Multi-temporal remote sensing data to monitor terrestrial ecosystem responses to climate variations in Ghana

Abstract

Operational monitoring of vegetation and its response to climate change involves the use of vegetation indices (VIs) in relation to relevant climatic data. This study analyses the temporal variations of vegetation indices in response to climatic data (temperature and precipitation) to better understand the phenological changes in the Wa-West and Tolon districts of Ghana during 1999–2011. This study also examines the inter-annual variation of vegetation indices and lag effects of climate variables (temperature and precipitation) using simple regression and correlation approaches. Results indicate that the mean Normalized Difference Vegetation Index (NDVI) and Normalized Difference Soil Index (NDSI) were significantly correlated with the mean temperature, whereby the value of NDVI increases with a decrease in temperature and value of NDSI increases with an increase in temperature. On examining seasonal variations, our findings indicated that the months of August and September have the highest mean NDVI values. This study confirms that consistently rising temperature and altered precipitation patterns have exerted a strong influence on temporal distributions and productivities of the terrestrial ecosystems of the Tolon and Wa-West districts of Ghana. Furthermore, this research demonstrates how vegetation indices can be used as an indicator to monitor phenological changes in the terrestrial ecosystem.

Keywords:

• Terrestrial ecosystem
• vegetation indices
• climate change
• lag effect

Acknowledgments

Daily rainfall and temperature data are provided by the Ghana Meteorological Agency for this study. We are also thankful to Dr. Hideki Kobayashi of JAMSTEC for providing SPOT satellite data and Jami Seirer for suggestions.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was carried out as a part of the research project CECAR-Africa project (Enhancing Resilience to Climate and Ecosystem Changes in Semi-Arid Africa: An Integrated Approach [FY2011∼FY2016]) of Japan Science and Technology Agency (JST) and the Japan International Cooperation Agency (JICA), and partly supported by the research programme on Climate Change Adaptation, Ministry of Education, Culture, Sports, Science and Technology.