Jugendwachstum und Schattentoleranz vegetativer Verjüngungen der Elsbeere (Sorbus torminalis Crantz)

2001

S. 11-15

34 Lit. Ang.

Unselbständiges Werk

200074700

Generative regeneration from seeds is described as very rare for the whole distribution of Sorbus trominalis in Europe. Regeneration is mostly found as root sucker regeneration. The introduction of Wild Service trees in silvicultural in-situ management strategies therefore requires information about the development of vegetative regeneration from root suckers. For this purpose natural regeneration was assessed from 1994-1999 for vitality and height growth on 101 plots of 3 m x 3 m. The tests trials were located 30 km northwest of the Harz mountains near Liebenburg. The light regimes were assessed for every plot using fish-eye photos and computer simulation models to determine the diffuse site factor (Diffsf). The results showed that the induction and establishment of the vegetative regeneration does not depend from the light regime of the plot. Even so the felling of the mothertree had no effect on induction. The phase of induction was found to be not light demanding. After establishment of the regeneration (plant height 50-80 cm) the further development was significant correlated with the light intensity of the plot. the survival was significantly reduced by fungi diseases if Diffsf was >30 %. With increasing age of the regeneration the correlation between height growth and Diffsf became more significant. The diameter in 30 % relatively plant height and the lengths of the branches was also significantly correlated with Diffsf. It was concluded that successful vegetative regeneration needs at minimum Diffsf >30 %. The regeneration showed under a light regime of Diffsf >30 % an annual average height increment of 25-30 cm. Under these conditions generative regeneration of Sycamore and especially Ash was established with an annual height increment of 60-110 cm. The regeneration has to be removed because the root suckers are otherwise lost in this competition. The canopy tolerance of Wild Service trees is not high enough to survive under the shadow of dense ash regeneration. At the end of the observation, assessments of the root systems were made. Even if the regeneration is about 3 m high (age 6-8) the root suckers are not independent from the root system they are coming from. Only in some cases small roots are occurring over the induction area but no cases were found where these secondary roots were well enough developed to give stability and to ensure nutrient and moisture supply. Compared to these root systems generative seedlings showed a strict tap root system. the adult roots from which the root suckers descend showed a secondary thickened root.