Solos ricos em carbono em Inselbergs de floresta tropical sazonalmente seca

Abstract

Soil is the largest reservoir of organic carbon (OC) on the planet, and Dry Forests play a crucial role in global climate regulation. Terrestrial ecosystems and the highlands of the Caatinga biome are promising environments for studying soil OC storage. Therefore, a global scientific production analysis on SOC in Dry Forests was conducted over a 25-year period. The research involved a literature search in major online databases, specifically Web of Science and Scopus. The compiled data included the number of publications, leading countries in research output, main thematic axes, and associated challenges. The results indicated a growing number of publications in recent years, particularly from India, Brazil, and Mexico. The main research themes were related to land use, forest management, and ecosystem services, while key challenges included deforestation, forest and soil degradation, and the scarcity of data on the subject. Additionally, over 90% of the studies highlighted concerns regarding climate change and global warming. Fieldwork involved soil and litter sampling on the slopes of three inselbergs in the Caatinga, within the morphostructural domain of the Borborema Plateau. The physical and chemical properties of the samples were analyzed and correlated with local topographic characteristics. Stable isotope analyses of δ¹³C and δ¹⁵N were also performed to trace the origin of soil organic matter. Data normality was assessed using the Shapiro-Wilk test (p > 0.05), and Spearman’s correlation coefficient was applied to evaluate relationships among variables. Data variability was measured using the Kruskal-Wallis test. Results indicated that OC and total nitrogen (TN) concentrations followed a pattern of higher accumulation on the mid-slope positions and were positively and significantly correlated with clay content, water availability, Ca²⁺, and Mg²⁺. A weak correlation was found between OC and P, suggesting distinct nutrient sources. The δ¹³C isotope signatures indicated that the organic matter originated under wetter conditions than those currently observed. These findings underscore the ecological and paleoenvironmental significance of inselbergs in Dry Forests, both for SOC storage and for understanding the natural landscape evolution.