Changes in Litter Organic Acid Release Characteristics During Litter Decomposition in Plantations Comprising Different Tree Species.

Abstract

Phosphorus deficiency restricts the productivity of plantation forests in southern China. Low-molecular-weight organic acids (LMWOAs) can promote insoluble P activation and improve P availability in red soils. However, few studies have investigated organic acids (OAs) released during litter decomposition under field conditions. A one-year litterbag decomposition experiment with monthly sampling was conducted using four common plantation tree species in subtropical China, namely, <i>Phoebe bournei</i>, <i>Michelia macclurei</i>, <i>Schima superba</i>, and <i>Cunninghamia lanceolata</i>, to determine changes in LMWOA composition, content, and release characteristics during decomposition. Seventeen LMWOAs were detected during litter decomposition, and OA types differed among tree species. The total amount of litter-derived OAs varied among species, following the order <i>S. superba</i> > <i>P. bournei</i> > <i>C. lanceolata</i> > <i>M. macclurei</i>, with the amount in <i>S. superba</i> being 1.15 times that in <i>M. macclurei</i>. The release characteristics of OAs differed significantly. <i>C. lanceolata</i>, <i>S. superba</i>, and <i>M. macclurei</i> exhibited a net release pattern, whereas <i>P. bournei</i> exhibited a release-enrichment-release pattern. <i>S. superba</i> and <i>M. macclurei</i> litter released significantly more OAs than <i>C. lanceolata</i>. Overall, this study provides field-based evidence for interspecific differences in litter-derived OAs dynamics and offers a basis for tree species selection in mixed plantations with potential implications for nutrient return and phosphorus cycling.