Environmental factors determining spontaneous recovery of industrially mined peat bogs: A multi-site analysis

Peat is still mined in many parts of the World. What to do with the peatlands after the peat mining has stopped is a question for restoration ecologists and to leave a disturbed site to spontaneous regeneration could be one option. The main question of our study was whether it is an effective means of restoration and under which circumstances. Spontaneous succession was studied in 11 industrially mined peatlands, which encompassed successional stages of different age. Vegetation samples (109), 5 m × 5 m in size, were recorded in the stages using visual estimation of percentage cover of all present vascular plants. The age, abiotic environmental characteristics (position of water table, water pH, and substratum chemistry), as well as biotic characteristics (proportion of land cover categories up to 100 m, 300 m and 1 km from each sample, and the distance to the nearest undisturbed peatland vegetation) were assessed for each sampled successional stage. Other characteristics were related to the whole localities (altitude, average annual temperature, and precipitation). The data were analyzed by multivariate statistics. The environmental variables, except K-content and land cover up to 100 m, exhibited some significant effects on the vegetation patterns. External, i.e., landscape factors, had together a larger effect on the course of succession than abiotic site factors. The most important particular factors included ground water level, substrate pH, and presence of undisturbed peatland vegetation in the surroundings. Also important was geographic location predominantly reflecting site altitude. Spontaneous recovery of the peatland vegetation was more successful on those sites where the water table was intentionally increased. The increase of the water table after peat extraction and preservation of the original undisturbed peatland vegetation in the area neighbouring a mined site during the process of peat extraction are recommended to promote spontaneous recovery of the peatlands.