Office Excel 2007 software.

Similarity in Species
Composition. e similarities in species composition were ranged from 2% to 71% between study sites in Majang forest biosphere reserves.
ere is dissimilarity in tree species composition between sites I and IV (2%), sites II and IV (4%), and sites III and IV (2%). e highest similarity species composition of the tree was 71% between sites I and II, whereas the lowest similarity was 2% between sites I and IV as well as between sites III and IV. Similarly, species composition similarity between site I and site III as well as between site II and site III was 61% and 63%, respectively (Table 6).
e frequency values of the woody species ranged from 0.1% to 99% in the MFBR.

Basal Area.
e basal area value ranges from 54.8 to 76.3 m 2 ·ha −1 from the study site I-IV, respectively. e lowest and highest basal area values were in the study sites I and IV, respectively (Table 5 and Appendixes 9-12). e mean basal area of the four study sites was 63.6 ± 5.4 m 2 ·ha −1 . e ANOVA result indicated that there was a significant difference in the basal area (P < 0.05) between study sites (F � 37.5, df � 53.44, P � 0.000003). Similarly, the basal area was significantly different (P < 0.05) between site I and site II (F � 6.123, P � 0.01912), site II and site III (F � 106.4, P � 0.0000081), and site III and site IV (F � 107.7, P � 0.0000075) ( Table 5). e total dominance was 54.5 m 2 ·ha −1 in site I, the highest 4.25 m 2 ·ha −1 (7.79%) and the lowest basal area 0.05 m 2 ·ha −1 (0.09%) were contributed by Celtis zenkeri and Teclea nobilis, respectively (Appendix 9). About 28.92 m 2 ·ha −1 (53.2%) of the total basal area was covered by ten large-sized tree species in study site I (Table 9). Cordia africana exhibited low density and high basal area due to its maximum average DBH value. A total of 25.62 m 2 ·h −1 (46.98%) was contributed by 27 species in study site I (Appendix 9).
In study site II, the total basal area was 56.8 m 2 ·ha −1 with the highest 4.03 m 2 ·ha −1 (7.09%) and the lowest basal area 0.04 m 2 ·ha −1 (0.07%) were contributed by P. altissima and P. fulva, respectively (Table 9 and Appendix 9). About     No. of species  In study site III, the total basal area was 67.1 m 2 ·ha −1 , the highest 3.76 m 2 ·ha −1 (7.09%) and the lowest basal area 0.07 m 2 ·ha −1 (0.11%) were exhibited by C. zenkeri and Castanea sativa, respectively (Table 9 and Appendix 11). About 30.07 m 2 ·ha −1 (44.9%) of the total basal area was covered by ten large-sized tree species in study site III. C. africana exhibited low density and high basal area due to its maximum average DBH value (Table 9). A total of 36.96 m 2 ·h −1 (55.14%) was contributed by 36 species in study site I (Appendix 11).
Similarly, in study site IV, the total basal area was 76.3 m 2 ·ha −1 , the highest 3.97 m 2 ·ha −1 (5.21%) and the lowest basal area 0.64 m 2 ·ha −1 (0.83%) were contributed by D. afromontana and B. abyssinica, respectively (Table 9 and Appendix 12). About 29.29 m 2 ·ha −1 (38.42%) of the total basal area was covered by ten large-sized tree species in study site III. C. africana exhibited low density and high basal area due to its maximum average DBH value (Table 9). A total of 46.96 m 2 ·h −1 (61.58%) basal area was contributed by 36 species in study site I (Appendix 12).

Importance Value Index.
e importance value index (IVI) of tree species showed a great variation, ranging from 1.1% to 9.8% in the overall study site (Appendix 2). e first top ten leading and ecologically most important tree species in the MFBR were C. zenkeri, P. altissima, B. unijugata, L. fraxinifolius, D. afromontana, A. toxicaria, B. abyssinica, C. toka, S. myriantha, and P. adolfi-friederici and contributed 68.5% of the IVI (

Population Structure Woody Species.
Tree species of the study area were divided into seven height and DBH classes. e overall height and DBH class distribution of all individuals of different sizes showed more or less an inverted J-shape distribution in the MFBR (Figures 7(a)  and 7(b)). Similarly, the distribution of individuals in different height and DBH classes was showed more or less an inverted J-shape distribution in each study site (Figures 8(a) and 8(b)). In this study, six representative patterns of population distribution based on DBH were revealed for tree species (Figures 9(a)-9(f )), which are mentioned as follows: (1) Inverted J-shape, which shows a pattern where species frequency distribution has the highest frequency in the lower diameter classes and a gradual decrease towards the higher classes; e.g., Celtis zenkeri and Lecaniodiscus fraxinifolius in study site II; Blighia unijugata and Antiaris toxicaria in study site III; and Schefflera myriantha in study site IV. is pattern represents abnormal population dynamics and shows poor reproduction and hampered regeneration since either most trees are not producing seeds due to age or there are losses due to predators after reproduction.

Regeneration Status of Woody Species.
e total density of seedlings, saplings, and trees was 3461 ha −1 , 1203 ha −1 , and 1350 ha −1 , respectively. Out of 80 trees species of DBH >5 cm, 7 tree species were not represented by seedlings and 11 tree species were not represented by saplings. Twelve tree species contributed 73.6% and 34.7% of the total seedling and sapling count, respectively (Table 10) In addition, the regeneration status of the top ten species in each study site is indicated in Tables 11-14. e regeneration status of all the woody plant species was categorised as "not regenerate" (9.6%), "poor" (30.7%), "fair" (59.5%), and "good" (10.8%) in all sites.

Site Factors versus Regeneration Status.
In the present analysis, site factors were computed and compared with the density of trees, saplings, and seedlings using Pearson correlation (r). e correlation result between natural regeneration of trees, saplings, and seedlings and site factors revealed both positive and negative relationships (Table 15). Canopy openness and harvesting index showed a negative relationship with seedling, sapling, and tree density. e Pearson correlation coefficient between canopy openness with seedling, sapling, and tree density were negative (r � −0.02, P � 0.09; r � −0.26, P � 0.08; and r � −0.13, P � 0.0004, respectively). Similarly, the harvesting index      14 International Journal of Forestry Research showed a negative relationship with seedling, sapling, and tree density (r � −0.03, Pp � 0.09; r � −0.29, P � 0.1; and r � −0.03, P � 0.000016, respectively). Elevation showed a significant positive relationship with sapling and tree density (r � 0.28, P � 0.000001, and r � 0.44, P � 0.000001, respectively), whereas tree density showed a significant negative relationship (r � −0.02, P � 0.000001). Slope also showed a positive relationship with seedling (r � 0.03, P � 0.07) and sapling (r � 0.12, P � 0.09) density, whereas tree density showed a negative relationship (r � −0.03, P � 0.94). In addition, canopy openness and harvesting index (r � −0.12, P � 0.07, and r � −0.06, P � 0.09, respectively) showed a negative relationships with herbaceous cover. e abundance of the herbaceous cover showed a negative relationship (r � −0.03, P � 0.172) with the density of seedlings (Table 15).

International Journal of Forestry Research
Dima forest (69 families, 145 genera, and 180 plant species) [45], Yayu forest (72 family, 163 genera, and 217 plant species) [4], and Bonga forest (92 families, 207 genera, and 285 plant species) [42]. e variation of plant species over different habitats of the forest could be attributed to a number of environmental factors, which impose impacts in both temporal and spatial scales [46]. us, environmental heterogeneity, regeneration capacity, moderate disturbance, and competition might shape and determine species richness of the forest. Moreover, from the identified woody species, Majang forest biosphere reserves sheltered relatively few numbers of endemic plant species to Ethiopia [47], i.e., Bothriocline schimperi, Clematis longicauda, and Vepris dainellii.

Density of Woody Species.
e stem densities varied with species composition, diameter size classes, and the degree of disturbance. Specifically, the stem densities of tree species with DBH > 5 cm in four study sites ranged from 1232 to 1478 stems ha −1 (Table 5) are lower than those reported from Wurg forest (1745 ha −1 ) [43], Masha forest (1681 ha −1 ) [48], and Gelesha forest (1659 ha −1 ) [49] in southwestern moist Afromontane forest and higher than a moist tropical forest (843 stems ha −1 ) [50]. On the other hand, the density mentioned in this study is more or less comparable with that of Agama forest (1446 ha −1 ) [41]. e variation of tree densities of MFBR study sites may be due to variations in elevation, aspect, species composition, age, structure [51], and disturbance levels [52]. e ratio of tree/shrub density (10 cm < DBH <20 cm and >20 cm) was taken as a measure of the class size distribution [56]. Accordingly, the value of the tree/shrub density ratio was 1.4 in Majang forest biosphere reserves, which is more or less comparable with Gelesha [53] and Gurafreda [58]. is similarity may be due to connection with geographical location, climatic condition, and altitude factors. On the other hand, the ratio a/b at MFBR was lower than that at Wurg, Agama, Jima, Menna Angetu, Belete, Masha, Masha Anderacha, and Komto; it indicates that all studies have higher proportions of small-sized individuals than the MFBR. is difference may be due to in the stage of secondary succession of the forests (Table 16).

Frequency of Woody
Species. Frequency indicates the homogeneity or heterogeneity of a given stand [27,60], an occurrence of a species in a given area which indicates how species are distributed [27,61]. In all study sites of MFBR, the frequency value of woody species ranges from 0.1% to 99%. e highest frequency was shown by Celtis zenkeri (88%) in study site I, Pouteria altissima (100%) in study site II, Celtis zenkeri (95%) in study site III, and Dracaena afromontana and Cyathea manniana (100%) in study site IV (Table 7). ese may be due to a wide range of seed dispersal mechanisms like wind, livestock, wild animals, and birds.
High values in lower frequency classes and low values in higher frequency classes indicate a high degree of floristic heterogeneity [62].
e frequency distribution of woody species in the MFBR shows that the number of tree species found in the first frequency classes is higher (A and B) and gradually decreases towards higher frequency classes (D and E), which is similar to that mentioned by Dibaba et al. [41] in Agama forest, Girma and Melese [43] in Wurg forest, Edae and Soromessa [49] in Gelesha forest in southwestern moist Afromontane, and Dibaba et al. [63] in dry Afromontane forest. In contrast, Mekonen et al. [64] found that the number of tree species found in the first frequency classes is lower (A and B) and gradually increases towards higher frequency classes (D and E) in Woynwuha natural forest in northwestern Ethiopia. Such variation may be due to uniform species composition or homogeneity in the area.

Basal Area.
A species with a greater basal area could be considered the most important species in a given study forest [65]. Basal area per hectare used as an indicator of degradation level or status of standing stock. If the basal area is very small, we can conclude that the forest is degrading. e total basal area of all woody species in the MFBR was about 139.8 m 2 with DBH > 5 cm, which is greater than that of Wurg, Belete, Gelesha, Bibita, and Agama in moist   (Table 17). ere was a significant difference between the MFBR study sites in terms of basal area. e total basal area ranges (56.8 to 76.3 m 2 ha −1 ) in the four study sites (I-IV) ( Table 5) are greater than the range of basal area (17 to 40 m 2 ha −1 ) reported in dry forests of the world [70]. e increments in the basal area from sites I-IV may be due to more number of individuals in higher diameter size classes with increments in elevation and minimal incidences of disturbance within the study site.
e highest basal area of individual tree species in the study site was contributed by C. zenkeri in the study sites I and III, P. altissima in study site II, and D. afromontana in site IV, whereas the highest density was exhibited by D. abyssinica in study site I, L. fraxinifolius in study site II, B. unijugata in study site III, and C. manniana in site IV.
is shows that the species with the highest basal area do not necessarily have the greater density and vice versa, which is also true, indicating a size difference between species [65].

Importance Value Index.
e importance value index is used for comparison of ecological key species [62] and ranking species for management and conservation priority. In this respect, the IVI of woody species of the MFBR was calculated from relative density, relative dominance, and relative frequency [71]. e species with larger IVI need monitoring and management, whereas the species with smaller importance value index need high conservation effort [62]. In this study, the maximum IVI was contributed by C. zenkeri (9.8) and the lowest was by F. thonningii in the MFBR or overall study area (1.1). e most ecologically significant tree species in the MFBR were C. zenkeri, P. altissima, B. unijugata, L. fraxinifolius, D. afromontana, A. toxicaria, B. abyssinica, C. toka, S. myriantha, and P. adolfi-friederici and could influence the overall forest structure (Table 7 and Appendix 2).

Population Structure of Woody Species.
Population structure refers to the spreading of individual species in random diameter-height size classes to provide the overall regeneration profile of woody and shrub species [72,73]. e structural patterns of the population could be understood as an indication of variation in population dynamics that may occur because of natural characters or due to humans and livestock interventions [74,75]. In this study, the population patterns of height and DBH class distribution of all individuals in different sizes showed more or less an inverted J-shape distribution in the total results of MFBR (Figures 7(a) and 7(b)). is means species frequency distribution had the highest frequency in the lower diameter and height classes and a gradual decrease towards the higher classes. e possible reason for the decreasing higher diameter class may be due to illegal logging of middle and high diameter class trees for various purposes by local people such as for fencing, farm implementing, house construction, and fuel wood. Similarly, the distribution of individuals in different height and DBH classes' dominant species showed more or less an inverted J-shape distribution in each study site (Figures 8(a) and 8(b)). An inverted J-shape population pattern is a normal plant population structure and shows the occurrence of species in a healthier condition. is is similar to other findings that reported moist Afromontane forest in southwestern parts of Ethiopia [41, 43, 48, 53-55, 57, 58, 69, 76] and dry Afromontane forest [66][67][68]. However, the overall population pattern does not indicate the trends of population dynamics and recruitment processes of individual species [20,63]. Specifically, six representative patterns of population distribution were exhibited in the MFBR, which is similar to other findings in Ethiopia [20,43,57,77,78]. Hence, generally assessing the population structure is important to provide a preliminary indication about the regeneration status of woody plants and shrubs in a studied forest [78,79].

Regeneration Status of Woody Species.
e status of forest regeneration depends on the composition, distribution, and density of seedlings, saplings, and adult trees in the forest [12]. e recruitment or regeneration condition of woody species is one of the main factors that are valuable to evaluate forest conservation status [80]. e population  [69] structure, characterised by the presence of a sufficient population of seedlings, saplings, and adults, indicates the successful regeneration of forest species [81]. In this study, the regeneration status of saplings and seedlings showed four regeneration patterns (no regeneration, poor, fair, and good). e "poor" and "no regeneration" patterns were exhibited by 28.1%, 44.3%, 29.2%, and 15.5% of the woody plants in study sites I, II, III, and IV, respectively, of MFBR.
us, the variation of hamper regeneration among study sites may be due to the presence of anthropogenic factors and environmental factors [12,82]. is result is more or less similar to that reported in Berbere forest (32.26%) [83], Wof-Washa (48%) [84], Central Highland (20.9%) [85], and Wurg forests (14%) [43]. e lower seedling count in the MFBR showed limited regeneration potential that could be due to unlimited vegetation exploitation by the local community. However, there are some germination of seeds due to few remaining mother trees; most of these seedlings vanished before reaching sapling and mature stages for various reasons including grazers, browsers pressure, and illegal exploitation [86]. e "poor" and "no regeneration" of the woody species in the study sites of MFBR generally falls below half percent. ese conditions might have occurred through the existence of disturbances such as overgrazing [9,66,[87][88][89], fuel wood collection, agricultural expansion, settlement, and poor biotic potential of tree species that affects the fruit setting and germination of seeds [20,90,91]. Poor regeneration is an indication of poor reproduction and hampered regeneration, which is due to old age individuals and loss of seeds by predators after reproduction or successful conversion of seedling to sapling stage [92]. Moreover, individuals in young stages of any species are more vulnerable to any kind of environmental stress and anthropogenic disturbance [93]. erefore, the absence of seedlings and saplings of woody species designates the immediate requirement of a forest management plan to improve forest regeneration [20,94].

Site Factors versus Regeneration Status.
In this study area, the correlation result between natural regeneration of trees, saplings, and seedlings and site factors revealed both positive and negative relationships (Table 15). e correlation analysis of elevation indicated a negative relationship with seedling and a positive relationship with sapling densities. e negative relationship of elevation with seedling density may be due to human disturbance coupled with population density increment when elevation increased, which is similar to the findings of other tropical forests [95].
e slope also showed a positive relationship with seedling and sapling densities. is may be due to difficulty to reach an area of human disturbance with increasing of the slope (Table 15).
Harvesting index and canopy openness showed a negative relationship with seedling, sapling, and tree densities, which ultimately affects the regeneration status of the species. For instance, illegal logging of tree species leads to a reduction in the mother tree or seed sources, and it facilitates the growth of understory, shrubs, and composition of species in the area.
is also enforces abiotic stress like evapotranspiration and loss of soil moisture that retard regeneration [88]. It was also reported that the canopy openness of forests affects the species composition, richness, and regeneration of tree species [96]. However, different studies reported that most species had increased regeneration with increased canopy openness [97,98]. is might be due to the species characteristics of shade-tolerant and intolerant species that exhibit variations of regeneration with the degree of canopy openness.
Numerous structural characteristics influence the regeneration of species, especially the stem density of trees and abundance of herbaceous cover. e density of trees had a negative relationship with that of seedlings; this may be due to high competition with trees and herbaceous cover, causing the survival of seedlings. is result coincides with previous results in tropical forests [99]. In other studies, however, positive correlations were found between densities of trees and herbaceous cover and seedling density [100]. e interactions between seedlings and herbaceous cover result in forest dynamics because dense herbaceous cover decreases light availability near the forest floor and results in the decline of seedling regeneration [101]. e seedlings density was reduced in response to high herbaceous cover, indicating competitive effects for space and resources between seedlings and their nontree competitors. Higher herbaceous cover played a major role in preventing successful seed germination, seedling establishment, growth, and survival [102].

Conclusion and Recommendation
e current study delivers important information about the state of woody plant species composition, structures, and regeneration of woody plant species and the impacts of site factors on the natural regeneration of tree species of Majang forest biosphere reserves. e results revealed that the diversity is high, with a total of 158 plant species belonging to 115 genera and 56 families. Among these, the plant species Dracaena afromontana, Celtis zenkeri, and Pouteria altissima were the most frequent and dominant with greater important value index (IVI) in MFBR. e overall height and DBH class distribution of all individuals of different sizes showed more or less an inverted J-shape distribution in MFBR. However, a few numbers of species showed an unhealthy population structure or poorly represented either in the lower or higher DBH and height classes. Considering seedling, sapling, and tree densities, the regenerating status of all the woody plant species were categorised as "not regenerate" (9.6%), "poor" (30.7%), "fair" (59.5%), and "good" (10.8%) in all sites. e correlation result between natural regeneration of trees, saplings, and seedlings and site factors revealed both positive and negative relationships. However, the main threat to the biosphere reserve is the illegal logging of some tree species for different purposes. erefore, awareness creation on sustainable forest management, utilisation, conservation of priority species, and livelihood diversification to the local community and encouraging community and private woodlot plantation in the transitional zone of the biosphere reserves are recommended.

Data Availability
e data used to support the findings of this study are available from the corresponding author upon request.

Conflicts of Interest
e authors declare that there are no conflicts of interest.