Silicious trichomes as a trait that may slow down leaf decomposition by soil meso- and macrofauna

Aims This study explored a possibility that leaf silicious trichomes slow down leaf mass loss by soil meso- and macrofauna. Methods We focused on closely related Moraceae tree species ( Broussonetia papyrifera and Morus australis ) with different leaf trichome densities. First, we conducted microscopic analyses of leaf trichomes and investigated nine other leaf traits. We then performed a 25-day decomposition experiment with bags of different mesh sizes that excluded and included meso- and macrofauna. A cafeteria experiment was also implemented to examine palatability of leaf powder (i.e. trichome effects removed) to the most abundant macrofauna ( Armadillidium vulgare ) in our decomposition site. Results Broussonetia papyrifera exhibited a 150-fold higher silicious trichome density on the lower leaf surface than M. australis . The carbon-to-nitrogen ratio was significantly lower in B. papyrifera than M. australis . In decomposition, the ash-free mass loss of B. papyrifera was significantly higher than that of M. australis in the <0.2-mm mesh bag. Similarly, in the cafeteria experiment with A. vulgare , mass loss of B. papyrifera leaf powder was significantly higher than that of M. australis . In the 5-mm mesh bag, however, the ash-free mass loss of B. papyrifera was significantly lower than that of M. australis . Conclusions Despite rich nutrient quality of B. papyrifera leaves, leaf decomposition of B. papyrifera with greater trichome densities was slower than that of M. australis only in the 5-mm mesh bag that permitted the entry of meso- and macrofauna. This suggests a suppressive effect of leaf silicious trichomes on decomposition by the large decomposers.