Degradation of communal rangelands in South Africa: towards an improved understanding to inform policy

In South Africa, the relative extent of range degradation under freehold compared to communal tenure has been strongly debated. We present a perspective on the processes that drive rangeland degradation on land under communal tenure. Our findings are based on literature as well as extensive field work on both old communal lands and ‘released’ areas, where freehold farms have been transferred to communal ownership. We discuss the patterns of degradation that have accompanied communal stewardship and make recommendations on the direction policy should follow to prevent further degradation and mediate rehabilitation of existing degraded land.Keywords: communal rangelands, land degradation, rehabilitation, social systemsAfrican Journal of Range & Forage Science 2013, 30(1&2): 57–6

Facilitation or Competition? Tree Effects on Grass Biomass across a Precipitation Gradient

Savanna ecosystems are dominated by two distinct plant life forms, grasses and trees, but the interactions between them are poorly understood. Here, we quantified the effects of isolated savanna trees on grass biomass as a function of distance from the base of the tree and tree height, across a precipitation gradient in the Kruger National Park, South Africa. Our results suggest that mean annual precipitation (MAP) mediates the nature of tree-grass interactions in these ecosystems, with the impact of trees on grass biomass shifting qualitatively between 550 and 737 mm MAP. Tree effects on grass biomass were facilitative in drier sites (MAP≤550 mm), with higher grass biomass observed beneath tree canopies than outside. In contrast, at the wettest site (MAP = 737 mm), grass biomass did not differ significantly beneath and outside tree canopies. Within this overall precipitation-driven pattern, tree height had positive effect on sub-canopy grass biomass at some sites, but these effects were weak and not consistent across the rainfall gradient. For a more synthetic understanding of tree-grass interactions in savannas, future studies should focus on isolating the different mechanisms by which trees influence grass biomass, both positively and negatively, and elucidate how their relative strengths change over broad environmental gradients. © 2013 Moustakas et al

Role of fire in preventing bush encroachment in the Eastern Cape

A serious bush encroachment problem has developed in the Eastern Cape and it has been suggested that this is partly the result of the elimination of regular, fierce veld fires. The author is of the opinion that it was rather the interaction of burning and wild browsing animals that played the major role in maintaining the original grasslands and preventing the encroachment of bush in the past. After a controlled burn had been applied to an area of dense, sweet grassveld, moderately encroached by Acacia karoo and other bush species, most of the bushes suffered a kill of stems and branches but coppiced from the base of the stem. Stocking lightly with goats controlled this coppice growth with no detrimental effect to the grass. These results indicate that a system of burning and browsing could be used in combating bush encroachment in certain situations.Keywords: sweetveld|goats|coppice growth|browsing|fires|bush encroachments|Eastern Cape Province|fire effects|browsers|grasslands|bushes|controlled burning

The eradication of Macchia (Fynbos) vegetation on the Amatole Mountains of the Eastern Cape

On the Amatole mountains of the Eastern Cape Province extensive tracts of grassveld have been invaded by Macchia (Fynbos) vegetation and rendered agriculturally unproductive. Two distinct Macchia communities occur, namely the Lowland Macchia dominated by Cliffortia linearifolia, and the Highland Macchia dominated by Erica brownleeae and Cliffortia paucistaminea. A similar experiment was laid out in each Community to determine the most effective method of eradicating the Macchia and replacing it with a grass sward. A wide range of treatments, comprising spraying with 2-4-5T weedicide, burning, cutting and stumping was applied. Stumping and burning most effectively eradicated C. linearifolia, whereas burning and, to a slightly lesser degree cutting and spraying, were very effective in eradicating E. brownleeae and C. paucistaminea.Keywords: eradications|fynbos|vegetation|Amatole Mountains|Eastern Cape Province|plants|grasslands|veld|grasses|invasions|productivity|experiments|methods|treatments|spraying|burning regimes|cutting trial

Fire behaviour in the Kruger National Park.

Fire research in the Kruger National Park has largely been focused on the effect of the season and frequency of burning on the vegetation. Very little information is available on the effect of fire behaviour and in particular fire intensity, on the flora of the park. Consequently a research project was conducted to develop statistical models for predicting fire intensity, flame height and rate of spread in the field. The development of these models constitutes the initial phase of determining the relationship between fire behaviour and vegetation response.Keywords:burning; effect of fire; fire; fire behaviour; fire intensity; flame height; kruger national park; Modelling; models; rate of spread; savanna; south africa; vegetation; Vegetation response; veld burningJournal of the Grassland Society of Southern Africa

Estimating grass fuel loads with a disc pasture meter in the Kruger National Park.

Reports the results of a study conducted to assess the efficiency of a new calibration procedure for the disc pasture meter, used for estimating the fuel load available for combustion during fires; The major portion of the fuel load in the savanna areas comprises surface fuels in the form of the standing grass sward. The disc pasture meter was successfully calibrated for estimating grass fuel loads in the main landscapes of the Kruger National Park. The calibration comprised estimating the mean disc height of a 4m2 quadrat and harvesting the grass as close to ground level as possible. Using a large quadrat gave highly satisfactory results indicating that this procedure should be considered as a standard method of calibration, particularly in grass swards having a low basal cover.Keywords: basal cover; Calibration herbage mass; disc pasture meter; Disc pasture meters; fire; fuel load; grass; Grass fuel loads; grass sward; grasses; kruger national park; method; pasture; savanna; south africa; Standing grass swardsJournal of the Grassland Society of Southern Africa