Download Biological, chemical and mechanical measures for active

Biological, chemical and mechanical measures for active regeneration of
compacted soils
Klaus von Wilpert, Juan Luis Flores Fernandez, Forest Research Institute, Germany, 79100 Freiburg,
Wonnhalde 4. e-mail: [email protected]
In Central Europe, Since the 1960s, repetitive passage of heavy forest machines on
unprotected forest soils has become a widespread problem in forestry due to soil
compaction. Soil compaction hampers soil aeration and thus root propagation of
trees. The aim of this study is to describe the establishment and growth of four woody
species planted in a block design in three skid trails without treatment treated with
lime, mulch and the combination of both and two untreated and undamaged control
plots. The base for this study is a controlled wheeling experiment at a silt clay loam
forest soil in the Swabian Alb. In 2012, the skid trails and the control plots were
planted with seedlings of Alnus incana, Alnus glutinosa, Rhamnus frangula and Salix
caprea. In 2012 and 2013, we measured the success of the tree species and the
different methods applied by analyzing the survival rate and biometric parameters for
the planted trees (tree height growth, crown diameter, basal diameter and shoot
length). At the treated skid trails the woody species showed an enhanced survival
rate and tree growth in comparison to the untreated skid trail and the uncompacted
control plots. It was also remarkable that both Alnus species presented a higher
survival rate than Rhamnus frangula and Salix caprea.
Moreover a new design of rhizotron windows has been developed, which allows for
an in situ root growth monitoring in forest soils under nature-near aeration conditions.
Aims of this approach are (1) to compare root growth in compacted soils treated with
different regeneration techniques (2) to analyze the CO2 concentrations measured by
diffusive soil gas samplers and behind the rhizotron windows in order to check if the
rhizotrons don´t influence the soil aeration status in an artificial way.
Diffusive soil gas samplers as well as rhizotron windows were installed at each
variant in order to perform a monthly monitoring.
The first results of this approach revealed that root growth was more intense at the
control plots and on mulched planted areas than at the untreated compacted sites.
CO2-concentrations were highest at the mulched sites and lowest at the control plots.
Furthermore, most of the locations presented higher CO2-concentrations at the wheel
tracks compared to the center of the skid trails. High correlations of CO2-concentrations between gas samplers in the close vicinity and those installed behind
rhizotron windows were observed for most of the situations and thus indicate that
rhizotron windows allow for a qualitatively sound observation of root growth.