Fairy circles are circular, barren structures in dry grasslands and the mechanisms generating and maintaining them are currently under intense discussion. Here, we analysed bacterial and fungal communities in Namib Desert fairy circle soils, in the tapetum lining of termite nests, the gut of the prevailing sand termite Psammotermes allocerus, and also in the neighbouring grass plants. The total and active microbial communities were analysed through amplicon sequencing of both DNA and RNA extracts, respectively, species-specific PCRs, and through cultivation of bacteria and fungi from the various samples. In the sandy soils, the active bacterial communities were substantially different from the total communities, which suggested the fairy circle soils to be highly selective environments in comparison to other drylands or even temperate soils. This appears to be even more true for fungi as amplification of fungal genes from RNA extracts was not possible. However, we observed a large diversity among cultured fungal species in comparison to cultured bacterial species, specifically in tapetum samples. Our results support the hypothesis that Psammotermes allocerus acts as a vector for plant pathogenic fungi and that their nests below the bare patches of fairy circles provide a refugium for the fungal plant pathogens.
Fairy circles are created, used and maintained by sand termites of the species complex Psammotermes allocerus. We used Amplified Fragment Length Analyses (AFLP) for a study of the genetic diversity pattern of termites from clusters of neighboring fairy circles. Our results suggest that all termites found within one fairy circle genetically are members of one colony. The neighboring colonies are genetically differing from each other. This observation supports the hypothesis that colonies are founded by reproductive alates flying in from further away and not by budding from a near-by colony.
The harvester termite Hodotermes mossambicus is not regarded as causing fairy circles. On the other hand, the harvester termites forage huge amounts of grass biomass in the Namib Desert and beyond. This article describes quite different patterns caused by Hodotermes mossambicus in the Namib Desert. In addition to the well-known homogeneous foraging pattern this article newly describes hexagonal patterns and rare circular patterns from the Kunene region in northwestern Namibia.
In seasonally inundated landscapes of southern central Africa very large termite mounds of Macrotermes natalensis offer a refuge for flood-intolerant trees during the flood season. In the matrix landscape surrounding these islands the seasonally waterlogged and then anaerobic soil conditions and the browsing by megaherbivores during the dry season allow for grass and herbaceous vegetation only. During the rainy season each termitarium forms an isolated island which due to its relative dryness allows survival of the trees and the associated fauna. During the dry season the termites try to establish new colonies with new mounds. However, the successful formation of new termitaria islands seems to be a rare event. In this case study from Dundumwezi in the Kafue National Park, Zambia, we provide a description of the termitaria islands and their vegetation. Furthermore, we analyse spatial patterns of termite mound islands in the surroundings of Kafue National Park und Bangweulu Plains / Kasanka National Park based on remote sensing imagery. Our results confirm that competition among colonies of large termitaria in homogeneous habitats causes very regular spatial patterns.
Termite species are generally identified based on morphological differences of soldiers. This approach is here applied for the sand termite species Psammotermes allocerus. By using high quality resolution images, measurements of 26 traits of head, labrum and mandibles, the CART method, as well as geometric-morphometric shape analyses of mandibles of large soldiers (> 7mm in total body lengths) a discrimination between soldiers of three geographical regions is possible. Soldiers collected from the Succulent Karoo, Southern Namib and Northern Namib differ significantly from each other. This study is a first attempt to show strong morphological variation and differentiation within the sand termite Psammotermes allocerus from the arid regions. Further research in additional geographical regions and the comparison of different development stages of soldiers are needed for a complete assessment of the morphological diversity of species.
Figure 10.1.2:Western portion of South Africa with place names used in text.The pink-shaded areas represent the extent of the Succulent Karoo Biome within South Africa following Mucina, et al., 2006; the northern extension of this biome in southern Namibia is not represented.Names of cities and towns are in italicized, black serif font.Names of various physiographic regions are in dark red sans serif font.The Sandveld and Swartland regions are within the Fynbos Biome.Names of major rivers are in blue sans serif type.Note two separate rivers named "Olifants" in the Western Cape-one draining to the Atlantic Ocean, the other to the Indian Ocean.
The sand termite Psammotermes allocerus is widely distributed in in southern Africa. To investigate the genetic diversity of this species 113 samples were collected in the arid regions of South Africa, Namibia and Angola in fairy circles and also in landscapes without fairy circles. The mitochondrial markers COI and COII were selected to perform Bayesian Inference analysis. The phylogenetic tree is composed of eight well-supported genetic groups within the species complex. In a synopsis with also studied morphological features the eight groups Northern Namib, Western Kalahari Basin, Nama, Southwestern Kalahari, East Gariep, Southern Namib, Tsau IIKhaeb and Succulent Karoo should be considered as distinct species. The species name P. allocerus should be used for termite collections of the Succulent Karoo due to their basal position in the phylogeny.
Biodiversityand the long-lasting civil war in Angola.The intactness and functionality of the ecosystems are, however, essential on a local as well as a continental scale, as the middle and lower reaches of the Zambezi River provide livelihoods for millions of people (Chenje et al., 2000; Emerton, 2003; Turpie et al., 1999).Therefore, to study and monitor biodiversity in the area and gain knowledge on land use and ecosystem function, we implemented a biodiversity observatory according to the BIOTA Africa standard (Jürgens et al., 2012) in Cameia National Park, Moxíco Province, in eastern Angola, in May Welcomme, 1979).These ecosystems are home to specialized plants and animals, thus representing a particular biodiversity (Ward, 1998).Concurrently, humans make use of the fl ooding cycle by fi shing in the fl ood season and grazing their cattle in the dry period (Abbott et al., 2007).While other fl ooded savannas have already been the target of extensive studies, little is known about the species richness and ecology of seasonally fl ooded grasslands in south-central Africa.In particular, the still largely natural Zambezi catchment in Angola and Zambia lacks data as a result of diffi cult accessibility Abstract: Eastern Angola and western Zambia are dominated by the Zambezi catchment, where high precipitation and a dense river network cause annual fl ooding of extensive areas from January to ¬May.Cameia National Park in Angola is such a seasonally fl ooded savanna.A SASSCAL Biodiversity Observatory was established in May 2016, as little is known about the area's particular fl ora and fauna.Based on three visits to the observatory, we present a fi rst description of the ecology of this dynamic ecosystem, its vegetation units and plant species, occurrence and turnover of bird assemblages, and human land-use practices.We observed that the turnover in species composition, temporal niches of functional groups and guilds, and land uses are controlled by seasonally changing fl ood, fi re, and precipitation patterns.Our results highlight the conservation value of the area; sustainable management plans and conservation strategies are urgently needed to restore the formerly dominant herbivore guilds and to prevent destructive agro-industrial development schemes. Resumo:Angola Oriental e Zâmbia Ocidental são dominadas pela bacia hidrográfi ca do Zambezi, onde a alta precipitação e a densa rede fl uvial causam inundações anuais de extensas áreas entre os
The "quality" of a given food item depends on the morphological adaptations and physiological requirements of the animal (Stolter et al., 2018).For ruminants the digestion of feeds by the microbiome is essential, therefore food selection is an indirect process.As a result, determining of the drivers behind food selection (e.g.plant quality) is a challenging issue.Nevertheless, some general assumptions about quality can be made:
Several socio-economically important indigenous tree species of southern Africa show limited natural regeneration while also being threatened by land conversion and overharvesting.Assisted tree regeneration -both artifi cial regeneration in nurseries and assisted natural regeneration in forests -is needed to allow the sustainable use of forest resources.Five studies of artifi cial and assisted natural regeneration of indigenous timber and fruit trees were performed independently from one another in Botswana, Namibia, and South Africa.They aimed to investigate and improve cultivation of seedlings, especially by testing the eff ects of temperature and diff erent seed pretreatments on germination in incubators and the eff ects of soil inoculation with plant growth-promoting bacteria in nursery conditions.One study compared direct seeding with enrichment planting in the forest.The germination tests showed that the seeds of most indigenous species tested should be given at least six weeks to germinate, with the exception of Bauhinia petersiana.Seed pretreatment, especially nicking and/or soaking, can improve germination for Strychnos cocculoides (+17%), Dialium englerianum (+68%), Erythrophleum africanum (+22%), and P. angolensis (+24%).Guibourtia coleosperma seed germinates well without any treatment.The germination rate of P. angolensis seed improved (+21%) after soil inoculation with plant growth-promoting and nitrogen-fi xing bacteria.The important fruit tree Schinziophyton rautanenii showed poor seed germination (7% to 30%), but the use of cuttings for S. rautanenii gave a 100% survival rate after about six months.Broadcasting seeds in the forest and covering them with soil resulted in more surviving seedlings than planting because of damage caused by rodents.Further nursery studies should focus on vegetative propagation and the optimal conditions for seedling growth and establishment of potential agroforestry tree species, while a range of assisted natural regeneration techniques remain to be tested for forests in the region.
Tropical woodlands are dominated by C4 grasses.The C4 photosynthetic pathway makes them tolerant to higher temperatures and drought but less tolerant to shade compared to
Northern Namibia is fed by the Kavango, the Kwando, and the Zambezi Rivers, which fl ow from Angola and Zambia
Rangelands in arid areas of southern Africa are prone to degradation through overutilization.Once degraded, rangelands recover very slowly or may not recover without external drivers such as very high-rainfall years.To what extent,at what pace, and to which state Succulent Karoo vegetation is able to recover from long-term exposure to high grazing pressure -from extensive commercial farming, for instance -is poorly understood.We analysed 17 years of annual vegetation monitoring data from the Hardeveld bioregion of the South African Namaqualand.The recording commenced one year after the grazing pressure on the rangeland had been reduced from as much as 120% to 30% of the recommended stocking rate.Non-metric multidimensional scaling (NMDS) of all 17 annual relevés for the 20 plots showed a strong division of the species composition into 8 upland and 12 lowland plots.When applying NMDS to the relevés for the plots separately, in comparison with the lowland plots, upland plots showed a stronger directional change where the species composition shifted away from the initial state.The year-to-year species turnover per habitat, however, was greater on lowland compared to upland habitats.The visualisation of the cover changes per life form type showed that both habitats diff ered in their life form composition, with a higher dominance of large shrubs in upland compared to lowland habitats.The outcome of the study revealed a habitat-specifi c response of vegetation to land use change.But even within the habitats, the vegetation showed plot-specifi c responses of the vegetation to the variances in abiotic factors.We suggest that further analyses should have a stronger focus on species-specifi c responses at the diff erent sites and employ a more refi ned life form classifi cation, adapted for the Succulent Karoo vegetation.
Water availability continues to hamper southern African nations' economic and societal development eff orts.Highly variable rainfall; observed and projected rainfall decrease; and the inability of governments to keep up with infrastructure provision for fast-growing populations and urban, agricultural, and industrial sectors; as well as a lack of suffi cient information and monitoring are some of the factors that limit the ability of decision-makers to manage water resources sustainably to promote social and economic development.Proper planning and management of water resources are not possible without a suffi cient understanding and assessment of interacting drivers and processes controlling and/or aff ecting the water system.Against this background, the water theme of the SASSCAL programme aimed to signifi cantly contribute to the knowledge base of southern African water resources, providing decision-makers with additional means to inform their planning eff orts and thereby improve access to water, water resources management, and sustainable water use.Extensive research was conducted in Angola, Botswana, Namibia, South Africa, and Zambia, as well as across national borders.The focus was on improving monitoring and hydro-climatic data generation; gaining a better understanding of groundwater and surface water dynamics; and exploring the interdependency of water resources, water-use patterns, and vulnerabilities of society; as well as improving modelling techniques for advanced (transboundary) water resources assessment and management.This paper provides an overview of the SASSCAL water-related tasks to highlight some of the outcomes achieved under the SASSCAL water theme.
