Sökning: "grazing degradation"
Visar resultat 1 - 5 av 13 avhandlingar innehållade orden grazing degradation.
1. Land Use Change in Space and Time : implications for plant species conservation in semi-natural grasslands
Sammanfattning : Land use change has during the last century altered the traditional rural landscape in Sweden, resulting in a major decline in species diversity. Traditional small-scale farming, with a remarkably high small-scale species richness, has changed in favour of rationalized agriculture, and many semi-natural grasslands, i.e. LÄS MER
2. Bush Encroachment and the Role of Browse in Cattle Production : An ecological perspective from a bush encroached grazing system, Olifants Drift, Kgatleng District, Southeast Botswana
Sammanfattning : The increase in density and cover of woody plant species is coincident with the introduction of cattle in southern Africa, and it is a wide spread phenomenon in the savannas of the world. The causes are little understood, but can only be speculated to be either anthropogenic or natural or a combination of both. LÄS MER
3. Plant ecological studies related to restoration of a degraded ecosystem in central Tanzania
Sammanfattning : Kondoa Irangi area is among the most degraded ecosystems in Central Tanzania as a result of heavygrazing, fire, collection of fuelwood and improper cultivation practices. The restoration process of thisdegraded ecosystem through natural regeneration is slowed by the semi-arid climate of the area combinedwith poor soil nutrient status. LÄS MER
4. Hierarchical responses to organic contaminants in aquatic ecotoxicological bioassays: from microcystins to biodegradation
Sammanfattning : In this thesis I explore the ecotoxicological responses of aquatic organisms at different hierarchical levels to organic contaminants by means of bioassays. The bioassays use novel endpoints or approaches to elucidate the effects of exposure to contaminants and attempt to give mechanistic explanations that could be used to interpret effects at higher hierarchical scales. LÄS MER
5. More Water, Less Grass? : An assessment of resource degradation and stakeholders’ perceptions of environmental change in Ombuga Grassland, Northern Namibia
Sammanfattning : The objectives of this thesis are to assess: to what degree have natural resources deteriorated in a grazing area in northern Namibia, how do perceptions of environmental change held by local stakeholders there, correspond to scientific assessments, and how do these relate to national estimates? Analysis of the process of developing national indicators for monitoring of land degradation concluded that specific indicators should be developed on national level, and in some instances even on local level as there are no universal causes of land degradation. According to farmers overgrazing and low rainfall since the early 1990s cause negative environmental changes in the study area, partly confirming findings from national monitoring. LÄS MER
