Leaf decomposition and flammability are largely decoupled across species in a tropical swamp forest despite sharing some predictive leaf functional traits

Abstract

Decomposition and fire are major carbon pathways in many ecosystems, yet potential linkages between these processes are poorly understood. We test whether variability in decomposability and flammability across species are related to each other and to key plant functional traits in tropical swamp forests, where habitat degradation is elevating decomposition and fire regimes.Using senesced and fresh leaves of 22 swamp tree species in Singapore, we conducted an in situ decomposition experiment and a laboratory flammability experiment. We analysed 16 leaf physical and biochemical traits as predictors of decomposability and components of flammability: combustibility, ignitability and sustainability.Decomposability and flammability were largely decoupled across species, despite some shared predictive traits such as specific leaf area (SLA). Physical traits predicted that thicker leaves with a smaller SLA and volume decomposed faster, while various cation concentrations predicted flammability components, particularly ignitability.We show that flammability and decomposability of swamp forest leaves are decoupled because flammability is mostly driven by biochemical traits, while decomposition is driven by physical traits. Our approach identifies species that are slow to decompose and burn (e.g. Calophyllum tetrapterum and Xanthophyllum flavescens), which could be planted to mitigate carbon losses in tropical swamp reforestation.

Accounting for seedling performance from nursery to outplanting when reforesting degraded tropical peatlands

“…While tropical peatland nursery studies have investigated tree species flooding tolerance (Santosa et al 2014; Tata et al 2022), to our knowledge these do not outplant survivors versus unflooded control seedlings to determine whether nursery flooding treatments influence outplanted seedling survival. Other relevant treatments may include mycorrhiza inoculation to avoid/reduce fertilizer use (Turjaman et al 2011; Graham et al 2013), full leaf scorching to stimulate post‐fire resprouting and identify species' fire regeneration adaptations (Hadi et al 2019), and seedling flammability (Rahman et al 2023). Research to address these questions using rigorous controlled experimental designs could thus be highly beneficial to revegetation efforts in tropical peatlands and more widely.…”