subsidized ditching projects in the late 1800s and early 1900s; 3) reports from the Swedish Roads and Waters Agency, which were published as a part of Sweden’s Official Statistics around the turn of the 20th century and provide information on the reclamation of mires performed each year (Väg- och vattenbyggnadsstyrelsen, 1872–1910); 4) forestry maps from 1941 that contained information on forestry measures, including ditches, established by the forest company Sandviks Ångsågs AB and covering about half of the study area, which had been acquired by the company; 5) the archives of the Umeå Timber Floating Association (Umeå flottningsförening), which contain information on dams and other installations; 6) aerial photos from 1963 and 2013; and finally 7) a LiDAR derived DTM from 2015.
The single most important source was the enclosure (sw. ‘laga skifte’) map of Abborrtjärn from 1880 (Figure 2c), which we used to define the study area. It was drawn to equitably share the village common land among the owners, and therefore shows the entire area divided into a large number of polygons which were classified as mire, meadow, forest, and so on. Each polygon was marked on the map and described in a table containing information on area and a grade representing value, by us interpreted as productivity. The grading was relative, with the most valuable land classified as grade 1 and less valuable land as proportionally higher numbers up to 100.
As for older conditions, the first map that gives any substantial information is the geometrical and geographic map of Degerfors from 1702, where land use is sketched and the amount of hay produced on different kinds of land is noted. The study area is included in the geographical part of the map, which gives an overview of the area around the village but does not include detailed measurements of the study area. Then follows the delineation map of Degerfors from 1785 (Figure 2a), drawn to establish the borders between Crown land and village land, but also showing fields, natural meadows, and other important resources claimed by the villagers, as well as a selection of unused mires. About 40% of the study area was included in this map. The first document focusing on our study area, the taxation map of Abborrtjärn, is from 1805 (Figure 2b), where the new village was formally recognized. Here, all units of arable land and meadows were assessed and graded according to an elaborate method (Björck, 1851: 531–533). For each meadow, a drawing was provided as well as the area and an estimated yield in weight. The area covered by this map was much smaller than the study area, but almost all of the mire meadows of the 1805 map were also included in the enclosure map from 1880.
To explore more recent conditions, we used data sets gathered for other studies with modern remote-sensing methods and made available through the Krycklan Catchment. Land cover in 1963 (Figure 2f) and 2013 (Figure 2h) had been classified from aerial photographs by a well-trained analyst from the Swedish National Forest Inventory (NFI), who defined polygons and classified them into standard land classes (Hasselquist et al., 2019). Also, most of the ditches of the area had been mapped and quantified using a 0.5 × 0.5 m digital terrain model (DTM) derived from a LiDAR flight from 2015 (Hasselquist et al., 2018). In both cases, the existing data sets were reused, but also slightly expanded with more data from the same sources because a small part of the study area had not been covered by the previous studies.
It is common practice to divide mires into bogs and fens, bogs receiving water only from precipitation and therefore being extremely nutrient-poor, whereas fens receive water that has been in contact with mineral soil and therefore has a higher content of minerals (Gunnarsson and Löfroth, 2014). However, as our study is based on both historical sources and current land-cover classification where this distinction is not followed, we have chosen to treat mires as one entity.
The entire study area had been mapped in great detail during