Modellierung des Höhenwuchses der Esche in der Verjüngungsphase in Abhängigkeit von der Beschattung

Freiburg im Breisgau

2004

S. 109-118

11 Abb., 24 Lit. Ang.

Artikel aus einem BuchUnselbständiges Werk

200113961

This paper examines natural mixed regeneration development in a forest gap which was established using the irregular group regeneration technique. Tree numbers, density and height were measured along a transect through the gap. This allowed mixture evolution and height growth at different light gradients to be compared over the whole phase up to the thicket stage. The study was carried out on site conditions with a full base saturation and a largely sufficient water regime; in geobotanic terms, a eutrophic beech forest. Results show that starting from a heterogeneous mixture of spontaneously regenerated seedlings, a considerable reduction in tree species in the dominant storey layer took place over 15 years. The extent of outmixing differed depending on light conditions. It was also clear that intrinsic competitive effects led more to outmixing than previously thought. Ash dominated in the bright gap centre and not only outgrew, but also suppressed other species. Beech dominated along the edge of the patch and under the old stand's shelter, up to light conditions of about 40 % at the outset to 60 % in the thicket phase. The reasons for this outmixing are discussed, in particular why mountain maple (Acer pseudoplantanus) was unable to compete with ash. Practical ways of achieving low-cost regeneration using natural opportunistic methods are detailed. A height growth reduction model for different light levels is presented for ash. The reduction in height growth for different ages also closely follows the same pattern, and corresponds to the model for saturation phenomenon. The calculation of top height/age functions for ash in permanent plots finally allows regeneration models to be developed for different shade and silviculture situation, in terms of canopy closure or gap width, for example.