Plant species richness and composition a long livestock grazing intensity gradients in a Namaqualand (South Africa) protected area

Abstract

The study described changes in floristic and vegetation structure in relation to livestock grazing intensity in a conservation area in the Succulent Karoo, South Africa. Grazing by goats and sheep is allowed in the Richtersveld National Park ͑a contractual National Park͒ which is also an area of high floristic richness and endemism. We used goat faecal pellet density, degree of trampling and percentage bare-ground at distances from the stock posts as surrogates for a gradient in grazing pressure. A stock post is the place where farmers keep, in most cases in an enclosure called a 'kraal', their animals at night and to which they return every evening after the day's herding. Twenty-seven stock posts were located in the Richtersveld National Park; nine stock posts on flats, footslopes and mountain each. We measured plant species richness and diversity, and mean percentage cover of the various plant growth forms ͑including the number of species falling into each growth form category͒ in each of the five 10 m ϫ 10 m plots ͑each 200 m apart͒ demarcated along a transect of one kilometre length from the centre of each stock post. The results showed that distance from the stock post does reflect grazing intensity use because densities in faecal pellets rapidly declined with increasing distances away from the stock post for all habitats studied. Faecal density was positively correlated with stocking density. Plant species richness and diversity was at a minimum near stock posts. Plants able to endure the effects of heavy grazing occurred near stock posts where declines in palatable plant species, assumingly sensitive to heavy grazing and trampling, were recorded. Grazing increased vegetation patchiness up to 800 m from the stock post for all the habitats. The degree to which this change in species composition occurred did not depend on stocking densities, suggesting that both grazing and landscape variability were responsible for vegetation changes in rangelands of that area of the Succulent Karoo biome.

Effect of Conservation on Plant Species Diversity, Kurdistan, Western Iran

“…According to results, the unprotected areas had the lowest diversity and the species richness was decreased as already observed by Connell (1978), Vujnovic et al (2002), Keeley et al (2003), Bouahim et al (2011), Krzic et al (2003), Hendricks et al (2005), Banda et al (2006), Dorrough et al (2007) and Cesa and Paruelo (2011). It should be noted that, in these areas, some species are selectively kept and other species have been removed.…”

Effects of domestic livestock on the vegetation of the Knersvlakte, South Africa

“…They attributed this to the low rainfall in the year of data collection. Similarly, HENDRICKS et al (2005) did not find differences in growth form in response to grazing pressure in the Richtersveld National Park.…”

Pits Conserve Species Diversity in an Overgrazed Grassland

“…Pothole develops more variable plant Plant communities were differentiated by the presence/absence of palatable plants on the flat ground. A few plant species persist and dominate on heavily-grazed areas where palatable plant species decline [8]. On the flats, i.e., in groups A and C, Pachysandra terminalis and Senecio cannabifolius, both of which were unpalatable plants for deer [12,24], were dominant in group C, while these two species were not common in group A. Cynanchum caudatum that was also unpalatable for deer was common in groups A and C. Soil hardiness was lower in group C than in group A, suggesting that differences in environmental factors were also related to the intensities of grazing and trampling.…”

“…Grazing by mammals, including deer, greatly affects plant species composition in relation to species attributes, such as palatability and morphological traits, and vice versa [8,23]. Particularly, deer are over-populated on the world-natural heritages assigned by UNESCO in Japan, and modify the ecosystems [30].…”