Terry Everson

Seed dynamics of Themeda triandra in the montane grasslands of South Africa

Seed production, viability, dispersal, predation and seed banks of Themeda triandra were determined to assess the potential of the seeds of this indigenous species in the re-establishment of degraded grassland. Annual seed production of T. triandra increased with length of burning rotation, ranging from 21 seeds m−2 in the annual winter burn to 757 seeds m−2 in the five-year burn. High predation of seeds (70–98%) and low viability (37% in 15-month-old seeds) contributed to the poor representation of T. triandra in the seed bank (<1.2%) when compared to the above-ground vegetation (<29.2%). These attributes, together with its poor dispersal (<1.75 m), indicate that seed dynamics of T. triandra will play a limited role in the restoration of grasslands in degraded areas.

Remote sensing based indicators of vegetation species for assessing rangeland degradation: Opportunities and challenges

Rangeland degradation is a serious hindrance to sustainable development in degraded areas. Mapping and monitoring vegetation species is an increasingly important issue across various fields of rangeland management. Remote sensing technology is a tool for mapping and monitoring vegetation species and it provides timely and relatively accurate information concerning degradation in biological rangeland resources. The objective of this review was to provide precise and essential information relating to the application of both multispectral and hyperspectral sensors as well as to their limitations with regard to mapping and monitoring rangeland degradation based on the abundance and distribution of vegetation species and algorithms used to process remotely sensed data when classifying these species. The abundance and distribution of the different vegetation species can be used to indicate the gradient level of rangeland degradation. It can be concluded, that up-to-date, spatial information and appropriate processing techniques are essential requirements for extracting increaser and decreaser spectral information that can be used for sustainable rangeland management. Key words:

The long-term effects of fire regime on primary production of montane grasslands in South Africa

Natural grasslands deliver essential ecosystem services through plant production, which enhances water supply, nutrient cycling, soil retention and greenhouse gas mitigation. Although the condition of montane grasslands for provision of ecosystem services is maintained by regular annual or biennial burning, controversy exists over the impact of different frequencies and seasons of burning on grassland productivity. The objective of this study was to determine the long-term effects of different burning regimes on primary production and quality of the montane grasslands of the KwaZulu-Natal Drakensberg. There were no significant differences in the mean standing live mass between 30 years of annual winter and biennial spring burning. However, in unburnt areas productivity was 20% lower (118.2 g m−2) than in regularly burnt grassland (144.7–154.5 g m−2). Crude protein did not vary between the annual winter and biennial spring treatments (95–113 kg ha−1), but was significantly lower in unburned areas (45 kg ha−1). However, an infrequent fire in a protected area caused a temporary spike in crude protein (16%) compared with regular burning (5–10%), which can benefit wildlife. We conclude that montane grasslands can be burnt annually or biennially in the dormant season to promote long-term productivity.

Evaluation of potential indicators for payment of environmental services on the impact of rehabilitation of degraded rangeland sites

An understanding of the response of indicators of rangeland degradation following rehabilitation is essential to the successful implementation of the Payment for Environmental Services initiative that is currently being developed in the communal rangelands of the Drakensberg mountains of South Africa. We evaluated the following four potential indicators of rangeland degradation: Range condition, basal cover, species diversity, and soil fertility. The indicators were measured in degraded and rehabilitated sites at Okhombe in Northern KwaZulu-Natal, South Africa. Two transects were established at each site for basal cover and species composition. Soil samples were collected from each site and their elements analysed. The results revealed that differences between the rehabilitated and degraded sites can be quantified using indicators of range condition, basal cover, and species diversity. There were highly significant differences in certain soil properties (that is, P 11.36 mg/kg, K 0.47 cmol/kg, pH 4.20, OC 6.33% and N 0.70%) after rehabilitation. Based on these results, we argue that these indicators have the potential to be used in monitoring and certifying the delivery of watershed services at a local level in this communal rangeland.

Spectral discrimination of increaser species as an indicator of rangeland degradation using field spectrometry

Discriminating increaser species is important for mapping rangeland degradation. The main objectives of this paper were to (1) determine whether four increaser species could be discriminated from each other and (2) determine the key wavelengths that have high discriminatory power. Spectral data were taken at canopy level from Hyparrhenia hirta, Eragrostis curvula, Sporobolus africanus and Aristida diffuse from Okhombe rangeland, KwaZulu-Natal province, South Africa. A field portable analytical spectral device with spectral range from 350 nm to 2500 nm was used in the analysis. Three-tier hierarchical techniques of One-way ANOVA, stepwise discriminant function analysis and canonical function analysis were used. The results revealed that there were statistically significant differences in spectral reflectance among four species on 439 wavelengths. The most important eight wavelengths (665 nm, 729 nm, 848 nm, 895 nm, 1039 nm, 998 nm, 681 nm and 972 nm) that have been selected for spectral discrimination were largely located in the visible, red-edge and near-infrared regions of the spectrum. The three tiers of analysis yielded species discrimination with an overall accuracy of 83 percent and a KHAT value of 0.77. The use of the spectroscopic approach applied in this study indicated that the increaser species were spectrally different. Therefore, these results encouraged further investigation into the possibility of mapping increaser species as indicators of different levels of rangeland degradation.

Tree legumes-temperate grass agroforestry system effects on inorganic soil nitrogen as ecosystem services provision for smallholder farming systems in South Africa

ABSTRACT Nitrogen is an essential macro-nutrient for plant growth and is indispensable for high agricultural food productivity and quality. Shortage of good quality forage under the dry winter season and low soil fertility conditions are the major constraints in rural farming systems in the Moist Tall Grassveld of the Upper Thukela, South Africa. The effect of legumes on inorganic soil nitrogen was assessed in an agroforestry trial (Leucaena leucocephala (Lam.) De Wit, Acacia karroo Hayne, Dactylis glomerata L., Festuca arundinacea Schreb.), by soil sampling method. In the agroforestry trial, total inorganic soil nitrogen accumulation was significantly greater under intercropping than under sole crop treatments and, irrespective of the treatments, significantly more nitrate than ammonium nitrogen was measured. The study demonstrated that intercropping grasses with tree legumes could provide important ecosystem services of nitrogen supply in the soil. The results suggested that introducing legume intercrops might constitute a relevant cropping strategy to improve the soil fertility status with regard to nitrogen while at the same time providing forage in smallholder farming systems in South Africa’s Moist Tall Grassveld regions.

Intercropping maize (Zea mays L.) with lablab (Lablab purpureus L.) for sustainable fodder production and quality in smallholder rural farming systems in South Africa

ABSTRACT An on-farm field experiment was conducted in South Africa’s rural Moist Tall Grassveld region which is characterized by overgrazing and a reduced grazing capacity. The grassland is sour veld and only provides palatable material during the 6-month growing season. The experiment was conducted to assess the effect of intercropping maize with lablab on maize fodder, grain yield, and quality, social and economic aspects. The results indicated superiority of intercropping over sole cropping, with intercropping treatments showing consistent superiority across 4 years of the experiment. Maize grain and fodder yields were positively influenced by intercropping with lablab. The maize fodder and total fodder yields were higher in intercropped than in sole maize plots. The maize grain DM yield of the first harvest in maize-only treatment was not significantly higher than in M + L treatment. Intercropping significantly increased crude protein of maize leaves and reduced the leaves’ fiber content. Crude protein contents were lower and fiber contents higher in maize stalks and leaves than in lablab. The field trial demonstrated that diverse plant communities in the form of intercropping provide sustainable production, positive environmental, and social impacts through reduced agrochemicals and are economically viable through cost avoidance and savings. The results of this study suggest that including lablab in traditional maize cropping systems can be beneficial when entanglement of maize is avoided by delayed under sowing of lablab.

Community Innovations in Sustainable Land Management: Lessons from the Field in Africa

Edited by Maxwell Mudhara, William Critchley, Sabina Di Prima, Saa Dittoh and Mohamed F Sessay2016, Routledge, 2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN, UK223 pages, hardcover and E-bookISBN 9781138190474 (hardcover), 9781315641003 (E-book). Price £110.00 (hardcover), £27.99 (E-book)

Landscapes as libraries : a history of the uKhahlamba Drakensberg from 1818 to 2009

A review of the history of Okhombe, a rural village in the uKhahlamba Drakensberg Mountain Region, was undertaken to explore a possible causal link between cattle grazing and soil erosion. Secondary data, digitized maps of aerial photographs, rainfall data, and cattle numbers were analysed. Four historical episodes were identified in the uKhahlamba Drakensberg Mountain Region since the 1800s, while changes in land use, rainfall, and cattle numbers in Okhombe were tracked. The research examines the dominant view of many government staff and scientists, that overstocking and overgrazing of cattle on communal lands has resulted in soil erosion. However, the landscapes of Okhombe and the wider uKhahlamba Drakensberg region were shaped by multiple factors, with legislated disenfranchisement and territorial segregation since the 1800s onwards leaving a lasting imprint. “Landscapes are libraries whose information is ignored by most academics. Approaching the history and future of a place through its landscape provides unique perspectives and opportunities” (Showers 2005: 1). Innovation , No.44, June 2012