From rainforests to drylands: a context-specific framework for mapping land use and land cover dynamics in Northeast Brazil (2000-2020)

Author(s)

Ganem, Khalil Ali ; Xue, Yongkang ; Dutra, Andeise Cerqueira ; Pareyn, Frans Germain Corneel ; Shimabukuro, Yosio Edemir

• Document type: Journal article
• Source: GIScience & Remote Sensing; v. 62, n. 1, p. 26-pg., 2025-12-31.

Abstract

Northeast Brazil (NEB), about three times the area of Spain, hosts >90% of Brazil's drylands along with tropical rain- and dry forests. Climate variability, 45-60% cloud cover, and scarce reference data limit land use and land cover (LULC) mapping accuracy to similar to 80% across much of the region. Here, we introduce NEB's first context-specific LULC framework, using phenologically timed annual MODIS mosaics (2000-2020) with <0.5% pixel gaps and minimal seasonal bias. Ecoregions were individually classified using customized random forest (RF) models with 56 features - including linear spectral unmixing fractions - prior to NEB-wide integration. Binary masks excluding non-mangrove pixels during RF training significantly improved mangrove-rainforest separation. Our two-tier classification scheme uniquely distinguishes NEB shrublands nationally, aligns with global datasets (7 Level-1 classes), and preserves ecoregion detail (16 Level-2 classes). Validated against >10,000 independent points, the 2018 NEB-wide map achieved 90.5% overall accuracy at Level-1. At Level-2, ecoregional accuracies were 95.9% (Amazon), 94.3% (Atlantic Forest), 89.4% (Cerrado), and 87.9% (Caatinga). Per-pixel spatial agreement with national and global datasets ranged from 29-70%. Between the 2000 and 2020 endpoints, similar to 540,000 km(2) of NEB underwent LULC changes, based on pixel counts. Forest declined 22%, grasslands 68%, and agriculture expanded 140% - roughly 10 million soccer fields - mainly in the Cerrado MaToPiBa (Maranhao, Tocantins, Piaui, Bahia) frontier. Meanwhile, encroachment around protected areas intensified, particularly in the Amazon. This open-access product (http://www.dsr.inpe.br/DSR/laboratorios/LAF) sets a benchmark for LULC mapping in global dryland-forest mosaics, positioning NEB as a model for data-driven land management. (AU)

• FAPESP's process: 22/01746-5 - The impact of climate change on drylands vegetation phenology in the Southern Hemisphere
• Grantee: Andeise Cerqueira Dutra
• Support Opportunities: Scholarships in Brazil - Doctorate