caa a22 4500 47711041X CHVBK 20180405111607.0 cr unu---uuuuu 170330e19960101xx s 000 0 eng 10.1007/BF00011159 doi (NATIONALLICENCE)springer-10.1007/BF00011159 Bernier N. Laboraitoire d'Ecologie Générale, Museum National d'Histoire Naturelle, 4 Avenue du Petit-Chateau, F-91800, Brunoy, France aut Altitudinal changes in humus form dynamics in a spruce forest at the montane level [Elektronische Daten] [N. Bernier] An altitudinal transect was studied at the montane level in a spruce forest, in order to describe changes in humus form dynamics. Whatever the elevation, the periodicity of humus form changes is copied on forest dynamics. Spruce regeneration is restricted both in space and time to favourable micro-site conditions accompanying tree fall gaps. One of these conditions is a shift from moder to mull humus form. As a result, this forest ecosystem shows a space-time mosaic pattern. The recovery of mull humus form takes more time as elevation increases and thus the ratio mull:moder progressively decreases. Simultaneously, burrowing earthworms become scarce. Nevertheless mull humus form does not change basically at increased elevation. On the other hand, moder has little organic matter at the lower montane level. At the mid montane level, accumulation of holorganic faeces into OH horizon is maximum. A mor-moder (few faunal traces) is observed during tree growth phase at the upper montane level. Lack of nutrient availability was hypothesized to explain the observed shift from mull to moder or mor-moder during the phase of intense tree growth. An increased independancy between the building of a moder humus profile and the actual accumulation of organic matter was the main change occurring with elevation. The transition to the subalpine level may thus be defined as the highest elevation up to which the forest ecosystem is able to reverse the mor-building process produced by tree growth. The discoupling between primary producers, plant debris accumulation and decomposers observed in the subalpine spruce forest leads to a breaking point in the carrying capability of humus for spruce seedlings. At high elevation spruce seedlings are mainly observed on rotten wood. The influence of humus form dynamics upon forest sustainability was discussed. The lack of humus biological activity at higher elevation was found to be a reason for the weakness of the forest ecosystem faced to the bilberry heath. Forest sustainability depends both on mull and moder. It was observed that moder failed to recover after mull along the forest cycle and turned to mor in harsh climate conditions. Consequences of management practices on the issue of competition between forest and heath were also discussed. Kluwer Academic Publishers, 1996 altitude nationallicence earthworms nationallicence forest sustainability nationallicence heathland nationallicence humus dynamics nationallicence spruce forest nationallicence Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl 178/1(1996-01-01), 1-28 0032-079X 178:1<1 1996 178 11104 https://doi.org/10.1007/BF00011159 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00011159 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Bernier N. Laboraitoire d'Ecologie Générale, Museum National d'Histoire Naturelle, 4 Avenue du Petit-Chateau, F-91800, Brunoy, France aut NATIONALLICENCE 773 0- Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl/ 178/1(1996-01-01), 1-28 0032-079X 178:1<1 1996 178 11104 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer