Fallen fruits stimulate decomposition of leaf litter of dominant species in NW Patagonia shrublands

Abstract

Background and aims: Leaf-litter decomposition rate (kL) regulates nutrient dynamics and is affected at microsite level by species traits, soil biota and microclimate conditions. Fallen fruits form part of the litter and some, particularly fleshy fruits, contain large quantities of nutrients and sugar. We estimated the amount of fruit fall to litter, and evaluated the effect of its decomposition and sugar content on kL in dominant species of NW Patagonia shrublands. Methods: We selected six woody species, four with fleshy and two with dry fruit. We followed 224 decomposition bags with leaf or leaf+fruit throughout 1 year. Fruit-litter and fruit sugar content were also measured. Results and conclusions: Fleshy fruit decomposition rate was associated with changes in kL, while no effects of dry fruit on kL were registered. We found that three of the fleshy fruits (R. cucullatum, R. rubiginosa and S. patagonicus) had a positive influence on kL due to their sugar content. In contrast, Berberis microphylla fruit had a negative effect on kL, probably due to the presence of antimicrobial substances in the fruit. Considering the abundance of these species and their copious fruit production, the fleshy fruits could play an important role in determining soil fertility.