In autumn 2013, we started to investigate the soil community of a similarly drainage-affected spring moor in the Sernitz valley (biosphere reserve Schorfheide-Chorin).
Within the EU-LIFE project “Schreiadler“ (lesser spotted eagle; www.lifeschreiadler.de) conducted by the Ministry of Environment, Health and Consumer Protection Brandenburg, this moor is restored by flat mowing (2014, 2015) and peat cutting (October 2015). The effects of these revitalisation mechanisms on the soil fauna (Oribatida, Collembola) are documented every six month to find out, if the development of a characteristic peat bog community can be induced.
Bioindication in acidic Sphagnum bogs
The oribatid mite fauna in different Sphagnum-dominated peat bogs (e.g. Müritz National Park, Harz National Park) is investigated and environmental parameters are measured (pH, C/N, vegetation) to characterize different types of peat bogs and derive the indicator value of oribatid mite species for ecological states of paet bogs.
The conservation area Dubringer Moor (percolation mire) is the largest moor complex (1,700 ha) of Saxony. Between 1986 and 1989, substantial (soil-) zoological and botanical investigations were carried out here. Oribatid mites were also sampled and stored as undetermined material in the museum collection. Comparing the current species inventory (sampling 2012: soil samples, pitfall traps; Oribatida, Araneae, Myriapoda, Carabidae) to the inventory 25 years ago revealed the consequences of increasing (drainage-induced) desiccation. The number of species characteristic for peat bogs was remarkably reduced and the abundances of species that still occur in the Dubringer Moor also decreased. However, the remaining individuals and species would so far most probably allow a fast regeneration of the peat bog community in case of a revitalisation project (Lehmitz 2014).
We furthermore compared the soil community of a birch forest having arisen from natural succession and a planted spruce forest on moor soils. Although the spruce forest grows on peat soil, no peat bog specific oribatid mite species were detected here (Lehmitz 2014).
Small-scale heterogeneity of stable isotopes (δ13C, δ15N) in Sphagnum and oribatid mites
Sample-specific stable isotope ratios were measured from Sphagnum samples and the extracted oribatid mites to a) investigate the trophic position of tyrphophilic oribatid mites and b) to find out if small-scale spatial heterogeneity of stable isotopes in food resources transfers to potential consumers. We found out that oribatid mites in Sphagnum bogs span over three trophic levels and that the small-scale spatial heterogeneity of δ15N in Sphagnum transfers to all trophic levels of oribatid mites (Lehmitz & Maraun 2016).
Dispersal mechanisms of oribatid mites
In different outdoor experiments carried out close to the opencast mining site Nochten, the immigration of oribatid mites into young soils was investigated. Wind dispersal as an immigration pathway was studied using sticky traps in different heights above ground level. Wind dispersal of oribatid mites in 160 m could be demonstrated. Furthermore, 12 circular plots were installed by excavating the upper 30 cm of meadow soil and replacing it by oribatid-free substrate from the opencast mine. By means of mini pitfall traps and minicontainer traps, active as well as passive above- and below-ground migration of oribatid mites was investigated at the species level for two years.
At the moment, we focus on aquatic dispersal of oribatid mites along running waters. Streams and rivers may transport oribatids and other soil animals over large distances und could therefore play an important role for population dynamics and the colonisation of new habitats (e.g. recolonisation of peatlands after recultivation). In the field, we record which oribatid mite species are transported in running waters, which species are able to colonise new soil after aquatic transport and how close the relationsship between different populations along a stream is. In combination to that, lab experiments about the survival rates of oribatids under water and about their ability to drift on the surface of running waters are performed.
Contribution to cross-section projects
Completed research focus
Red list and complete species list of earthworms (Lumbricidae et Criodrilidae) of Germany
At the Free University of Berlin, the project “Creation of Red Lists 2020 – Preparatory Phase (FKZ 3511 861100)” was carried out on behalf of the Federal Agency for Nature Conservation (BfN). The aim of the project was to optimise the methods used to compile Red Lists. Since there was no Red List of Germany’s lumbricides until 2016 and the number of species was manageable, a Red List was compiled (in print) using the BfN’s methodology and tools, using this group of animals as an example.
In cooperation with Germany’s lumbricide experts, a checklist of German lumbricide species was first drawn up (Lehmitz et al. 2014), as it was not known exactly how many earthworm species there are in Germany. In addition, as much data as possible from literature and collections as well as from institutions and private persons on earthworm records of the last 100 years were collected and evaluated, mainly using the soil animal database edaphobase. The risk analysis for Red Lists was then carried out based on the current population situation, population trend and possible risk factors. The Red List also included an analysis of Germany’s responsibility for the individual species.