Effects of temperature and litter type on fungal growth and decomposition of leaf litter

The dependence of fungal decomposition of leaf litter on incubation temperature and litter types used as substrata was assessed under pure culture conditions. Isolates of Xylaria sp., a major ligninolytic fungus in cool temperate forests in Japan, were used as the fungal material. Xylaria sp. is mesophilic; maximum growth and decomposition occurred at 25 degrees C. In the temperature test, the decomposition pattern of beech leaf litter by three isolates of Xylaria sp. changed at a threshold at 25 degrees C. Cellulolytic activity increased with temperature from 5 to 25 degrees C, whereas above 25 degrees C ligninolytic activity increased at the expense of cellulolytic activity, leading to suppressed overall decomposition as a result of the higher temperature. The mass loss of leaf litter caused at 20 degrees C by an isolate of Xylaria sp. was variable among 15 litter types and was correlated negatively with acid-unhydrolyzable residue (AUR) content and positively with total carbohydrate content for the 15 litter types. The effects of temperature and litter type on the growth and decomposition of leaf litter by Xylaria sp. may have implications for changes in fungal decomposition of leaf litter that would be predicted in response to future environmental changes.