Past uppermost tree limit in the Central European Alps (Switzerland) based on soil and soil charcoal

The uppermost limits of past treelines in the Alps are established using soil type and soil charcoal mass. In all the studied sites, a sharp decrease of soil charcoal mass is correlated with the upper altitudinal limit of podzols. On the basis of this evidence, the uppermost tree limit reached 2500 +/- 100 m a.s.l. in the Valaisan Alps during the Holocene, i.e., it was 250 +/- 100 in higher than today's potential treeline. Consequently, the timberline would have reached 2400 +/- 100 m a.s.l.. From the strong decline of charcoals concentration in soils above 2500m a.s.l., we infer that conifer species were rare or very rare above this altitude during the Holocene. Joint interpretation of charcoal, pollen, soil and macrofossil data suggest that alpine meadows with at most scattered conifers were present throughout the Holocene in the today's middle and upper alpine belt.