Isohyet-driven variability in aboveground biomass across agroforestry parklands of Central-southern Niger

Abstract

Abstract

Agroforestry parklands are a key land use in the Sahel, where they are central to the productivity of these areas and to the overall success of agroecosystems under variable climatic conditions and soils. However, there is currently an insufficient quantification of the distribution of woody, crop, and herbaceous biomass components along rainfall gradients and of their relative contributions. In this paper, we seek to quantify and characterize the variability of aboveground biomass, its structural elements, and their variability along a gradient driven by isohyet in central-southern Niger. Data were collected during the rainy season in the Maradi area along a north-south rainfall gradient (200–500 mm) using a stratified sampling strategy, covering 96 plots (2,500 m 2 ) for woody biomass, within which 485 trees were measured, and 480 crop area quadrats (25 m 2 ), as well as 480 herbaceous area quadrats (1 m 2 ). We used a mixed-method approach to estimate the aboveground biomass, including non-destructive methods for woody biomass and destructive methods for crop and herbaceous biomass. Our results indicate that the total aboveground biomass level had a large increase on the rainfall gradient, from the value of 2680 ± 420 kg DM ha −1 in the 200–300 mm zone to 5090 ± 1120 kg DM ha −1 in the 400–500 mm zone ( p < 0.001). The system was dominated by crop biomass (70–82%), woody biomass (12–20%) and herbaceous biomass (4–8%). All component data exhibited wide variability across rainfall zones ( p < 0.001). Above-ground biomass in Sahelian agroforestry parklands across these regions is primarily driven by rainfall gradients and vegetation composition, although land-use practices may also be additional parameters to consider. The present research provides critical evidence for climate-smart agroforestry, sustainable land management, and dryland restoration strategies in the Sahel.