Functional aspects of the roostsystem from Juncus effusus L. for the regeneration of compacted soils in forests

Johannes Fritz1, Marina Leibfried1, Anke Kühne1, Helmer Schack-Kirchner1, Friederike Lang1
1 chair of soil ecology, University of Freiburg

P 12.13 in Restoration and rehabilitation of ecosystems

Poster Session 2 on Tuesday, 16:30-18:00

Soil-compaction is a widespread problem in forest-ecosystems and leads to negative modifications of soil gas- and water balance. Juncus effusus L. (soft rush) is a prominent representative of compaction-tolerant pioneer plants, growing even in the most deformed parts of compacted wheel tracks. Due to the formation of aerenchyma, the plant is able to open up the soil forming a widely branched root system. Hence we hypothesize that Juncus effusus L. could trigger an accelerated regeneration of compacted forest soils. We want to investigate the potential aeration by aerenchyma on the root-surrounding soil and the pore volume released through mortality and the conversion of rizospheric-space. Representative specimens of Juncus effusus L. from a skid trail on a clayey site in south-western Germany were excavated, the spatial extension of the root system, the root density and the root-to-shoot-ratio were determined. Gas diffusivity and macro porosity of soil-ring-samples both, with and without individual plants of Juncus effusus L. have been measured. This was done sequentially for each sample at the following stages: soil-ring-samples with untreated plants, with roots and shoots cut from both sides of the soil-ring and in addition two weeks after the forced mortification of the remaining plants and roots by glyphosate. The gaseous diffusion coefficients of samples with intact individuals were low due to entire filling of available pore-space by roots. After cutting off the roots and shoots, gas is able to pass through aerenchyma of the plants, hence the higher diffusion coefficient after treatment of the samples. After the accelerated mortification of plants the root system partially degrades, pore space is released and leads to an increased gas diffusivity of the sample. Obviously the plants are able to penetrate large compartments of compacted topsoils. However, a positive effect on the soil aeration regarding to the regeneration of soil structure becomes evident only after the release of the newly formed pore system by root degradation.

Letzte Änderung 19.06.2014