Remarkable increase in tree density and fuelwood production in the croplands of northern Nigeria

Abstract

This paper examines trends in woody vegetation and tree species composition in the Sudan zone of West Africa, using the Kano region of northern Nigeria as a case study. The study compares data on tree density, fuelwood production and tree species composition from fieldwork conducted in 1981 and 2016, as well as on several dates of aerial and satellite images since the 1960s. Recent satellite-based reports of greening in arid West Africa as a response to recovery from droughts in the 1970s and 1980s, are examined to explain the observed trends. Tree densities in the goods and services hinterland of Kano city have at least doubled since the drought period, and no decline, rather a slight increase was observed during the drought decades. This contradicts reports of woody vegetation trends from the more arid and less densely populated Sahel zone, which generally observed decline during the drought years and current recovery to pre-drought levels. The remarkable increase in tree numbers in Kano region is accompanied by increasing fuelwood production as suggested by greater concentration by farmers on tree species highly valued for fuel, at the expense of other traditional species. The main driver of such trends is thought to be rapid population growth in the context of a remaining dependence on wood as fuel by both urban and rural populations in Nigeria. Climate is thought to play only a minor role in explaining the trends.These observations confirm trends in woodfuel production observed in Kano region more than three decades previously, and indicate a somewhat Boserupian response to Malthusian-type pressures on available resources. Nevertheless, a return to rainfall levels of the drought decades combined with climate change predictions of increasing temperatures in dryland Africa, may have serious consequences for rural households if energy sources are not diversified.

Agricultural productivity in relation to climate and cropland management in West Africa

“…This part of the country has witnessed an increase in tree density to support the growing population's ( Supplementary Fig. 3) reliance on fuelwood as a source of household energy 44 . Just 200 kilometers north of Kano, in the Zinder region of Niger, the parklands of the Magaria -Boune cluster show distinct positive trends in iNDVI and residuals.…”

Income and greenhouse gas (GHG) emission trade-offs on smallholder farms at two sites in northern Nigeria

“…Another limitation of our study is the relatively small sample of farms and the limited regional coverage of the empirical analyses. Although the farms analysed appear to be representative of common farm types in the northern Nigeria region based on previous literature (Ajiegbe et al 2010;Berkhout et al 2011;Usman & Nichol 2018;Yusuf et al 2018;Ayinde 2019), diversity in the characteristics of farms within the region make it difficult to generalise our empirical findings about changes to income and production activities, other than the above-noted conclusion that restrictions on GHG emissions will have a negative effect on income. However, the use of representative farm types at the two sites and with different production characteristics provides some initial evidence that effects may be similar for other types of farms within the region studied.…”

Monitoring Dryland Trees With Remote Sensing. Part A: Beyond CORONA—Historical HEXAGON Satellite Imagery as a New Data Source for Mapping Open-Canopy Woodlands on the Tree Level

“…The 3 m-threshold (i.e., 7 m 2 ) for small trees also corresponds well to the minimum detectable crown size of 6 m 2 for desert trees given by Andersen (2006) for CORONA KH-4a imagery. Schlesinger and Gramenopoulos (1996) and Usman and Nichol (2018) observed a detection threshold of approx. 4 m diameter for trees on CORONA images of western Sudan and northern Nigeria, respectively.…”

“…. Therefore, visual interpretation of changes in tree counts is the most common method employed in monitoring woodlands on the tree-level (Schlesinger and Gramenopoulos, 1996;Gonzalez et al, 2012;le Polain de Waroux and Lambin, 2012;Usman and Nichol, 2018). The lower size limit for tree detection differs between studies, since the spatial resolution and radiometric quality of historical AP and VHRS images varies considerably.…”