Regreening of South Central Niger: Two decades of remote sensing and field data
For more than four decades, the countries of West Africa have faced a strong degradation of the productive potential of their agro-sylvo-pastoral systems, under the combined effects of climate change and human pressures. However, over the past three decades a process of “re-greening” or “re-vegetation” which has taken place through the practice of Farmer Managed Natural Regeneration (FMNR) has countered the trend of land degradation. This study aims to highlight on a small scale re-greening in Center-Sud du Niger by comparing field data with those of satellite images of two (2) pioneer villages (Dan Saga and El Guiéza) of the practice of FMNR in the region of Maradi. For this, three Landsat images from 1999, 2008 and 2018 were used. A transition matrix was established to analyze changes in land cover. The Standardized Precipitation Index (SPI) from 1996 to 2018 was used to highlight climate trends. Previous and current survey dendrometric measurements were used to assess tree and shrub density and vegetation dynamics. The results of the satellite imagery show a geographically consistent model of the increase in vegetation productivity, characterized by an increase in the difference in the normalized vegetation index, thus translating a tendency to regreening. The results show regression of areas with little greening (NDVI <0 and 0-0.14) in all study sites between 1999 and 2018. In contrast, the areas re-greened (NDVI> 0.14) are increasing in area. During this period, the rainfall tended to be strongly arid, with 11 years of drought compared to 9 years of humidity. This shows the persistence of the rainfall deficit. The characteristics of woody stands reveal a trend towards the reconstitution of plant resources. The high proportion of relatively young individuals and the dynamics of the vegetation of more than 70% evidence this. The results of this study confirm the re-greening of the southern Niger strip.
Keywords: Farmer Managed Natural Regeneration (FMNR), normalized vegetation index (NDVI), Standardized Precipitation Index (SPI), regreening, climate change, Niger