Assessment of terrestrial carbon stocks from regional to agricultural landscapes using SMAP-L4 Carbon Net Ecosystem Exchange dataset: review and application (Maradi, Republic of Niger)

International audienceContinental carbon (C) sequestration plays a major role in climate change resilience, mitigation, and agro-ecological intensification. Soil Moisture Active Passive Global Daily Carbon Net Ecosystem Exchange dataset (SMAP L4) is used for monitoring daily terrestrial C stocks, given the high potential of semiarid areas for Sustainable Goals achievements, in terms of human issues and surface areas. Inter-and intra-annual variation of Global Primary Productivity (GPP), Net Ecosystem CO2 Exchange (NEE), Soil Heterotrophic Respiration (RH) and Soil Organic Carbon (SOC) were analyzed from 2015 to 2020, across the region of Maradi (Niger) and 15 sites with rainfed crops and vegetal mosaics. To quantify temporal trends of C indicators across years, Mann-Kendall were conducted based on yearly GPP days of min/max. It underlined declines of SOC in the northern part of Maradi (τ >-0.6), rising in the south (τ > +0.6). Univariate monitoring (e.g. 2162 daily measurements) of GPP and RH showed asymmetries in their distribution (positive skews, GPP ̅ =1.19 gC m-2 d-1 , Me=0.88 gC m-2 d-1 ; RH ̅ =0.679 gC m-2 d-1 ; Me=0.485 gC m-2 d-1). This result might be attributed to local variations of Plant Functional Types and microbial activities. Averaged NEE stressed a slightly negative C balance among sites (overall ̅ =-0.003 gC m-2 d-1), suggesting their storage capacity. Processing aspects being set up, a consolidation of those first results should be done. Satellite data records analysis argue for the implementation of Man-Environment observatories in Maradi as a pilot region, for both remote and local understanding of C behavior in agroecosystems and multiscale counseling