Crossdating of disturbances by tree uprooting: Can treethrow microtopography persist for 6000Â years?

Responses in the radial growth of trees near by uprooting disturbances were usually detectable for 20 years, and were specific to each region and tree species. Repeated tree-censuses (13,795 trees from 72.84 ha) suggested that the ratio of bole breakages to uprootings was 2-3:1, and that the treethrow rotation period approximated 1250-1380 years for some sites in Central Europe. At our European, beech-dominated sites, the maximal longevity of the treethrow microtopography was ca. 220 years on the fine-textured Haplic Cambisols and exceeded 1700 years on sandy-loam Entic Podzols. Finally, on the sand-textured Albic Podzols of northern Michigan, even greater longevities were achieved, with one mound returning a 14C age of 5260 ± 30 BP (median of calibration age 4077 BC) - by far the oldest feature reported in the literature. Sedimentation rates in treethrow pits, calculated using the 210Pb technique, were 0.05-0.28 cm year−1 in the beech-dominated European forests, and 0.07-1.4 cm year−1 in the hardwoods of Michigan. Radiocarbon dating of fungal sclerotia in treethrow pits can also help inform the disturbance history.