Savanna Research Articles

Germplasm collection and ex situ conservation of Adansonia digitata in Ghana

ABSTRACT Baobab (Adansonia digitata L.) domestication and conservation have become necessary due to its increasing global usage and decreasing population. Although it is resilient and survives harsh environmental conditions, its destruction due to anthropogenic and natural forces could lead to genetic erosion. Therefore, it is important to domesticate the baobab and provide it with the necessary husbandry practices to ensure its survival. The objective of the study was to collect baobab germplasm across the Volta Region of Ghana for conservation. A reconnaissance survey was conducted and followed with germplasm collection. As a result, 109 accessions were collected within latitude 5°47ʹ46.24190ʹʹ to 7° 9ʹ34.15030ʹʹN and longitude 0°11ʹ35.25ʹʹto1°8ʹ36.74180 ʹʹE. They were from mangrove swamps, woodland savannah, grassland savannah and deciduous forest. The scions were grafted on pre-raised rootstocks. They are represented on a bar chart, and a three-dimensional map drawn indicating the geographic locations of collection. The lowest and highest altitudes at the ground at which the accessions were taken were 4 m and 287 m, respectively. The accessions were planted in the Ho Technical University ex situ gene bank. The collection will help in the maintenance of baobab genetic diversity, serve as materials for studies and crop improvement, and improve biodiversity.

The contribution of small and medium diameter trees in West African Savanna to regional biomass and carbon pools

The contribution of small and medium diameter trees in West African Savanna to regional biomass and carbon pools

Functional traits of Ziziphus mucronata below mistletoe-infected trees in a semi-arid African savanna

Mistletoes are increasingly associated with elevated leaf litter, soil nutrients, and soil moisture, resources which influence variations in plant functional traits. Despite this recognition, variations in the functional traits of understorey plants with overstorey (host) tree mistletoe infection are yet to be examined. Here, we measured the different functional traits (height, stem diameter, canopy area, leaf area, specific leaf area, whole-leaf thickness, leaf dry matter content, and chlorophyll content) of Ziziphus mucronata, a dominant woody plant beneath mistletoe-infected Vachellia karroo trees in semi-arid savanna. Two-sample t-tests were used to compare host size, mistletoe infection intensity, and trait variables between low and high mistletoe-infected trees. The relationships between Ziziphus mucronata functional traits vs. host tree diameter and the number of mistletoes per tree were explored using regression analysis and visualized using a regression biplot based on a redundancy analysis (RDA). Host tree height, canopy area, and canopy volume were strongly positively (r > 0.7, p < 0.05) related to mistletoe infection intensity. While most of the traits did not vary with mistletoe infection, the chlorophyll content and leaf area of understorey Z. mucronata increased with host tree size, being greater beneath high than low mistletoe-infected trees. These variations are linked to changes in limiting resources such as light, soil nutrients, and soil moisture due to accumulation of mistletoes and increase in size as the host tree ages. As a result, the understorey plants shifted from being resource conservative to being acquisitive as limiting resources increased. The general lack of trait plasticity in understorey Z. mucronata suggests that plastic allocation responses may not be a general consequence of mistletoe infection.

Encephalartos natalensis association with non-cyanobacterial species increased reliance on atmospheric nitrogen in acidic and nutrient-deficient savanna woodland ecosystem soils

Encephalartos natalensis, commonly known as the “Natal Giant,” is an evergreen cycad growing in nutrient-deficient and acidic savanna woodland ecosystem soils. The ability of E. natalensis to grow in nutrient-deprived and acidic soils may be linked to its association with nitrogen (N2) fixing bacteria housed in the coralloid roots. This study investigated the effects of soil characteristics (pH, total cation, nutrient concentrations, and total exchange acidity) on plant nutrition and N source (soil and atmosphere) reliance of E. natalensis growing in Edendale, KwaZulu-Natal. Leaves and coralloid roots were harvested from E. natalensis cycads in a disturbed savanna woodland for bacterial identification, N-isotope analysis, and plant nutrition. Encephalartos natalensis rhizosphere soils were phosphorus (P) deficient and had a pH of 5.75. The culturable bacteria isolated for E. natalensis coralloid roots belonged to the Bacillus, Paenibacillus, Lysinibacillus, and Beijerinckia genera. Encephalartos natalensis plants relied more on N derived from the atmosphere (72.61%) than N derived from the soil (36.99%). Correlations were observed between soil N, percentage N derived from the atmosphere, and percentage N derived from the soil. Soil P was correlated with pH. The findings of this study suggest that E. natalensis established symbioses with non-cyanobacterial N2-fixing bacteria and relies on atmospheric N for N nutrition in acidic and nutrient-deficient savanna woodland ecosystem soils.

Morphological and productivity responses of Guinea grass (Panicum maximum) under large trees in a South African savanna

Morphological and productivity responses of Guinea grass (Panicum maximum) under large trees in a South African savanna

Analysis of Rainfall Projections in Historical and Future Periods Using Coupled Model Intercomparison Project (CMIP) Phase 6 in Indonesia

Abstract Climate change is a phenomenon that occurs today and has great potential in the future. The impact of this climate change phenomenon is hydrometeorological disasters such as 7loods, droughts, and storms, where the agricultural sector is the most vulnerable sector to the impact of these issues. Therefore, the aims of this study to assess the conditions that have occurred in the past (between 1950 - 2013) to project the potential that will occur in the future (between 2035 - 2080) of hydrometeorological disasters. The model results show that historically, areas with tropical rainfall (Af), tropical monsoon (Am), and tropical savanna (Aw) climate types experienced a decrease in total annual rainfall of up to 500 mm/year during 1950 - 2013. However, in contrast, future projections for the region show a signi7icant increase with a rainfall range of 3000 - 4500 mm/year. The above conditions will certainly spread to various problems in other agricultural cultivation environments such as soil capability levels to research results so that research on the study of rainfall conditions and hydrometeorological disasters is very important.

Observing super-coarse carbonaceous aerosol particles containing chloride in a tropical savanna climate at an agro-forest site in Thailand

Coarse aerosol particles containing chloride in tropical forests are significant for understanding biogeochemical cycles and atmospheric processes, with implications for environmental health and climate change mitigation. This study explored the sources of super-coarse carbonaceous aerosol particles containing chloride in a tropical savanna climate. Aerosol samples were collected from an agro-forest site in Thailand during the dry season and analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared (FTIR) spectroscopy. By examining the morphology and elemental compositions of individual aerosol particles, along with employing Positive Matrix Factorization (PMF) and backward trajectory analysis, potential sources were identified. The findings revealed two primary sources for the super-coarse aerosol particles: a mixture of biomass burning smoke and inorganic salts (likely from saline soil and sea salt), as well as halophilic fungal spores. FTIR analysis indicated the presence of compounds linked to biomass burning and clay minerals, influenced by prevailing northeast and southeast winds. Recommendations for future research include continued monitoring, correlation with meteorological parameters, and the application of transmission electron microscopy (TEM) for more detailed visualization and confirmation of aerosol sources.

Seasonal changes in the abundance and distribution of large terrestrial mammals in old Oyo National Park, Nigeria

Seasonal distribution of large terrestrial mammals in African protected areas is shaped by factors such as food and water availability, breeding cycles, and predation risks. This study utilised encounter rates derived from diurnal distance sampling to examine seasonal variations in the abundance and distribution of these mammals within Old Oyo National Park, Nigeria. Notably, the abundance and distribution in the Marguba range, characterised by mixed open savanna woodland, differed significantly between the dry and wet seasons, as well as among various sub-habitats and ranges during the dry season. The impact of key factors—(1) resource availability (food and water) and/or (2) poaching threat—remains critical and potentially influential in driving these seasonal differences. Further investigation to ascertain the effect of poaching and determine the impact of other controlling factors is crucial. Understanding the effects of these factors is essential for the effective and sustainable management and conservation of large terrestrial mammals in the study area.

Greenhouse gas emission from prescribed fires is influenced by vegetation types in West African Savannas

Greenhouse gas (GHG) emissions from prescribed fires are poorly investigated, resulting in a high uncertainty in GHG budgets. Using, a carbon mass balance approach and experimental prescribed fires in 80 plots, this study assessed carbon emissions and established emission factors (EFs) for carbon dioxides (CO2), carbon monoxide (CO), and methane (CH4) across climate zones and vegetation types. In grass and shrub savannas, fires could burn intensely due to the lower moisture content and continuous spatial distribution of biomass fuel, causing greater carbon emissions with 1.61 ± 0.13 t C ha−1 and 1.01 ± 0.13 t C ha−1, respectively. Despite their low carbon emissions, tree savannas (1658.17 ± 11.13 g kg−1) and woodlands (1629.94 ± 12.23 g kg−1) have the highest EFs, which can be attribute to the high carbon content of biomass fuel in these vegetation types. Vegetation types and their interaction with climate zones have a substantial impact on carbon emissions and carbon species EFs, and should therefore be considered in assessing GHG emissions from fires. The findings from this study provide a useful basis for improving the national measurement, reporting, and verification of GHG emissions and for improving the measurement of the global balance of GHG emissions from fires.

Analysis of radiative heat flux using ASTER thermal images: Climatological and volcanological factors on Java Island, Indonesia

This study focuses on analysing natural Radiative Heat Flux (RHF) anomalies to map out the heat distribution across the Java Island. Leveraging remote sensing techniques, we calculated natural RHF anomalies using Land Surface Temperature (LST) and Land Surface Emissivity (LSE) data obtained from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) imagery. A key aspect of our approach was distinguishing between natural and anthropogenic heat sources by cross-referencing the LST Map with the Land Use Land Cover (LULC) map of Java Island. The study interprets natural RHF anomalies by examining regional trends in non-volcanic areas and local trends within volcanic regions, considering climatological and volcanological factors. Relation with climatological factors involves assessing soil moisture parameters from Soil Moisture Active Passive (SMAP) data, precipitation from monthly Global Precipitation Measurement (GPM) data, and classifications according to the Köppen-Geiger climate schema. Our regional analysis reveals high natural RHF anomalies in the northern regions of West Java, parts of Central Java, and most of East Java, attributed to low soil moisture and low precipitation in savanna and monsoon climates. On a more localised scale, RHF values are significantly high in volcanic areas, particularly around Central and East Java's volcanoes, such as Mt. Merapi, Mt. Slamet, Mt. Semeru, the Sidoarjo Mud Volcano, and Mt. Ijen. The Natural RHF anomalies at volcanoes in West Java were identified as not being high except at Mt Patuha. These areas exhibit average natural RHF anomalies ranging between 32.22 W/m2 and 115.13 W/m2, indicating strong and intense volcanic activity. The insights obtained from these findings explain the overall thermal characteristics of Java Island and highlight the presence of subsurface thermal zones associated with volcanic activity and geothermal potential.

Identifying the major metabolic potentials of microbial-driven carbon, nitrogen and sulfur cycling on stone cultural heritage worldwide

Microbial activities and biochemical reactions are responsible for the biodeterioration of stone cultural heritage, but information on microbial metabolic potentials remains elusive. Here we profiled microbial community signatures and its functional traits on stone cultural heritage from different climate zones globally using sequencing datasets available publicly. Bacterial community on stone cultural heritage shows a significant separation between BSk (cold semi-arid climate) and Cfb (temperate oceanic climate) with Aw (tropical savanna climate) as a transition region. Importantly, the ubiquity of ammonia oxidizers and nitrite oxidizers on stone cultural heritage under different climates supports the active production and accumulation of nitrates while ammonia/ammonium can be supplied by dinitrogen fixation and dissimilatory nitrate reduction to ammonium (DNRA), together with the hydrolysis of urea, arginine, formamide and cyanate. Sulfate accumulation on stone cultural heritage is mainly resulted from the microbial-driven transformation of organosulfur and thiosulfate, with little dissimilatory reduction of sulfate. Pseudorhodoplanes was identified and reported in elemental sulfur turnover for the first time. Notably, carbon sequestration via the reductive tricarboxylic acid (rTCA) cycle and an incomplete 3-hydroxypropionate/4-hydroxybutynate (HP/HB) cycle other than the Calvin Benson-Bassham (CBB) cycle is also significant on stone cultural heritage under relatively humid climate. These results advance our understanding of microbial metabolic potentials and their genetical partitioning patterns on stone cultural heritage of different climate zones globally.

Generic and Specific Models for Volume Estimation in Forest and Savanna Phytophysiognomies in Brazilian Cerrado.

The Cerrado has high plant and vertebrate diversity and is an important biome for conserving species and provisioning ecosystem services. Volume equations in this biome are scarce because of their size and physiognomic diversity. This study was conducted to develop specific volumetric models for the phytophysiognomies Gallery Forest, Dry Forest, Forest Savannah, and Savannah Woodland, a generic model and a model for Cerrado forest formation. Twelve 10 m × 10 m (100 m²) (National Forest Inventory) plots were used for each phytophysiognomy at different sites (regions) of the Federal District (FD) where trees had a diameter at breast height (DBH; 1.30 m) ≥5 cm in forest formations and a diameter at base height (Db; 0.30 m) ≥5 cm in savanna formations. Their diameters and heights were measured, they were cut and cubed, and the volume of each tree was obtained according to the Smalian methodology. Linear and nonlinear models were adjusted. Criteria for the selection of models were determined using correlation coefficients, the standard error of the estimates, and a graphical analysis of the residues. They were later validated by the chi-square test. The resultant models indicated that fit by specific phytophysiognomy was ideal; however, the generic and forest formation models exhibited similar performance to specific models and could be used in extensive areas of the Cerrado, where they represent a high potential for generalization. To further increase our understanding, similar research is recommended for the development of specific and generic models of the total volume in Cerrado areas.

Two decades of land cover change and anthropogenic pressure around Bontioli Nature Reserve in Burkina Faso

Protected areas (PAs) are critical for ecosystem maintenance and providing services that benefit both wildlife and people. Nevertheless, climate change and anthropogenic pressures are posing an increasing challenge. Surrounded by high human population densities, there is still a paucity of information on how the land cover in Burkina Faso's PAs is changing, and what kinds of human activities are the main drivers. In this study, we examined the change in land use and land cover (LULC) in the Bontioli Nature Reserve (NR), one of Burkina Faso's most important protected areas, and assessed anthropogenic pressure within and around. Landsat imagery (ETM+ and OLI-TIRS) is used to categorise and estimate the change in LULC in 2000, 2010, and 2022 with the Random Forest algorithm on the Google Earth Engine platform. Regression analysis was applied to examine the relationship between the LULC categories and population increase. We found significant changes and correlations in LULC trends and population growth over time. From 2000 to 2022, wooded savanna, tree savanna, and shrub savanna decreased by 20.8 %, 6.8 %, and 4.5 %, respectively, while cropland increased by 26.3 %, along with grass savanna by 5 %. Population growth correlated with increased agriculture and decreased vegetative area with R2 of 0.903 and 0.793, respectively. Efforts should be made to create harmony between humans and nature through various approaches such as nature-based solutions to enable efforts for the reserve sustainable management (SDG15).

Temporal and trophic niche partitioning among arboreal ants in a Neotropical woodland savanna

Abstract Niche partitioning is a key mechanism for explaining species coexistence, including the coexistence of ants in trees of the Brazilian savanna (cerrado). However, we have limited information on the extent to which arboreal ant species exploit different food resources and/or have different daily foraging schedules. We tested these ideas through a baiting experiment, and by measuring the isotopic signature (δ15N) and the critical thermal maximum (CTmax) of the 14 most common species found in a typical cerrado tree species. Although most species foraged on all bait types offered, species‐specific preferences were noted for about one‐third of the species. We also found a wide variation in mean δ15N between species, reflecting interspecific differences in trophic position. Most (71.4%) species foraged predominantly on a given period of the day, ranging from strictly nocturnal species to those that foraged mainly in the afternoon. Species with a higher heat tolerance (higher CTmax) often foraged at warmer periods of the day than those with a lower tolerance. Despite the evidence of trophic and temporal niche partitioning, other mechanisms, such as nesting site specialization and behavioural trade‐offs, are required to explain species coexistence in this arboreal ant assemblage, as several species pairs largely overlapped both in their diet and time of foraging. Importantly, our results provide additional support for the idea that physiological restriction to high temperatures is important for understanding interspecific differences in foraging activity schedules.

Physiological responses of Lizard, Toad and Pigeon during rainy season in tropical savanna climate

BackgroundThis study investigated the adaptation mechanisms of Pigeons, Toads and Lizards during the rainy season in tropical savanna climates. Male Agama Lizards (Agama agama), Afep Pigeons (Columba unicincta) and Toads (Sclerophrys perreti) were captured at a location in Ibadan, Oyo state. Five (5) Lizards marked: L1 to L5, Afep Pigeons marked: B1 to B5 and Toads marked: T1 to T5. Each of the animals was manually constrained within six to eight hours of capture, and a 1.0-ml syringe was used to obtain blood from the heart or coccygeal vein. Blood samples were collected in an EDTA and plain bottle, respectively. Plasma and sera samples were separated by centrifugation at − 4 °C using a cold centrifuge and then analysed for creatinine, urea, glucose, Mg+, k+, Cl−, Na+, albumin, TP, ALP, ALT, AST, GGT, MDA, SOD, CAT, GSH and haematological parameters. Cervical dislocation was performed on the animals before organs such as kidneys and liver were collected from each of the animals. Each organ collected from each animal was placed in separate plain tubes (filled with phosphate buffer).ResultThe Pigeon had higher body temperature, urea, glucose, ALP, PCV, haemoglobin concentration, neutrophil and triglyceride compared to the Lizard and Toad, while the Toad had higher Na+, Mg+ and Cl−, basophil and monocytes compared to Pigeon and Lizard and the Lizard has higher creatinine, lymphocyte and cholesterol compared to the Pigeon and Toad. On the liver oxidative stress markers, the Pigeon has higher superoxide dismutase and reduced glutathione compared to the Lizard and Toad, while the Toad has higher MDA and catalase compared to the Pigeon and Lizard. On the kidney oxidative stress markers, the Pigeon has higher MDA compared to the Lizard and Toad, while the Toad has higher catalase than the Pigeon and Lizard.ConclusionsFrom this study, the elevated level of lymphocytes in Lizard and eosinophil, basophil and monocytes in Toad suggests that Lizards and Toad are more vulnerable to inflammation. The high value of cholesterol in Lizard and triglyceride in Pigeon as observed in this study may relate to the degree of stress. Also, the activation of antioxidant systems under comparative study is a part of the survival strategy of animals like amphibians, reptiles and aves when facing environmental problems.

Trace Elements and Proximate Analysis of &lt;i&gt;Boswellia dalzielii&lt;/i&gt; Stem Bark

Boswellia dalzielii (B. dalzielii) Hutch is a tree plant of the Burseraceae family found in Savannah woodlands. The decoction of stem bark has been reported to be useful in treating gastrointestinal diseases, rheumatism, septic sores, and sexual ailments. Additionally, it has demonstrated antifungal, antibacterial, and anti-inflammatory properties. The research was undertaken to evaluate the trace element contents and nutritional contents of the stem bark of B. dalzielii using standard methods of the Association of Official Analytical Chemists (AOAC). The elemental analysis showed the presence of: Zn (5.82±0.021 mg/kg), Cu (4.22±0.017 mg/kg), Mn (31.24±0.114 mg/kg), and Fe (9.12±0.318 mg/kg), Se (3.13m±0.223 g/kg) Cr (0.0026±0.211 mg/kg), Co (0.00 mg/kg), Mo (0.0016±0.001 mg/kg), Cd (0.0037±0.117 mg/kg), Ni (0.0016±0.324 mg/kg), and I (4.15±0.214 mg/kg). While the proximate analysis revealed the presence of the following: ash content (5.97±0.315%), moisture (6.22±0.115%), protein (18.52±0.018%), fiber 16.2±0.215%), crude fat (6.02±0.002%), and carbohydrate (31.73±0.224%). Trace elements have well-characterized physiological functions within the body. They regulate biological processes, thereby stabilizing the structures of cells when they are supplied at the normal level, but their deficiency leads to different kinds of diseases. The study suggests that the trace elements present in the bark sample of B. dalzielii may be of value and may have prognostic significance in the early diagnosis and therapy evaluation of some diseases, especially various types of cancer, as well as in anti-diabetic agents. The results of the proximate analysis depict the potentiality of the plant as a good source of nutraceuticals.

High resolution stable isotope ratios in modern African land snails: Testing inferred environmental conditions

High-resolution sub-annual stable oxygen isotope data were measured in modern land snail shells collected from different climatic zones in Africa to search for patterns in seasonal δ18O cycles associated with specific hydroclimates, keyed to flora/biozones. Thirty-three recently dead shells were collected between 1995 and 2012, and collection localities were divided into five climate types: tropical forest, woodland savannah, bushland savannah, woodland monsoon, and arid/semi-arid. Thirteen genera are represented in the collection. Sampling covered at least one year in the life of the land snails, often multiple years. A comparison of measured data to predicted δ18O values, using local temperature and rain δ18O value, shows that predictions tend to be lower than measured values, suggesting that surface waters or snail body waters have undergone some evaporation. Predictions based on night-time temperatures (average monthly minimum T) are closer to, but still underestimate, measured values compared to day-time (maximum) temperatures in a majority of cases. The largest range in δ18O values for individual shells occurs in the bushland savannah and woodland monsoon biomes. Longer seasonal intervals of dry conditions lead to greater δ18O ranges in shells, although if the dry interval approaches 10 months in the year the amplitude is again reduced. This is in agreement with other oxygen isotope studies of high-resolution land snail shell samples, which show very high δ18O variance in strong monsoon climates.

Influence of the Season of Year and Stage of Postharvest Processing on Anthracnose Severity in Bananas in a Savanna Climate in the Brazilian Northeast

ABSTRACTBanana cultivation has great socio‐economic importance in the Cariri region (state of Ceará), Brazil. This study aimed to monitor the severity of anthracnose (caused by Colletotrichum musae) in bananas (cv. Prata) collected at three postharvest processing steps (dehanding, first washing and second washing) in packinghouses of four producing companies (A, B, C and D) in the wet (February–May) and dry (September–December) seasons of production in 2019. Averaged across packing companies and processing stages, disease severity was higher in the wet season (42.4%) than in the dry season (19.6%), but disease variability, expressed by the coefficient of variation, was higher in the dry season. In most cases, there were significant (p ≤ 0.05) differences among processing stages within each packinghouse and season, but the stage with the highest disease severity was not consistent. In other words, there was no predictable change in disease severity from dehanding to first and second washing. It was impossible to identify a single pattern in the severity of anthracnose in banana fruits collected from different companies and stages of postharvest processing, and this may be associated with the management adopted in each production area.

Comparative Analysis of Aerosol Direct Radiative Forcing During COVID-19 Lockdown Period in Peninsular India

AbstractThe load of aerosols in the atmosphere has been increasing gradually due to industrialization and urbanization. This increase has contributed to change in the Earth’s radiation budget through the absorption or scattering of radiation. The aerosol direct radiative forcing (ADRF) is a measurement utilized to comprehend the impact of cooling or warming up of the atmosphere directly by aerosols. Our study examined the impact of aerosols during the COVID-19 pandemic by comparing them to the average from the preceding 5-year period (2015–2019) in peninsular India. The measure of aerosols deployed in this study is the Aerosol Optical Depth (AOD), and the study was carried out on three distinct time frames: prior to lockdown, during lockdown, and post lockdown. The study revealed that the ADRF increased during all the three time frames of 2020 compared to the average of 2015–2019, and the other time scales experienced an increase in ADRF as well. The most notable rise in ADRF and decrease in temperature occurred in the tropical savanna and warm semi-arid climate regions during the pre-lockdown period. During lockdown, the increase in ADRF was seen throughout the study area, and a decrease in temperature was observed only in the tropical monsoon region. In the post-lockdown period, the decline in ADRF was accompanied by a fall in temperature in the tropical savanna region. This study provides insights into the effect of aerosols on ADRF in peninsular India and highlights the importance of monitoring and regulating aerosol emissions to mitigate the changes in temperature.

Isolation and characterization of mung bean (Vigna radiata L.) rhizobia in Myanmar

We collected soil samples from six major mung bean cropping regions in Myanmar: Sagaing, Mandalay, Nay Pyi Taw, and Magway in the tropical savanna climate zone and Bago and Yangon in the tropical monsoon climate zone. All fields grew mung bean for at least 5 years and had no history of rhizobial inoculation. Mung bean ‘Yezin-11’, a popular cultivar in Myanmar, was inoculated with soil suspensions. From the nodules formed on the roots, we isolated 55 rhizobial strains. Identification of the isolates revealed the dominant species of indigenous rhizobia in each region. We identified 53 Bradyrhizobium strains and 2 Ensifer strains. Bradyrhizobium yuanmingense was dominant in the tropical savanna zone and Bradyrhizobium sp. (B. liaoningense or B. diversitatis) and B. centrosematis were dominant in the tropical monsoon zone. Principal component analysis indicates that the dominance of B. yuanmingense in the tropical savanna zone might be due to high concentration of NO3-N and P2O5 in the soil. It also indicates that the dominance of B. centrosematis in the tropical monsoon zone might be caused by drastically low pH and high concentration of NH4 in the soil. Bradyrhizobium centrosematis YGN-M9, B. yuanmingense SGG-M3, and Bradyrhizobium sp. BGO-M5 significantly increased nodulation (nodule number and nodule dry weight), acetylene reduction activity, and shoot dry weight, respectively, relative to Ensifer terangae MDY-M6. Co-inoculation with these three strains increased nodulation significantly compared with single inoculation of BGO-M5. The characterization of mung bean rhizobia and selection of microbial inoculant candidates will be useful for the development of microbial inoculants in Myanmar.