Ameaça silenciosa: análise histórica e tendências futuras da supressão dos campos naturais do bioma Pampa pela expansão agrícola

Abstract

The Brazilian Pampa faces critical challenges. It has the smallest extent of protected areas and the highest proportional rate of native vegetation loss among Brazilian phytogeographic domains. In this study, we investigated the historical suppression of native grassland vegetation in the Pampa biome using annual MapBiomas data (1985–2023). A generalized linear model (GLM) with a temporal autocorrelation structure was employed to analyze the impact of expanding soybean cropland and silviculture areas on grassland loss, focusing on municipalities with the highest losses. Through predictive modeling, we projected future scenarios of grassland heritage loss in private areas (~85% of the biome’s total area), integrating spatiotemporal variables derived from historical trends. The results reveal a concerning acceleration in grassland suppression, intensifying markedly over the past two decades. While initial periods (1985–1990 and 1985–1995) showed minimal losses, recent intervals (2013–2023 and 2018–2023) reached critical levels. Over 38 years, cumulative native grassland loss reached 3.5 million hectares (38.55% of the original 1985 extent). Post-2003, suppression escalated sharply, with losses equivalent to 29.98% of the remaining grassland area in 2003 and 26.4% of the original 1985 area. Four Rio Grande do Sul mesoregions accounted for 85.2% of municipalities with the highest losses: Southeast (25.9%), Central-Western (20.4%), Metropolitan Porto Alegre (20.4%), and Southwest (18.5%). In the municipalities with the greatest losses, the expansion of soybean and silviculture together explained 87% of the total variation in grassland suppression. Our most robust projections indicate that, without immediate intervention, native grasslands in private areas could disappear before the end of this century, within 64–73 years. The results highlight the rapid conversion of the Pampa’s natural grasslands, threatening its rich biodiversity, essential ecosystem services, and the traditional ways of life that depend on them. Implementing effective policies is essential to mitigating this process and ensuring the preservation of the Pampa’s environmental and cultural heritage for future generations.