Atlantic forest and leaf traits: an overview

Abstract

Leaf traits in Atlantic forest are modulated by environmental filters and biotic interactions. More information about leaf traits and nutrient are needed. Categorizing tree species according to their relationships with ecosystem processes in the Atlantic forest (AF) biome is fundamental to better understand their functionality in this high biodiversity hotspot. For categorizing vegetation, leaf traits are extremely useful and this is the first compilation of leaf traits focusing on photosynthesis, water relations, nutrients, and functional diversity across major AF vegetation types: (1) rainforest (ombrophilous dense and mixed ombrophilous Araucaria forest), (2) seasonal semi-deciduous forest, (3) deciduous forests, and (4) coastal plain forests (restingas). Species showed high plasticity of photosynthetic traits from early developmental stages, including adjustments in Rubisco carboxylation capacity, maximum photosynthetic capacity, photochemical and non-photochemical quenching, specific leaf area (SLA), and chlorophyll and spongy parenchyma thickness. Montane rainforest tree species showed lower SLA and longer leaf lifespan in comparison to lowland rainforest species. Tree communities are structured by environmental filtering leading to trait convergence in early successional stages or in stressful ecosystems such as restingas, and by biotic interactions leading to trait divergence in later stages. Altitudinal gradients in litter production and below/aboveground biomass stocks in AF show contrasting patterns in comparison to other tropical forests, with important consequences for responding to climate change. However, the identity of limiting elements to growth still represents a critical gap in leaf trait data for AF species. Other gaps in knowledge of AF leaf traits are highlighted for consideration in future studies.