Table 1.

Percentage of trees growing at the highest altitudes in the three selected valleys, according to the main factors limiting a treeline potential upward shift. Only at the Veny valley geomorphological factors are more important than human impacts in determining the treeline altitude. Here, on the left side of the valley, trees are growing on the southern flanks of Mt Blanc, also resulting in a strongly lowered treeline (VE_GEO in Fig. 1)

	Human impact	Geomorphological factors	Climate	Total nr. of trees
Veny	47.4	52.6	–	38
Valpelline–Etroubles	68.5	30.3	1.1	178
Gressoney	75.8	24.2	–	157