Floristic composition, structure and regeneration status as affected by agro-climatic variation in the Bale mountains national park, South-eastern Ethiopia

doi:10.21203/rs.3.rs-4926262/v1

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Research Article

Floristic composition, structure and regeneration status as affected by agro-climatic variation in the Bale mountains national park, South-eastern Ethiopia

https://doi.org/10.21203/rs.3.rs-4926262/v1

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Background

The Bale Mountains National Park (BMNP) is an internationally significant biodiversity hotspot located in the Bale eco-region, southeastern highlands of Ethiopia. Despite its huge ecological importance, habitat degradation occurs at an alarming rate across different agro-climatic zones, posing a severe threat to the survival of many species. This study aims to assess the effects of agro-climatic variation on floristic composition, structure, and explore the human-induced factors responsible for ecosystem changes in the park.

Results

A total of 144 sampling plots covering an area of 5.76 ha were established across three altitudinal gradients with four replications to collect representative vegetation data. Mean species comparison across agro-climatic zones was determined using one-way ANOVA and significant differences were reported with p < 0.05. Results showed that both species richness (76) and mean DBH of woody species (49.63 ± 1.34 cm) were significantly higher in the sub-moist mid highland than in the cold humid afro-alpine zone (29) and in the cool moist mid highlands (31 and 44.50 ± 1.42 cm, respectively). The density of seedlings, saplings, and mature trees was significantly higher in the sub-moist mid highland compared to the cool moist mid highlands.

Conclusion

The study concludes that the sub-moist mid-highland harbors most species and has trees with higher DBH, requiring protection against ecological degradation due to human activities. The higher altitude cold humid afro-alpine zone is ecologically fragile and needs a comprehensive natural resource management strategy that combines restoration and protection of the natural ecosystem.

Habitat degradation

agro-climatic variation

DBH

floristic structure

The Bale Mountains National Park (BMNP) is an acclaimed biodiversity hotspot nestled within the Bale eco-region, located in the southeastern highlands of Ethiopia. Spanning over 1000 km², the park boasts Africa's largest Afro-alpine habitat above 3000 meters above sea level [1]. Additionally, BMNP encompasses the second-largest expanse of moist tropical forest in Ethiopia, including the renowned Harenna forest, which stands as a critical biodiversity hub [2]. The park's vegetation showcases exceptional specialization, adapting to a spectrum of environmental conditions influenced by diverse topography, slopes, climate dynamics, and soil characteristics [3].

Despite its significant ecological value, the Bale eco-region faces escalating habitat degradation across various agro-climatic zones, posing a dire threat to biodiversity [4]. Within the boundaries of the BMNP, human settlement expansion and intensified livestock practices, coupled with a shift towards mixed farming from traditional activities like honey collection, are raising concerns [5]. Particularly in the sub-Afroalpine zone (> 3500 meters above sea level), encroachment by settlements and farmlands for barley cultivation and livestock grazing is rampant [6]. This encroachment is significantly altering the micro-climate and causing habitat degradation in the afro-alpine vegetation [7]. Additionally, the bio-diverse tepid moist forest in the Harenna area, situated in the lower parts of the eco-region, faces severe anthropogenic pressures linked to forest-dependent livelihoods [8]. The issue is especially acute in the peripheries and core zones of BMNP, where human-induced forest fires, encroaching agriculture, and cattle grazing are leading to habitat modifications and the conversion of pristine forest areas into coffee plantations [9].

Despite the acknowledged ecological significance of the BMNP and the looming threats it confronts, there exists a notable research gap concerning the precise impacts of agro-climatic variations on the floristic composition and structural dynamics within the park. Previous studies have predominantly focused on overarching vegetation cover patterns and generic biodiversity assessments, overlooking the intricate influence of specific agro-climatic zones on plant diversity and regeneration processes. This dearth of detailed understanding hinders the formulation of targeted conservation strategies tailored to address the distinct challenges encountered across different ecological zones within BMNP.

This study is significant as it aims to provide detailed insights into the relationship between agro-climatic variation and vegetation dynamics in BMNP. By examining the floristic composition and structural characteristics across various agro-climatic zones within the park, the research seeks to inform more nuanced and effective conservation practices. Understanding these relationships is crucial for developing adaptive management strategies that can mitigate the impacts of climate change and human activities on these fragile ecosystems. The ecological principles applied in this study and the information generated can be used for the paramount management of ecosystems under different agro-climatic conditions of the Ethiopian highlands. The overall objective of the study is to assess the effects of agro-climatic variation on the floristic composition, structure, and regeneration status of vegetation in BMNP. As a result, it seeks to contribute to the broader goals of biodiversity conservation and sustainable ecosystem management in one of Ethiopia's most important protected areas.

Description of the study area

The Bale Mountains National Park (BMNP) in southeastern Ethiopia spans 2,178 km² and is geographically located between 6º29'–7º10' N latitude and 39º28'–39º57' E longitude (Fig. 1). The park's altitudinal range, from 1,450 meters at Magnetea to 4,377 meters at Tulu Dimtu, results in diverse agro-climatic zones: semi-arid lowlands (500–1,600 meters), sub-moist mid highlands (1,600–3,000 meters), cool moist mid highlands (3,000–3,400 meters), cold sub-humid highlands (3,400–3,800 meters), and very cold humid afro-alpine zones (> 3,800 meters). The sub-moist mid highland zone is the most extensive, covering 37% of the area. Rainfall is bimodal, with an annual mean of 1,425 mm, ranging from 450 mm in the semi-arid lowlands to 2,400 mm in the cool moist mid highlands. Temperatures vary from − 15ºC in higher altitudes to 26ºC in lower areas (Fig. 2). The primary soil types include Chromic Luvisols, Pellic Vertisols, Eutric Nitisols, and Eutric Cambisols and Orthic Luvisols.

Sampling design

Fieldwork for this study was conducted during both dry and wet seasons in three phases: November 2020 to January 2021, May to June 2021, and August to September 2021. A combination of stratified and systematic sampling methods was employed to collect vegetation samples across different altitudinal zones, following the methodology of Bonham [11]. Initially, the study area was stratified into three agro-climatic zones based on the agro-climatic classification of Ethiopia [11, 12]. The agro-climatic zones (ACZ) selected for this study include the sub-moist mid highland (1,600–3,000 m asl), designated as ACZ 1; the cool moist mid highland (3,000–3,400 m asl), designated as ACZ 2; and the cold humid afro-alpine zone (3,800–4,200 m asl), designated as ACZ 3. Twelve parallel transect lines were established along the altitudinal gradient at intervals of 500 meters. Four sample plots, each measuring 20 m x 20 m, was systematically placed along each transect line at 100-meter altitudinal intervals. In total, 144 sample plots were established, covering an area of 5.76 hectares, to obtain representative vegetation data across the study area.

Plant diversity, population structure and regeneration status

To analyze plant diversity, we computed the most commonly used diversity indices: Species richness (S), Shannon-Wiener index (H'), and Pielou’s evenness index (J'), as recommended by Magurran [14] and Morris et al. [15]. Vegetation structure was characterized by calculating the density, frequency, dominance, and their relative values for each woody species, following the methods outlined by Kent [16]. Additionally, the population structure of woody species was assessed by categorizing stems into defined diameter at breast height (DBH) and height classes, based on the protocol by Hundera et al. [17]. Specifically, DBH was classified into 14 classes at 10 cm intervals, and height was grouped into 12 classes at 5 m intervals.

Basal area was computed using the formula BA=(d200)²× π, and the basal area for all plots was converted to a per-hectare basis. To evaluate the regeneration status of woody species, we counted the number of seedlings, saplings, and mature trees, comparing their abundance as described by Pandey and Shukla [18]. Human-induced factors were identified through field observations and key informant interviews. Park experts and local elders, selected purposively for their reliability, provided insights into human-related problems affecting the area.

Survey data

Field observation, focus group discussion (FGD) and key informant interview has been conducted in the study to obtain supplementary data and in-depth information to enrich the data acquired from field measurement. Two-stage sampling was used to select the sampled kebeles. First, the study area was stratified into three agro-climatic zones: ACZ 1, ACZ 2, and ACZ 3. These zones were used for soil and vegetation analysis. The community's livelihood strategy (farming and livestock production) and population characteristics (rapid population growth) were then used to select six kebeles, two from each agro-climatic zone. Rira and Hawo were Kebeles in ACZ 1, Gojera and Morebawa in ACZ 2, and Garba Guracha and Rafu in ACZ 3. As suggested by Bhawana [19] and Jayasekara [20], a total of 48 elders from each kebele were chosen to take part in the FGD, with participants ranging in age from 4 to 10. Elders were chosen because they had lived in the study area for a long time and knew a lot about the area's past and present ecosystem conditions. In addition, KIIs were carried out in order to gather comprehensive data on the characteristics of LULCC and the factors that led to it. Purposive sampling was used to select four experts from each agro-climatic zone out of a total of twelve key informants. Experts from various BMNP sites, including the park manager, served as key informants.

Statistical data analysis

Vegetation data collected across different agro-ecological zones were analyzed using R statistical software version 3.5.2. Mean comparisons among agro-climatic zones were conducted employing one-way analysis of variance (ANOVA). In all statistical tests, differences were considered statistically significant at a threshold of p < 0.05.

Floristic composition along the agro-climatic zone

Tables 1 and 2 presented descriptive statistics and mean differences in species diversity across the agro-climatic zones of the BMNP. Overall species richness did not show significant differences (p < 0.05) among the agro-climatic zones, with the highest mean value of 94 species recorded in the cool moist mid highland zone. The sub-moist mid highland zone followed with 85 species, while the cold humid afro-alpine zone had the lowest species richness of 72 species. However, the mean (± SE) species richness per 400 m² plot was significantly higher in the cool moist mid highland compared to the sub-moist mid highland (Tables 1). The species richness in the cold humid afro-alpine zone did not significantly differ from the other two agro-climatic zones.

Herbaceous species richness was significantly higher (p < 0.05) in both the cool moist mid highland (60 species) and the cold humid afro-alpine zone (43 species) compared to the sub-moist mid highland (18 species). Conversely, woody species richness was significantly higher in the sub-moist mid highland (76 species) than in the cool moist mid highland (31 species) and the cold humid afro-alpine zone (29 species) at p < 0.05. The number of endemic species was significantly higher (p < 0.05) in the cool moist mid highland (14 species) compared to the cold humid afro-alpine zone (11 species) and the sub-moist mid highland (2 species).

Asteraceae was the most species-rich family in the cool moist mid highland and cold humid afro-alpine zones, with 21 and 16 species respectively. In the sub-moist mid highland, Celasteraceae and Rutaceae were the richest families, each with 7 species. Helichrysum was the most species-rich genus in the cool moist mid highland and cold humid afro-alpine zones, with 6 and 5 species respectively. In the sub-moist mid highland, Hippocratea and Olea were the richest genera, each with 3 species.

Table 1

Descriptive statistics on species richness in agro-climatic zones of the BMNP
Statistics	ACZ 1	ACZ 2	ACZ 3
Min	5	6	7
Max	21	23	21
Mean	10.35	12.40	11.29
Standard deviation	4.04	4.19	3.79
Standard error	0.58	0.60	0.55
df	143
MS	50.13
F	3.12
P-value	0.047
Note: Min: minimum and Max: maximum, df: degrees of freedom, MS: Mean squares, ACZ 1: Sub-moist mid highland, ACZ 2: Cool moist mid highland, ACZ 3: Cold humid afro-alpine zone.

The mean (± SE) Shannon diversity and Pielou’s evenness indices did not show significant differences (p < 0.05) among the agro-climatic zones. However, both indices were highest in the cool moist mid highland, followed by the sub-moist mid highland and the cold humid afro-alpine zone (Table 2). The computed Sorensen’s similarity index indicated that the sub-moist mid highland shared 31% floristic similarity with the cool moist mid highland and 4% similarity with the cold humid afro-alpine zone. In comparison, the cool moist mid highland and the cold humid afro-alpine zone shared 7% floristic similarity. Overall, the floristic similarity among the agro-climatic zones was weak, indicating distinct plant communities within each zone.

Table 2

Mean differences of species richness, diversity, and evenness
Agro-climatic zones	S	H’	J
ACZ 1	10.35 ± 0.58^b	2.71 ± 0.05	0.77 ± 0.02
ACZ 2	12.40 ± 0.60^a	3.02 ± 0.03	0.86 ± 0.01
ACZ 3	11.29 ± 0.55^ab	2.69 ± 0.09	0.81 ± 0.05
Mean	11.35 ± 0.57	2.81 ± 0.06	0.81 ± 0.02
F	3.12	0.75	1.65
P-value	< 0.05	0.051	0.072
Note: S: Species richness, H’: Shannon diversity index, J: Pielou’s evenness index, ACZ 1: Sub-moist mid highland, ACZ 2: Cool moist mid highland, ACZ 3: Cold humid afro-alpine zone.

Vegetation structure along the agro-climatic zone

The structural characteristics of woody species were analyzed in the sub-moist mid highland and cool moist mid highland zones, as woody species with a DBH > 2 cm were absent in the cold humid afro-alpine zone. The mean woody species density did not show a significant difference (p < 0.05) between the sub-moist mid highland and the cool moist mid highland (Table 3). However, the overall density of woody species was higher in the sub-moist mid highland, with 914 stems per hectare, compared to 653 stems per hectare in the cool moist mid highland.

Table 3

Mean differences of vegetation structure parameters
Agro-climatic zones	Density (stems ha^− 1)	BA (m² ha^− 1)	DBH (cm)	Height (m)
ACZ 1	65.28 ± 11.90	6.50 ± 1.76	49.95 ± 1.34^a	23.02 ± 0.53
ACZ 2	46.65 ± 12.15	5.70 ± 0.67	44.50 ± 1.42^b	21.94 ± 0.61
Mean	55.97 ± 12.02	6.10 ± 1.21	47.23 ± 1.38	22.48 ± 0.57
F	1.20	2.31	7.67	1.74
P-value	< 0.056	0.082	< 0.05	0.063
Note: BA: Basal area, DBH: Diameter at breast height, ACZ 1: Sub-moist mid highland, ACZ 2: Cool moist mid highland.

The mean basal area of woody species did not show significant differences (p < 0.05) between the two agro-climatic zones (Table 3). Nonetheless, the overall basal area was higher in the sub-moist mid highland, with 91.16 m² ha⁻¹ compared to 79.10 m² ha⁻¹ in the cool moist mid highland. Conversely, the mean DBH of woody species in the sub-moist mid highland was significantly higher (p < 0.01) than in the cool moist mid highland (Table 3). The mean height of woody species did not significantly differ (p < 0.05) between the two agro-climatic zones.

Woody species with a DBH > 2 cm across the agro-climatic zones were classified into 14 DBH classes. The distribution pattern of woody species across these classes exhibited an inverted J-shape beyond the second DBH class. Most individuals were concentrated in the third DBH class (21–30 cm), with a sharp decline in density towards higher DBH classes (Fig. 4a and b). The sub-moist mid highland recorded the highest density of woody species, with approximately 12.38% of the species having a DBH > 100 cm, contributing to the higher basal area in this zone. The largest recorded DBH was 187.58 cm for Juniperus procera in the cool moist mid highland and 129.62 cm for Syzygium guineense in the sub-moist mid highland.

The height distribution of woody species in both agro-climatic zones was categorized into 12 classes. Consistent with the DBH distribution, the height distribution of woody species followed an inverted J-shape pattern (Fig. 5a and b). The tallest recorded tree species was Olea capensis, reaching 52 meters in the sub-moist mid highland, while Juniperus procera reached 45 meters in the cool moist mid highland.

Croton macrostachyus was the most frequently occurring woody species in the sub-moist mid highland, present in 81% of the sample plots, followed by Podocarpus falcatus at 63% and Syzygium guineense at 48% frequency. In contrast, Juniperus procera was the most frequently occurring species in the cool moist mid highland, found in 79% of the sample plots, followed by Hypericum revolutum at 71% and Hagenia abyssinica at 60% frequency. The dominance of woody species, as indicated by the Importance Value Index (IVI), ranged from 0.77 to 38.45 in the sub-moist mid highland, and from 1.34 to 96.47 in the cool moist mid highland (Table 4). The most dominant species in the sub-moist mid highland was Croton macrostachyus with an IVI of 38.45, followed by Syzygium guineense at 27.22, and Podocarpus falcatus at 25.16. In the cool moist mid highland, Juniperus procera was the most dominant species with an IVI of 96.47, followed by Hypericum revolutum at 58.47, and Hagenia abyssinica at 52.18.

Table 4

IVI of top 10 woody species in ACZ 1 and ACZ 2 with their corresponding relative values
Species	R_de (%)		R_fr (%)		R_do (%)		IVI
	ACZ 1	ACZ 2	ACZ 1	ACZ 2	ACZ 1	ACZ 2	ACZ 1	ACZ 2
Juniperus procera	0.18	24.12	0.63	23.60	1.05	48.75	1.86	96.47
Olea europae	0.91	3.53	2.52	6.21	1.84	11.68	5.26	21.42
Myrsine melanophoeos	22.14	5.03	5.49	2.99	0.82	0.31	28.45	8.33
Hypericum revolutum	-	32.29	-	21.12	-	5.06	-	58.47
Hagenia abyssinica	-	8.83	-	18.01	-	25.34	-	52.18
Rapanea melanophloeos	-	7.71	-	13.66	-	5.50	-	26.94
Croton macrostachyus	21.56	-	12.26	-	4.63	-	38.45	-
Syzygium guineense	5.98	-	7.23	-	14.01	-	27.22	-
Podocarpus falcatus	11.78	-	9.43	-	3.95	-	25.16	-
Ehretia cymosa	7.79	-	5.35	-	8.09	-	21.22	-
Note: R_de: Relative density, R_fr: Relative frequency, and R_do: relative dominance, ACZ 1: Sub-moist mid highland, ACZ 2: Cool moist mid highland.

Woody species regeneration status along the agro-climatic zone

The mean densities of seedlings, saplings, and mature trees were significantly different between the sub-moist mid highland and cool moist mid highland at p < 0.05 (Table 5). In the sub-moist mid highland, the total densities were 5363 seedlings ha^− 1, 2930 saplings ha^− 1, and 940 mature trees ha^− 1. In contrast, the cool moist mid highland had total densities of 3668 seedlings ha^− 1, 1921 saplings ha^− 1, and 627 mature trees ha^− 1. The highest seedling and sapling densities in the sub-moist mid highland were recorded for Croton macrostachyus, with 967 seedlings ha^− 1 and 629 saplings ha^− 1. In the cool moist mid highland, the highest densities were for Juniperus procera (190 seedlings ha^− 1) and Hypericum revolutum (302 saplings ha^− 1).

Table 5

Mean differences in the seedling, sapling, and mature tree
Agro-climatic zones	Seedling	Sapling	Mature tree
ACZ 1	1592.40 ± 147.46^a	884.84 ± 81.94^a	297.01 ± 27.50^a
ACZ 2	1089.11 ± 142.59^b	580.13 ± 75.95^b	198.11 ± 25.94^b
Mean	1340.75 ± 145.02	732.48 ± 78.94	247.56 ± 26.72
F	8.43	7.25	4.25
P-value	< 0.01	< 0.05	< 0.05

Driving factors for plant composition and structure change

Changes in plant species composition and structure across the designated agro-climatic zones of the BMNP are driven by both direct and indirect factors. Over the past 40 years, direct drivers such as overgrazing, illegal logging, agricultural development, and settlement expansion have been prominent, particularly affecting the cool moist mid highland and sub-moist mid highland zones. The Gaysay grassland in the cool moist mid highland, which is rich in endemic and medicinal plant species, faces critical challenges from unrestricted livestock grazing. In the cold humid afro-alpine zone, recurrent fires and grazing are significant stresses. Indirect factors, including rapid population growth and poverty, exacerbate these impacts. Field observations and interviews identified seven key drivers of landscape change, with farmland and settlement expansions as the leading proximate factors, while population growth and climate issues were significant underlying causes. These pressures have led to extensive human activity, notably illegal settlements from the park's northern sides, intensifying farming and overgrazing, particularly in the Gaysay grassland in the cool moist mid highland.

Table 6

Driving factors of landscape change in the BMNP
Drivers	Percent (%)	Rank
Farmland expansion	30.46	1
Settlement expansion	19.41	2
Population growth	14.56	3
Overgrazing	12.43	4
Forest fire	11.34	5
Illegal logging	7.62	6
Climate related problems	4.18	7

Effects of agro-climatic variation on floristic composition

Agro-climatic zones significantly influence species distribution and spatial pattern changes in landscapes due to their direct effects on habitat microclimates [21]. In the study, species richness, Shannon diversity, and evenness indices were not significantly different across altitudes but were higher in the cool moist mid highland, likely due to the diversity and density of herbaceous species in this zone. This finding aligns with Rahbek et al. [22], who noted that species richness and diversity tend to peak at intermediate altitudes and decline at lower and higher elevations. Mid-altitudinal ranges favor species coexistence from both lower and higher altitudes [22, 23].

Lower and middle altitudes host more plant species than higher altitudes due to extreme environmental conditions at higher elevations, which only a few species can tolerate [25]. Similar patterns were observed in other highland and mountainous regions, such as the Wof-Washa highlands [8], the subarctic mountain tundra [26], the southwest Ethiopian highlands [27], and the western Himalaya [28]. The lower species richness and diversity in the cold humid afro-alpine zone are attributed to harsh conditions that hamper species growth and reproduction, along with low soil nutrient availability [28, 29].

The Sorensen’s similarity index indicated weak floristic similarity among agro-climatic zones, reflecting distinct environmental features and habitat preferences of specialized plant species, particularly in the cold humid afro-alpine zone. Species adapted to this severe climate cannot thrive outside it. However, floristic similarity was higher between the sub-moist mid highland and the cool moist mid highland (31%) compared to the similarity between the cool moist mid highland and the cold humid afro-alpine zone (7%), and between the sub-moist mid highland and the cold humid afro-alpine zone (4%). This higher similarity between the sub-moist mid highland and the cool moist mid highland could be due to similar plant growth and adaptation strategies in these zones [8].

Effects of agro-climatic variation on floristic structure

The absence of woody species with DBH > 2 cm in the cold humid afro-alpine zone is primarily attributed to the severe climatic conditions at high altitudes, including very low temperatures, low humidity, low sunlight intensity, and high wind velocity [30, 31]. These harsh environmental factors significantly hinder the growth and development of woody species, making it difficult for them to thrive in such conditions. The higher basal area of woody species in the sub-moist mid highland is due to the presence of large DBH tree species; about 12.38% of the woody species in this zone have a DBH > 100 cm. This contrasts with the lower basal area in the cool moist mid highland, which can be attributed to selective cutting of larger and medium-sized trees, a result of high levels of human disturbance observed during field assessments. Furthermore, agro-climatic zone differences significantly (p < 0.05) affect the regeneration capacity of woody species in the BMNP. The significantly higher densities of seedlings, saplings, and mature trees in the sub-moist mid highland indicate that this zone has a higher reproduction and recruitment potential compared to other zones. This difference is largely due to the more favorable climatic conditions in the sub-moist mid highland, such as higher temperatures and humidity, which enhance the growth performance of seedlings and saplings and the reproductive potential of mature trees [32, 33].

Factors influencing plant composition and structure

The variations observed in plant species composition and structural characteristics across the agro-climatic zones of the Bale Mountains National Park (BMNP) result from a combination of direct and indirect factors. The expansion of settlements and farmlands in the cool, moist mid-highland has resulted in unrestricted livestock grazing, posing a significant threat to the ecological balance of the region. This result were coincide with the reported by Muche et al., [35]; in the north-eastern highlands of Ethiopia and Deribew and Dalacho [36] in the central highlands of Ethiopia. Concurrently, indirect influences such as rapid population growth and poverty drive heightened human activities, including the establishment of illegal settlements, which subsequently lead to intensified agricultural practices and extensive overgrazing in the cold, humid Afro-alpine zone as similarly reported by Ewunetu et al., [37] and Mezgebu and Workineh [38]. With population growth, the demand for arable land escalates, prompting the adoption of more extensive and unsustainable land use methods. Climate change adds complexity to these dynamics by altering precipitation patterns and temperature regimes, consequently impacting plant growth and survival [38, 39].

In conclusion, the agro-climatic zones in the Bale Mountains National Park (BMNP) exhibit distinct patterns of species distribution and spatial changes influenced by various direct and indirect factors. The research highlights how species richness and diversity vary across altitudes, with the cool moist mid highland supporting higher levels likely due to its favorable herbaceous species diversity. This finding is consistent with the general trend of peak species richness at intermediate altitudes. The harsh environmental conditions in the cold humid afro-alpine zone result in lower species richness and diversity, reflecting the challenges plants face in such extreme climates. The analysis of floristic similarity underscores the unique environmental features and habitat preferences of specialized plant species, particularly in the cold humid afro-alpine zone, emphasizing the need for targeted conservation efforts in these areas.

Based on these findings, it is recommended to implement conservation strategies that prioritize the protection of biodiversity hotspots within the BMNP, especially in the cold humid afro-alpine zone. This includes regulating human activities such as unrestricted livestock grazing, illegal settlements, and intensified agricultural practices that threaten ecosystem integrity. Sustainable land management practices should be promoted to mitigate the impacts of population growth and climate change on plant communities. Collaboration among stakeholders, including government agencies, conservation organizations, and local communities, is crucial for effective conservation planning and implementation. Additionally, further research into the specific adaptation strategies of plant species to different agro-climatic zones can provide valuable insights for conservation and management strategies tailored to the unique challenges of each zone within the BMNP.

ACZ

Agro-climatic zones

ANOVA

Analysis of variance

Basal area

BMNP

Bale Mountains National Park

DBH

Diameter at breast height

Pielou’s evenness index

R_de

Relative density

R_do

relative dominance

R_fr

Relative frequency

Shannon-Wiener index

Species richness.

Acknowledgements

Special thanks to Ethiopian Wildlife Authority for allowing us to conduct this study on site.

Authors’ contributions

AM conceived, designed, collected the data, analyzed, and wrote the manuscript. EE supervised the inception, design, and edited the manuscript. All authors read and approved the final manuscript.

Funding

No funding was received for the study.

Availability of data and materials

The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Author details

¹Department of Natural Resource Management, College of Agriculture and Environmental Science, Arsi University, 193 Assela, Ethiopia. ²Centre for Environmental Science, College of Natural and Computational Science, Addis Ababa University, 1176 Addis Ababa, Ethiopia.

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No competing interests reported.

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Floristic composition, structure and regeneration status as affected by agro-climatic variation in the Bale mountains national park, South-eastern Ethiopia

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Abstract

Background

Results

Conclusion

Figures

Introduction

Methods

Description of the study area

Sampling design

Plant diversity, population structure and regeneration status

Survey data

Statistical data analysis

Results

Floristic composition along the agro-climatic zone

Vegetation structure along the agro-climatic zone

Woody species regeneration status along the agro-climatic zone

Driving factors for plant composition and structure change

Discussion

Effects of agro-climatic variation on floristic composition

Effects of agro-climatic variation on floristic structure

Factors influencing plant composition and structure

Conclusion

Abbreviations

Declarations

References

Additional Declarations

Status:

Version 1