Diverse recalcitrant substrates slow down decomposition of leaf litter from trees in a serpentine ecosystem

Abstract

Litter decomposition in serpentine ecosystems has been studied solely addressing heavy metals like Ni. We aimed to show how leaf nutrients, cell-wall components and lamina mass per area and microbial communities affect litter decomposition in a cool-temperate serpentine ecosystem. Reciprocal transplant leaf-litter decomposition was observed in three tree species (Clethra barbinervis, Magnolia obovata, and Quercus serrata) common to serpentine and non-serpentine ecosystems. Thirteen litter quality variables of the initial litter and microbial respirations from decomposed litter were assessed. Litter from the serpentine ecosystem decomposed slower than that from the non-serpentine ecosystem. Compared with all species, C. barbinervis showed high heavy metal concentration, cellulose content, and lamina dry mass per area; M. obovata showed low Ca concentration; and Q. serrata exhibited high lignin/N ratio in litter from the serpentine ecosystem. Litter placed in the serpentine site decomposed faster than that placed in the non-serpentine site, but basal microbial respiration rates from litter did not differ between decomposition sites. Litter from serpentine ecosystems adversely influenced decomposition rate owing to its diverse recalcitrant litter quality. Our study suggested the feasibility of litter quality evaluation based on multiple litter traits for better-understanding of litter decomposition in serpentine ecosystems.