Soil–climate interactions drive above-ground biomass in the Caatinga, the largest Neotropical seasonally dry tropical forest

Abstract

Background and aimsSoil properties are key drivers of vegetation structure, yet their influence on above-ground woody biomass (AGBW) in seasonally dry tropical forests (SDTFs) remains underexplored, particularly at larger scales. This gap is evident in the Caatinga, Latin America’s largest SDTF, known for its biodiversity and carbon storage potential. We investigated relationships among soil, climate, and vegetation properties to understand accumulation patterns of AGBW in SDTFs.MethodsWe used standardised soil and vegetation data from 29 research plots spanning diverse geological and floristic conditions. Linear mixed models and multi-model inference were applied to analyse relationships between AGBW and environmental variables, including soil texture, fertility, plant-available soil water, mean annual precipitation (MAP), temperature, and climatic water deficit (CWD). Structural equation modelling (SEM) was utilised to assess how environmental variables influenced community-weighted maximum stem diameter, wood density, functional richness, and their combined effects on AGBW.ResultsAGBW was influenced by MAP, soil fertility, maximum plant-available soil water, and CWD. SEM indicated that soil nutrient availability shaped community functional traits, reflecting trade-offs between growth and water-use strategies. In turn, species’ maximum stem diameter and, to a lesser extent, functional richness positively influenced AGBW, underscoring the role of soil-mediated functional traits in shaping biomass.ConclusionAGBW in the Caatinga is shaped by soil, climate, and their interactions, with soil properties exerting strong effects on community functional diversity and composition. Our findings highlight patterns of functional trait variability and biomass storage, offering insights for biodiversity conservation and carbon sequestration in SDTFs under global environmental change.