Factors affecting recent vegetation change in north-east Libya

Ahwaidi, GMA

Abstract

Over the last few decades global warming and human intervention have led to changes and deterioration in natural vegetation across the world. The Al Jabal Al Akhdar, in north east Libya, is one of those areas that have experienced changes in land cover. This region has environmental and economic importance in providing suitable habitat for wildlife and providing services for local communities and cities in the Libyan Desert. The overall aim of this thesis was to evaluate the factors which have affected vegetation cover change in the Al Jabal Al Akhdar region over the last 42 years.

There were three key objectives to this research: (1) to assess changes in natural and semi-natural vegetation cover in the north-east of Libya using forty years of satellite image data, (2) to assess land cover change and the effects of human activities in the study area over a period of 42 years, (3) to assess the factors affecting vegetation change in the study area. A further objective was to assess climate change in the study area using the climate data which was available from three climatic stations as climate change may be responsible for vegetation cover change in the areas that have low human activity.

To address these objectives, remote sensing techniques were used to assess vegetation cover change and the changes in human activity from 1972 to the present. Satellite images provide data that cannot be collected by traditional methods and provide a historical archive of what the landscape looked like in the past. This study used multi-temporal Landsat images, which are freely available, for the period from 1972 to the present and provide the key temporal record of vegetation change on the Earth. Vegetation Indices (NDVI, SAVI and EVI), derived from the spectral reflectance of leaves and canopies, were used to assess the changes in vegetation cover over time. Image classification was also used to characterise the nature of land cover change, in particular the impact of human intervention.

A key finding related to Objective (1) was that some areas have experienced a statistically significant change in vegetation indices over the 42 years which was interpreted as a change in vegetation cover in the areas in question. A key conclusion related to Objective (2) was that land cover had changed in the study area over the period of study. The influence of human activities was exerted through increased land use and decreased areas of forest and shrubland in the region. The outputs of the above-mentioned objectives and the effects of climate change were used to assess Objective (3), to detect which factors caused vegetation cover change in the Al Jabal Al Akhdar region. The main factors causing vegetation change were the effects of human activities in the areas adjacent to human settlements, while in the sparsely populated areas in the south of the study area, vegetation cover changes may be related to recent climate change.

In conclusion, although the number of available Landsat images used to delineate the changes in vegetation cover was limited, the methods used to interpret the images for vegetation indices and image classification were invaluable in determining important results for the objectives of the thesis. The results obtained from assessing vegetation cover and land cover change and patterns of changes are major steps towards filling the information gap and creating a database for monitoring land cover in the study area. This effort will contribute towards facilitating decision-making on mitigating the impact of land use dynamics on land cover as well as provide a basis for future research.

Citation

Ahwaidi, G. Factors affecting recent vegetation change in north-east Libya. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Feb 19, 2018
• Publicly Available Date: Mar 19, 2018
• Additional Information: Funders : Libyan embassy
• Award Date: Jul 19, 2017