Klaus Kellner

Exploring differences of soil quality as related to management in semiarid rangelands in the western Bophirima District, North West province, South Africa

Differences in land-use management may result in different rangeland condition (soil, vegetation and biodiversity) and productivity. Vegetation condition in contrasting land-use management systems is well documented in semiarid rangelands, but relatively little information is available on soil quality. This study explores soil quality indicators in contrasting land-use management systems (communal, commercial and game/conservation) to compare degradation status. Soil samples collected in all land-use management systems were analysed for chemical, biochemical and microbiological properties. Soils were acidic (pH = 6.33) and nutrients deficient (average organic C [Corg] 0.37%, available P 3.04 mg kg−1, cation exchange capacity [CEC] 2.99 cmol(+) kg−1). Significant differences (pH, p < 0.0001; Ca2+, p < 0.0001; Mg2+, p = 0.001; Na+, p = 0.014; CEC, p < 0.0001; Corg, p = 0.004; dehydrogenase, p = 0.003; acid phosphatase, p = 0.001; urease, p < 0.0001) were found between the conservation and both the communal and commercial land-use management. Only few indicators of soil quality showed significant differences between the commercial and communal management. No clear gradient of soil degradation could be detected. Results recommend caution when assessing degradation across contrasting land-use management systems, and within a specific management system. Further research across a wide range of sites within management and taking into consideration spatial soil and vegetation distribution is required to understand land-use management effects on rangeland condition.

A conceptual tool for improving rangeland management decision-making at grassroots level: the local-level monitoring approach

For many years, rangeland monitoring has mainly been the field of scientists, academics and extension workers trying to fine-tune methods to assess the condition of rangelands. Frameworks and monitoring systems developed with their associated indicators are often complex and inaccessible to land users who lack the advanced equipment to implement them, and the relevant training to analyse and interpret monitoring results. After reviewing the challenges and opportunities in rangeland monitoring, this paper describes the local-level monitoring (LLM) conceptual tool, which is flexible, adaptive and easy to use by local land users for monitoring and documenting changes in natural resources and livestock conditions in order to guide and support management responses accordingly. As a concept, the LLM approach is currently being tested and implemented by agricultural extension services in the Dr Ruth Segomotsi Mompati District municipality (North West province, South Africa). At this stage, the LLM concept should be seen as a continuous and evolving learning process that will be updated over the long term through decision support to include several other components essential to implement effective and sustainable rangeland management practices by local land users.

Post-wildfire regeneration of rangeland productivity and functionality – observations across three semi-arid vegetation types in South Africa

Wildfires can have significant impacts on rangeland productivity and functionality causing substantial economic losses to affected farmers. In August 2011, such wildfires swept through the North West province of South Africa, destroying large areas of grazing and farm infrastructure. There is little information available on how the regional semi-arid rangelands respond to fire. In order to increase knowledge on short-term regeneration capacities of burned rangelands, the recovery of grass phytomass, composition and diversity as well as the frequency distribution of patch types (i.e. grass-, litter- and bare patches) were assessed in the growing season following the fire. Burned and unburned sites were compared in two regional grasslands and one savanna type receiving between 480 and 700 mm rainfall y−1. Fire significantly reduced phytomass production, and lowered the grazing capacity and potential grazing days across vegetation types. In general, grass diversity, composition and relative frequencies remained unaffected documenting an overall good regeneration potential of the grass sward. An increased proportion of bare patches and decrease of litter indicated that the post-fire environment lost functionality with respect to erosion control, nutrient cycling and water infiltration. Gained insights provide valuable baseline information for future impact assessments and research into the fire dynamics of investigated vegetation types.

The effect of reseeding methods on secondary succession during cropland restoration in the Highveld region of South Africa

The Grassland biome is the most transformed biome in South Africa, with cultivation and other human impacts having the largest effect on pristine grasslands. Conversion of natural grassland to cropland agriculture destroys natural vegetation seed banks. When croplands on the South African Highveld are abandoned, secondary succession often leads to low diversity Hyparrhenia hirta dominated plant communities. To investigate the effect of reseeding on secondary succession and botanical diversity, various reseeding treatments of cropland restoration were established on a recently abandoned cropland at Suikerbosrand Nature Reserve. Plots combining two seed mixtures, two seeding rates and two sowing methods were monitored and evaluated. The sowing method (plough vs rip-line) had the largest influence on the suppression of relic weeds as well as possible establishment of local non-sown species. The rip-line plots, where more resources were available due to spaces between the rip-lines, initially experienced higher densities of relic weeds followed by an increase in local non-sown species densities. Hyparrhenia hirta was one of the non-sown perennials increasing in the rip-line plots. The growth of H. hirta and relic weeds was, however, controlled in the plough plots, where species densities and phytomass production of perennial sown-in species were the highest.

Enhancing Participatory Evaluation of Land Management through Photo Elicitation and Photovoice

Land management evaluation can be made more relevant and holistic by incorporating local knowledge and perspectives. We examined whether photo elicitation and photovoice could enhance semi-structured interviews in capturing local livestock farmers’ knowledge and perspectives in a participatory evaluation in Mier and Molopo, South Africa. The participants discussed themes including veld condition, land management, and evaluation criteria. Photo elicitation provided more details (62% of instances analyzed [Mier]; 58% [Molopo]) and new information (75% of instances analyzed [Mier]; 65% [Molopo]) beyond those in semi-structured interviews. Photo elicitation also enriched data with personal or concrete examples, comparisons, contrasts, explanatory information, and revelation of attitudes or values. Photovoice created opportunities for mutual learning among the participants. The main drawbacks for the two photographic methods were additional time and equipment requirements, and the risk of omission. These two methods represent unrealized potential for supporting natural resource management research and projects.

Quantifying the woody component of savanna vegetation along a density gradient in the Kalahari Bushveld: a comparison of two adapted point-centered quarter methods

Bush encroachment is a serious problem in savanna rangelands of southern Africa. There is a strong interest in practical and reliable assessment methods to quantify related vegetation changes in the woody layer such as the widely applied point-centred quarter (PCQ) methods. Several variations of these distance methods exist but their results differ due to differences in sampling effort and methodological accuracy. The aim of this study was to compare the performance of two recently developed adapted PCQ methods. These methods were used to estimate density, productivity and diversity of the woody layer of a semiarid savanna along a degradation gradient in the Kalahari rangelands. It was found that both adapted PCQ methods (APCQ10 and APCQ20, with the APCQ20 method using less recording points but a larger sampling area and higher sampling intensity per recording point) provided similar results for density, phytomass, available browse and browsing capacity in open, dense and encroached savanna types. Significant differences between the methods were obtained in differentiating height classes, which were, however, largely restricted to the woody layer above 2 m in open savanna types. There, applying the APCQ20 method avoided an under-sampling of larger shrubs and trees and increased precision in data assessment. This was confirmed by a better representation of species frequency distributions, as well as the density, phytomass and diversity status of the woody layer. These differences disappeared as the woody vegetation became denser with the APCQ10 method providing similar results to that of the APCQ20 method in densely vegetated and encroached savanna types. From a practical point of view, the APCQ10 method has a range of advantages in dense vegetation, where restricted movement impedes effective data collection. It is concluded that the APCQ20 method should be used to quantify open savanna communities, whereas the APCQ10 method is more suitable in dense stands of >1200 tree equivalents ha–1. Overall, the two APCQ methods were effective for assessing and monitoring woody savanna layers for management purposes but, for research, their accuracy still needs to be investigated in comparison to other assessment methods.

Integrating approaches to monitor, map and address land degradation and desertification

This special issue concentrates on some of the difficulties regarding the complex interplay of processes that have to be considered when describing and assessing land degradation and desertification at different scales and time intervals. Land degradation and desertification have been on the global agenda for many years prior to the inception of the United Nations Convention to Combat Desertification (UNCCD) in 1994. Agenda 21, which created the United Nations Conference on Environment and Development (UNCED) in Rio de Janeiro in 1992, led the commitment in the development of global conventions, of which the UNCCD, United Nations Convention for Biodiversity (UNCBD) and the Framework for the Convention of Climate Change (FCCCC) are the most important with regard to land degradation and desertification challenges. It was recognised that Africa was the continent most severely impacted by desertification and hence the UNCCD highlights Africa in its aims to combat desertification and mitigate the effects of drought. A total of 193 countries worldwide are currently Parties of the Convention and have ratified the UNCCD. Despite this, debate still continues over many of the fundamental considerations for a scientific understanding of land degradation, including the causes and extent of desertification. People living in dryland areas, which are highly vulnerable to desertification, are amongst the world’s poorest, most marginalised and politically weak citizens. The underlying causes of both poverty and desertification are extremely complex and are compounded by rapidly expanding human populations. Despite the global concern and the many years of effort and investment made for prevention, mitigation or restoration, the problems of desertification and land degradation still persist. The six papers presented in this special section form part of a project funded by the South Regional Cooperation Fund for Scientific Research and Technological Development through the National Research Foundation (NRF), with the title, ‘Assessing, understanding and preventing desertification in SADC’. The papers were developed from oral presentations during a four-day regional desertification workshop held in Pretoria at the South African National Biodiversity Institute (SANBI) in September 2008, which brought together both policy-makers and scientists from different Southern African Development Community (SADC) countries. Can we recognise different types of dryland degradation and, if yes, are different approaches required for dealing with them? The paper by Scholes proposes a conceptual model that suggests desertification can be simplified to a limited set of syndromes. The causes, drivers and diagnostic symptoms of each syndrome, such as the conditions under which the degradation occurs, are discussed and possible remedial actions are suggested for different land-use systems. The use of syndromes allows for increased clarity of communication and scientific research on the often well-known and broadly accepted processes of dryland degradation. An attempt is made to estimate the extent and severity of the various syndromes, including a quantification and robust way of estimating the social costs of desertification. It is widely recognised that whatever the reasons for desertification, it occurs through an interaction between climatic and human factors. Archer and Tadross explore the two-way interaction between climate change and desertification using a number of southern African case studies. An improved understanding of these links calls for a fresh appraisal of the role of desertification in climate change, in adaptation and mitigation efforts, and in biodiversity preservation. A clear convergence is apparent between the sustainable land management solutions being promoted by the UNCCD and adaptation strategies envisaged to counter impacts of climate change. Addressing desertification requires that it can be measured and monitored, and the papers by Espach et al. and Kellner and Moussa present two different approaches for this. Espach et al. highlight the urgent need for timely, accurate data on land, water, natural resources and impacts of grazing capacity. They present a case study from Namibia to illustrate how one can combine various practical approaches and methodologies to estimate the seasonal herbaceous biomass production using satellite imagery, land-cover mapping and a quantitative yield method of determining available forage. Through combining all these methods (information from remote sensing, adjusted with scientifically established coefficients for woody cover in savanna areas, accessibility and palatability, and the incorporation of other quantitative methods such as a ground-truthing mechanism), they present a tool to estimate rangeland productivity and thus grazing capacity and the impacts on natural resources. The implementation of a monitoring system that engages the land users, in collaboration with other institutions at local level, is discussed by Kellner and Moussa. The paper describes a local-level monitoring (LLM) field guide designed to help land users at grassroots level to monitor several rangeland components by using simple and cost-effective indicators and methods. This methodology enables land users to recognise changes in natural resource and livestock condition and adjust management responses accordingly. The LLM approach is currently being tested and implemented by agricultural extension services in South Africa.

Southern African Arid Lands: Current Status and Future Prospects

Southern Africa south of 150° S latitude includes all or part of several countries. The situation in the dryland portion of each of them is described and the underlying factors are explained. Land degradation affects significant areas of most of the countries. Measures taken to arrest and reverse land degradation are explained. Climate change, trends and projections are discussed. Various scenarios are offered.

Soil properties changes after short-term livestock exclusion in "degraded" communally managed rangelands in the western Bophirima District, South Africa.

Livestock grazing and detrimental overgrazing are commonly associated with severe rangeland degradation particularly in communally managed pastoral systems in South Africa. Effects of grazing exclusion on vegetation are well documented, but there is a dearth of quantitative research conducted in communal managed range-lands to investigate the extent of associated soil properties changes. This study compared soil characteristics between grazed and 6 years adjacent exclosure plots at three communally managed sites namely Austrey, Southey/Eska and Tseoge in the western Bophirima District. A slow rate of change in soil properties between the grazed and exclosure plots was observed and differences were site-specific where detected. Phosphorus was significantly different at Tseoge (p = 0.001) and nitrate at Southey/Eska site (p<0.0001). Soil organic carbon was not affected by grazing exclusion at all sites, but the activity of ß-glucosidase activity was significantly different between exclosure and grazed plots. The activity of dehydrogenase was significantly different at Southey/ Eska site only (p = 0.002), whereas soil microbial biomass showed significant difference only at Tseoge site (p = 0.03). These results suggest that short-term livestock removal does not lead to a significant improvement of soil condition, as reflected by changes in soil properties. Caution is recommended when interpreting these results beyond the constraints imposed by the design of the study and the lack of information about livestock management practices and regimes at the sites.