标题：Investigations on spatial heterogeneity of humus forms and natural regeneration of Larch (<i>Larix decidua Mill</i>.) and Swiss Stone Pine (<i>Pinus cembra L.</i>) in an alpine timberline ecotone (Upper Engadine, Central Alps, Switzerland)
摘要：The north-west facing study area in the Upper Engadine (Central Alps, Switzerland) encompasses the
whole timberline ecotone between 2200 m and 2400 m
a.s.l.. By dendroecological methods, clear differences
concerning quantity and age structure of the natural
regeneration of the main tree species Swiss stone pine
(<i>Pinus cembra L.</i>) and larch (<i>Larix decidua Mill.</i>) at
different sites could be detected.The differing site conditions, closely linked to the microtopography, determine distribution and age structure of natural tree
regeneration, as well as humus forms. On exposed sites
characterised by Tenuic Humimors, an intensive natural regeneration of, in particular, Swiss stone pine
occurs. In depressions with a Rhizic Leptomoder, the
density of tree regeneration is low and a high tree mortality
could be observed. The results indicate that the
site conditions most important for the natural regeneration of trees in the timberline ecotone are reflected
in the site-specific humus form.
