The contribution of leaching to nutrient release from leaf litter of two emergent tree species in a Malaysian tropical peat swamp forest

Abstract

To understand the role of abiotic leaching in nutrient release within the nutrient-deficit tropical peat swamp forest (TPSF), an experiment was conducted over 30 days using leaf litter from two common emergent TPSF trees, Koompassia malaccensis and Shorea uliginosa. The main objectives were to determine leaf litter nutrient leaching dynamics, and the effect of water pH and potential microbial influence on nutrient release. Leaf litter (single species and combined) was subjected to 3 treatments: peat water (natural acidic conditions), poisoned peat water (NaN3 as microbial poison) and deionized water (control). Despite loss of nutrients from the leaves, this was not associated with the loss of mass or carbon (C) from the leaves because they are resistant to decomposition. Nutrient loss occurred in the order of phosphorus (P) > nitrogen (N) > C whereby litter P content was quickly exhausted. Microbial activity only affected the bioavailable P (PO4−) whereby initial litter P release stimulated microbial growth, which resulted in the subsequent immobilization of P. Lastly, the effect of pH was not profound in this study. In conclusion, abiotic leaching from leaf litter releases considerable amounts of nutrients (notably PO43−) and functions as an important autochthonous nutrient source for the TPSF.