# The Effects of Landscape Change on Plant Diversity and Structure in the Bale Mountains National Park, Southeastern Ethiopia

Authors: Annissa Muhammed; Eyasu Elias
Journal: International Journal of Ecology
 (2021)

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## Abstract

Bale Mountains National Park is one of the protected areas in Ethiopia that holds the largest area of Afroalpine habitat in Africa and the second largest stand of moist tropical forest. Nevertheless, human settlements, overgrazing, and recurrent fire are the main problems in the park. This study aimed to determine the effects of human-induced landscape change in floristic composition and structure in the park. The vegetation data were collected systematically from 96 sample plots laid along 24 line transects in the edge and interior habitats of the six land cover types. Vegetation composition and landscape structural analysis were made usingR software version 3.5.2 and FRAGSTATS version 4.2.1, respectively. Patch number was strong and positively affected species richness (r = −0.90, p<0.05), diversity (r = −0.96, p<0.01), and basal area (r = −0.96, p<0.001), whereas mean patch size was strong and negatively influenced species richness (r = 0.95, p<0.05), diversity (r = 0.87, p<0.05), and basal area (r = 0.82, p<0.05). The overall species richness, Shannon diversity index, and Margalef index were significantly higher in the edge habitat; however, the mean basal area of woody species was significantly higher in the interior habitat at p<0.05. This study uncovered that the park is floristically rich and diverse, and it provides a variety of ecological and economic benefits to the surrounding community and to the nation at large. However, these benefits are gradually declining due to the high level of anthropogenic activities in the park. Thus, integrated environmental management strategy that blends with sustainable use of natural resources should be implemented to minimize the threats.


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## Body

## 1. Introduction

Landscapes all over the world are alarmingly changed and fragmented due to anthropogenic factors such as urbanization, agricultural expansion, forest fire, and climate change [1, 2]. Most of the global changes responsible for the reduction in population and biodiversity are exacerbated by fragmentation [3, 4]. The primary causes of global biodiversity reduction are the destruction and degradation of natural ecosystems [5]. Predominantly, habitat loss and fragmentation are presently the main threats to terrestrial biodiversity [6]. Moreover, habitat fragmentation can affect the species interactions and community composition, as invasive or pest species, and may substitute the original species pool and increase the transmission and prevalence of the disease in small fragments [7]. Moreover, the species richness and abundance usually decrease with reduced patch size [8]. As landscapes become more fragmented, patch diversity increases with subsequent increase in the edge, exotic, and generalist species and ultimately leads to the reduction in landscape quality as habitat for species [9]. Accordingly, species richness in interior habitat, particularly indigenous and specialist species, tends to decrease [10]. The number of species existing in a patch tends to rise with patch size up to a certain limit, and the types of species found also tend to vary in size [8]. Size and shape interact to influence the amount of interior area remaining in a particular habitat fragment [2].Tropical montane ecosystem is one of the hot spot ecosystems on Earth that comprises more than 200,000 species of flowering plants [11, 12]. The Ethiopian highland, which is located in the tropical region, encompasses over 50% of the Afromontane vegetation in Africa [13]. A suitable geographical position, a wide range of altitude, a high amount of rainfall, and a wide range of temperature variations equip the area with huge ecological diversity and a wealth of biological resources [14]. However, severe deforestation coupled with the cultivation of steep marginal lands, overgrazing, and sociopolitical uncertainty has resulted in rigorous land degradation over large areas of the country [15]. The overdependence of the country’s economy on agricultural production and the existence of more than 80% of the population in the highlands [16, 17] mainly contribute to the degradation of ecological resources and biodiversity loss.The mountainous landscape and the mosaic of natural vegetation in the Bale Mountains have considerable economic, recreational, esthetic, and scientific importance [14]. The Bale Mountains National Park (BMNP) is the most significant conservation area situated in this region of Ethiopia and established in 1969 to preserve the endemic and indigenous floras and faunas in the area [18, 19]. It is one of the 34 International Biodiversity Hotspots and meets the requirements for the World Heritage Site and Biosphere Reserve Listing [20]. However, the park is facing a critical challenge from the illegal settlement and overgrazing and that leads to the change in its landscape structure and function. As a result, the habitats in the park are changing and the provision of ecological services from it is substantially reduced. Consequently, no research provides detailed information about the landscape structure and its potential impact on vegetation composition and structure in the park. Therefore, this research was aimed to analyze the potential impact of landscape change in floristic composition, diversity, and structure in the BMNP. Particularly, a comparative analysis was made among the edge and interior habitats of the park.


## 2. Materials and Methods

### 2.1. Study Area Description

BMNP is located within the geographic bounds of 6°53′08″N latitude and 39°44′03″E longitude and 400 km southeast of Addis Ababa, Ethiopia (Figure1). It comprehends a wide range of habitats between 1450 m and 4377 m altitude. The park holds the largest area of Afroalpine habitat (about 1000 km2) above 3000 m asl in Africa and the second largest stand of moist tropical forest [21]. It is one of the 34 International Biodiversity Hotspots and also qualifies for World Heritage Site and Biosphere Reserve Listing [22]. It received rainfall that ranged from 520 to 2370 mm annually [23], and the distributional pattern is bimodal with heavy rains from July to October (highest peak in August) and small rains from March to June (highest peak in April). The mean monthly minimum and maximum temperatures are 5.6°C and 21.4°C, respectively. Its soil is fertile silty loam of reddish-brown to black clay soils dominated by Vertic Cambisols and Leptosols [24].Figure 1
Location map of the study area.


### 2.2. Vegetation Sampling Design

From 13 to 20 November 2018, a reconnaissance survey was conducted to get insights into the vegetation physiognomy and establish sampling sites in the study area. Following, the actual fieldwork was performed in the dry season between November 2019 and January 2020. A total of 96 sample plots (20 × 20 m) were systematically laid along 24 line transects in eight directions along three altitudinal gradients at 100 m elevational differences as it maximizes the distance between plots and minimizes spatial correlation among the observations [25]. To make a comparison between the vegetation data, an equal number of sample plots have been laid on the edge and interior habitats following Daye [26].


### 2.3. Species Identification

Plant species in the nested plots were identified at the field with the help of local peoples (for vernacular names) and by referring different volumes of Flora of Ethiopia and Eritrea books [27, 28]. For the species that were difficult to identify in the field, representative specimens were cut, numbered, and pressed at the site. The collections were named using folk taxonomy, and identification of formal taxonomy was determined using the voucher specimens at the National Herbarium, Addis Ababa University.


### 2.4. Floristic Composition and Structure

The most commonly used diversity indices of species richness (S), Simpson index (D), Shannon–Wiener index (H′), Pielou’s evenness index (J′), Whittaker β-diversity (βw), Margalef index (DM), and Berger–Parker index (d) were computed to analyze the patterns of plant diversity in the edge and interior habitats following Magurran [29] and Økland [30] using equations (1)–(4):(1)H′=−∑i=1sPilnPi,where H′ is the Shannon diversity index, Pi is the proportion of individuals, and ln is the natural logarithm.(2)J=H′Hmax,where Hmax is the maximum level of diversity possible within a given population (ln S) and S is species richness.(3)β−diversity=a+c2a+b+c,where a is the number of shared species in two sites and b and c are the numbers of species unique to each site.The Margalef diversity index (DM) was computed using the following formula:(4)DM=s−1lnN,where DM is the Margalef diversity index, S is the number of species, and N is the total number of individuals in the sample.The woody species density, frequency, dominance, and their relative values in the interior and edge habitats were computed to obtain the important value index and describe the woody species structure following Ellenberg and Mueller-Dombois [31] and Martin [32] using equations (5)–(8). Moreover, DBH, tree height, and basal area were analyzed to determine the population structure following Kitessa et al. [33] and Van der Maarel [34]:(5)BA=πd24,where BA is the basal area, π = 3.14, and d is the DBH (cm).(6)Fr=Pi∑i=1sPi×100,where Fr is the frequency of a species and Pi is the number of plots in which the ith species occurred.(7)Rde=ni∑i=1sni×100,where Rde is the relative density and ni is the number of individuals of the ith species.(8)IVI=Rde+RFr+RDo,where IVI is the importance value index, Rde is the relative density, RFr is the relative frequency, and RDo is the relative dominance.


### 2.5. Measurement of Landscape Structure

Landsat images of the years 1985, 1995, 2005, and 2017 were processed using ArcGIS version 10.3 to produce time-series datasets of land use/land cover. Then, eight landscape indices were analyzed using the processed land use/land cover data following McGarigal et al. [35] and Smiraglia et al. [36]. The indices include patch number (PN), mean patch size (AREA_MN), total core area (TCA), edge density (ED), area-weighted mean shape index (SHAPE_AM), mean Euclidean nearest neighbor distance (ENN_MN), and interspersion and juxtaposition index (IJI). Edge habitat was identified by deducting 50 m from the edge of each vegetation type. FRAGSTATS software version 4.2.1 was used to compute the landscape patterns in each land cover class and the entire landscape [37]. The two-way analysis of variance (two-way ANOVA) and linear regression analysis were made to test significant differences between fragmentation indices and species composition and structure parameters following the post hoc Tukey’s highly significance difference (Tukey’s HSD) test at 5% significance level using PAST software version 4.02 [38].


## 2.1. Study Area Description

BMNP is located within the geographic bounds of 6°53′08″N latitude and 39°44′03″E longitude and 400 km southeast of Addis Ababa, Ethiopia (Figure1). It comprehends a wide range of habitats between 1450 m and 4377 m altitude. The park holds the largest area of Afroalpine habitat (about 1000 km2) above 3000 m asl in Africa and the second largest stand of moist tropical forest [21]. It is one of the 34 International Biodiversity Hotspots and also qualifies for World Heritage Site and Biosphere Reserve Listing [22]. It received rainfall that ranged from 520 to 2370 mm annually [23], and the distributional pattern is bimodal with heavy rains from July to October (highest peak in August) and small rains from March to June (highest peak in April). The mean monthly minimum and maximum temperatures are 5.6°C and 21.4°C, respectively. Its soil is fertile silty loam of reddish-brown to black clay soils dominated by Vertic Cambisols and Leptosols [24].Figure 1
Location map of the study area.


## 2.2. Vegetation Sampling Design

From 13 to 20 November 2018, a reconnaissance survey was conducted to get insights into the vegetation physiognomy and establish sampling sites in the study area. Following, the actual fieldwork was performed in the dry season between November 2019 and January 2020. A total of 96 sample plots (20 × 20 m) were systematically laid along 24 line transects in eight directions along three altitudinal gradients at 100 m elevational differences as it maximizes the distance between plots and minimizes spatial correlation among the observations [25]. To make a comparison between the vegetation data, an equal number of sample plots have been laid on the edge and interior habitats following Daye [26].


## 2.3. Species Identification

Plant species in the nested plots were identified at the field with the help of local peoples (for vernacular names) and by referring different volumes of Flora of Ethiopia and Eritrea books [27, 28]. For the species that were difficult to identify in the field, representative specimens were cut, numbered, and pressed at the site. The collections were named using folk taxonomy, and identification of formal taxonomy was determined using the voucher specimens at the National Herbarium, Addis Ababa University.


## 2.4. Floristic Composition and Structure

The most commonly used diversity indices of species richness (S), Simpson index (D), Shannon–Wiener index (H′), Pielou’s evenness index (J′), Whittaker β-diversity (βw), Margalef index (DM), and Berger–Parker index (d) were computed to analyze the patterns of plant diversity in the edge and interior habitats following Magurran [29] and Økland [30] using equations (1)–(4):(1)H′=−∑i=1sPilnPi,where H′ is the Shannon diversity index, Pi is the proportion of individuals, and ln is the natural logarithm.(2)J=H′Hmax,where Hmax is the maximum level of diversity possible within a given population (ln S) and S is species richness.(3)β−diversity=a+c2a+b+c,where a is the number of shared species in two sites and b and c are the numbers of species unique to each site.The Margalef diversity index (DM) was computed using the following formula:(4)DM=s−1lnN,where DM is the Margalef diversity index, S is the number of species, and N is the total number of individuals in the sample.The woody species density, frequency, dominance, and their relative values in the interior and edge habitats were computed to obtain the important value index and describe the woody species structure following Ellenberg and Mueller-Dombois [31] and Martin [32] using equations (5)–(8). Moreover, DBH, tree height, and basal area were analyzed to determine the population structure following Kitessa et al. [33] and Van der Maarel [34]:(5)BA=πd24,where BA is the basal area, π = 3.14, and d is the DBH (cm).(6)Fr=Pi∑i=1sPi×100,where Fr is the frequency of a species and Pi is the number of plots in which the ith species occurred.(7)Rde=ni∑i=1sni×100,where Rde is the relative density and ni is the number of individuals of the ith species.(8)IVI=Rde+RFr+RDo,where IVI is the importance value index, Rde is the relative density, RFr is the relative frequency, and RDo is the relative dominance.


## 2.5. Measurement of Landscape Structure

Landsat images of the years 1985, 1995, 2005, and 2017 were processed using ArcGIS version 10.3 to produce time-series datasets of land use/land cover. Then, eight landscape indices were analyzed using the processed land use/land cover data following McGarigal et al. [35] and Smiraglia et al. [36]. The indices include patch number (PN), mean patch size (AREA_MN), total core area (TCA), edge density (ED), area-weighted mean shape index (SHAPE_AM), mean Euclidean nearest neighbor distance (ENN_MN), and interspersion and juxtaposition index (IJI). Edge habitat was identified by deducting 50 m from the edge of each vegetation type. FRAGSTATS software version 4.2.1 was used to compute the landscape patterns in each land cover class and the entire landscape [37]. The two-way analysis of variance (two-way ANOVA) and linear regression analysis were made to test significant differences between fragmentation indices and species composition and structure parameters following the post hoc Tukey’s highly significance difference (Tukey’s HSD) test at 5% significance level using PAST software version 4.02 [38].


## 3. Results and Discussion

### 3.1. Landscape Structure Change

The analysis of landscape structure in this study revealed that the habitats in the BMNP are progressively transformed. The area has shown an increase in PN by 40.2% and a decrease in AREA_MN by 28.7% from 1985 to 2017. According to Oertli et al. [39], the high number of separated patches in a habitat indicates a high level of fragmentation. Across the entire study period, SHAPE_AM, which indicates the complexity of patch shape, increased by 18.8%. A higher perimeter-area relationship characterizes the rapid rate of fragmentation in the landscape [40]. Moreover, there was inconsistency in the values of ED; however, it was increased by 22.3% over the study period. As it was emphasized by McGarigal [37], the oscillation of ED indicated a major reduction in the spatial heterogeneity of the landscape. Conversely, the study area has shown a declining trend in TCA by 10.6% from 1985 to 2017. This was due to the escalated level of disturbances in the study area. As it was reported by Kidane et al. [41], the most dominant practices in the Bale Mountains, especially after 1995, were the upward expansion of agriculture and enrichment plantation.The isolation of patches within the landscape of the study area was increased from 105.22 m to 111.94 m overtime (Table1). This result is in agreement with the result reported by Tolessa et al. [42] in the central highlands of Ethiopia and Daye [26] in Southwest Ethiopia. Conversely, the intermixing of patches in the study area showed an overall declining trend from 95.38 to 86.77 over the study period. This result showed that the BMNP constitutes more scattered patches compared to other similar areas studied by Posada Posada [43] and Tolessa et al. [42].Table 1
Landscape structural characteristic of the BMNP from 1985 to 2017.
YearNPAREA_MN (ha)SHAPE_AMTCA (km2)ED (m/m2)ENN_MN (m)IJI (%)1985258648.4224.971568.9160.53107.2777.691995305827.1224.121489.1069.18105.2279.292005293297.4229.361471.0266.44111.9470.782017362676.0029.671402.5974.02109.2175.46%40.22−28.6818.83−10.6022.281.81−2.87Note. The negative sign of percentage implies a decreasing trend, and the positive sign implies an increasing trend.


### 3.2. Overall Floristic Composition and Structure

A total of 205 plant species belonging to 71 families and 153 genera were recorded (Table2). Of these, 50 species were trees, 52 were shrubs, 12 were lianas, and 91 were herbs. Asteraceae was the most dominant family with 31 species, followed by Fabaceae with 11 species. Conversely, Helichrysum was the most abundant genus with 9 species, followed by Alchemilla and Trifolium with 5 species each. Twenty endemic species, including Euphorbia dumalis S. Carter, Lobelia rhynchopetalum Hemsl., and Thymus schimperi subsp. Schimperi Ronniger was identified in this study. The overall Shannon diversity and evenness index of the study area were 4.34 and 0.81, respectively. This indicated that the study area was more diverse compared to other similar vegetation areas including Bonga forest [44], Agama forest [45], and Munessa forest [13]. Conversely, the total density of seedlings, saplings, and mature trees in the study area was 8751, 4413, and 1567 individuals ha−1, respectively. This was lower than other comparable areas such as Kuandisha forest [46] and Wof-Washa forest [47]. The ratios of seedling to mature tree, sapling to mature tree, and seedling to sapling were 5.58, 2.82, and 1.98, respectively. This shows the recruitment potential of the forest is relatively higher [48].Table 2
List of plant species identified in the BMNP.
Scientific nameFamilyLocal name (Or.)HabitColl. no.Acacia oerfota (Forssk.) Schweinf.FabaceaeWangaSAM168Acacia senegal (L.) Willd.CelastraceaeKarxafaSAM172Achyranthes aspera L.AmaranthaceaeRoppe, Qorsa WaranssaHAM094Agrostis sclerophylla C.E. Hubb.PoaceaeMergeseriHAM009Ajuga bracteosa Wall. ex Benth. in Wall.Lamiaceae—HAM078Albizia gummifera (J. F. Gmel.) C.A.Sm.MimosaceaeKarchofeTAM174Alchemilla abyssinica Fresen.RosaceaeHindriffHAM043Alchemilla cryptantha Steud. ex A Rich.RosaceaeHindriffHAM159Alchemilla haumanii Rothm.Rosaceae—HAM055Alchemilla pedata A. Rich.RosaceaeHindriff, IndriifHAM017Alchemilla rothii Oliv.Rosaceae—HAM052Alepidea peduncularis Steud. ex A. Rich.Apiaceae—HAM060Allophyllus macrobotrys GilgSapindaceaeAbaraTAM131Allophylus abyssinicus (Hochst.) Radlk.SapindaceaeSararaTAM178Anaptychia liucomeleana Wain.PhysciaceaeLichenHAM054Annona reticulata L.AnnonaceaeGishtaTAM161Anthemis tigreensis J. Gay ex A. Rich.Asteraceae—HAM012Argemone mexicana L.PapaveraceaeQore HareeHAM018Artemisia afra Jacq. ex Willd.AsteraceaeTepenea, TepenoHAM007Asparagus africanus Lam.AsparagaceaeSeritiSAM199Asplenium aethiopicum (Burm.f.) Bech.AspleniaceaeQumbutaHAM155Astragalus atropilosulus (Hochst.) BangeFabaceaeHaraEAM037Bidens macroptera (Sch. Bip. ex Chiov.) MesfinAsteraceaeHade golaHAM040Blyttia fruticulosum (Decne.) D.V.FieldApocynaceaeHombaH(clim)AM122Brachycorythis buchananii (Schltr.) RolfeOrchidaceaeShumbura galaHAM066Bromus pectinatus Thunb.PoaceaeAlanmuressaHAM106Calpurnia aurea (Ait.) Benth.FabaceaeCheekataSAM167Carduus leptacanthus Fresen.AsteraceaeQore HareeHAM107Carduus nyassanus (S. Moore) R.E. FriesAsteraceaeQore HareeHAM033Carissa edulis (Forssk.) VahlApocynaceaeHagamssa(Or), Agam(Amh)SAM181Carissa spinarum L.ApocynaceaeHarangmaSAM200Casimiroa edulis La Llave & Lex.RutaceaeKasmiraTAM163Catha edulis (Vahl) Forssk. ex Endl.CelastraceaeJimaaSAM143Celtis africana Burm.f.UlmaceaeMeteqammaTAM116Centella asiatica (L.) Urb.ApiaceaeBalee, QuduHAM064Cerastium afromontanum T.C.E. Fr. & Weim.CaryophyllaceaeDuqusha chuffaHAM087Citrus aurantifolia (Christm.) SwingleRutaceaeLomiiSAM186Citrus sinensis (L.) OsbeckRutaceaeBurtukanaSAM187Clematis hirsuta Perr. & Guill.RanunculaceaeFitiiLiAM114Coffea arabica L.RubiaceaeBuunaSAM121Combretum ghasalense Engl. & DielsCombretaceaeDhandhaasaTAM190Commelina africana L.CommelinaceaeGura JarsaHAM020Cordia africana Lam.BoraginaceaeWodessaTAM160Craterostigma plantagineum HochstetterScrophulariaceae—HAM102Crepis carbonaria Sch. Bip.AsteraceaeMarga HoffiHAM025Crepis ruepellii Sch. Bip.Asteraceae—HAM071Crotolaria agatiflora Schweinf. Sub.sp. ErlangeriBak. F.FabaceaeShashamaneSAM201Croton macrostachyus Hochst. ex Del.EuphorbiaceaeMakkannisaTAM119Cuscuta kilimanjari Oliv.ConvolvulaceaeSegenitiH(clim)AM098Cycniopsis humifusa (Forssk.) Engl.Scrophulariaceae—HAM080Cynoglossum amplifolium Hochst. ex DC.BoraginaceaeQarccabbaaHAM081Cynoglossum coeruleum Hochst.BoraginaceaeQarccabbaaHAM026Cynoglossum lanceolatum Forssk.Boraginaceae—HAM058Cyperus schimperianus Steud.CyperaceaeAlandoHAM023Dianthoseris schimperi A. RichAsteraceae—HAM056Dicrocephala integrifolia (L.f.) KuntzeAsteraceae—HAM105Diospyros abyssinica (Hiern) F. WhiteEbenaceaeLookooTAM153Diospyros mespiliformis Hochst. ex A.DCEbenaceaeKolatiTAM176Discopodium eremanthum Chiov.SolanaceaeMeraroSAM084Dracaena afromontana Mildbr.DracaenaceaeRuukeessaTAM194Echinops hoehnelii Schweinf.AsteraceaeQore HareeSAM099Echinops macrochaetus Fresen.AsteraceaeTuqa, QoreeHAM036Ehretia cymosa Thonn.BoraginaceaeUlaagaaTAM135Elaeodendron buchananii (Loes) Loes.CelasteraceaeXillooTAM137Entada abyssinica Steudel ex A. Rich.MimosoideaeKontirSAM075Erica arborea L.EricaceaeSatooS/TAM073Erica trimera (Engl.) BeentjeEricaceae—SAM065Erythrina brucei Schweinf.FabaceaeWaleensuTAM175Euclea schimperi (A.DC.) DandyEbenaceaeMiheesaTAM164Euphorbia depauperata A. Rich.EuphorbiaceaeGuri XixiqoHAM010Euphorbia dumalis S. CarterEuphorbiaceaeGuriiSAM090Eurynchium pulchellum (Hedw.) Jenn.BrachytheciaceaeHasufe (O), Mosses (E)EAM044Euryops prostratus B. Nordenst.Asteraceae—SAM051Fagaropsis angolensis (Engl.) MilneRutaceaeSiisaaTAM150Ferula communis L.ApiaceaeGnidaHAM014Festuca abyssinica A.Rich.Poaceae—HAM062Ficus vasta Forssk.MoraceaeQiltuTAM169Filicium decipiens (Wight & Am.) Thw.SapindaceaeCaanaaTAM156Flacourtia indica (Burm.f.) Merr.SalicaceaeHokokuSAM180Galium simense Fresen.RubiaceaeMaxxaneHAM016Geranium arabicum Forssk.GeraniaceaeBuchaHAM068Geranium kilimandscharicum Engl.GeraniaceaeBalee TiqoHAM097Gouania longispicata Engl.RhamnaceaeWayebossaaH(clim)AM128Grevillea robusta A. Cunn. ex R. Br.ProteaceaeGrevilleaTAM170Gynura pseudochina (L.) DC.AsteraceaeRaffuHAM101Habenaria peristyloides A. Rich.OrchidaceaeKerkashawHAM112Hagenia abyssinica (Bruce) J.F. Gmel.RosaceaeHexxooTAM082Haplocarpha rueppellii (Sch. Bip.) Beauv.Asteraceae—HAM113Hebenstretia angolensis RolfeScrophulariaceae—HAM104Hebenstretia dentata L.Scrophulariaceae—HAM032Helichrysum citrispinum Del.Asteraceae—SAM042Helichrysum foetidum (L.) Moench.Asteraceae—HAM011Helichrysum formosissimum (Sch.Bip.) Sch.Bip. ex A.Rich.Asteraceae—SAM063Helichrysum globosum A. Rich.Asteraceae—HAM024Helichrysum gofense Cufod.Asteraceae—HAM006Helichrysum harenensis Mesfin.AsteraceaeUfea/HoffiiHAM039Helichrysum quartitianum A. Rich.AsteraceaeAgadenaHAM095Helichrysum schimperi (Sch. Bip. ex A. Rich.) MoeserAsteraceaeBaduberaHAM048Helichrysum splendidum (Thunb.) Less.AsteraceaeBaduberaSAM001Hibiscus calyphyllus Cavan.MalvaceaeHincinniHAM146Hippocratea africana (Willd.) Loes.CelasteraceaeGaguroH(clim)AM145Hippocratea goetzei LoesCelasteraceaeGaalee GaguroH(clim)AM152Hippocratea pallens Planchon ex OliverCelasteraceaeXara'aH(clim)AM147Hydrocotyle mannii Hook.f.Apiaceae—HAM072Hypericum peplidifolium A. Rich.HypericaceaeHAM035Hypericum revolutum VahlHypericaceaeGerembaT/SAM002Hypericum scioanum Chiov.Hypericaceae—HAM031Inula confertiflora A. Rich.AsteraceaeHaxxawiiSAM197Jasminum abyssinicum Hochst. ex DcOleaceaeDikiiH(clim)AM123Juniperus procera L.CupressaceaeHindessaTAM083Kalanchoe petitiana A. Rich.Crassulaceae—SAM103Kniphofia foliosa Hochst.AsphodelaceaeLelaHAM008Kniphofia insignis RendleAsphodelaceaeLela XixiqoHAM027Kniphofia isoetifolia Steud. ex Hochst.AsphodelaceaeLela XixiqoHAM013Landolphia buchananii (Hall.f.) StapfApocynaceaeHombaH(clim)AM151Lannea schimperi (Hochst. ex A.Rich.) Engl.AnacardiaceaeAndarkuSAM185Leonotis ocymifolia (Burm.f.) IwarssonLamiaceaeBokoluSAM202Lepidotrichilia volkensii (Gurke) LeroyMeliaceaeSaakarroTAM148Leucaena leucocephala (Lam.) de WitMimosoideaeLucinaaSAM189Lobelia rhyncopetalum Hemsl.LobeliaceaeTaruurra(O), Jibra(Am)SAM041Macaranga capensis (Baill.) SimEuphorbiaceaeArgooTAM140Malva verticillata L.MalvaceaeLitaSAM029Mangifera indica L.AnacardiaceaeMangoTAM162Margaritaria discoidea (Baill.) WebsterPhyllanthaceaeBulalaTAM141Maytenus arbutifolia (A. Rich.) WilczekCelastraceaeKombolchaTAM173Maytenus obscura (A. Rich.) Cuf.CelastraceaeKombolcha, Duqusha (Or.)SAM091Maytenus undata (Thunb.) BlakelockCelastraceaeKombolchaSAM100Melia azedarach L.MeliaceaeKinin zafTAM191Mimusops kummel A.DC.SapotaceaeQolatiTAM120Moraea schimperi (Hochst.) Pic.-Serm.IridaceaeLogaSAM115Myrsine africana L.MyrsinaceaeQachamoSAM203Myrsine melanophoeos (L.) R. Br.MyrsinaceaeTuullaaTAM074Nepeta azurea R.Br. ex Benth.Lamiaceae—SAM003Ocotea kenyensis (Chiov.) Robyns & WilczekLauraceaeGigichaTAM118Oldenlandia herbacea (L.) Roxb.RubiaceaeOmachessaaHAM028Olea capensis L.ssp. macrocarpa (C.H.Wright)Verdc.OleaceaeGagamaTAM132Olea europaea L. subsp. cuspidata (Wall.ex G.Don)OleaceaeEjerssaaTAM157Olea welwitschii (Knobl.) Gilg. & Schellenb.OleaceaeOnomaaTAM134Osyris compressa (P.J.Bergius) A.DC.SantalaceaeWaatooSAM183Osyris quadripartita Decne.SantalaceaeKaroSAM198Pentaschistis minor (Ballard & C.E.Hubb.) Ballard & C.E.Hubb.Poaceae—HAM061Phytolacca dodecandra L´Herit.PhytolaccaceaeHandodeH(clim)AM205Piliostigma thonningii (Schum.)FabaceaeLilluuTAM165Plantago africana Verdc.PlantaginaceaeQinxaa, BaalleeHAM045Podocarpus falcatus (Thunb) C.NPodocarpaceaeBirbirssaaTAM130Poecilostachys oplismeoides (Hack.) W.D.ClaytonPoaceaeDaaffaHAM144Polygala steudneri Chod.PolygalaceaeGrisa/GarasitaHAM005Polyscias fulva (Hiern) HarmsAraliaceaeKooribaaTAM139Polystichum ammifolium (Poir.) C.Chr.DryopteridaceaeQumbuta, GammanyeeHAM069Pouteria adolfi-friederici (Engl.) BaehniSapotaceaeGudubaTAM138Pseudognaphalium luteo-album (L.) Hilliard and BurttAsteraceae—HAM070Psidium guajava L.MyrtaceaeZeytunaSAM177Psychotria orophila PetitRubiaceaeUlaagaaSAM154Psydrax schimperiana Spermacoce L.RubiaceaeGalleTAM149Pteris confusa (Lansgd & Fisch.) KuhnPteridaceaeQumbutaHAM126Ranunculus multifidus Forssk.RanunculaceaeSherifHAM077Rapanea melanophloeos (L.) MezMyrsinaceaeTullaTAM196Rhus natalensis (Bernh. ex Krauss) F.A.BarkleyAnacardiaceaeDabaqaaSAM171Ricinus communis L.EuphorbiaceaeKoboo, GuloSAM179Rosa abyssinica LindleyRosaceaeGoraSAM093Rubus erlangeri Engl.RosaceaeHatoSAM004Rubus steudneri Schwienf.RosaceaeGoraSAM086Rumex abyssinicus Jacq.PolygonaceaeShabee HagaHAM050Rumex nepalensis Spreng.PolygonaceaeShabeeHAM021Rytidosperma subulata (A. Rich.) CopePoaceaeMarga Hori, QechaHAM110Salvia merjame Forssk.LamiaceaeOkotuSAM015Salvia nilotica Jacq.LamiaceaeOkotuHAM030Sanicula elata Buch. -Ham. ex D.DonApiaceaeGalee Simbira, SidissaHAM079Satureja simensis (Benth.) Briq.LamiaceaeToshimbataHAM049Scabiosa columbaria L.DipsacaceaeAnamuroHAM067Schefflera abyssinica Forst. & Forst. f.,AraliaceaeGatameeTAM136Schefflera volkensii (Engl.) HarmsAraliaceaeAnshaTAM204Schinus molle L.AnacardiaceaeQondabarbereTAM166Senecio ochrocarpus Oliv. and HiernAsteraceaeAgadenaHAM046Senecio ragazzii Chiov.AsteraceaeAgadenaHAM089Senecio schultzii Hochst. ex A.Rich.Asteraceae—HAM057Setaria megaphylla (Steud.) T.Durand & Schinz.PoaceaeSookoraHAM127Solanum anguivi Lam.SolanaceaeMujule WorabessaSAM111Solanum garae FriisSolanaceae—SAM085Solanum marginatum L.f.SolanaceaeHidiiSAM076Spathodea campanulata (S.nilotica)BignoniaceaeHoroqaTAM182Sporobolus africanus (Poir.) Robyns and TournayPoaceaeMarga Hilensa (Or)HAM088Sporobolus pyramidalis P.Beauv.PoaceaeChitaHAM124Stellaria sennii Chiov.CaryophyllaceaeDuqushu, DinbibaHAM108Strychnos mitis S. MooreLoganiaceaeMuluqaaTAM133Swertia lugardae BullockGentianaceae—HAM053Syzygium guineense (Willd.) DC.MyrtaceaeBadeesaTAM117Teclea nobilis Del.RutaceaeHadheessaTAM184Thymus schimperi RonnigerLamiaceaeTossigneHAM047Trema orientalis (L.) Bl.UlmaceaeTala’aaTAM188Trifolium acaule Steud. ex A.Rich.Fabaceae—HAM059Trifolium rueppellianum Fresen.FabaceaeSidissa (Maget)HAM092Trifolium semipilosum Fresen.FabaceaeSidissaHAM019Trifolium simense Fresen.Fabaceae—HAM034Trifolium substerraneum L.FabaceaeSidisa (O), Alfalfa(E)HAM038Triumfetta pentandra A. RichMalvaceaeGurbiiH(clim)AM125Ursinia nana DC.AsteraceaeQinxxaHAM022Urtica dioecia L.UrticaceaeDobi(Or), Sama(Amh)SAM158Urtica simensis SteudelUrticaceaeDobiiHAM109Vepris dainellii (Pichi-Serm.) KokwaroRutaceaeArabeTAM129Vernonia amygdalina Del.AsteraceaeEbichaSAM192Vernonia auriculiferaHiern.AsteraceaeRejiiSAM193Warburgia ugandensis SpragueCanellaceaeBifi, kanafaTAM142Zehneria scabra (Linn.f.) Sond.CucurbitaceaeHarolaH(clim)AM096Ziziphus abyssinicaA.Rich.RhamnaceaeKankuraSAM195H, herb; S, shrub; T, tree; Li, liana; H (clim), herbaceous climber; E, epiphyte; PH, parasitic herb; Or., Oromifa; Coll. no., collection number.Woody species density with DBH°>°2 cm was 1567 individuals ha−1. This was relatively higher compared to other similar vegetation areas such as the Wof-Washa forest [48] and Agama forest [45]. The most frequent woody species was Croton macrostachyus Hochst. ex Del with 81% frequency followed by Juniperus procera L. (79%), Podocarpus falcatus (Thunb) C.N (63%), and Hagenia abyssinica (Bruce) J.F. Gmel (60%). Conversely, the total basal area of woody species was 170.26 m2 ha−1, and it was considerably higher compared to other similar vegetation areas in Ethiopia. About 75% of the basal area was contributed by five tree species such as Juniperus procera (46.71 m2 ha−1), Syzygium guineense (Willd.) DC (24.76 m2 ha−1), Cordia africana Lam (20.95 m2 ha−1), Hagenia abyssinica (18.47 m2 ha−1), and Ehretia cymose Thonn (15.86 m2 ha−1). Consequently, Juniperus procera was the dominant woody species with an IVI of 26.43. The species with higher IVI values in the study area was among the characteristic species in similar vegetation types in Ethiopia [49, 50].


### 3.3. Floristic Composition and Structure in the Edge and Interior Habitat

A total of 136 species belonging to 111 genera and 59 families were identified in the edge habitats of the sampled patches, whereas 117 species that belonging to 84 genera and 40 families were recorded in the interior habitats. From the identified life forms, 19 species were trees, 22 species were shrubs, 86 species were herbs, and 7 species were lianas in the edge habitats, whereas 28 species were trees, 21 species were shrubs, 57 species were herbs, and 11 species were lianas in the interior habitats. The overall means (±SE) species richness (35 ± 4.2), Shannon diversity index (2.93 ± 0.17), and Margalef index (5.68 ± 0.69) of the edge habitat were significantly higher compared to the interior habitat atp<0.05 (Table 3). These variations could be due to the differences in site productivity, habitat heterogeneity, and disturbance factors [44, 51] or the invasion of exotic plant species [52]. However, the woody species richness in the interior habitat (28) was significantly higher than the edge (17). Moreover, the evenness index in the interior habitats (0.83 ± 0.04) was higher, but not significant, than the edge habitat (0.79 ± 0.05). This result was in agreement with the finding in [53]. Abiotic factors, seed predation, loss of pollinators and seed dispersers, and tree mortality were reported as the common causes for the differences in woody species composition between the edge and interior habitats [53, 54]. The computed Sorensen’s similarity index depicted that the number of species in the edge habitats was 45% similar to the species in the interior habitats. This value indicated that the similarity between the edge and interior habitat was weak [13]. The mean density of seedling (995.42 ± 19.27 individuals ha−1), sapling (509.29 ± 9.06 individuals ha−1), and mature trees (187.60 ± 4.70 individuals ha−1) in the interior habitat was significantly higher compared to the edge. This indicates that the recruitment potential of the interior forest was significantly higher compared to the edge habitat [48]. This could be due to the increased mortality rates of seedling, sapling, and mature trees in the edge habitats [53, 55].Table 3
Mean (±SE) values of species richness and diversity indices.
Diversity indicesEdge habitatInterior habitatSpecies richness (S)35 ± 4.2a29 ± 3.6bSimpson index (D)0.10 ± 0.020.11 ± 0.03Shannon–Wiener index (H′)2.93 ± 0.17a2.43 ± 0.11bPielou’s evenness index (J′)0.79 ± 0.050.83 ± 0.04Whittakerβ-diversity (βw)1.83 ± 0.261.34 ± 0.31Margalef index (DM)5.68 ± 0.69a3.72 ± 0.92bBerger–Parker index (d)0.19 ± 0.030.24 ± 0.04Note. Values with different letters indicate significant differences between habitats (p=0.05).The mean woody species density in the interior habitat (85 ± 22.17 stems ha−1) was significantly higher compared to the edge habitat (70 ± 16.53 stems ha−1) at p<0.05 (Figure 2(a); Tables 4 and 5). This could be due to the selective cutting of trees for timber production, house construction, and firewood in the edge habitats, which ultimately leads to a reduction in the density of large trees and greater canopy openness [56]. Moreover, the seedlings are most affected by edge effect due to their sensitivity to environmental changes and biotic interactions [57, 58]. Conversely, the mean basal area of woody species in the interior habitat (11.16 ± 1.82 m2 ha−1) was significantly higher than the edge habitat (3.99 ± 0.54 m2 ha−1) at p<0.05 (Figure 2(b); Tables 4 and 5). This was due to the significantly higher mean DBH (78.62 ± 4.56 cm, p<0.001) and height (33.63 ± 2.71 m, p<0.05) of woody species [59] in the interior habitat than the edge. There were 27.32% of larger diameter individual tree species with DBH > 100 cm recorded in the interior habitat, whereas 4.09% of individuals with DBH > 100 cm were identified in the edge habitat. Microenvironmental conditions such as high temperature, low relative humidity, high wind force, low soil nutrient, and litter moisture in the edge habitats may contribute to the changes in tree abundance and distribution in the forest [60, 61].Figure 2
Box plot showing woody species density (a) and basal area (b) in the habitats.
(a)(b)Table 4
Woody species structure in the edge habitats of the BMNP.
SpeciesAbundanceBasal area (m2 ha−1)Density (stem ha−1)Relative densityRelative frequencyRelative dominanceIVICeltis africana121.9491.796.355.1813.32Cordia africana104.1581.494.7614.8121.06Croton macrostachyus222.34173.286.356.2715.90Diospyros abyssinica30.9520.451.595.087.12Ehretia cymosa127.3191.794.7615.6422.19Hagenia abyssinica326.84254.787.9414.6227.34Hypericum revolutum1741.9313625.9711.112.9540.03Juniperus procera906.637013.4312.708.8735.00Lepidotrichilia volkensii40.4830.603.172.596.36Macaranga capensis60.4450.903.172.346.41Maytenus undata540.00428.064.760.0012.82Myrsine melanophoeos1700.2813325.377.940.6133.92Olea capensis41.0830.604.765.7811.14Olea welwitschii60.1750.901.591.794.27Podocarpus falcatus400.68315.9712.701.2119.88Pouteria adolfi-friederici30.1920.451.592.014.05Syzygium guineense286.70224.184.7610.2419.18Total67042.13523100100100300IVI: importance value index.Table 5
Woody species structure in the interior habitats of the BMNP.
SpeciesAbundanceBasal area (m2 ha−1)Density (stem ha−1)Relative densityRelative frequencyRelative dominanceIVIAllophylus macrobotrys60.7150.792.861.765.41Celtis africana160.25132.123.810.466.39Croton macrostachyus1428.6411118.816.679.1534.62Diospyros abyssinica40.0830.531.900.583.01Ehretia cymosa740.83589.804.762.0616.62Erica arborea30.0220.451.590.172.20Elaeodendron buchananii180.42142.384.760.627.77Fagaropsis angolensis30.0220.400.950.181.53Hagenia abyssinica4010.43315.307.629.6722.58Hypericum revolutum80.0561.066.670.187.90Juniperus procera12831.5410016.957.6229.2453.81Lepidotrichilia volkensii40.0130.530.950.111.59Macaranga capensis60.0350.791.900.122.82Margaritaria discoidea40.0330.531.900.132.56Maytenus undata490.06386.492.860.169.50Mimusops kummel30.0420.400.950.271.62Myrsine melanophoeos320.10254.241.900.376.51Ocotea kenyensis321.13254.246.671.2012.10Olea europaea80.7261.061.901.774.73Olea welwitschii60.1750.792.861.244.89Podocarpus falcatus786.666110.337.626.1824.13Polyscias fulva30.2420.400.951.793.14Pouteria adolfi-friederici82.6161.063.814.839.70Psydrax schimperiana40.0830.531.900.312.74Schefflera abyssinica30.2020.400.951.492.84Strychnos mitis280.28223.713.810.528.04Syzygium guineense359.55274.646.6723.6034.90Vepris dainellii40.2530.531.900.943.37Warburgia ugandensis60.2550.791.900.943.64Total75575.41590100100100300IVI: importance value index.Juniperus procera was the dominant woody species in the edge habitat with an IVI of 32.49, whereas Croton macrostachyus was dominant in the interior habitat with an IVI of 40.61 (Tables 5 and 6). Accordingly, Juniperus procera, Hagenia abyssinica, and Syzygium guineense were identified as generalists that abundantly occurred in both edge and interior habitats, whereas Hypericum revolutum Vahl. was identified as marginalized species that characteristically dominated the edge habitats [62, 63]. However, no woody species was found as a specialist that typically occurred in the interior habitats.Table 6
IVI of woody species in the edge and interior habitats.
SpeciesRelative density (%)Relative frequency (%)Relative dominance (%)IVIEdgeInteriorEdgeInteriorEdgeInteriorEdgeInteriorJuniperus procera11.7220.138.7911.9411.9825.0332.4937.10Croton macrostachyus2.8622.334.4010.458.477.8315.7340.61Hagenia abyssinica5.215.035.4911.9419.768.2830.4725.25Syzygium guineense3.655.357.694.4813.8420.2125.1830.03Podocarpus falcatus5.2112.266.5911.941.645.2913.4429.49Myrsine melanophoeos22.145.035.492.990.820.3128.458.33Ehretia cymosa1.5611.643.307.464.019.298.8728.38Hypericum revolutum22.66—7.69—3.99—34.34—Cordia africana1.57—4.48—8.79—14.84—Ocotea kenyensis4.17—7.69—2.33—14.19—


### 3.4. Effects of Landscape Change in Floristic Composition and Structure

The computed regression analysis among the landscape indices and species composition and structural parameters in this study revealed that only PN and AREA_MN significantly affected both the species composition and structural properties of the study area. Accordingly, PN was strong and negatively affected the overall species richness (r = −0.90, p<0.05) and Shannon diversity index (r = −0.96, p<0.01) (Table 7). Conversely, the overall species richness (r = 0.95, p<0.05) and Shannon diversity (r = 0.87, p<0.05) have shown strong and positive correlation with AREA_MN. This implies that as the number of fragmented habitats increases, species richness and diversity, particularly interior-dependent species, decreases. However, edge-dependent species comfortably flourished. One of the consequences of habitat fragmentation is an increase in the proportional abundance of the edge influenced habitat and its adverse impacts on interior-sensitive species [64]. Undoubtedly, while some species (e.g., habitat specialists) suffer from fragmentation, others benefit from it (e.g., generalists and edge species) [65]. Consequently, PN was strong and negatively correlated with AREA_MN (r = −0.71, p<0.001). This implies that as the PN increases, the area of fragments decreases; as a result, small fragments contain a smaller species richness and lower species density than large fragments [66]. Large areas of habitat tend to support more individuals and, hence, more species [67].Table 7
Pearson's correlation coefficient between the landscape indices and floristic composition and structural parameters.
S1H′0.95∗1BA0.96∗0.94∗1Density0.99∗∗0.90∗0.93∗1PN−0.90∗−0.96∗−0.96∗∗−0.84∗1AREA_MN0.95∗0.87∗0.82∗0.72∗−0.71∗∗∗1SHAPE_AM−0.42−0.64−0.53−0.280.48∗−0.011COA−0.56−0.370.340.66−0.87∗0.41−0.79∗∗∗1ED0.650.78−0.77−0.540.54∗−0.910.25−0.161ENN_MN−0.37−0.56−0.59−0.280.77∗∗∗−0.260.73∗∗−0.81∗∗∗0.041IJI−0.42−0.28−0.32−0.370.58∗−0.59∗∗0.37−0.610.370.17321SH′BADensityPNAREA_MNSHAPE_AMCOAEDENN_MNIJINote. The star indicates significant level between values (∗p<0.05, ∗∗p<0.01, and ∗∗∗p<0.001).Besides, modifying the spatial pattern of the landscape habitat size reduction and increase in isolation cause an alteration in the dispersal rate, affecting survival and mortality of individuals [8]. Many population and community changes in habitat fragments were commonly attributed to edge effects [66]. Interior species may be affected by the size decrease in their habitat, by edge effect, and by competition with generalists [68, 69]. The most threatened endemic species due to edge effect in the BMNP were Helichrysum harennense Mesfin, Kniphofia insignis Rendle, Rubus erlangeri Engl., and Vepris dainellii Pichi Serm Kokwaro. Also, the most common invasive species in the study area favored by edge effect was Achyranthes aspera L, which is also common in the disturbed forests and forest edges of the dry Afromontane forests and moist Afromontane forests in Ethiopia [70]. The gradual decline in the more sensitive species may induce a species turnover in fragments and cascade effects [62, 63].Among the landscape indices computed, only PN and AREA_MN significantly affected some of the floristic structural properties assessed. Thus, the PN was strong and negatively affected the woody species density (r = −0.84, p<0.05) and basal area (r = −0.96, p<0.01), as well as AREA_MN was strong and positively affected the density (r = 0.71, p<0.05) and basal area (r = 0.82, p<0.05) of woody species. Habitat destruction, isolation, and transformation affect the structure and dynamics of populations, communities, and ecosystems, as well as ecological processes [71]. Generally, as AREA_MN and COA of patches increase, species richness, diversity, evenness, woody species density, basal area, DBH, and height also increase. However, as PN, SHAPE_MN, ED, ENN_MN, and IJI of patches increase, floristic composition and structural variables decrease. This implies that the landscape composition and configuration change may potentially affect the vegetation composition and structure of a particular area.


## 3.1. Landscape Structure Change

The analysis of landscape structure in this study revealed that the habitats in the BMNP are progressively transformed. The area has shown an increase in PN by 40.2% and a decrease in AREA_MN by 28.7% from 1985 to 2017. According to Oertli et al. [39], the high number of separated patches in a habitat indicates a high level of fragmentation. Across the entire study period, SHAPE_AM, which indicates the complexity of patch shape, increased by 18.8%. A higher perimeter-area relationship characterizes the rapid rate of fragmentation in the landscape [40]. Moreover, there was inconsistency in the values of ED; however, it was increased by 22.3% over the study period. As it was emphasized by McGarigal [37], the oscillation of ED indicated a major reduction in the spatial heterogeneity of the landscape. Conversely, the study area has shown a declining trend in TCA by 10.6% from 1985 to 2017. This was due to the escalated level of disturbances in the study area. As it was reported by Kidane et al. [41], the most dominant practices in the Bale Mountains, especially after 1995, were the upward expansion of agriculture and enrichment plantation.The isolation of patches within the landscape of the study area was increased from 105.22 m to 111.94 m overtime (Table1). This result is in agreement with the result reported by Tolessa et al. [42] in the central highlands of Ethiopia and Daye [26] in Southwest Ethiopia. Conversely, the intermixing of patches in the study area showed an overall declining trend from 95.38 to 86.77 over the study period. This result showed that the BMNP constitutes more scattered patches compared to other similar areas studied by Posada Posada [43] and Tolessa et al. [42].Table 1
Landscape structural characteristic of the BMNP from 1985 to 2017.
YearNPAREA_MN (ha)SHAPE_AMTCA (km2)ED (m/m2)ENN_MN (m)IJI (%)1985258648.4224.971568.9160.53107.2777.691995305827.1224.121489.1069.18105.2279.292005293297.4229.361471.0266.44111.9470.782017362676.0029.671402.5974.02109.2175.46%40.22−28.6818.83−10.6022.281.81−2.87Note. The negative sign of percentage implies a decreasing trend, and the positive sign implies an increasing trend.


## 3.2. Overall Floristic Composition and Structure

A total of 205 plant species belonging to 71 families and 153 genera were recorded (Table2). Of these, 50 species were trees, 52 were shrubs, 12 were lianas, and 91 were herbs. Asteraceae was the most dominant family with 31 species, followed by Fabaceae with 11 species. Conversely, Helichrysum was the most abundant genus with 9 species, followed by Alchemilla and Trifolium with 5 species each. Twenty endemic species, including Euphorbia dumalis S. Carter, Lobelia rhynchopetalum Hemsl., and Thymus schimperi subsp. Schimperi Ronniger was identified in this study. The overall Shannon diversity and evenness index of the study area were 4.34 and 0.81, respectively. This indicated that the study area was more diverse compared to other similar vegetation areas including Bonga forest [44], Agama forest [45], and Munessa forest [13]. Conversely, the total density of seedlings, saplings, and mature trees in the study area was 8751, 4413, and 1567 individuals ha−1, respectively. This was lower than other comparable areas such as Kuandisha forest [46] and Wof-Washa forest [47]. The ratios of seedling to mature tree, sapling to mature tree, and seedling to sapling were 5.58, 2.82, and 1.98, respectively. This shows the recruitment potential of the forest is relatively higher [48].Table 2
List of plant species identified in the BMNP.
Scientific nameFamilyLocal name (Or.)HabitColl. no.Acacia oerfota (Forssk.) Schweinf.FabaceaeWangaSAM168Acacia senegal (L.) Willd.CelastraceaeKarxafaSAM172Achyranthes aspera L.AmaranthaceaeRoppe, Qorsa WaranssaHAM094Agrostis sclerophylla C.E. Hubb.PoaceaeMergeseriHAM009Ajuga bracteosa Wall. ex Benth. in Wall.Lamiaceae—HAM078Albizia gummifera (J. F. Gmel.) C.A.Sm.MimosaceaeKarchofeTAM174Alchemilla abyssinica Fresen.RosaceaeHindriffHAM043Alchemilla cryptantha Steud. ex A Rich.RosaceaeHindriffHAM159Alchemilla haumanii Rothm.Rosaceae—HAM055Alchemilla pedata A. Rich.RosaceaeHindriff, IndriifHAM017Alchemilla rothii Oliv.Rosaceae—HAM052Alepidea peduncularis Steud. ex A. Rich.Apiaceae—HAM060Allophyllus macrobotrys GilgSapindaceaeAbaraTAM131Allophylus abyssinicus (Hochst.) Radlk.SapindaceaeSararaTAM178Anaptychia liucomeleana Wain.PhysciaceaeLichenHAM054Annona reticulata L.AnnonaceaeGishtaTAM161Anthemis tigreensis J. Gay ex A. Rich.Asteraceae—HAM012Argemone mexicana L.PapaveraceaeQore HareeHAM018Artemisia afra Jacq. ex Willd.AsteraceaeTepenea, TepenoHAM007Asparagus africanus Lam.AsparagaceaeSeritiSAM199Asplenium aethiopicum (Burm.f.) Bech.AspleniaceaeQumbutaHAM155Astragalus atropilosulus (Hochst.) BangeFabaceaeHaraEAM037Bidens macroptera (Sch. Bip. ex Chiov.) MesfinAsteraceaeHade golaHAM040Blyttia fruticulosum (Decne.) D.V.FieldApocynaceaeHombaH(clim)AM122Brachycorythis buchananii (Schltr.) RolfeOrchidaceaeShumbura galaHAM066Bromus pectinatus Thunb.PoaceaeAlanmuressaHAM106Calpurnia aurea (Ait.) Benth.FabaceaeCheekataSAM167Carduus leptacanthus Fresen.AsteraceaeQore HareeHAM107Carduus nyassanus (S. Moore) R.E. FriesAsteraceaeQore HareeHAM033Carissa edulis (Forssk.) VahlApocynaceaeHagamssa(Or), Agam(Amh)SAM181Carissa spinarum L.ApocynaceaeHarangmaSAM200Casimiroa edulis La Llave & Lex.RutaceaeKasmiraTAM163Catha edulis (Vahl) Forssk. ex Endl.CelastraceaeJimaaSAM143Celtis africana Burm.f.UlmaceaeMeteqammaTAM116Centella asiatica (L.) Urb.ApiaceaeBalee, QuduHAM064Cerastium afromontanum T.C.E. Fr. & Weim.CaryophyllaceaeDuqusha chuffaHAM087Citrus aurantifolia (Christm.) SwingleRutaceaeLomiiSAM186Citrus sinensis (L.) OsbeckRutaceaeBurtukanaSAM187Clematis hirsuta Perr. & Guill.RanunculaceaeFitiiLiAM114Coffea arabica L.RubiaceaeBuunaSAM121Combretum ghasalense Engl. & DielsCombretaceaeDhandhaasaTAM190Commelina africana L.CommelinaceaeGura JarsaHAM020Cordia africana Lam.BoraginaceaeWodessaTAM160Craterostigma plantagineum HochstetterScrophulariaceae—HAM102Crepis carbonaria Sch. Bip.AsteraceaeMarga HoffiHAM025Crepis ruepellii Sch. Bip.Asteraceae—HAM071Crotolaria agatiflora Schweinf. Sub.sp. ErlangeriBak. F.FabaceaeShashamaneSAM201Croton macrostachyus Hochst. ex Del.EuphorbiaceaeMakkannisaTAM119Cuscuta kilimanjari Oliv.ConvolvulaceaeSegenitiH(clim)AM098Cycniopsis humifusa (Forssk.) Engl.Scrophulariaceae—HAM080Cynoglossum amplifolium Hochst. ex DC.BoraginaceaeQarccabbaaHAM081Cynoglossum coeruleum Hochst.BoraginaceaeQarccabbaaHAM026Cynoglossum lanceolatum Forssk.Boraginaceae—HAM058Cyperus schimperianus Steud.CyperaceaeAlandoHAM023Dianthoseris schimperi A. RichAsteraceae—HAM056Dicrocephala integrifolia (L.f.) KuntzeAsteraceae—HAM105Diospyros abyssinica (Hiern) F. WhiteEbenaceaeLookooTAM153Diospyros mespiliformis Hochst. ex A.DCEbenaceaeKolatiTAM176Discopodium eremanthum Chiov.SolanaceaeMeraroSAM084Dracaena afromontana Mildbr.DracaenaceaeRuukeessaTAM194Echinops hoehnelii Schweinf.AsteraceaeQore HareeSAM099Echinops macrochaetus Fresen.AsteraceaeTuqa, QoreeHAM036Ehretia cymosa Thonn.BoraginaceaeUlaagaaTAM135Elaeodendron buchananii (Loes) Loes.CelasteraceaeXillooTAM137Entada abyssinica Steudel ex A. Rich.MimosoideaeKontirSAM075Erica arborea L.EricaceaeSatooS/TAM073Erica trimera (Engl.) BeentjeEricaceae—SAM065Erythrina brucei Schweinf.FabaceaeWaleensuTAM175Euclea schimperi (A.DC.) DandyEbenaceaeMiheesaTAM164Euphorbia depauperata A. Rich.EuphorbiaceaeGuri XixiqoHAM010Euphorbia dumalis S. CarterEuphorbiaceaeGuriiSAM090Eurynchium pulchellum (Hedw.) Jenn.BrachytheciaceaeHasufe (O), Mosses (E)EAM044Euryops prostratus B. Nordenst.Asteraceae—SAM051Fagaropsis angolensis (Engl.) MilneRutaceaeSiisaaTAM150Ferula communis L.ApiaceaeGnidaHAM014Festuca abyssinica A.Rich.Poaceae—HAM062Ficus vasta Forssk.MoraceaeQiltuTAM169Filicium decipiens (Wight & Am.) Thw.SapindaceaeCaanaaTAM156Flacourtia indica (Burm.f.) Merr.SalicaceaeHokokuSAM180Galium simense Fresen.RubiaceaeMaxxaneHAM016Geranium arabicum Forssk.GeraniaceaeBuchaHAM068Geranium kilimandscharicum Engl.GeraniaceaeBalee TiqoHAM097Gouania longispicata Engl.RhamnaceaeWayebossaaH(clim)AM128Grevillea robusta A. Cunn. ex R. Br.ProteaceaeGrevilleaTAM170Gynura pseudochina (L.) DC.AsteraceaeRaffuHAM101Habenaria peristyloides A. Rich.OrchidaceaeKerkashawHAM112Hagenia abyssinica (Bruce) J.F. Gmel.RosaceaeHexxooTAM082Haplocarpha rueppellii (Sch. Bip.) Beauv.Asteraceae—HAM113Hebenstretia angolensis RolfeScrophulariaceae—HAM104Hebenstretia dentata L.Scrophulariaceae—HAM032Helichrysum citrispinum Del.Asteraceae—SAM042Helichrysum foetidum (L.) Moench.Asteraceae—HAM011Helichrysum formosissimum (Sch.Bip.) Sch.Bip. ex A.Rich.Asteraceae—SAM063Helichrysum globosum A. Rich.Asteraceae—HAM024Helichrysum gofense Cufod.Asteraceae—HAM006Helichrysum harenensis Mesfin.AsteraceaeUfea/HoffiiHAM039Helichrysum quartitianum A. Rich.AsteraceaeAgadenaHAM095Helichrysum schimperi (Sch. Bip. ex A. Rich.) MoeserAsteraceaeBaduberaHAM048Helichrysum splendidum (Thunb.) Less.AsteraceaeBaduberaSAM001Hibiscus calyphyllus Cavan.MalvaceaeHincinniHAM146Hippocratea africana (Willd.) Loes.CelasteraceaeGaguroH(clim)AM145Hippocratea goetzei LoesCelasteraceaeGaalee GaguroH(clim)AM152Hippocratea pallens Planchon ex OliverCelasteraceaeXara'aH(clim)AM147Hydrocotyle mannii Hook.f.Apiaceae—HAM072Hypericum peplidifolium A. Rich.HypericaceaeHAM035Hypericum revolutum VahlHypericaceaeGerembaT/SAM002Hypericum scioanum Chiov.Hypericaceae—HAM031Inula confertiflora A. Rich.AsteraceaeHaxxawiiSAM197Jasminum abyssinicum Hochst. ex DcOleaceaeDikiiH(clim)AM123Juniperus procera L.CupressaceaeHindessaTAM083Kalanchoe petitiana A. Rich.Crassulaceae—SAM103Kniphofia foliosa Hochst.AsphodelaceaeLelaHAM008Kniphofia insignis RendleAsphodelaceaeLela XixiqoHAM027Kniphofia isoetifolia Steud. ex Hochst.AsphodelaceaeLela XixiqoHAM013Landolphia buchananii (Hall.f.) StapfApocynaceaeHombaH(clim)AM151Lannea schimperi (Hochst. ex A.Rich.) Engl.AnacardiaceaeAndarkuSAM185Leonotis ocymifolia (Burm.f.) IwarssonLamiaceaeBokoluSAM202Lepidotrichilia volkensii (Gurke) LeroyMeliaceaeSaakarroTAM148Leucaena leucocephala (Lam.) de WitMimosoideaeLucinaaSAM189Lobelia rhyncopetalum Hemsl.LobeliaceaeTaruurra(O), Jibra(Am)SAM041Macaranga capensis (Baill.) SimEuphorbiaceaeArgooTAM140Malva verticillata L.MalvaceaeLitaSAM029Mangifera indica L.AnacardiaceaeMangoTAM162Margaritaria discoidea (Baill.) WebsterPhyllanthaceaeBulalaTAM141Maytenus arbutifolia (A. Rich.) WilczekCelastraceaeKombolchaTAM173Maytenus obscura (A. Rich.) Cuf.CelastraceaeKombolcha, Duqusha (Or.)SAM091Maytenus undata (Thunb.) BlakelockCelastraceaeKombolchaSAM100Melia azedarach L.MeliaceaeKinin zafTAM191Mimusops kummel A.DC.SapotaceaeQolatiTAM120Moraea schimperi (Hochst.) Pic.-Serm.IridaceaeLogaSAM115Myrsine africana L.MyrsinaceaeQachamoSAM203Myrsine melanophoeos (L.) R. Br.MyrsinaceaeTuullaaTAM074Nepeta azurea R.Br. ex Benth.Lamiaceae—SAM003Ocotea kenyensis (Chiov.) Robyns & WilczekLauraceaeGigichaTAM118Oldenlandia herbacea (L.) Roxb.RubiaceaeOmachessaaHAM028Olea capensis L.ssp. macrocarpa (C.H.Wright)Verdc.OleaceaeGagamaTAM132Olea europaea L. subsp. cuspidata (Wall.ex G.Don)OleaceaeEjerssaaTAM157Olea welwitschii (Knobl.) Gilg. & Schellenb.OleaceaeOnomaaTAM134Osyris compressa (P.J.Bergius) A.DC.SantalaceaeWaatooSAM183Osyris quadripartita Decne.SantalaceaeKaroSAM198Pentaschistis minor (Ballard & C.E.Hubb.) Ballard & C.E.Hubb.Poaceae—HAM061Phytolacca dodecandra L´Herit.PhytolaccaceaeHandodeH(clim)AM205Piliostigma thonningii (Schum.)FabaceaeLilluuTAM165Plantago africana Verdc.PlantaginaceaeQinxaa, BaalleeHAM045Podocarpus falcatus (Thunb) C.NPodocarpaceaeBirbirssaaTAM130Poecilostachys oplismeoides (Hack.) W.D.ClaytonPoaceaeDaaffaHAM144Polygala steudneri Chod.PolygalaceaeGrisa/GarasitaHAM005Polyscias fulva (Hiern) HarmsAraliaceaeKooribaaTAM139Polystichum ammifolium (Poir.) C.Chr.DryopteridaceaeQumbuta, GammanyeeHAM069Pouteria adolfi-friederici (Engl.) BaehniSapotaceaeGudubaTAM138Pseudognaphalium luteo-album (L.) Hilliard and BurttAsteraceae—HAM070Psidium guajava L.MyrtaceaeZeytunaSAM177Psychotria orophila PetitRubiaceaeUlaagaaSAM154Psydrax schimperiana Spermacoce L.RubiaceaeGalleTAM149Pteris confusa (Lansgd & Fisch.) KuhnPteridaceaeQumbutaHAM126Ranunculus multifidus Forssk.RanunculaceaeSherifHAM077Rapanea melanophloeos (L.) MezMyrsinaceaeTullaTAM196Rhus natalensis (Bernh. ex Krauss) F.A.BarkleyAnacardiaceaeDabaqaaSAM171Ricinus communis L.EuphorbiaceaeKoboo, GuloSAM179Rosa abyssinica LindleyRosaceaeGoraSAM093Rubus erlangeri Engl.RosaceaeHatoSAM004Rubus steudneri Schwienf.RosaceaeGoraSAM086Rumex abyssinicus Jacq.PolygonaceaeShabee HagaHAM050Rumex nepalensis Spreng.PolygonaceaeShabeeHAM021Rytidosperma subulata (A. Rich.) CopePoaceaeMarga Hori, QechaHAM110Salvia merjame Forssk.LamiaceaeOkotuSAM015Salvia nilotica Jacq.LamiaceaeOkotuHAM030Sanicula elata Buch. -Ham. ex D.DonApiaceaeGalee Simbira, SidissaHAM079Satureja simensis (Benth.) Briq.LamiaceaeToshimbataHAM049Scabiosa columbaria L.DipsacaceaeAnamuroHAM067Schefflera abyssinica Forst. & Forst. f.,AraliaceaeGatameeTAM136Schefflera volkensii (Engl.) HarmsAraliaceaeAnshaTAM204Schinus molle L.AnacardiaceaeQondabarbereTAM166Senecio ochrocarpus Oliv. and HiernAsteraceaeAgadenaHAM046Senecio ragazzii Chiov.AsteraceaeAgadenaHAM089Senecio schultzii Hochst. ex A.Rich.Asteraceae—HAM057Setaria megaphylla (Steud.) T.Durand & Schinz.PoaceaeSookoraHAM127Solanum anguivi Lam.SolanaceaeMujule WorabessaSAM111Solanum garae FriisSolanaceae—SAM085Solanum marginatum L.f.SolanaceaeHidiiSAM076Spathodea campanulata (S.nilotica)BignoniaceaeHoroqaTAM182Sporobolus africanus (Poir.) Robyns and TournayPoaceaeMarga Hilensa (Or)HAM088Sporobolus pyramidalis P.Beauv.PoaceaeChitaHAM124Stellaria sennii Chiov.CaryophyllaceaeDuqushu, DinbibaHAM108Strychnos mitis S. MooreLoganiaceaeMuluqaaTAM133Swertia lugardae BullockGentianaceae—HAM053Syzygium guineense (Willd.) DC.MyrtaceaeBadeesaTAM117Teclea nobilis Del.RutaceaeHadheessaTAM184Thymus schimperi RonnigerLamiaceaeTossigneHAM047Trema orientalis (L.) Bl.UlmaceaeTala’aaTAM188Trifolium acaule Steud. ex A.Rich.Fabaceae—HAM059Trifolium rueppellianum Fresen.FabaceaeSidissa (Maget)HAM092Trifolium semipilosum Fresen.FabaceaeSidissaHAM019Trifolium simense Fresen.Fabaceae—HAM034Trifolium substerraneum L.FabaceaeSidisa (O), Alfalfa(E)HAM038Triumfetta pentandra A. RichMalvaceaeGurbiiH(clim)AM125Ursinia nana DC.AsteraceaeQinxxaHAM022Urtica dioecia L.UrticaceaeDobi(Or), Sama(Amh)SAM158Urtica simensis SteudelUrticaceaeDobiiHAM109Vepris dainellii (Pichi-Serm.) KokwaroRutaceaeArabeTAM129Vernonia amygdalina Del.AsteraceaeEbichaSAM192Vernonia auriculiferaHiern.AsteraceaeRejiiSAM193Warburgia ugandensis SpragueCanellaceaeBifi, kanafaTAM142Zehneria scabra (Linn.f.) Sond.CucurbitaceaeHarolaH(clim)AM096Ziziphus abyssinicaA.Rich.RhamnaceaeKankuraSAM195H, herb; S, shrub; T, tree; Li, liana; H (clim), herbaceous climber; E, epiphyte; PH, parasitic herb; Or., Oromifa; Coll. no., collection number.Woody species density with DBH°>°2 cm was 1567 individuals ha−1. This was relatively higher compared to other similar vegetation areas such as the Wof-Washa forest [48] and Agama forest [45]. The most frequent woody species was Croton macrostachyus Hochst. ex Del with 81% frequency followed by Juniperus procera L. (79%), Podocarpus falcatus (Thunb) C.N (63%), and Hagenia abyssinica (Bruce) J.F. Gmel (60%). Conversely, the total basal area of woody species was 170.26 m2 ha−1, and it was considerably higher compared to other similar vegetation areas in Ethiopia. About 75% of the basal area was contributed by five tree species such as Juniperus procera (46.71 m2 ha−1), Syzygium guineense (Willd.) DC (24.76 m2 ha−1), Cordia africana Lam (20.95 m2 ha−1), Hagenia abyssinica (18.47 m2 ha−1), and Ehretia cymose Thonn (15.86 m2 ha−1). Consequently, Juniperus procera was the dominant woody species with an IVI of 26.43. The species with higher IVI values in the study area was among the characteristic species in similar vegetation types in Ethiopia [49, 50].


## 3.3. Floristic Composition and Structure in the Edge and Interior Habitat

A total of 136 species belonging to 111 genera and 59 families were identified in the edge habitats of the sampled patches, whereas 117 species that belonging to 84 genera and 40 families were recorded in the interior habitats. From the identified life forms, 19 species were trees, 22 species were shrubs, 86 species were herbs, and 7 species were lianas in the edge habitats, whereas 28 species were trees, 21 species were shrubs, 57 species were herbs, and 11 species were lianas in the interior habitats. The overall means (±SE) species richness (35 ± 4.2), Shannon diversity index (2.93 ± 0.17), and Margalef index (5.68 ± 0.69) of the edge habitat were significantly higher compared to the interior habitat atp<0.05 (Table 3). These variations could be due to the differences in site productivity, habitat heterogeneity, and disturbance factors [44, 51] or the invasion of exotic plant species [52]. However, the woody species richness in the interior habitat (28) was significantly higher than the edge (17). Moreover, the evenness index in the interior habitats (0.83 ± 0.04) was higher, but not significant, than the edge habitat (0.79 ± 0.05). This result was in agreement with the finding in [53]. Abiotic factors, seed predation, loss of pollinators and seed dispersers, and tree mortality were reported as the common causes for the differences in woody species composition between the edge and interior habitats [53, 54]. The computed Sorensen’s similarity index depicted that the number of species in the edge habitats was 45% similar to the species in the interior habitats. This value indicated that the similarity between the edge and interior habitat was weak [13]. The mean density of seedling (995.42 ± 19.27 individuals ha−1), sapling (509.29 ± 9.06 individuals ha−1), and mature trees (187.60 ± 4.70 individuals ha−1) in the interior habitat was significantly higher compared to the edge. This indicates that the recruitment potential of the interior forest was significantly higher compared to the edge habitat [48]. This could be due to the increased mortality rates of seedling, sapling, and mature trees in the edge habitats [53, 55].Table 3
Mean (±SE) values of species richness and diversity indices.
Diversity indicesEdge habitatInterior habitatSpecies richness (S)35 ± 4.2a29 ± 3.6bSimpson index (D)0.10 ± 0.020.11 ± 0.03Shannon–Wiener index (H′)2.93 ± 0.17a2.43 ± 0.11bPielou’s evenness index (J′)0.79 ± 0.050.83 ± 0.04Whittakerβ-diversity (βw)1.83 ± 0.261.34 ± 0.31Margalef index (DM)5.68 ± 0.69a3.72 ± 0.92bBerger–Parker index (d)0.19 ± 0.030.24 ± 0.04Note. Values with different letters indicate significant differences between habitats (p=0.05).The mean woody species density in the interior habitat (85 ± 22.17 stems ha−1) was significantly higher compared to the edge habitat (70 ± 16.53 stems ha−1) at p<0.05 (Figure 2(a); Tables 4 and 5). This could be due to the selective cutting of trees for timber production, house construction, and firewood in the edge habitats, which ultimately leads to a reduction in the density of large trees and greater canopy openness [56]. Moreover, the seedlings are most affected by edge effect due to their sensitivity to environmental changes and biotic interactions [57, 58]. Conversely, the mean basal area of woody species in the interior habitat (11.16 ± 1.82 m2 ha−1) was significantly higher than the edge habitat (3.99 ± 0.54 m2 ha−1) at p<0.05 (Figure 2(b); Tables 4 and 5). This was due to the significantly higher mean DBH (78.62 ± 4.56 cm, p<0.001) and height (33.63 ± 2.71 m, p<0.05) of woody species [59] in the interior habitat than the edge. There were 27.32% of larger diameter individual tree species with DBH > 100 cm recorded in the interior habitat, whereas 4.09% of individuals with DBH > 100 cm were identified in the edge habitat. Microenvironmental conditions such as high temperature, low relative humidity, high wind force, low soil nutrient, and litter moisture in the edge habitats may contribute to the changes in tree abundance and distribution in the forest [60, 61].Figure 2
Box plot showing woody species density (a) and basal area (b) in the habitats.
(a)(b)Table 4
Woody species structure in the edge habitats of the BMNP.
SpeciesAbundanceBasal area (m2 ha−1)Density (stem ha−1)Relative densityRelative frequencyRelative dominanceIVICeltis africana121.9491.796.355.1813.32Cordia africana104.1581.494.7614.8121.06Croton macrostachyus222.34173.286.356.2715.90Diospyros abyssinica30.9520.451.595.087.12Ehretia cymosa127.3191.794.7615.6422.19Hagenia abyssinica326.84254.787.9414.6227.34Hypericum revolutum1741.9313625.9711.112.9540.03Juniperus procera906.637013.4312.708.8735.00Lepidotrichilia volkensii40.4830.603.172.596.36Macaranga capensis60.4450.903.172.346.41Maytenus undata540.00428.064.760.0012.82Myrsine melanophoeos1700.2813325.377.940.6133.92Olea capensis41.0830.604.765.7811.14Olea welwitschii60.1750.901.591.794.27Podocarpus falcatus400.68315.9712.701.2119.88Pouteria adolfi-friederici30.1920.451.592.014.05Syzygium guineense286.70224.184.7610.2419.18Total67042.13523100100100300IVI: importance value index.Table 5
Woody species structure in the interior habitats of the BMNP.
SpeciesAbundanceBasal area (m2 ha−1)Density (stem ha−1)Relative densityRelative frequencyRelative dominanceIVIAllophylus macrobotrys60.7150.792.861.765.41Celtis africana160.25132.123.810.466.39Croton macrostachyus1428.6411118.816.679.1534.62Diospyros abyssinica40.0830.531.900.583.01Ehretia cymosa740.83589.804.762.0616.62Erica arborea30.0220.451.590.172.20Elaeodendron buchananii180.42142.384.760.627.77Fagaropsis angolensis30.0220.400.950.181.53Hagenia abyssinica4010.43315.307.629.6722.58Hypericum revolutum80.0561.066.670.187.90Juniperus procera12831.5410016.957.6229.2453.81Lepidotrichilia volkensii40.0130.530.950.111.59Macaranga capensis60.0350.791.900.122.82Margaritaria discoidea40.0330.531.900.132.56Maytenus undata490.06386.492.860.169.50Mimusops kummel30.0420.400.950.271.62Myrsine melanophoeos320.10254.241.900.376.51Ocotea kenyensis321.13254.246.671.2012.10Olea europaea80.7261.061.901.774.73Olea welwitschii60.1750.792.861.244.89Podocarpus falcatus786.666110.337.626.1824.13Polyscias fulva30.2420.400.951.793.14Pouteria adolfi-friederici82.6161.063.814.839.70Psydrax schimperiana40.0830.531.900.312.74Schefflera abyssinica30.2020.400.951.492.84Strychnos mitis280.28223.713.810.528.04Syzygium guineense359.55274.646.6723.6034.90Vepris dainellii40.2530.531.900.943.37Warburgia ugandensis60.2550.791.900.943.64Total75575.41590100100100300IVI: importance value index.Juniperus procera was the dominant woody species in the edge habitat with an IVI of 32.49, whereas Croton macrostachyus was dominant in the interior habitat with an IVI of 40.61 (Tables 5 and 6). Accordingly, Juniperus procera, Hagenia abyssinica, and Syzygium guineense were identified as generalists that abundantly occurred in both edge and interior habitats, whereas Hypericum revolutum Vahl. was identified as marginalized species that characteristically dominated the edge habitats [62, 63]. However, no woody species was found as a specialist that typically occurred in the interior habitats.Table 6
IVI of woody species in the edge and interior habitats.
SpeciesRelative density (%)Relative frequency (%)Relative dominance (%)IVIEdgeInteriorEdgeInteriorEdgeInteriorEdgeInteriorJuniperus procera11.7220.138.7911.9411.9825.0332.4937.10Croton macrostachyus2.8622.334.4010.458.477.8315.7340.61Hagenia abyssinica5.215.035.4911.9419.768.2830.4725.25Syzygium guineense3.655.357.694.4813.8420.2125.1830.03Podocarpus falcatus5.2112.266.5911.941.645.2913.4429.49Myrsine melanophoeos22.145.035.492.990.820.3128.458.33Ehretia cymosa1.5611.643.307.464.019.298.8728.38Hypericum revolutum22.66—7.69—3.99—34.34—Cordia africana1.57—4.48—8.79—14.84—Ocotea kenyensis4.17—7.69—2.33—14.19—


## 3.4. Effects of Landscape Change in Floristic Composition and Structure

The computed regression analysis among the landscape indices and species composition and structural parameters in this study revealed that only PN and AREA_MN significantly affected both the species composition and structural properties of the study area. Accordingly, PN was strong and negatively affected the overall species richness (r = −0.90, p<0.05) and Shannon diversity index (r = −0.96, p<0.01) (Table 7). Conversely, the overall species richness (r = 0.95, p<0.05) and Shannon diversity (r = 0.87, p<0.05) have shown strong and positive correlation with AREA_MN. This implies that as the number of fragmented habitats increases, species richness and diversity, particularly interior-dependent species, decreases. However, edge-dependent species comfortably flourished. One of the consequences of habitat fragmentation is an increase in the proportional abundance of the edge influenced habitat and its adverse impacts on interior-sensitive species [64]. Undoubtedly, while some species (e.g., habitat specialists) suffer from fragmentation, others benefit from it (e.g., generalists and edge species) [65]. Consequently, PN was strong and negatively correlated with AREA_MN (r = −0.71, p<0.001). This implies that as the PN increases, the area of fragments decreases; as a result, small fragments contain a smaller species richness and lower species density than large fragments [66]. Large areas of habitat tend to support more individuals and, hence, more species [67].Table 7
Pearson's correlation coefficient between the landscape indices and floristic composition and structural parameters.
S1H′0.95∗1BA0.96∗0.94∗1Density0.99∗∗0.90∗0.93∗1PN−0.90∗−0.96∗−0.96∗∗−0.84∗1AREA_MN0.95∗0.87∗0.82∗0.72∗−0.71∗∗∗1SHAPE_AM−0.42−0.64−0.53−0.280.48∗−0.011COA−0.56−0.370.340.66−0.87∗0.41−0.79∗∗∗1ED0.650.78−0.77−0.540.54∗−0.910.25−0.161ENN_MN−0.37−0.56−0.59−0.280.77∗∗∗−0.260.73∗∗−0.81∗∗∗0.041IJI−0.42−0.28−0.32−0.370.58∗−0.59∗∗0.37−0.610.370.17321SH′BADensityPNAREA_MNSHAPE_AMCOAEDENN_MNIJINote. The star indicates significant level between values (∗p<0.05, ∗∗p<0.01, and ∗∗∗p<0.001).Besides, modifying the spatial pattern of the landscape habitat size reduction and increase in isolation cause an alteration in the dispersal rate, affecting survival and mortality of individuals [8]. Many population and community changes in habitat fragments were commonly attributed to edge effects [66]. Interior species may be affected by the size decrease in their habitat, by edge effect, and by competition with generalists [68, 69]. The most threatened endemic species due to edge effect in the BMNP were Helichrysum harennense Mesfin, Kniphofia insignis Rendle, Rubus erlangeri Engl., and Vepris dainellii Pichi Serm Kokwaro. Also, the most common invasive species in the study area favored by edge effect was Achyranthes aspera L, which is also common in the disturbed forests and forest edges of the dry Afromontane forests and moist Afromontane forests in Ethiopia [70]. The gradual decline in the more sensitive species may induce a species turnover in fragments and cascade effects [62, 63].Among the landscape indices computed, only PN and AREA_MN significantly affected some of the floristic structural properties assessed. Thus, the PN was strong and negatively affected the woody species density (r = −0.84, p<0.05) and basal area (r = −0.96, p<0.01), as well as AREA_MN was strong and positively affected the density (r = 0.71, p<0.05) and basal area (r = 0.82, p<0.05) of woody species. Habitat destruction, isolation, and transformation affect the structure and dynamics of populations, communities, and ecosystems, as well as ecological processes [71]. Generally, as AREA_MN and COA of patches increase, species richness, diversity, evenness, woody species density, basal area, DBH, and height also increase. However, as PN, SHAPE_MN, ED, ENN_MN, and IJI of patches increase, floristic composition and structural variables decrease. This implies that the landscape composition and configuration change may potentially affect the vegetation composition and structure of a particular area.


## 4. Conclusion

This study recognized that the Bale Mountains National Park has a diverse biodiversity and is an ecologically significant area. It contains a variety of life forms with good ecological integration. It also harbors a number of endemic floras and faunas. However, currently, anthropogenic disturbances strongly impaired the plant species composition and structure as well as the overall ecological integrity of the landscape. The progressive settlement and agricultural land expansion at the expense of natural forest and grassland coupled with human-induced recurrent fire and livestock grazing in park became a potential threat to the landscape structure. This was due to the escalated human and livestock population and their corresponding demands and necessities increment in the park. Both the floristic composition and structure were affected by the expansion of edge habitat and shrinkage of interior habitat. Species richness and diversity were higher in the edge habitat, whereas density, frequency, and basal area were higher in the interior habitat. Therefore, maintenance of the habitats heterogeneity in the park is essential for long-term population persistence. Moreover, human activities in the park should be banned and settlements in the park should be relocated to other areas to avoid their potential impacts on the floras and faunas. Finally, studies on microenvironmental factors such as light availability, air and soil temperature, humidity, and soil nutrients along the edge and interior gradient should be conducted to determine their effect on species richness, composition, and structure.



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*Source: 6628282-2021-03-09.xml*