Composição da paisagem ao longo da distribuição de Callicebus coimbrai Kobayashi & Langguth, 1999 e sua relação com a ocorrência da espécie

Abstract

Land use and land cover (LULC) changes are among the main drivers of biodiversity decline, promoting habitat loss and fragmentation and affecting the distribution and abundance of organisms. The conversion of natural landscapes into anthropogenic matrices restricts native vegetation to isolated remnants. In this context, arboreal primates are particularly affected due to their essential dependence on forested habitats. Here, we characterized the landscape composition throughout the distribution of Callicebus coimbrai Kobayashi & Langguth, 1999, an Endangered primate endemic to the Atlantic Forest between the São Francisco River and the Recôncavo region of Bahia. We used LULC data from MapBiomas (collection 9) to analyze current (2023), comparative (1985 and 2023), and temporal (1985–2023) landscape composition within the species’ known occurrence and across 65 landscapes at different spatial scales (1 km, 2 km, and 3 km radii). We identified 18 LULC classes within the current distribution of C. coimbrai, with predominance of Forest Formation (21.68%), Pasture (~44%), Mosaic of Uses (15.89%), and Savanna Formation (3.12%). The comparative analysis showed significant differences across all classes (χ² = 175.17, df = 17, p < 0.01), and the temporal analysis revealed conversion of Forest Formation (~50%) and Savanna Formation (37.65%) mainly into Pasture. Significant differences were found for Forest Formation, with higher proportions at 1 km (W = 1778; p < 0.01) and 2 km (W = 1476; p < 0.01) radii; Pasture, with lower proportion at the 1 km radius (W = 691; p = 0.01) compared to the overall distribution mean; Mosaic of Uses, with lower values at 2 km (W = 701; p = 0.02) and 3 km (W = 719; p = 0.02) radii; and Forestry, with the highest values across all classes (p < 0.01). Among spatial scales, significant differences were detected for Forest Formation (H² = 8.78; p = 0.01), Pasture (H² = 7.82; p = 0.02), Forestry (H² = 7.18; p = 0.02), and Urban Area (H² = 27.08; p < 0.01). Our results indicate that forests where the species occurs have been continuously degraded by cattle ranching and agriculture, the main threats to the conservation of C. coimbrai. Forest Formation may be becoming insufficient to ensure the species’ long-term persistence and viability. The historical process of landscape occupation and transformation, although perceptible at broader scales, may not yet fully demonstrate emerging effects but may generate an “extinction debt,” with impacts on C. coimbrai populations in future generations. This study reinforces the need for conservation strategies and may support and guide future management actions.