Desertification in the Sahel Region: A Product of Climate Change or Human Activities? A Case of Desert Encroachment Monitoring in North-Eastern Nigeria Using Remote Sensing Techniques

Desertification has become one of the most pronounced ecological disasters, affecting arid and semi-arid areas of Nigeria. This phenomenon is more pronounced in the northern region, particularly the eleven frontline states of Nigeria, sharing borders with the Niger Republic. This has been attributed to a range of natural and anthropogenic factors. Rampant felling of trees for fuelwood, unsustainable agriculture, overgrazing, coupled with unfavourable climatic conditions are among the key factors that aggravate the desertification phenomenon. This study applied geospatial analysis to explore land use/land cover changes and detect major conversions from ecologically active land covers to sand dunes. Results indicate that areas covered by sand dunes (a major indicator of desertification) have doubled over the 25 years under consideration (1990 to 2015). Even though 0.71 km2 of dunes was converted to vegetation, indicative of the success of various international, national, local and individual afforestation efforts, conversely about 10.1 km2 of vegetation were converted to sand dunes, implying around 14 times more deforestation compared to afforestation. On average, our results revealed that the sand dune in the study area is progressing at a mean annual rate of 15.2 km2 annually. The land cover conversion within the 25-year study period was from vegetated land to farmlands. Comparing the progression of a sand dune with climate records of the study area and examining the relationship between indicators of climate change and desertification suggested a mismatch between both processes, as increasing rainfall and lower temperatures observed in 1994, 2005, 2012, and 2014 did not translate into positive feedbacks for desertification in the study area. Likewise, the mean annual Normalized Difference Vegetation Index (NDVI) from 2000 to 2015 shows a deviation between vegetation peaks, mean temperatures and rainfall. On average, our results reveal that the sand dune is progressing at a mean annual rate of about 15.2 km2 in the study area. Based on this study’s land cover change, trend and conversion assessment, visual reconciliation of climate records of land cover data, statistical analysis, observations from ground-truthing, as well as previous literature, it can be inferred that desertification in Nigeria is less a function of climate change, but more a product of human activities driven by poverty, population growth and failed government policies. Further projections by this study also reveal a high probability of more farmlands being converted to sand dunes by the years 2030 and 2045 if current practices prevail.Peer Reviewe

Mapping the Impacts of Anthropogenic Activities on Vegetation in the Area Councils of FCT using Remote Sensing

Globally, amongst all the factors threatening the existence of landcover in the biosphere, agriculture and urbanization plays the most potent role aside from the natural factor of climate. The study examines the effect of human factors on vegetal cover and identifies the drivers of the changes within the area councils of the FCT over a period of three decades. The need to conserve limited natural resources is threaten by the effect of increased population and their continuous anthropogenic activities on this limited resource, thus the vegetation cover which represents an important natural resource for both humans and other species is lost due to reckless and unsustainable usage. Using geospatial techniques, the magnitude of human activities of development is assessed as it affects vegetation cover. The results of the analysis show a tremendous impact of anthropogenic activities as the landcover continue to deplete from 1987 – 2016. Human impacts were identified as the major driver of vegetal cover change in all area councils as it increases from 11510.89km2 to 85563.01km2 in AMAC, 765.55km2 to 82820.74km2 in Gwagwalada, 1621.73km2 to 54267km2 in Kwali, 1259.49km2 to 4985.56km2 in Abaji, 6621.80km2 to 34295.20km2 in Kuje and 15678.82km2 to 24925.94km2 in Bwari.The study recommends that continuous inventory of human impacts should be carried out to check mate the unsustainable management practices of human induced activities in the study area. It concludes that anthropogenic activities are on the rise thus measures should be taken to mitigate its effects to ensure better environmental sustainability