Desert Science, Research and Training for Namibia's sustainable future
The Desert Science, Research and Training Programme is the 2013 version of Gobabeb’s popular GTRIP course for postgraduate Namibians. DeSeRT had a unique brand because it focused on a unique and diverse part of the central Namib: the triangle formed by the confluence of the Khan and Swakop rivers. This area, known for its high biodiversity and scenic attractiveness, is also the location of the new Husab Uranium Mine. Consequently, DeSeRT aimed to understand the potential ecological impacts of this mine, and contribute to the debate on how to mitigate and/or restore such impacts. Three candidates, Cammy Ndaitwah, Elise Nghalipo and Ndapewa Iipinge, studied aspects of the ecology of the arid ecosystem. Elise and Ndapewa’s projects were designed to provide baselines for future monitoring programmes, while Cammy’s study continued NERMU’s interest in the endemic Husab sand lizard.
We thank Go Green Fund of Nedbank and Swakop Uranium who supported the project with generous grants. Further financial and logistical support as provided by Gobabeb’s NERMU Project (the Namib Ecological Restoration and Monitoring Unit), and Gobabeb associates and partners Sebastian Kirchoff (PhD student from the Humboldt University in Berlin) and Ian Murray (postdoc at the University of the Witwatersrand in Johannesburg) co-supervised some of the projects. A number of visiting scientists graciously presented lectures.
Highlights from the projects
PROJECT 1: The recovery of biological soil crust in response to rehabilitation: Biological Soil Crust (BSC) is a cohesive organic layer on the surface of the soil, created by fog-adapted organisms such as hypolithic (“below the rock”) cyanobacteria (called HLC) and lichens, that bind soil particles together, aid water retention and dispersion, and fix atmospheric nitrogen. HLC are easily disturbed and often destroyed during recreational and mineral exploration off-road driving. As planned, the study established the baseline, but also found that recovery of HLC after disturbance takes many years. No evidence was found that raking (the currently preferred rehabilitation method) increased the rate of recovery. A site that was disturbed 43 years ago have also not yet recovered HLC cover similar to the adjacent undisturbed areas. But a lot is not yet known: e.g. different rehabilitation techniques – raking, sweeping, watering, and so on – may have different outcomes. In addition, severity of disturbance, frequency of disturbance, and external climatic factors, may all impact the recovery rate of HLC and BSC in general, and therefore need to be studied in more detail.
PROJECT 2: Correlates of the health of plants, as a baseline for a future monitoring programme: Desert plants are components of biodiversity and, through providing habitat and food to other organisms, also functional elements that affect overall biodiversity. Plants naturally experience many stressors, such as dust, that lead to physiological stress from which they can recover, but a long-term stressor may cause the death of a plant and eventually affect the fortunes of the whole population. Dust occurs naturally in arid zones, but mining activities generate excessive amounts of dust. With the development of the Husab Uranium Mine in a biodiversity-rich part of the Namib Naukluft Park, dust was identified as a potential significant impact on the plants of the area. This project was therefore designed to establish both standardised techniques of measurement and baseline values for plant health and stress (general plant health, growth rate, reproductive health and physiological stress of Welwitschia, pencil bush and dollar bush) relative to the location of Husab Mine.
An ancillary investigation also showed that the amount of dust currently on plants increases significantly closer to the mine and closer to roads. More importantly, the physiological health of Welwitschia plants was significantly lower when covered with road dust than without it, confirming the negative effect of dust on plants and highlighting the importance of understanding this impact at the physiological level. Questions for further study relate to the rate of change in health status, the critical stress levels at which plants start dying, the relative magnitude of stress caused by mine dust (vs other natural stressors) and the population-level effect of stress on reproduction and mortality rates. This study thus achieved its primary aim of providing the baseline data and standardised techniques for a long-term monitoring programme, assisting the company to detect and mitigate the impacts of dust on the natural environment.
PROJECT 3: The Husab sand lizard’s ecology, spatial distribution and behaviour, and potential for impacts by mining: Impacts on species with restricted ranges are an important aspect of the overall impacts of mining on the Namib’s biodiversity. Although there are many invertebrate and vertebrate endemics with extremely small ranges in the central Namib, the Husab sand lizard (Pedioplanis husabensis), a Namib-endemic species that occurs near the Khan and Swakop rivers, is a good example of such an organism that is also in potential conflict with mining. Previous studies have shown that the Husab sand lizard may be a habitat specialist, preferring light-coloured rocky substrates. Extreme habitat specialisation such as this could partly explain its small range and furthermore restricts the options for the management of impacts. However, previous studies focused on only a small part of its known range. The current study, part of a larger set of projects on the topic and on the species, added more sites and more observations of its habitat preference. Different from previous studies, which found that the species was confined to rock, half of the observed lizards were found on sand, while 43% were found on rocks and 7% on gravel. The study also confirmed that the species avoids dark-coloured substrates and prefers surface temperatures between 40 and 49°C. Previous studies did not look at vegetation associations; the current study showed a clear preference of the lizards for low vegetation
(grass and shrub) cover, avoiding completely bare and higher than 10-25% cover. Similar to previous studies, the lizards were mostly active from 10:00 to 12:00 every day.
Overall the findings from this study suggest that the behaviour and habitat preference of the species is more general than originally suspected, allowing more options for managing (mitigation and restoration) potential impacts on the species by mining and exploration activities. As such, the study achieved its aims of extending our knowledge of the habitat and behavioural ecology of this species and will allow more options for managing impacts.
What will happen in 2014
The DeSeRT Programme is continuing in 2014, albeit under an old acronym: GTRIP (Gobabeb Training and Research Internship Programme). GTRIP 2014 will be continuing the theme of ecological restoration of arid areas, but will focus exclusively on understanding the nature of disturbance to and the factors that affect the recovery of soil surface ecosystems (including HLC). To improve efficiency of supervision and training, the 2014 course will not be conducted at a single mine, but will be concentrated on areas surrounding Gobabeb itself.