Linking Farmer Knowledge and Biophysical Data to Evaluate Actions for Land Degradation Mitigation in Savanna Rangelands of the Molopo, South Africa

The over-utilization of semi-arid savanna rangelands in the North-West Province of South Africa has resulted in profound habitat transformations. A common regional indicator of rangeland deterioration is the imbalance in the grass:woody ratio characterized by a loss of grass cover with increased shrub or tree density. This can result in profound reductions of rangeland productivity forcing farmers to apply active or passive actions to improve rangeland condition to mitigate economic losses. This study forms part of the multinational EU-project PRACTICE (Prevention and Restoration Actions to Combat Desertification: An Integrated Assessment) and aims to evaluate locally applied restoration and management actions using a participatory approach. Actions included rotational grazing, chemical control of woody species and re-vegetation with grasses, and were evaluated by common and site-specific indicators suggested by the farming community. Members of an identified multi-stakeholder platform ranked these indicators according to their relative importance, and results were combined with biophysical measurements for each indicator in a multi-criteria decision analysis. Preliminary results showed rotational grazing management and re-vegetation actions perform equally well in maintaining and restoring an open savanna with a high forage production, followed by selective shrub control. This type of participatory assessment helps to identify best practices, but there is still an urgent need to create legal policy frameworks and institution-building to support local-level implementation in all socio-ecological and economic settings, particularly in communal areas

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

Disc pasture meter calibration to estimate grass biomass production in the arid dunefield of the south-western Kalahari

The disc pasture meter (DPM) is a tool that is widely used to estimate aboveground standing grass biomass (ASB) in a rapid and non-destructive manner. Depending on the species composition, rangeland condition and local climate, available DPM calibrations may fail in providing precise measurements for a certain area. We calibrated a DPM for the arid dunefield savanna of the south-western Kalahari as found in the Northern Cape province of South Africa and bordering Namibia and Botswana. Assessments were done at 30 sites and restricted to inter-dune areas. The site selection accounted for different grazing conditions to ensure a better representation of the variability in ASB in the region. We determined grass species composition, basal cover and dry matter production in relation to height readings of the DPM. The grass sward was dominated by the species Stipagrostis ciliata, S. obtusa and Schmidtia kalahariensis, with a mean density of 25 cm point-to-tuft distances. Based on 90 paired observations of ASB and disc height (x; cm), the equation ӯ (kg ha−1) = 213.37(x) + 103.36 (r 2 = 0.760) was established. In comparison to other models, the equation avoids an overestimation of ASB in this vegetation type, and thus leads to more accurate estimations.Keywords: forage production, grazing, range management, savanna, Stipagrostis sp

Species, functional groups and community structure in seed banks of the arid Nama Karoo : grazing impacts and implications for rangeland restoration

The regeneration potential of grazing-affected Nama Karoo vegetation was evaluated by comparing soil seed banks of different microsites across a fence-line contrast in arid Namibia. Seed banks under low and high grazing pressure reflected the condition of the standing vegetation in terms of composition, community structure and species abundance distributions. However, a close concordance between vegetation and seed bank was restricted to the herbaceous and grassy vegetation within the inter-shrub matrix. The divergence of seed bank communities across the fence-line was low at community level but high at the level of species abundances. Continuous severe grazing increased the abundance of small-seeded, prostrate forbs with round seeds and favored unpalatable, annual grasses over palatable, perennial grasses. Microsites provided a source of small-scale variation in seed bank community composition and were dissimilar between the rangelands. Results indicated an advanced divergence in the vegetation at the degraded site with seed banks of species common under sustainable grazing being drastically reduced. Their low abundance, even in safe sites, suggests that long-distance dispersal is one of the main limiting factors for natural re-establishment after disturbance. The inertia in recovery of Namibian degraded rangelands through seed limitation can be overcome only by active species introduction

Appendix C. Interannual standard deviations of total plant cover and the diversity measures at heavier and lighter grazing intensities at a 1000-m² scale.

Interannual standard deviations of total plant cover and the diversity measures at heavier and lighter grazing intensities at a 1000-m² scale

Appendix B. Nonmetric multidimensional scaling ordination (Bray-Curtis) of species based on their mean cover values for the period 2005–2009 at 1000-m² scale.

Nonmetric multidimensional scaling ordination (Bray-Curtis) of species based on their mean cover values for the period 2005–2009 at 1000-m² scale

Appendix A. Diversity measures at heavier and lighter grazing intensity at 1000-m² scale.

Diversity measures at heavier and lighter grazing intensity at 1000-m² scale