Changes in Litter Decomposition Across Succession in a Post-mined Peatland, Northern Japan

Litter decomposition along successional sere after peat mining was monitored for 3 years on post-mined peatland in Sarobetsu Mire, northern Japan. The litter of two dominant species ( Rhynchospora alba and Moliniopsis japonica ) was examined in 3 different successional habitats. We used the litterbag method to measure litter decomposition. We also measured changes in litter decomposition properties (carbon, nitrogen, and phospholipid fatty acids) with the environments (solar radiation and peat moisture). Bareground without litter showed the highest fluctuation of solar radiation and temperature, but the litter decomposition was slowest. Therefore, photodegradation and physical abrasion had affected weakly on litter decomposition. The concentrations of carbon, nitrogen, and phosphorus were not different between the two litter species showing that the litter decomposition pathways of these two species were specific in each habitat because of stable isotopes. Phospholipid fatty acids indicated that fungi contributed more to litter decomposition than bacteria in vegetated habitats with time. These results suggested that biodegradation, particularly by fungi, was the determinant in litter decomposition. The fungal activity was determined by vegetation cover suggesting that restoration to the original vegetation was desirable soon after peat mining to return the in-situ litter decomposition.