Effects of Water Level via Controlling Water Chemistry on Revegetation Patterns After Peat Mining

Abstract

The recovery of plant communities is related to various environmental factors, in particular, waterlevel and chemistry, after peat mining. The changes over time after peat-mining were annually monitored from 2002 to 2007 in Sarobetsu peatland mined during 1970 and 2003, northern Japan, by using permanent plots setting up in various ages after mining. Rhynchospora alba was the earliest colonizer in the post-mined peatland, and three grasses followed. The recovery was slow when waterlevel was low, while Sphagnum papillosum, being predominant in pre-mined peatland, established well in post-mined sites with high waterlevel of which values were equivalent to post-mined site. Water chemistry was variable according to the effect of waterlevel in the post-mined peatland, while they were relatively stable in pre-mined peatland. Therefore, with large scale, merged with post-and pre-mined peatlands, water chemistry became the first determinants manipulated by waterlevel. In conclusion, high waterlevel that decreases nutrients in groundwater is a prerequisite to promote Sphagnum recovery in a post-mined peatland. Also, low pH was related to nutrient uptake by vascular plants and dilution by groundwater, and was advantageous for Sphagnum establishment. Re-establishment of vascular plants may promote the stabilization of water chemistries and facilitate revegetation towards the original Sphagnum peatland.