Browsing by Author "Muasya, Muthama"
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- ItemOpen AccessAre wetland plant communities in the Cape flora influenced by environmental and land-use changes?(2014) Ramjukadh,Carla-Louise; Day, Jenny; Muasya, MuthamaConsiderable attention has been given over the past few years to the distribution and environmental condition of wetlands in South Africa. A 1987-1989 study investigated over one hundred wetlands to establish unique discernible features for grouping and classifying wetlands in the Cape Floristic Region. In the current study, a representative subset of the wetlands surveyed in 1988/89 was re-examined. This thesis characterizes and assesses wetland plant communities and wetland types in both data sets, attempts to identify the major environmental factors influencing plant species distribution in the wetlands, assesses changes in plant species community composition over time; and asks whether surrounding land-use has influenced these. In the current study, of the 142 plants species recorded, 114 were identified to species with 28 to genus level. The historical vegetation data includes 173 plants, of which 115 were identified to species with 58 to genus level.
- ItemOpen AccessCharacterization of the intraspecific variation within the nickel (Ni) hyperaccumulator species Senecio coronatus (Asteraceae): a preliminary analysis of genetic population structure and shoot proteome expression(2013) Wolf, Michael; Ingle, Robert; Bishop, Jacqueline; Muasya, MuthamaHeavy metal (HM) accumulator plants possess the ability to actively hyperaccumulate and detoxify exceptionally high concentrations of metals in their aboveground tissues, without exhibiting any apparent signs of toxicity. Despite nickel (Ni) hyperaccumulator plants representing the largest percentage of known metal accumulator taxa (over 75%), the underlying genetic and molecular basis of Ni accumulation remains unclear. A prominent difficulty in understanding Ni hyperaccumulation has been the severe lack of intraspecific variation in the trait. Hence, the study of a single species exhibiting a significant degree of variation is highly desirable. as it avoids the use of inter-species comparative studies mostly utilized to date. The Ni hyperaccumulator Senecio coronatus (Asteraceae) has been reported to contain a significant degree of phenotypic plasticity with respect to the amount accumulated and subsequent cellular distribution of Ni. This apparent intraspecific variation means that S. coronatus may represent a useful system in which to study Ni hyperaccumulation. No population genetics study has been carried out to date on this species, and the evolutionary relationships between hyper and non- accumulator populations were unknown. Here, results are presented from a genetic analysis of 15 naturally occurring S. coronatus populations. Analysis of molecular variance (AMOVA) and phylogenetic analysis (based on non-coding nuclear and plastid markers) suggest that Ni accumulation may have evolved twice within S. coronatus, as hyperaccumulator plants from site Kaapsehoop, cluster with non-accumulating serpentine populations and demonstrate distinct genetic differentiation from other accumulator populations. Four populations were selected for a preliminary comparative shoot proteome analysis by means of two-dimensional SDS-polyacrylamide gel electrophoresis (2D SDS-PAGE) to identify proteins potentially involved in Ni hyperaccumulation. This analysis identified nine chloroplastic proteins involved in plant energy production and metabolism as overexpressed in hyperaccumulator plants from Agnus Mine and Kaapsehoop, compared to hypertolerant non-accumulator and non-serpentine plants from Galaxy Mine and Pullen Farm, respectively. However, no difference in photosynthetic efficiency, as determined by chlorophyll fluorescence measurements, was detected between these populations.
- ItemOpen AccessEdaphic factors and rhizobia influence the distribution of legumes (Fabaceae) in the Core Cape Subregion of South Africa(2018) Dludlu, Meshack Nkosinathi; Muasya, Muthama; Chimphango, Samson B MFabaceae is the second most speciose plant family in the Core Cape Subregion (CCR) of South Africa, a Mediterranean type ecosystem, with mostly nutrient-poor soils. A majority of the legumes occurring in this region belong to the predominantly nitrogen-fixing subfamily Papilionoideae and they employ a variety of strategies for nutrient acquisition. However, legumes are neither uniformly nor randomly distributed in the CCR landscape. Instead, distinct legume species assemblages tend to occupy particular habitats within the landscape. The drivers of this distribution pattern are yet to be determined. In this thesis, it was hypothesized that edaphic factors (soil chemical and physical characteristics) and the distribution of rhizobia have influenced legume distributions in the CCR landscape. The influence of edaphic factors on the distribution of legume species assemblages in the Cape Peninsula (a microcosm of the CCR) is the subject of the second chapter of the thesis. It was hypothesized that the composition of legume species assemblages is correlated with soil physical and chemical properties and that the interaction of Phosphorus (P) and the three cations that often bind P, i.e. Aluminium, Calcium and Iron, making it unavailable to plants, drive legume species assemblages in the landscape. Soils from 27 legume sites, spanning all major soil types of the Cape Peninsula, were analysed for 31 chemical and physical properties. Surveys of legume species present at each site were conducted to generate a presence/absence matrix. Canonical correspondence analysis was used to test for a correlation between legume species composition and edaphic factors. The strength of the association between legume species composition and site groupings based on edaphic properties was assessed using indicator species analysis. A significant correlation between edaphic factors and species composition was found and the key edaphic parameters driving the relationship were clay content, iron (Fe), potassium (K), sulphur (S) and zinc (Zn). Indicator species, characteristic of the various edaphic habitats were also identified. These findings indicate that distinct edaphic habitats are occupied by discrete legume species assemblages, implying a significant influence of edaphic factors on the legume distributions. Chapter three of the thesis sought to determine if the ecological parameters; altitude, pH and soil type influence the distribution of the two main rhizobial genera (Burkholderia and Mesorhizobium) that nodulate various legumes of the CCR, and to determine the diversity and phylogenetic position of rhizobia that associate with the narrowly distributed and rare Indigofera superba in the CCR. The first objective was pursued through molecular characterisation of rhizobial strains isolated from nodules of legume species collected in the field across the Cape Peninsula. DNA sequences for 16S rRNA, recA and nodA were combined with data from a previous study that sampled broadly within the CCR and phylogenetic analyses were conducted. Tests for phylogenetic signals for the three ecological parameters were conducted, using the D statistic for soil type and Pagel’s λ for altitude and pH. These analyses were used to test the hypothesis that closely related species occupy similar habitats with respect to each of the three ecological parameters. For the study of rhizobial symbionts of Indigofera superba, field nodules were sampled from multiple populations across its distribution range and a phylogeny of its symbionts was reconstructed in a matrix that included symbionts of diverse legumes from different habitats within the CCR. The results showed that Burkholderia is restricted to acidic habitats, while Mesorhizobium occurs in both acidic and alkaline habitats. Additionally, both rhizobial genera showed significant phylogenetic clustering for pH and most soil types. However, none of the genera showed a phylogenetic structure with respect to altitude. These findings indicate that pH and soil type influence the distribution of rhizobia in the CCR. Implications of these findings for the distribution of legumes in the landscape are discussed. For the narrowly distributed I. superba, the results showed that it associates with diverse strains within the genus Burkholderia and such strains are not phylogenetically distinct from strains isolated from localities outside its distribution range. These findings lead to the hypothesis that I. superba does not exhibit rhizobia specificity at the intrageneric level. Testing of this hypothesis through analysis of its nodulation capability on soils from outside its distribution range is recommended. The fourth chapter of the thesis determined the extent of horizontal gene transfer among rhizobial genera in the Core Cape Subregion (CCR) of South Africa and reconstructed the ancestral symbionts of the legumes. Phylogenies of two chromosomal genes (16S rRNA and recA) and one nodulation gene (nodA) of rhizobia, isolated from diverse legumes in the CCR, were reconstructed using Bayesian and Maximum Likelihood techniques. A cophylogenetic analysis was used to test for congruence between the chromosomal and the nodA phylogenies. Five genera of rhizobia (Bradyrhizobium, Burkholderia, Ensifer, Mesorhizobium and Rhizobium) were studied. A phylogeny of the legumes was reconstructed from matK and rbcL DNA sequences and it was used to reconstruct their ancestral rhizobia, using Bayesian methods. The chromosomal phylogeny of the rhizobia was mostly incongruent with that of nodA, indicating potential horizontal inheritance of the latter. The nodA genes of Burkholderia, Mesorhizobium and Rhizobium had different evolutionary histories from their counterparts in other parts of the globe. Burkholderia was reconstructed as the ancestral symbionts of the CCR legumes. Evidence of co-diversification between the legumes and their symbionts was observed and this highlights a potential role of the legume-rhizobia interaction to the high diversity of legumes in the CCR. Finally, the availability of compatible rhizobia and their competitive ability are discussed as possible drivers for the lack of shared legumes between the CCR’s Fynbos biome and the Kwongan of Australia. Overall, the study shows that edaphic factors and biotic interactions (rhizobia) have significant influence on the distribution of legumes in the Cape Peninsula and the larger Core Cape Subregion of southern Africa. These findings are consistent with the theory that edaphic factors and biotic interactions have a strong influence on species distributions at local and site spatial scales.
- ItemOpen AccessExtinctions: Past and Present Week 5 - Threats to plants(2017-03-17) Chinsamy-Turan, Anusuya; Muasya, MuthamaIn this video, Professor Anusuya Chinsamy-Turan interviews Professor Muthama Muasya, a plant scientist, about the threats facing plants from humans' impact on their habitats. He discusses how plants show up in the fossil record, and some of the existing threat to the plant species in the Western Cape region of South Africa. This is video 3 in Week 5 of the Extinctions: Past and Present MOOC.
- ItemOpen AccessThe implications of fynbos phytogeography for wetland photoassessment(2011) Corry, Fynn; Day, Jenny; Muasya, Muthama; Sieben, ErwinThe initial focus of the present study was intended to develop phyto-assessment tools for the evaluation of the environmental condition of lowland wetlands in the Fynbos biome of the South Western Cape of South Africa. A field survey and analysis of freshwater wetland vegetation across the Cape coastal lowlands (below 200m a.s.l.) was undertaken in the present study to explore the potential to identify aspects of the vegetation that could serve as indicators of the present environmental state within wetlands. The Braun Blanquet approach was employed for the vegetation sampling of 59 wetlands in three subregions of the coastal lowlands of the Fynbos biome.
- ItemOpen AccessMolecular phylogenetics, taxonomy and niche-based conservation risk assessment of Thesium L. (Santalaceae)(2020) Zhigila, Daniel Andrawus; Muasya, MuthamaThesium L. (Santalales: Santalaceae) is a large (360 species) genus of hemiparasitic perennial or annual species with a mainly Old-World distribution and a greatest concentration in southern Africa (ca. 186 species). Although Thesium is a major component of southern African flora, it often goes unnoticed and is poorly studied. The last revision of the entire genus was done by De Candolle in 1857. South African Thesium was last revised by Hill almost a century ago. Since Hill's revision, the number of collections have grown, and 49 new species have been described. Currently, no comprehensive Thesium taxonomic key exists, and species delimitation remains difficult due to a high variation in character states, rendering the genus in need of major revision. Within southern Africa, ca. 103 species occur in the Greater Cape Floristic Region (GCFR), of which about 72 are regional endemics. The GCFR Thesium, including ecologicalspecialists and generalists, offers an appropriate system for evaluating both the correlates of range extent, specialisation and the relative extinction risks associated with both ecological strategies. Here, it is predicted that a combination of edaphic, elevation and climate variables influence the geographic range of Thesium in the GCFR. Recent phylogenetic hypotheses revealed that Thesium is paraphyletic with respect to Austroamericium, Chrysothesium, Kunkeliella and Thesidium, suggesting the need for generic realignment. In addition, existing subgeneric and sectional classifications of this large genus lack a phylogenetic basis, thus compromising their predictive value. Using an expanded taxon sampling and a combination of nuclear (ITS) and chloroplast (matK, rpl32- trnL and trnL-F) DNA sequence data, chapter two re-assesses the phylogenetic relationships of Thesium and uses these as the basis of a new subgeneric classification of the genus. The phylogeny obtained confirms the need to place the four segregate genera into synonymy, resulting in a monophyletic Thesium. In addition, it resolves five, well-supported major clades within Thesiumwhich I recognize as subgenera. The South African endemic subgenus Hagnothesium is sister to the Eurasian subgenus Thesium (including Thesium, Kunkeliella and Mauritanica). The subgenus Psilothesium, occurring in tropical South America (formerly genus Austroamericium) and tropical Africa, is sister to the rest of the subgenera, which are all confined to South Africa. Within the latter, the subgenus Discothesium consists of subtropical and temperate species, whereas subgenus Frisea, comprising previously recognized sections Annulata, Barbata Frisea, Imberbia and Penicillata, is restricted to the GCFR. To facilitate identification of subgenera, I present identification keys, assigned species, provide brief diagnoses, identified ancestral morphological characters and, supply distribution and ecological data. Thesium subgenus Hagnothesium is endemic to the GCFR. In the past, there has been a propensity in revisionarywork ofthe subgenus Hagnothesium to split taxa into distinctspecies or vice-versa. Consequently, 15 different names exist although only six are accepted formally. Following recent molecular phylogenetic studies, the monophyly of the subgenus Hagnothesium is now well-established, but the circumscription of species within the section remains problematic given the complicated nomenclatural history which has added further confusion. Chapter three presents a revision of subgenus Hagnothesium using a total evidence approach to propose a modern taxonomy. I studied both herbarium collections and plants in their natural populations to circumscribe species boundaries, geographical ranges and estimates of their conservation status. Species of the subgenus Hagnothesium are dioecious, generally having four- merous, campanulate flowers, spikes borne in bract axils and arranged along the length of branchlets, with valvate perianth lobes and a short to absent hypanthial tube. The following eight species were recognized, of which one is here described as new: T. fragile L.f., T. fruticulosum (A.W.Hill) J.C.Manning & F.Forest, T. hirtum (Sond.) Zhigila, Verboom & Muasya comb. nov., T. leptostachyum A.DC., T. longicaule Zhigila, Verboom & Muasya nom. nov., T. microcarpum A.DC., T. minus (A.W.Hill)J.C.Manning & F.Forest and T. quartzicolum Zhigila, Verboom & Muasya sp. nov. I provide updated taxonomic keys, species descriptions, illustrations, distribution maps, new combinations, synonyms, and notes on the red list status for each species. In addition, six new species of Thesium endemic to the GCFR (but not included in subgenus Hagnothesium) are described and illustrated in chapter four. These are: Thesium aspermontanum Zhigila, Verboom & Muasya sp. nov., T. dmmagiae Zhigila, Verboom & Muasya sp. nov., T. neoprostratum Zhigila, Verboom & Muasya sp. nov., T. nigroperianthum Zhigila, Verboom & Muasya sp. nov., T. rhizomatum Zhigila, Verboom & Muasya sp. nov., and T. stirtonii sp. nov. Also, Thesium assimile var. pallidum is elevated to species rank as T. sawae Zhigila, Verboom & Muasya stat. nov. Morphological and ecological differences between species, along with their putative affinities, preliminary conservation status, phenology, etymology and distributional maps are presented. Narrow-ranged species are expected to be more at greater risk of extinction than generalists due to climate change. Such risk is greatest in biodiversity hotspots such as the GCFR, which house both ecological specialists and generalists. It was hypothesized that range size, ecological specialization and consequent climatically-modulated extinction-risk are all phylogenetic structured, such that climate change will precipitate a disproportionate loss of phylogenetic diversity. Past and future species distribution ranges were developed using MaxEnt models based on present-day occurrences and environmental conditions. There was a strong positive correlation between the ecological niche breadth of species, as determined by large-scale environmental variables, and their range extents. One hundred and one Thesium species were modelled, of which 71 species (83%) were predicted to have had broad range sizes during the Last Glacial Maxima, and 27 species (17%) recorded range contractions historically to the present. Similarly, 45 species (44%) will potentially expand their ranges, while 51 species (50%) are predicted to reduce their ranges in the future. Of the 65 species currently ranked as Least Concern or Data Deficient in the South African Red list, 24 species will likely shift into higher extinction risk categories. Interestingly, five ecological specialists (5%), although having experienced a range reduction from the LGM to the present, are predicted to persist in the face of future climate change. However, the range extent, ecological specialisation and extinction risk are phylogenetically random and therefore should have a negligible impact on the phylogenetic diversity of the GCFR Thesium. Overall, this study confirms the monophyly of the genus Thesium and sets its infrageneric classification scheme in place. The context of this classification framework allows the systematic revision of the genus, one clade at a time. Towards this goal, I revised the Hagnothesium clade and additionally described six new species from other clades. The climate, elevation and soil variables influence the distribution range and specialism of GCFR Thesium clades. However, ecological specialism of species and extinction risks were predicted to be phylogenetically random.
- ItemOpen AccessPhosphorous uptake and utilization efficiency in cluster root and non-cluster root forming species of the Core Cape Subregion, South Africa(2015) Basic, Dunja; Chimphango, Samson; Muasya, MuthamaThe Core Cape Subregion (CCR) is made up of a mosaic of highly weathered and nutrient leached soil substrates in the Western Cape. Plant available phosphorus (P) in these soils is very low, generally ranging from 0.4-3.7 µg P g-1 soil and as a result plants have evolved a number of traits to enhance P-acquisition, such as increased root surface area (SA) and specific root length (SRL), cluster root and root hair proliferation and exudation of organic acids and acid phosphatases (APase) from the roots. Crop yield is limited worldwide due to the unavailability of P and P-fertilization is showing limited success due to soil retention. Sustainable management of this would include exploiting plants with natural adaptations for enhanced P acquisition and utilization. The aim of this study was to discover whether cluster root forming species are more efficient at P acquisition than non-cluster root species. This was achieved by focusing on two objectives: (1) to characterize root traits for increased P acquisition in different soils of the CCR and (2) comparing P-uptake and utilization efficiencies of cluster root species to non-cluster root species under glasshouse and natural conditions. Plants from Fabaceae, Polygalaceae, Proteaceae, Cyperaceae, and Juncaceae were grown in two different glasshouse experiments and observed in a field study.
- ItemOpen AccessPlant community patterns and diversity in sites impacted by Eucalyptus camuldulensis Dehnh. : insights from the Berg River, Western Cape / Alison Midgley(2013) Midgley, Alison; Muasya, MuthamaAlien Eucalyptus and Acacia species are amongst the most prolific invaders of the Berg River catchment, in the Western Cape. This study assessed the effects of invasive species and the potential for passive successional restoration in a heavily invaded riparian site (>80% aerial cover), a cleared riparian site and a pristine reference site. Three plots were demarcated per site, and transects were taken perpendicular to the river on the lower, middle and upper bank. Three 2m2 quadrats were intensively sampled per transect. Species diversity and community composition of indigenous and alien species were compared by measuring herbaceous, shrub and tree cover. Soil conditions, such as texture, salinity, acidity and moisture, were also compared. Distinctly different plant communities were found in each site, although cleared and invaded sites were more similar to each other. Cleared sites showed >45% cover by invasive successional species and grasses atypical of natural succession patterns. It was proposed that restoration constraints (e.g. method of clearance, intensity of prior invasion, land-use) were encouraging alien re-colonisation. However, there was evidence that the overall the trajectory of successional was favourable for indigenous trees and species. It was suggested that active re-vegetation of indigenous tree species, and adherence to correct clearance methods would aid site restoration.
- ItemOpen AccessPsoralea margaretiflora (Psoraleeae, Fabaceae): A new species from the Sneeuberg Centre of Floristic Endemism, Eastern Cape, South Africa(2011) Stirton, Charles; Clark, Vincent; Barker, Nigel; Muasya, MuthamaAbstractA new species of Psoralea is described. Psoralea margaretiflora C.H. Stirton & V.R. Clark is endemic to the Sneeuberg Centre of Floristic Endemism, Eastern Cape, South Africa. This resprouter is characterised by its small greenish-white flowers with a small trifid purple nectar patch and translucent veins; 5(–7)-pinnate leaflets; multi-branching erect short seasonal flowering shoots; and tall habit of many stiff bare stems with the seasonal shoots massed at the apex. It is most similar to Psoralea oligophylla Eckl. & Zeyh., a widespread species found in the Eastern Cape. The reseeder Psoralea oligophylla differs in its lax virgate spreading habit with numerous long glaucous seasonal shoots; single stem, 1(–3)- glaucous leaflets; more numerous white flowers; and standard petals with a purple ring surrounding a bright yellow nectar patch.
- ItemOpen AccessA systematic study of the South African genus Prionium (Thurniaceae)(2013) Munyai,Rabelani; Muasya, Muthama; Chimphango, SamsonThe South African monocotyledonous plant genus Prionium E. Mey (Thurniaceae; Cyperid clade) is an old, species-poor lineage which split from its sister genus Thurnia about 33 - 43 million years ago. It is a clonal shrubby macrophyte, widespread within the Fynbos biome in the Cape Floristic Region (CFR) with scattered populations into the Maputaland-Pondoland Region (MPR). This study of the systematics of the genus Prionium investigates whether this old lineage comprising of a single extant species P. serratum, is morphologically, genetically and ecologically impoverished, and identifies apomorphic floral developmental traits in relation to its phylogenetic position as sister to the Cyperid families, Juncaceae and Cyperaceae. Sampling for morphological, molecular and ecological studies was done to obtain representatives from its entire distribution range, falling within the phytogeographic regions of the CFR (North West, NW; South West, SW; Agulhas Plain, AP; Langeberg, LB) and extending into Eastern Cape (South East, SE) and KwaZulu Natal (KZN). Samples for the floral ontogenetic study were collected to obtain representatives of the Cyperid clade families: Cyperaceae (Eriophorum, Scirpus), Juncaceae (Juncus, Luzula) and Thurniaceae (Prionium).
- ItemOpen AccessUnravelling multidimensions of the flora of Kenya floristics, herbivory defences, and phylogenetic diversity(2023) Kimeu, John; Muasya, MuthamaThe wealth of plants in the vegetation of Kenya, owing to the country's wide range of climatic and ecological regions, can be complex and hence defies easy definition. This thesis, consisting of a literature review, four data chapters and a synthesis, addresses multiple aspects of that vegetation, including floristics, functional traits and phylogenetics, using a multidimensional approach, with a purpose to disentangle and explain drivers and patterns of the vegetation. The purpose of the study is achieved by focusing on the following four objectives: (1) assessing plant species composition and climate to present correlative support for the three African phytochoria divisions (Afromontane Archipelago, Somali-Masai and Zanzibar-Inhambane) prominent in the vegetation of Kenya; (2) investigate evidence for species filtering on the basis of soil properties maintaining broad-leaved non-spiny Combretum – Terminalia and narrow-leaved spiny Acacia – Commiphora woodlands mosaics in a mesic savanna ecosystem in south-eastern Kenya; (3) to evaluate structural and chemical plant defense manifestations between woody plants of the broad-leaved non-spiny Combretum – Terminalia and narrow-leaved spiny Acacia – Commiphora woodlands studied in Objective 2; and (4) to infer age, phylogenetic diversity and structure for the phytochoria of Africa predominantly represented in the vegetation of Kenya. Objective 1 (chapter 2) assessed community composition and climatic homogeneity phenomena for the three African phytochoria prominent in the vegetation Kenya. To test the phytochoria's taxonomic structure, occurrence data from 32 regional plant inventory checklists distributed across the phytogeographical regions of Kenya were grouped using multivariate analysis techniques. The checklists were intensively searched from published sources (i.e., journal articles and technical reports), which are considered representative of the vegetation of Kenya at species (70%) and genera (78%) levels, and at least comprise five samples for each phytochorion. To test climatic homogeneities for the studied phytochoria, 19 climatic variables of the BIOCLIM dataset extracted in each of the plant inventory areas were used, and a test of phytochoria-climate correlations executed in the canonical correspondence analysis (CCA). The study results show that vegetation types in Kenya were mainly partitioned by both precipitation and temperature vectors gradients, rather than on discontinuities in phytochoria units. For example, heterogeneity was observed in the Somali-Masai phytochorion, frequently interspersed with granitic hills, supporting montane-like vegetation at their summits. Precipitation was the most influential climatic variable in determining occurrence of vegetation type in the vegetation of Kenya, with its facets perhaps compounded by elevation and temperature. While phytochoria typically represent geographical areas with largely homogenous plant species composition that contrast with other phytochoria, in contrast, data presented in this study demonstrates that the vegetation of Kenya does not support the phytochoria classification. Instead, the vegetation is highly heterogeneous, partitioned by both precipitation and temperature vectors which change rapidly within a short distance particularly in response to elevation gradients. In chapter 3 (objective 2), I explored if soil characteristic is one of the micro-environmental filters driving and maintaining broad-leaved non-spiny Combretum – Terminalia and narrowleaved spiny Acacia – Commiphora woodlands as mosaics at the mesic savanna landscape of southern Kenya — herein testing evidence for species filtering on the basis of soil properties. I analysed empirical field data of woody species and soil characteristics from 57 plots that included 25 from Combretum – Terminalia and 32 from Acacia – Commiphora vegetation formations. I compared floristic composition and soil characteristics between the two systems and correlated edaphic statuses and vegetation states. I encountered 2,749 woody plant individuals, representing 115 species, 87 genera and 40 families. I found that the two vegetation types had discrete woody species composition and soil characteristics, and a significant speciesedaphic association. These results affirmed evidence for species filtering on the basis of soil properties (objective 2) and also a widely held view that soil characteristics are among the important micro-environmental filters driving and maintaining woody vegetation mosaics in the tropics. Objective 3 (chapter 4), which builds on the results of objective 2, evaluates whether there is a dichotomy on defence traits and perhaps on leaf nutrients levels, where spines and higher leaf nutrients are associated with fine-leaved plants occurring in nutrient richer soils whereas broadleaved plants occurring in nutrient poor soils have low nutrients but high tannin and carbon levels in their leaves. I used data of 93 plants for eight species from eight sites — four sites from fertile Acacia – Commiphora vegetation (42 plants) and another four sites from infertile broadleaved non-spiny Combretum – Terminalia vegetation (39 plants). Nutrient levels, and chemical and morphological defenses results did not show a consistent divide between the broad-leaved non-spiny Combretum – Terminalia and narrow-leaved spiny Acacia – Commiphora woody communities. Instead, the study found a range of defense-trait and leaf nutrients levels combinations. The results, thus, do not support the study hypothesis and only partially upheld the generally view regarding existence of trade-off between structural and chemical defenses for the dry African savannas woody plants partitioned on soil statuses. Instead, the results corroborate the emerging notion that a section of spiny woody species growing in nutrient-rich soils in African savanna landscapes invest in chemical anti-herbivore defenses equally to non-spiny broad-leaved plants growing in nutrient-poor soils in African savannas. Objective 4 (Chapter 5) inferred age, phylogenetic diversity, as well as phylogenetic structure of three major African phytochoria dominant in the vegetation of Kenya—with the aim to test aspects of “museum and/or cradle” of plant radiations. This was achieved through applications of large-scale DNA barcoding, including novel sequencing of over 200 Kenyan species and adding these to a matrix of ~2000 vascular plants. Maximum Likelihood (ML) methods implemented in RAxML software was used to create study phylogeny, which was dated using fossil-derived calibrations using the penalised likelihood algorithm as implemented in treePL. Phytochoria spatial occurrence data of the sequenced species was obtained from the African Plant Database, and taxon occurrences mapped onto the phylogeny using the phylobase package. The constructed phylogeny and species spatial occurrence data were both analysed in the Picante R-library to compute age, phylogenetic diversity and phylogenetic structure indices, which include phylogenetic diversity (PD), Net Relatedness Index (NRI), Nearest Taxon Index (NTI) and evolutionary distinctiveness (ED) of lineages for each phytochorion. The study found that divergence times for the Somali-Masai lineages are within < 10 Ma, a range that is much younger than of the Afromontane Archipelago and Zanzibar-Inhambane phytochoria. Afromontane Archipelago and Zanzibar-Inhambane phytochoria, in addition to containing taxa of younger divergences (i.e., < 10 Ma), also have lineages older than 10 Ma age range. The Zanzibar-Inhambane phytochorion had relatively higher PD, NRI and NTI values compared to the Somali-Masai and Afromontane Archipelago, while the ED measure among the phytochoria was similar, where the upper and lower quantiles overlapped. However, Zanzibar-Inhambane compared to Afromontane Archipelago and Somali-Masai had a higher number of outlier ED scores. Investigated phylogenetic indices support the hypothesis that Zanzibar-Inhambane is a “museum” of plant radiations, while the other phytochoria are mostly cradles of evolution. Overall, contrary to the common standard style in science that relies on a single dimension, a holistic understanding is needed to disentangle drivers and patterns of biodiversity. The current study applied a multidimensional approach to unravel multiple dimensions of the vegetation of Kenya. For example, using novel multivariate techniques that enable a quantitative approach, I have been able to rigorously test the phytochoria classification in the vegetation of Kenya. Through multivariate techniques I have advanced knowledge on ecology of the broad-leaved non-spiny Combretum and fine-leaved spiny Acacia vegetation types in the mesic savannas of south-eastern Kenya and perhaps elsewhere in Africa. Lastly, through applications of DNA barcoding, the study has contributed a novel insights and data for the vegetation of Kenya, opening opportunities for further work in the country in the field of community phylogenetics.