Aptroot, A. 2012. Changes in the epiphytic flora on four Tilia trees in Belgium over 59 years. — Herzogia 25: 39 – 45.
The epiphytes on four Tilia trees in southern Belgium, which were studied by Barkman in 1952, were re-investigated in 1999 and 2011. In 1952, 19 species of epiphytes (including 12 lichen species) were recorded; in 1999, there were 65 epiphyte species (including 49 lichens), and in 2011, 53 epiphyte species (including 41 lichens) were found. The enormous increase in species between 1952 and 1999 is primarily attributable to colonization by additional species, which is an early stage of natural succession, whereas the reduction in species between 1999 and 2011 is most probably due to competition, the next step in the natural succession, when larger mosses and foliose lichens became dominant over crustose lichens and the whole bark surface had been covered by epiphytes. Global warming also may have influenced the species composition in the last decades.