Posted: Sat Feb 08, 2014 12:42 pm
by KoutaR
NTS,

The two regions with deciduous broadleaf forest as natural vegetation – Europe and eastern North America – apparently have quite similar potentials for native tree heights. If we compare laser/tape measured absolute height records, Europe leads at the moment. However, if we compare Rucker indexes the east US wins due to higher species diversity.

I tried to find a new method for the comparison. We cannot compare what species reach in the two regions as there are very few shared native species, but we can compare genera. In the table below, I have listed the height records by genera in the both regions. Only those genera are included for which there are known laser/tape measurements in the both regions in the native species ranges. For Europe, I did not include the species in the Canary Islands as it is unclear if the islands are in Europe. I did also not include Larix decidua (European larch) as all the measurements we have are outside its native range. Further, I did not include Sorbus domestica and S. torminalis (which both are much taller than S. aucuparia) because according to the molecular studies they should be placed in their own genera (as Cormus domestica and Torminalis clusii). The averages of the genus records for the two regions are very close to each others.



EurVsEastUS.jpg




I suppose that the measurers pay less attention to the low tree species than to tall ones, so the records of the tall species may be closer to the actual height potentials. In the second table below I have included only the genera with known 20+ m trees in both regions. Now we end up in the exactly same averages!



EurVsEastUS20.jpg




Please correct me if there are errors in the US records.

Kouta