Desert Research Foundation of Namibia

Windhoek, Namibia

Desert Research Foundation of Namibia

Windhoek, Namibia
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Kaseke K.F.,Stellenbosch University | Kaseke K.F.,Gobabeb Research Center | Mills A.J.,Stellenbosch University | Brown R.,University of Cape Town | And 3 more authors.
Pure and Applied Geophysics | Year: 2012

"Non rainfall" atmospheric water (dew, fog, vapour adsorption) supplies a small amount of water to the soil surface that may be important for arid soil micro-hydrology and ecology. Research into the direct effects of this water on soil is, however, lacking due to instrument and technical constraints. We report on the design, development, construction and findings of an automated microlysimeter instrument to directly measure this soil water cycle in Stellenbosch, South Africa during winter. Performance of the microlysimeter was satisfactory and results obtained were compared to literature and fell within the expected range. "Non rainfall" atmospheric water input into bare soil (river sand) was between 0.88 and 1.10 mm per night while evaporation was between 1.39 and 2.71 mm per day. The study also attempted to differentiate the composition of "non rainfall" atmospheric water and results showed that vapour adsorption contributed the bulk of this input. © 2011 Springer Basel AG.

Kaseke K.F.,Stellenbosch University | Kaseke K.F.,Gobabeb Research Center | Mills A.J.,Stellenbosch University | Henschel J.,Gobabeb Research Center | And 3 more authors.
Pure and Applied Geophysics | Year: 2012

The effect of desert pavements (gravel mulch) on near surface soil micro-hydrology has been inadequately studied. Micro-hydrology in arid ecosystems occurs due to a daily non rainfall atmospheric water cycle, consisting of an input phase (dew, fog, vapour adsorption) and an evaporation phase. A winter comparative study between a bare soil (control) and gravel mulch using the automated microlysimeter approach was conducted in Stellenbosch, South Africa in 2008. Results showed that dew deposition and direct water vapour adsorption were significantly higher into bare soil compared to gravel mulch. In contrast, however, soil moisture from rain persists for a longer time under gravel mulch compared to bare soil. This result suggests that the greatest impact of gravel mulch on soil micro-hydrology is towards conserving moisture and could explain why the treatment is used in dry-land agriculture in Mediterranean regions. © 2011 Springer Basel AG.

Kaseke K.F.,Stellenbosch University | Kaseke K.F.,Gobabeb Research Center | Mills A.J.,Stellenbosch University | Esler K.,Stellenbosch University | And 3 more authors.
Pure and Applied Geophysics | Year: 2012

"Non-rainfall" water is important to the soil water balance and ecology of arid ecosystems. A component of this "non-rainfall" water in the Namib Desert, fog, exhibits spatial variation implying variability in composition and significance of each vector (dew, fog, vapour adsorption) to ecology at different locations. The composition of "non -rainfall" water input directly into soil was investigated at two sites in the Central Namib Desert, Kleinberg and Gobabeb. Results showed spatial variation in composition between the sites, although vapour adsorption dominated input at both sites. Fog contributed more to total "non rainfall" atmospheric water closer to the coast (Kleinberg) compared to further inland (Gobabeb) but was lower than expected at both sites. Absolute values of fog input at both sites showed the opposite trend, Kleinberg 0. 38 mm per night compared to Gobabeb 8. 7 mm per night. This difference was attributed to the development of a mechanical crust on the soil surface at Kleinberg, which resulted in a significant reduction of vapour adsorption compared to Gobabeb. The crust also led to a significant reduction in evaporation from the sample at Kleinberg compared to the one at Gobabeb. Ecological differences between the two sites can be attributed to the development of the soil crust on the sample at Kleinberg and not on the sample at Gobabeb. © 2012 Springer Basel AG.

Stomeo F.,University of the Western Cape | Stomeo F.,Kenya International Livestock Research Institute | Valverde A.,University of the Western Cape | Valverde A.,University of Pretoria | And 7 more authors.
Extremophiles | Year: 2013

The Namib Desert is considered the oldest desert in the world and hyperarid for the last 5 million years. However, the environmental buffering provided by quartz and other translucent rocks supports extensive hypolithic microbial communities. In this study, open soil and hypolithic microbial communities have been investigated along an East-West transect characterized by an inverse fog-rainfall gradient. Multivariate analysis showed that structurally different microbial communities occur in soil and in hypolithic zones. Using variation partitioning, we found that hypolithic communities exhibited a fog-related distribution as indicated by the significant East-West clustering. Sodium content was also an important environmental factor affecting the composition of both soil and hypolithic microbial communities. Finally, although null models for patterns in microbial communities were not supported by experimental data, the amount of unexplained variation (68-97 %) suggests that stochastic processes also play a role in the assembly of such communities in the Namib Desert. © 2013 Springer Japan.

Kramer H.A.C.,University of California at Berkeley | Montgomery D.M.,Desert Research Foundation of Namibia | Eckhart V.M.,Grinnell College | Geber M.A.,Cornell University
Plant Ecology | Year: 2011

At scales from microsites to entire ranges, species' distributions reflect limited adaptation and/or limited dispersal. To what extent are specific distribution patterns and processes similar across scales? We investigated environmental effects-presumed because of adaptation-and independent spatial effects-presumed because of dispersal-on distribution at two scales (landscape patches of approximately 1,300 m2, sampled along transects, and 4-m2 cells, sampled in contiguous grids within populations) and on individual performance (water status, reproduction) in the California annual, Clarkia xantiana ssp. xantiana. Because water limitation helps set this species' regional borders, we expected occupancy and performance at smaller scales to correlate with topographic and soil features affecting water relations. At the patch scale, environmental features associated with reduced water stress (i.e., steep slopes that face north; coarse, soft soils; igneous rather than metasedimentary parent rock) predicted occupancy. Spatial aggregation was not detected, but incomplete occupancy of apparently suitable patches indicated that dispersal limits occupancy. At the scale of small cells, relationships between environmental variables, occupancy, density, and performance varied among populations. Associations sometimes resembled those at the patch scale but sometimes opposed them. Spatial aggregation in cell occupancy and/or density occurred in all populations, implying limited dispersal, whereas spatial aggregation of water potential values in some populations might have arisen from spatially structured unmeasured environmental variables. Limited adaptation to drought and limited patch colonization appear to affect patch occupancy in C. xantiana ssp. xantiana, whereas smaller-scale patterns indicate consistent effects of limited dispersal and somewhat variable environmental effects. © 2011 Springer Science+Business Media B.V.

Valverde A.,University of Pretoria | Makhalanyane T.P.,University of Pretoria | Seely M.,Desert Research Foundation of Namibia | Cowan D.A.,University of Pretoria
Molecular Ecology | Year: 2015

Most ecological research on hypoliths, significant primary producers in hyperarid deserts, has focused on the diversity of individual groups of microbes (i.e. bacteria). However, microbial communities are inherently complex, and the interactions between cyanobacteria, heterotrophic bacteria, protista and metazoa are likely to be very important for ecosystem functioning. Cyanobacterial and heterotrophic bacterial communities were analysed by pyrosequencing, while metazoan and protistan communities were assessed by T-RFLP analysis. Microbial functionality was estimated using carbon substrate utilization. Cyanobacterial community composition was significant in shaping community structure and function in hypoliths. Ecological network analysis showed that most significant co-occurrences were positive, representing potential synergistic interactions. There were several highly interconnected associations (modules), and specific cyanobacteria were important in driving the modular structure of hypolithic networks. Together, our results suggest that hypolithic cyanobacteria have strong effects on higher trophic levels and ecosystem functioning. © 2015 John Wiley & Sons Ltd.

Klintenberg P.,Mälardalen University | Jamieson M.,Tranas Utbildnings Centrum | Kinyaga V.,Desert Research Foundation of Namibia | Odlare M.,Mälardalen University
Energy Procedia | Year: 2014

Management of solid waste and wastewater in Namibia is a growing concern. This study investigated the biogas potential of slaughter waste at a small stock abattoir in southern Namibia. Laboratory experiments with five different mixes of blood; stomach content and manure from sheep were tested. Preliminary findings suggest that the most optimum mixture of slaughter waste was relatively large amounts of stomach and intestine content. The blood proportion should be kept relatively low, since the high nitrogen contents in the blood may inhibit the biogas production. The substrate mixture reflecting the actual ratio of waste generated in the slaughter process resulted in the highest methane production. This suggests that it is possible to produce viable amounts of biogas only using the waste produced at the abattoir, without adding other green substrate. Findings presented here together with results from a larger biogas digester, will be elaborated in the full paper. © 2014 The Authors.

Akhtar-Schuster M.,University of Hamburg | Thomas R.J.,Longwood University | Stringer L.C.,University of Leeds | Chasek P.,International Institute for Sustainable Development | And 2 more authors.
Land Degradation and Development | Year: 2011

The need to mainstream land degradation issues into national policies and frameworks is encouraged by international mechanisms such as the United Nations Convention to Combat Desertification (UNCCD) and the Millennium Development Goals (MDGs, 2000). However, mainstreaming has faced a number of interrelated institutional, financial, legal, knowledge and policy barriers. As such, despite 15 years of existence of the UNCCD, successes in reversing and/or preventing land degradation are widely perceived to be limited. This paper highlights the nature of these barriers to mainstreaming and identifies ways in which specific limitations that hamper mainstreaming of land degradation into national, regional and international activities and policies may be overcome. It also identifies institutional infrastructures through which scientific findings may more effectively enter policy, suggesting that scientific bodies are required to strategise, coordinate and stimulate the global scientific research community to support mainstreaming and the up-scaling of efforts to combat land degradation. Such a scientific body could also stimulate national cross-sectoral and multi-stakeholder knowledge exchange. The paper then moves to the national level to examine mainstreaming processes in Namibia, a country particularly advanced in taking a more integrated approach. Although the Namibia case study shows an impressive degree of integration, there are still many lessons to be learned in order to further strengthen mainstreaming processes. These lessons form the basis of our conclusion and recommendations, which outline a potential way forward. Copyright © 2010 John Wiley & Sons, Ltd.

Wassenaar T.D.,Center for Monitoring Research | Henschel J.R.,Center for Monitoring Research | Pfaffenthaler M.M.,Fauna and Flora International | Mutota E.N.,Center for Monitoring Research | And 2 more authors.
Journal of Arid Environments | Year: 2013

The Namib Desert is an ancient desert on the west coast of southern Africa. The Namib has unique endemic biodiversity and scenic landscapes, with a major part contained in the Namib Naukluft Park and the adjacent Dorob National Park, together forming a major tourism attraction in Namibia. There are currently large exploration and mining developments in the central Namib, fuelled by rising global demand for uranium. Mining contributes significantly to the Namibian GDP, but through destruction of habitats and ecological processes, may cause environmental degradation and loss of ecosystem services. Additionally, Namibia stands to lose a significant part of the biological diversity that makes it unique. These direct impacts are occurring in the context of regional climatic changes that are predicted to have their own severe impacts on biodiversity. A number of tools exist to counter these impacts, among which ecological restoration is an important one. Yet the extent of the damage to ecological processes and functions of the Namib, the interactions with climate change and the mechanisms through which the impacts will occur are still not well known. There is thus a crucial need for a better understanding of these arid ecosystems and their response to disturbance, to devise better restoration techniques, and to inform decision makers about management options. This paper analyses the extent of the threats to the central Namib's ecosystems and biodiversity due to mining, identifies critical knowledge gaps for restoration, defines policy needs, and proposes a broad strategy which is intended to be a framework for research, planning and management for sustainable use of this unique desert. © 2012 Elsevier Ltd.

Li B.,Indiana University – Purdue University Indianapolis | Wang L.,Indiana University – Purdue University Indianapolis | Kaseke K.F.,Indiana University – Purdue University Indianapolis | Li L.,Indiana University – Purdue University Indianapolis | Seely M.K.,Desert Research Foundation of Namibia
PLoS ONE | Year: 2016

Soil moisture is a key variable in dryland ecosystems since it determines the occurrence and duration of vegetation water stress and affects the development of weather patterns including rainfall. However, the lack of ground observations of soil moisture and rainfall dynamics in many drylands has long been a major obstacle in understanding ecohydrological processes in these ecosystems. It is also uncertain to what extent rainfall controls soil moisture dynamics in fog dominated dryland systems. To this end, in this study, twelve to nineteen months' continuous daily records of rainfall and soil moisture (from January 2014 to August 2015) obtained from three sites (one sand dune site and two gravel plain sites) in the Namib Desert are reported. A process-based model simulating the stochastic soil moisture dynamics in water-limited systems was used to study the relationships between soil moisture and rainfall dynamics. Model sensitivity in response to different soil and vegetation parameters under diverse soil textures was also investigated. Our field observations showed that surface soil moisture dynamics generally follow rainfall patterns at the two gravel plain sites, whereas soil moisture dynamics in the sand dune site did not show a significant relationship with rainfall pattern. The modeling results suggested that most of the soil moisture dynamics can be simulated except the daily fluctuations, which may require a modification of the model structure to include non-rainfall components. Sensitivity analyses suggested that soil hygroscopic point (sh) and field capacity (sfc) were two main parameters controlling soil moisture output, though permanent wilting point (sw) was also very sensitive under the parameter setting of sand dune (Gobabeb) and gravel plain (Kleinberg). Overall, the modeling results were not sensitive to the parameters in non-bounded group (e.g., soil hydraulic conductivity (Ks) and soil porosity (n)). Field observations, stochastic modeling results as well as sensitivity analyses provide soil moisture baseline information for future monitoring and the prediction of soil moisture patterns in the Namib Desert. © 2016 Li et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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