Multiple abiotic and biotic drivers of long-term wood decomposition within and among species in the semi-arid inland dunes: A dual role for stem diameter

Litter decomposition in sunny, semi-arid and arid ecosystems is controlled by both biotic factors including litter traits and abiotic factors including UV light, but for wood decomposition it still remains uncertain which of these environmental factors are the predominant controls among different woody species. In these dry ecosystems, it is likely that the stem diameter and spatial position of the dead wood are of particular importance especially where wood can be buried versus exposed due to substrate displacement by wind. Here we focus on the fact that stem diameter can affect decomposition rates both via the relative surface exposure to sunlight or soil and via higher resource quality of narrower stems to decomposers. In a field manipulation experiment, we investigated the relative importance of litter position (sand burial vs. surface vs. suspended above the surface), UV radiation (block versus pass) and stem diameter class (