Workpackages of Subproject S03a

Workpackage WP03a.1

Dr. Claudia Görke, University of Tuebingen, Spezielle Botanik & Mykologie, Auf der Morgenstelle 1, 72076 Tübingen
claudia.goerke@uni-tuebingen.de

Mycodiversity of the soil studied with mainly morphological tools

Short description: The aim of this work package is to understand the role of soil fungi and AM fungi in arid and semi-arid ecosystems. There is the necessity of more samples to asses the variability of each of the observatories before conclusions about the changes of biodiversity along the transect become possible. Understanding the impact of land use on soil fungi and mycorrhiza becomes possible by comparing different land use systems. Another focus is the change of species composition and activity during the year. As grazed grasses in Nabaos 7 in 2001 were non-mycorrhizal, but grass-seedlings in 2002 were mycorrhizal, the mycorrhization rate will be followed during the raining season.

Workpackage WP03a.2

Dr. Claudia Görke, University of Tuebingen, Spezielle Botanik & Mykologie, Auf der Morgenstelle 1, 72076 Tübingen
claudia.goerke@uni-tuebingen.de

Mycodiversity of the soil studied with molecular tools

Short description: Mycodiversity of the soil is usually studied by various isolation techniques. These are indirect methods with several limitations. In order to assess the diversity of species that are not detected by cultivation techniques, primer sets with specificity for different fungal phyla will be used. After isolation of DNA from soil, PCR using different sets of primers yields mixed products. Sequencing (for attribution to known species) can only take place after cloning. Despite having many steps, this approach nevertheless has the potential for automation.

As reported by Viaud et al. (2000), the overlap of sequences derived from cultures and direct DNA isolation of the same soil sample, is low. Isolating DNA from soil particles after different pre-treatments will address this problem. The relationship of sequences derived from these samples can give insights into the composition of the spore pool and the active mycelium.

AM fungi: results gained in the pilot phase of the BIOTA project show that the distribution of species in the North is poorly understood: spores show a high diversity, whereas sequences from grass roots do not. Monitoring diversity of AM fungi in the roots of different plant families gives insights into the distribution of species.

Workpackage WP03a.3

Dr. Claudia Görke, University of Tuebingen, Spezielle Botanik & Mykologie, Auf der Morgenstelle 1, 72076 Tübingen
claudia.goerke@uni-tuebingen.de

Influence of enclosure experiments on soil fungi and arbuscular mycorrhiza

Short description: Enclosure experiments are designed in order to monitor the change in biodiversity when herbivores are excluded. This is particularly important in Nabaos 7, as plant cover in comparison to the adjacent land in Gellap Ost 3 is strongly reduced, possibly due to overgrazing.

Arbuscular mycorrhizae are beneficial for plants, so their presence and ability to infect plants is vital for the establishment of a healthy plant community. The influence of grazing on mycorrhization rate and spore numbers will be assessed in co-operation with S06.

Workpackage WP03a.4

Dr. Claudia Görke, University of Tuebingen, Spezielle Botanik & Mykologie, Auf der Morgenstelle 1, 72076 Tübingen
claudia.goerke@uni-tuebingen.de

Dispersal of AM spores in Gellap Ost 3 / Nabaos 7

Short description: AM fungi are important in the rehabilitation of degraded land. The site in Nabaos 7 contains degraded land with little vegetation cover. Nevertheless, spore counts are not significantly different from those of the adjacent site in Gellap Ost 3 that is not degraded. As mature grasses in Nabaos 7 are non-mycorrhizal, the origin of those spores is doubtful. Analysing the dispersal of AM spores can help to resolve the question of whether the spores are produced in Nabaos 7 or transported there from Gellap Ost 3, thereby allowing predictions on the mode of inoculation with AM spores.