Overall, steppes, Sudanian savannas and Sahelian short grass savannas have experienced dramatic losses during the last 38 years, yet they remain the predominant land cover classes, accounting for 30 percent, 18.5 percent, and 15 percent of the mapped area, respectively, in 2013. The decrease in steppe is largely explained by the expansion of sandy areas in the Akle Azaouad (AKA) and Tilemsi (T) ecoregions. Increasing aridity also impacted the steppes, pushing them southward, in places encroaching on the Sahelian savannas. Losses of Sahelian and Sudanian savannas, however, result more from human activity — the expansion of agriculture that has occurred across southern Mali.
Cropland area increased by a factor of 2.3 over the 38-year period, which is equivalent to an average annual increase of 3.5 percent, or 1,300 sq km per year. Agricultural expansion can be seen across the south, especially in Haut Bani Niger (HBNN – Upper Bani Niger), Koutiala Plateau (PK) and Kaarta (K) ecoregions. In these regions, agricultural landscapes now predominate over natural ones. In 1975 the Séno Plain, east of the Plateau Dogon in the Gondo-Mondoro (GM) ecoregion, was already predominantly agricultural. By 2013 it is uniformly devoted to cropland. Cropland expansion is driven by the need to feed a rapidly increasing population and has accelerated between 2000 and 2013, facilitated by modern technology. Likewise, irrigated agriculture areas have increased
by 400 percent, or 4,600 sq km, mainly along the Niger River and its tributaries in the southern part of the Inland Delta.
The Inland Niger Delta is a highly dynamic and complex ecoregion of landscapes that interact with the ebb and flow of seasonal flooding (see Inland Niger Delta). There is also considerable year-to-year variation in the extent of flooding. Despite this, the land cover types within the Delta have remained relatively stable, although there has been some encroachment of irrigated cropland in the southern Delta.
Natural habitat destruction is a major environmental issue in Mali. In addition to savannas, gallery forests have decreased by 23 percent due to population and agriculture pressures between 1975 and 2013. Clearing these forests causes severe water erosion, which removes the topsoil, reducing land productivity and creating conditions that lead to desertification. On a positive note, the hundreds of swamp forests that occur in natural depressions across the semiarid Sahel remain largely intact, providing critical habitat for wildlife.