Biophysical and economic assessment of carbon dynamics in the Itajaí-Açu Valley Basin in Southern Brazil

The aim of this study is to conduct a biophysical and economic assessment of carbon stocks associated with changes in land use and cover (LULC) in the Itajaí-Açu Valley Basin (IVB). The IVB is immersed in the Atlantic rainforest, considered one of the most diverse, as well as one of the most threatened, forests on the planet. The Valley is also home to important urban and industrial centers located along the riverbanks. Since its colonization in the second half of the 19th century, the region has constantly suffered from natural disasters, such as floods and landslides. With the expected escalation in extreme weather events in the near future due to climate change, these natural disasters may increase in intensity and frequency. Maps of LULC and the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) program were used to quantify and value the carbon stock and sequestration for three periods. The results show that between 2000 and 2020, there was an increase in forestry (354.64%), mosaic (57.43%), and pasture (43.08%) areas in the IVB, while a decrease was observed for natural forest (-4.38%), nonforest natural formation (-69.56%), and agriculture (-68.69%). The carbon stock values were 259,328,452 Mg C in 2000; 265,079,768 Mg C in 2010; and 262,577,960 Mg C in 2020. The carbon sequestration in the period 2000-2010 represented an economic benefit of US$138 million. Conversely, between 2010 and 2020, there were net carbon emissions equivalent to US$60 million. Over the entire period analyzed, there was a gain of US$78 million in ecosystem services related to carbon stocks. Targeted policies, such as Payment for Ecosystem Services programs, market-based incentives for carbon credits, and public investments in forest conservation and restoration, can bring economic, social, and ecological benefits, ensuring the continued provision of ecosystem services in the region.