Between 20 at least 20% of tropical forests were selective logged ( 8), while other anthropogenic drivers and extreme droughts are increasing forest fires, with 54 million ha burned annually in the 1990s ( 9). Many of the remaining primary forests are also degraded. Deforestation is a key driver of change-more than 100 million ha of primary tropical forests have been converted to agriculture and silviculture in the last 40 y ( 6, 7). Despite their global importance, tropical forests are being severely affected by human activities ( 5). Tropical forests host two-thirds of all terrestrial biodiversity ( 1), account for one-third of terrestrial productivity and evapotranspiration ( 2), and store half of all terrestrial carbon ( 3, 4). Our study demonstrates the importance of considering multiple ecosystem components and LULCTs to understand the consequences of human activities in tropical landscapes. Forest clearance for pasture was the most prevalent and high-impact transition, but we also identified other LULCTs with high impact but lower prevalence (e.g., forest to agriculture). Across all LULCTs, biodiversity was the most affected ecosystem component, followed by carbon stocks, but the magnitude of change differed widely among LULCTs and individual variables. Here, we quantified the impacts of 18 LULCTs on three ecosystem components (biodiversity, carbon, and soil), based on 18 variables collected from 310 sites in the Brazilian Amazon. Although the impacts of deforestation are well studied, multiple land-use and land-cover transitions (LULCTs) occur in tropical landscapes, and we do not know how LULCTs differ in their rates or impacts on key ecosystem components. Human activities pose a major threat to tropical forest biodiversity and ecosystem services. Aragão, Danielle de Lima Braga, Plinio Barbosa de Camargo, Carlos Eduardo Pellegrino Cerri, Raimundo Cosme de Oliveira Jr, Mariana Durigan, Nárgila Moura, Victor Hugo Fonseca Oliveira, Carla Ribas, Fernando Vaz-de-Mello, Ima Vieira, Ronald Zanetti, and Jos Barlow -18 Authors Info & Affiliations
Cássio Alencar Nunes, Erika Berenguer, Filipe França, +18, Joice Ferreira, Alexander C.
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