Since the year 1800, wetlands, including marshes, fens and bogs, lost more than 80 % of their former area in Switzerland, mainly due to river corrections, drainage and land improvement. During the first and second world war, the exploitation of peat bogs peaked, and peat bogs have nowadays almost vanished from the Swiss lowlands. Since a public referendum in 1987 on mire conservation, the loss of area of fens and bogs has largely stopped in Switzerland, and the most precious ones have been listed in two national inventories on fens and on raised and transitional bogs, respectively. These mires of national importance are now protected by law. However, how do the different mires listed in these inventories develop with respect to their quantity (i. e. has their area been secured)? Are there ongoing negative effects on their quality in terms of loss of specialised plant species, typical vegetation types or red list species? Are there small, but permanent negative influences of nutrient inflow from surrounding agricultural land or by atmospheric nitrogen deposition? Do the mires of Switzerland dry out, because their hydrology is hampered due to the fact that old drainage systems are still in place? Is the protected vegetation negatively affected by unsuitable management such as grazing or trampling? Does encroachment by woody species threaten the typical light-demanding flora of mires? If so, large-scale restoration measures are needed to preserve the remnants of fens and bogs in Switzerland. How effective are the respective restoration measures already taken? These are the main questions tackled in this book.