Vegetation gradients in relation to temporal fluctuation of environmental factors in Bekanbeushi peatland, Hokkaido, Japan

The relationship between vegetation gradients and temporal variation of groundwater table depth, groundwater pH and electrical conductivity was studied in Bekanbeushi peatland, northern Japan. These environmental factors were expressed using four statistical parameters: maximum, minimum, mean and standard deviation or coefficient of variation during the growing season. The bog–fen–swamp/marsh gradient was primarily explained by minimum, maximum and mean groundwater table depth and minimum pH. The separation between the bog and the fen by minimum pH was particularly clear. Minimum conductivity was secondarily important for explaining this vegetation gradient. The swamp–marsh gradient was explained by the standard deviation of groundwater table depth. Maximum pH and conductivity were not significant in explaining either of these gradients. This study suggests that parameters that are obtained from the consecutive measurement of environmental factors may have differing significance in explaining vegetation gradients in these peatlands, and values from a single sampling may miss important ecological information.