2.2. Site selection criteria
In order to effectively utilize the dendrochronological dating, a suppositional gradient of age was constructed on the basis of directly measured characteristics (thickness of A-horizon on mound, steepness of mound, etc., Šamonil et al., 2009). Pit–mound features designated for dating were then chosen regularly along this AGN 205728 gradient; this sampling scheme allowed us to obtain a representative selection of pit–mound pairs of various age.
Treethrows were dated by linking information of a repeated tree-census and dendrochronological survey. This method was called crossdating (Šamonil et al., 2013a).
In 1975, all living trees with a chromatid diameter at breast height (DBH = 1.3 m) of ≥ 20 cm were measured in Razula, across an area of 22.84 ha, and all living trees with DBH ≥ 10 cm were measured in 1995 and 2009 (www.pralesy.cz). For each tree, we determined the actual DBH as well as the health of each individual (living/dead/standing/lying/stump/broken/uprooted, etc.). At the same time, each tree was identified on the previous stem map. By comparing individual stem maps we were able to determine if a tree had uprooted in 2009–1995, 1995–1975 or before 1975; the length of intervals between measurements delimit accuracy of dating.