The effects of exploitation on the activity of Chrysoblephus laticeps in a thermally variable environment
- Authors: Mlotshwa, Nonhle Thubelihle
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424346 , vital:72145
- Description: Embargoed. Expected release date 2025. , Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
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The effects of short-duration overnight kraaling on herbaceous vegetation and soils in mesic grassland
- Authors: Mgwali, Nompendulo
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424721 , vital:72178
- Description: Land degradation is widespread in communal rangelands in the grassland biome of South Africa, and often attributed to overstocking and lack of coordinated management. Excessive pressure on the herbaceous component has contributed to the uncontrolled spread of opportunistic invasive alien woody species e.g. Acacia mearnsii in many degraded areas, resulting in significant loss of ecosystem service capacity, along with soil and land productivity. Short-duration overnight kraaling has been suggested as a tool for restoring degraded rangelands. Recent studies in semi-arid savannas and shrublands have reported increased grass cover, soil nutrients and palatability and concluded that short-duration kraaling is a low-cost and effective way of restoring degraded rangelands using livestock. However, the response of different plant functional types and communities to such intense livestock impact may vary depending on local context. This study used twelve paired kraal and control sites to investigate the effects of short-duration (7-24 days) overnight kraaling of livestock on herbaceous vegetation and soils in a mesic grassland. The study area is generally considered to be overgrazed but has considerable variation in grass composition and basal cover. Sites included relatively intact natural grassland and sites where wattle infestations had been cleared and where mostly bare ground remained. I tested the hypotheses that overnight kraaling would result in (1) increased basal cover due to introduction of grass seed and stimulation of germination through hoof action, (2) increased infiltration due to hoof action, and (3) increased soil nutrients and organic matter due to dung and urine deposition. I also hypothesized that factors such as a site’s initial grass cover, its slope, the occurrence and amount of rainfall before and during kraaling, and the kraaling intensity (number of livestock and duration of the kraaling event) would influence the magnitude and direction of the kraaling effect. The effect of kraaling on vegetation was strongly dependent on initial condition. Kraaling increased basal cover of grasses when sites had low initial basal cover, but decreased basal cover if initial values were over 50%. Infiltration increased if kraaling took place during or after rain but decreased if kraaling took place when soils were dry. Kraaling increased soil P and K. In mesic grasslands, short-duration overnight kraaling is promising as a tool for rehabilitating degraded sites but should be avoided where the grass sward is relatively intact. I recommend that the suitability of kraaling be further evaluated per vegetation type and local context. , Thesis (MSc) -- Faculty of Science, Botany, 2023
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