Advancing NPP modelling to support sustainable management in Brazil’s semi-arid ecosystems

The Caatinga, the largest tropical dry forest in South America, holds significant yet often unrecognized potential for carbon sequestration and ecosystem functioning despite its highly seasonal and water-limited environment. However, carbon dynamics in this biome remain poorly quantified, especially regarding how vegetation structure, climate variability, and land-use interventions influence net primary productivity (NPP). This knowledge gap is particularly concerning given that the Caatinga is the Brazilian biome most severely affected by land degradation. Approximately 12% of its territory is classified within the two highest degradation classes, characterized by vegetation loss, low productivity, and depleted soil organic matter. This degradation process disproportionately affects traditional populations, such as Indigenous Peoples, Quilombola communities, and smallholder farmers, who rely directly on natural resources for their livelihoods.

To address this gap, we integrate satellite-based remote sensing, eddy-covariance observations, and ecological modeling to investigate spatial and temporal patterns of NPP under contrasting vegetation conditions and management regimes. First, we estimate NPP using a Light Use Efficiency (LUE) model driven exclusively by remote sensing inputs and compare these outputs with flux tower-derived NPP calculated from flux measurements collected during both a dry year and a wet year. This comparison enables the assessment of how semi-arid constraints, such as recurrent droughts, elevated temperatures, and soil water scarcity, shape photosynthetic efficiency and biomass accumulation. Once validated, the LUE model is applied to characterize spatial and temporal patterns of NPP in two contrasting socio-ecological contexts: a degraded area and a recovering area. This approach allows us to evaluate how contrasting management conditions influence the capacity of Caatinga vegetation to assimilate carbon.

Preliminary results indicate a strong sensitivity of NPP to rainfall variability and canopy structure, with degraded areas showing reduced carbon sequestration compared to conserved areas. These findings contribute to broader discussions on sustainable land management in the Brazilian Semi-Arid region and the urgent need for inclusive public policies to mitigate land degradation, protect ecosystems, and support the livelihoods of local communities.