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Objectives: Climate change is expected to have major impacts on plant species distribution worldwide. These changes can affect plant species in three ways: the timing of seasonal activities (phenology), physiology and distribution. This study aims to predict the effect of shifting climatic conditions on the major vegetation units along an aridity gradient through Namibia. Study area: Namibia’s vegetation is characterised by open woodland in the northeast to low open shrubland in the southern part of the country. These differences are a result of increasing aridity from north to south with a rainfall gradient from 100 mm to 600 mm. Namibia is projected to have an increase in annual mean temperature of 2°C by the end of the 21st century. Methods: A vegetation classification was done for 1,986 relevés using cluster analysis, a Multi-Response Permutation Procedure and indicator species analysis. The current distribution of the vegetation classes was modelled with Random Forest. Future projections for the most important climate variables were used to model the potential distribution of the vegetation units in 2080. This modelling approach used two scenarios of Representative Concentration Pathways (4.5 and 8.5) from two Global Climate Models – the IPSL–CM5A–LR and HAdGEM2–ES. Results: The predicted distribution shows a high expansion potential of Eragrostis rigidior-Peltophorum africanum mesic thornbush savannas, Combretum africanum-Terminalia sericea broad-leafed savannas and Senegalia mellifera-Dichrostachys cinerea degraded thornbush savannas towards the south under both scenarios. Conclusions: The model indicated the ability to classify and predict vegetation units to future climatic conditions. Half of the vegetation units are expected to undergo significant contraction. Overall, RCP8.5 conditions favour the proliferation of certain vegetation types, particularly Combretum collinum-Terminalia sericea broad-leafed savannas and Senegalia mellifera-Dichrostachys cinerea degraded thornbush savannas, potentially displacing other vegetation types. Taxonomic reference: Klaassen and Kwembeya (2013) for vascular plants, except Kyalangalilwa et al. (2013) for the genera Senegalia and Vachellia s.l. (Fabaceae). Abbreviations: CDM = Community Distribution Model; CMIP5 = Coupled Model Inter-comparison Project Phase 5; EVI = Enhanced Vegetation Index; GCM = General Circulation Model; IV = Indicator Value; ISA = Indicator Species Analysis; MAP = mean annual precipitation; MAT = mean annual temperature; MRPP = Multi-Response Permutation Procedure; NMS = Non-Metric Multidimensional Scaling; RF = Random Forest; RCPs = Representative Concentration Pathways; SDM = species distribution model.

Aims: The Karstveld in Namibia has been recognized as an area of high plant diversity. However, this area is also recognised as a hotspot of various forms of degradation including bush encroachment. Minimal baseline data on the composition and diversity of vegetation in this area is available, therefore this paper is a first attempt to rectify this data deficiency. Study area: The Karstveld in Namibia is formed around the Otavi Mountain Range in northern Central Namibia, consisting of strongly karstified carbonate bedrock, rising up to 2000 m a.s.l. The Karstveld includes the Ovambo Basin plains with shallow calcrete soils north of the range, up to the Omuramba Ovambo. Because of orographic effects, the area receives some of the highest rainfall in Namibia, with up to 600 mm per year. Methods: A set of 889 relevés with 868 species was selected from the GVID ID AF-NA-001 database. A partial data set, using trees, shrubs, dwarf shrubs and grasses only, was used for the classification with modified TWINSPAN. The initial result yielded four main groups, according to which the data was split and further classified. Several vegetation types observed during field surveys were not reflected in the classification results; these were refined using Cocktail with known characteristic species. Results: The four main units represented wetlands and grasslands with six associations, a Thornbush savanna – Karstveld transition zone with four associations, Kalahari vegetation with four associations and the Karstveld proper with eight associations. The latter are grouped together as the Terminalietea prunioides, with two orders and three alliances recognised under them. We describe 16 associations according to the ICPN. Conclusions: Although the associations presented in this paper are clearly defined, there exists a high degree of diversity within these. The Karstveld is also extraordinary species rich within the context of the arid to semi-arid Namibian environment. Taxonomic reference: Klaassen and Kwembeya (2013) for vascular plants, with the exception of the genus Acacia s.l. (Fabaceae), for which Kyalangalilwa et al. (2013) was followed. Abbreviations: ga = annual grass; gp = perennial grass; GPS = Global Positioning System, referring to a hand-held ground receiver; hl = herb layer, containing all hemicryptophytes, therophytes and geophytes, but excluding grasses (Poaceae); ICPN = International Code of Phytosociological Nomenclature (Theurillat et al. 2021); MAP = mean annual precipitation; NMS = nonmetric multidimensional scaling (Kruskal 1964); RDL = Red Data List (IUCN Species Survival Commission 2001); s1 = tall shrubs, i.e. multi-stemmed phanerophytes between 1 and 5 m; s2 = short shrubs, i.e. chamaephytes or ‘dwarf shrubs’ below 1 m; SOTER = Global and National Soils and Terrain Digital Database (FAO 1993); t1 = tall trees, > 10 m; t2 = short trees, between 5 and 10 m; t3 = low trees, i.e. single-stemmed phanerophytes between 2 and 5 m; TWINSPAN = Two Way Indicator Species Analysis (Roleček et al. 2009); WGS84 = World Geodetic System, 1984 ensemble.

Global patterns of regional plant diversity are relatively well known, but whether they hold for local communities is debated. This study created multi-grain global maps of alpha diversity for vascular plants to provide a nuanced understanding of plant diversity hotspots and improve predictions of global change effects on biodiversity.

The characterization and evaluation of the recent status of biodiversity in Southern Africa’s Savannas is a major prerequisite for suitable and sustainable land management and conservation purposes. This paper presents an integrated concept for vegetation type mapping in a dry savanna ecosystem based on local scale in-situ botanical survey data with high resolution (Landsat) and coarse resolution (MODIS) satellite time series. In this context, a semi-automated training database generation procedure using object-oriented image segmentation techniques is introduced. A tree-based Random Forest classifier was used for mapping vegetation type associations in the Kalahari of NE Namibia based on inter-annual intensity- and phenology-related time series metrics. The utilization of long-term inter-annual temporal metrics delivered the best classification accuracies (Kappa = 0.93) compared with classifications based on seasonal feature sets. The relationship between annual classification accuracies and bi-annual precipitation sums was conducted using data from the Tropical Rainfall Measuring Mission (TRMM). Increased error rates occurred in years with high rainfall rates compared to dry rainy seasons. The variable importance was analyzed and showed high-rank positions for features of the Enhanced Vegetation Index (EVI) and the blue and middle infrared bands, indicating that soil reflectance was crucial information for an accurate spectral discrimination of Kalahari vegetation types. Time series features related to reflectance intensity obtained increased rank-positions compared to phenology-related metrics.

The establishment of communal conservancies aims to have the local communities share in the benefits especially of wildlife resources, in this way spearheading the conservation of the environment. The Desert Margins Programme in Namibia aimed to develop vegetation resource data for the Otjituuo, Okamatapati, Ozonahi, African Wild Dog, Otjinene, Epukiro, Otjombinde, Omuramba Ua Mbinda, Eiseb and Ondjou communal conservancies, in order to assist with natural resource planning. For this purpose, a phytosociological survey of this area, with 422 relevés, was conducted during 2004. The data was captured in Turboveg and forms part of the Namibian phytosociological database (GIVD AF-NA-001). The data was split into two, representing two major land forms, the ‘hardeveld’ and the ‘sandveld’, respectively. A classification was undertaken using the Modified two-way indicator species analysis (TWINSPAN) procedure. Further refinements, based on field observations and literature sources, were performed using Cocktail procedures. Thirteen vegetation associations were formally described in this article, of which two were subdivided into subassociations. These associations can broadly be grouped into broad-leaved savanna types typical of the central and northern Kalahari of Namibia and microphyll savannas found on the transitions to the Central Plateau. One association, the Burkeo africanae–Pterocarpetum angolensis, forms the southern fringe of the Zambesian Baikiaea Woodlands ecoregion of the World Wildlife Fund, whilst all the other associations fall within the Kalahari Acacia–BaikiaeaWoodlands ecoregion. The Combreto collini–Terminalietum sericeae is the most widespread association and dominates the landscape. Threats to the vegetation include overutilisation and regular fires, both of which could easily lead to desertification. This threat is aggravated by global climate change. Conservation implications: This article described 13 plant associations of the central Kalahari in eastern Namibia, an area hitherto virtually unknown to science. The information presented in this article forms a baseline description, which can be used for future monitoring of the vegetation under communal land use.

The eastern communal conservancies are situated along the western fringe of the Kalahari basin. Under a very short rainfall gradient, the vegetation abruptly changes from microphyllous Acacia-dominated savannas to mesophyll savannas, dominated by Terminalia sericea and Combretum spp. We hypothesise that this is caused by changes in soil moisture availability brought about by changes in soil texture from loamy soils to deep sands (the ‘inverse texture effect’). For this analysis, we used vegetation and soils data derived from a recognisance survey of the natural resources of the study area. As the sites in the soil and vegetation surveys did not overlap, it was decided to use only synoptic data for the plant associations in the analysis. Non-metric multidimesional scaling ordination was utilised as ordination technique of the vegetation data and various environmental parameters, including soil texture, soil hydraulic parameters, climatic and fire regime parameters, were overlaid as biplots onto the resulting graph, as were various plant functional attributes particularly related to climatic conditions. The main environmental gradient identified within the study area is the rainfall gradient. This relatively short gradient, however, does not explain the marked change in vegetation observed within the study area. This change is attributed to the change in soil type, in particular, the soil texture and the associated soil hydraulic parameters of the soil. This gradient is closely correlated to leaf size, explaining the change from microphyll savannas to mesophyll savannas along the change from loamy to sandy soils. One of the lesser understood mechanisms for the survival of these mesophyll plants on sandy soils seems to be a deep root system, which is actively involved in water redistribution within the soil profile – by hydraulic lift, inverse hydraulic lift and stem flow. Conservation implications: Understanding these mechanisms will greatly assist in understanding savanna dynamics. With the threat of global climate change, we postulate that the vegetation will gradually change from the present mesophyll to a microphyll savanna, but that the grass sward will probably not develop very well. Shrub and tree removal (‘bush harvesting’) is likely to speed up the desertification process within this area.

In many parts of Africa, spatially-explicit information on plant α-diversity, i.e., the number of species in a given area, is missing as baseline information for spatial planning. We present an approach on how to combine vegetation-plot databases and remotely-sensed land surface phenology (LSP) metrics to predict plant α-diversity on a regional scale. We gathered data on plant α-diversity, measured as species density, from 999 vegetation plots sized 20 m × 50 m covering all major vegetation units of the Okavango basin in the countries of Angola, Namibia and Botswana. As predictor variables, we used MODIS LSP metrics averaged over 12 years (250-m spatial resolution) and three topographic attributes calculated from the SRTM digital elevation model. Furthermore, we tested whether additional climatic data could improve predictions. We tested three predictor subsets: (1) remote sensing variables; (2) climatic variables; and (3) all variables combined. We used two statistical modeling approaches, random forests and boosted regression trees, to predict vascular plant α-diversity. The resulting maps showed that the Miombo woodlands of the Angolan Central Plateau featured the highest diversity, and the lowest values were predicted for the thornbush savanna in the Okavango Delta area. Models built on the entire dataset exhibited the best performance followed by climate-only models and remote sensing-only models. However, models including climate data showed artifacts. In spite of lower model performance, models based only on LSP metrics produced the most realistic maps. Furthermore, they revealed local differences in plant diversity of the landscape mosaic that were blurred by homogenous belts as predicted by climate-based models. This study pinpoints the high potential of LSP metrics used in conjunction with biodiversity data derived from vegetation-plot databases to produce spatial information on a regional scale that is urgently needed for basic natural resource management applications.

Limited historic vegetation data (prior to the 1980s) are available for Namibia. Finding such historic data at Haribes prompted a follow-up survey of the vegetation. We present a classification of the recent data in this paper as a first step towards comparing the two data sets. Six new associations (three with two subassociations each) are formally described. The landscape at Haribes is dominated by a pan with surrounding hummock dunes. The pan supports the Lycio cinereum – Salsoletum, whilst on the hummock dunes the Salsolo – Tetragonietum schenckii can be found. The surrounding plains and escarpment can be divided into three landforms: the torras with the Monsonio umbellatae – Boscietum foetidae, the ranteveld with the Acacio senegal – Catophractetum alexandri (and two subassociations) and calcrete ridges with the Zygophylo pubescentis – Leucosphaeretum bainesii. Dry river beds on the farm support two subassociations of Anthephoro pubescentis – Ziziphodetum mucronatae. The area covered by each dominant landform has been calculated after being mapped. The composition and diversity of the associations are briefly compared to other known vegetation descriptions within the Nama-Karoo. Since November 2011, Haribes has been used as a resettlement farm. This may result in the overutilisation of the limited grazing resources, to the extent that the present, fairly dense Acacio senegal – Catophractetum alexandri of the ranteveld is feared to become degraded to resemble the Monsonio umbellatae – Boscietum foetidae of the torras. Conservation implications: This paper describes six plant associations of the Nama-Karoo biome in arid southern Namibia. The information presented forms a baseline description, which can be used for future monitoring of the vegetation under altered land use.