EN
The lagg of ombrotrophic peatland studied is the ecotone connecting two contrasting in respect of trophic conditions ecosystems: acidic bog and fertilized arable fields. Differences of element content in the waters of these habitats concerns the concentration of Ca, Mg, Na, Cl and pH value. The periodical inflow of waters from agriculture catchment alkalize this zone and, as a result, threaten the ecological system of bog, what is realized by increasing lagg area at the cost of bog area and by decay of ombrotrophic flora components.