Effects of spot liming on shoot growth, root proliferation and nutritional status of planted beech (Fagus sylvatica L.).

摘要

The influence of patchwise incorporation of lime into the mineral soil (spot liming) on shoot growth, coarse root proliferation, and nutritional status of juvenile beech stands was investigated on 5 plots in the Harz mountains (Niedersachsen, Germany). Repeated reports of snow bending in advanced-plantings raised the question if spot liming inhibits root proliferation into the less favourable surrounding soil, thereby reducing tree stability. 161 beech trees from advanced-plantings (with and without spot liming) and natural regeneration were excavated in order to count the number of coarse roots (diameter >=2 mm) and calculate the root cross sectional area (WQA) in horizontal and vertical layers. Furthermore shoot length and diameter, leaf area index (LAI) and foliar concentrations of N, P, K, Ca and Mg were analysed. Seven and 13 years after establishment, trees on limed spots still showed higher foliar Ca and P concentrations, enhanced height growth and significantly higher LAI than untreated control trees. However, there were indications that treatment effects were already fading out. A negative influence of spot liming on coarse root proliferation into the untreated soil was not observed. Significantly enhanced WQA of limed trees compared to the control in some measuring layers support the conclusion that tree anchorage is rather intensified than weakened by spot liming. The ratio of WQA in 30 cm depth to shoot cross sectional area indicated that vertical anchorage of planted trees, irrespective of treatment, was generally reduced than in natural regeneration. The frequency of severe root deformations and abnormally flat root systems was higher in planted trees compared to natural regeneration. In order to reduce the risk of snow bending it is recommended to use small planting stock or apply direct sowing for the introduction of beech under Norway spruce canopy.