Possibilities of using the German Federal States’ permanent soil monitoring program for the monitoring of potential effects of genetically modified organisms (GMO)

Background In the Directive 2001/18/EC on the deliberate release of genetically modified organisms (GMO) into the environment, a monitoring of potential risks is prescribed after their deliberate release or placing on the market. Experience and data of already existing monitoring networks should be included. The present paper summarizes the major findings of a project funded by the Federal Agency for Nature Conservation (Nutzungsmöglichkeiten der Boden—Dauerbeobachtung der Länder für das Monitoring der Umweltwirkungen gentechnisch veränderter Pflanzen. BfN Skripten, Bonn-Bad Godesberg 369, 2014). The full report in german language can be accessed on http://www.bfn.de and is available as Additional file 1. The aim of the project was to check if it is possible to use the German permanent soil monitoring program (PSM) for the monitoring of GMO. Soil organism communities are highly diverse and relevant with respect to the sustainability of soil functions. They are exposed to GMO material directly by feeding or indirectly through food chain interactions. Other impacts are possible due to their close association to soil particles. Results The PSM program can be considered as representative with regard to different soil types and ecoregions in Germany, but not for all habitat types relevant for soil organisms. Nevertheless, it is suitable as a basic grid for monitoring the potential effects of GMO on soil invertebrates. Conclusions PSM sites should be used to derive reference values, i.e. range of abundance and presence of different relevant species of soil organisms. Based on these references, it is possible to derive threshold values to define the limit of acceptable change or impact. Therefore, a minimum set of sites and minimum set of standardized methods are needed, i.e. characterization of each site, sampling of selected soil organism groups, adequate adaptation of methods for the purpose of monitoring of potential effects of GMO. Finally, and probably most demanding, it is needed to develop a harmonized evaluation concept. Electronic supplementary material The online version of this article (doi:10.1186/s12302-015-0057-2) contains supplementary material, which is available to authorized users.


English Summary
Possibilities of using the German diurnal butterfly monitoring program (TMD) and the permanent soil monitoring program of the German federal states for the monitoring of GMO

Introduction
The overall aim of this project was to assess the question whether it is possible to embed the permanent soil monitoring program of the German federal states into the monitoring program required by Directive 2001/18/EC on the deliberate release into the environment of genetically modified organisms (GMO;MIDDELHOF et al. 2006;). The individual aims were: 1. Formulation of technical requirements of a meaningful and scientifically sound monitoring of the effects of GMO on the soil habitat (especially at agricultural sites) and in particular the compilation of potential effect pathways to soil through GMO cultivation by means of a literature research.
2. Technical evaluation of possibilities and limitations of the use of permanent soil monitoring sites (Boden-Dauerbeobachtungflächen; BDF) of the German federal states for GMO-monitoring including a description of the status of method harmonization and data management as well as identification of meaningful indicators.
3. Formulation of the possibilities to expand or adapt the federal permanent soil monitoring and/or complementary monitoring modules for the GMO-monitoring based on results of previous or potential cultivation of MON810 in Germany.
4. Evaluation of data availability and possibilities of data analysis for the GMOmonitoring, development of a model for data flow and management and formulation of a proposal for a cooperation model.

Exposure pathways of GMO
The definition and assessment of exposure pathways serve the purpose to estimate, whether or to what extent soil organisms (individual populations of a single species or whole communities) are confronted with any of the following impacts during GMO cultivation ):  GMO-specific active substances (e.g., Bacillus thuringiensis Cry proteins) or their metabolites;  physiologically altered GM plant components (e.g., a modified starch content);  agricultural management practices that wouldn't be performed to the same extent without GMO cultivation (e.g., an increased application of herbicides).
The possible exposure pathways can be classified in various ways:  organism-related approach (e.g., : direct exposure towards living or dead GMO materials; this classification is mainly based on experience with GM maize and the Bt toxin.  GMO-related approach : exposure through transport of GMO materials. Since the complex exposure conditions in the field have rarely been assessed so far , theoretical considerations were in-cluded: horizontal gene transfer (EFSA 2005), unintentional release and second growth  as well as pollen dispersal .

Exposure of BDF towards GMO
BDF are potentially exposed towards GMO, possibly influencing their usability within a monitoring program. Within this project only pollen dispersal was considered as a pathway with a profound impact potential while other pathways were regarded as being less relevant due to spatially and temporarily limited GMO release and the strong alteration (e.g., decomposition) of GMO material in dung or manure. Literature data regarding the dispersal of pollen vary from a few meters to several kilometres (BIOSICHERHEIT 2010. In this project three distances (50, 150, 1000 m) were considered as dispersal and effect scenarios.

Soil organisms relevant to the monitoring of GMO related effects
Up to now there is little experience regarding the assessment of GMO related effects in the field ; see also the overview compiled by THEIßEN & RUSSELL (2009). Based on the experience and considerations presented so far a technical committee of the Association of German Engineers (Verein Deutscher Ingenieure; VDI) developed a guideline with proposals for choosing organism groups within the scope of GMO-monitoring (VDI 2012;. In order to assess the biological soil quality in technically appropriate fashion organism taxa should be selected according to the following criteria: important ecological function within the ecosystem, representativeness for a trophic level; close association with the mineral soil or the litter layer; --sufficient species diversity to differentiate between sites; good taxonomical and ecological knowledge; wide distribution in Central Europe; existing standardized sampling methods; potential for routine use, e.g. regarding simplified determination methods; availability of data from existing monitoring programs. At least four different taxa should be used that facilitate the inclusion of different trophic (epigeic-endogeic) as well as functional (feeding type) levels.

Technical evaluation of possibilities and limitations of the use of BDF of the German federal states for GMO-monitoring
The German permanent soil monitoring program: Introduction The aim of the German permanent soil monitoring program is to assess the current state of soils and its monitoring in the long term (UBA 2011). To this end, there are 795 German BDF that are, however, unevenly distributed (see below figure) .
Currently, the permanent soil monitoring program of the German federal states focuses on physical and chemical measurements that are transferred into the database "BDF -Bodendauerbeobachtungsflächen" at the German Federal Environmental Agency within the scope of the administrative agreement of federal and state agencies regarding data exchange. In only a few cases standardized biological data are collected. The position of the BDF, their properties (e.g., biotope type, land use, texture, etc.) and available biological data were compiled in the database Bo-Info .

Representativeness of BDF
In order to assess the representativeness of BDF for a monitoring of effects of GMO on the soil biocoenosis the classification of biotope types according to  was used as a basis of valuation. Biotope types harbour synecologically different soil animal communities and additionally integrate the factors (in particular soil type, moisture and nutrient supply) relevant for this differentiation of communities . To date, mainly only three biotope types are represented by a sufficient number of BDF: arable land (351), grassland (102) and deciduous forests (242).

Exposure of BDF
In order to ensure a sustainable use of the BDF program for the monitoring of GMO the question had to be answered to what extent existing BDF had already been exposed towards GMO and what intensity of exposure may be expected from future cultivation of GMO. The insect resistant maize variety MON810 was chosen as an example GMO (the only GMO cultured on a broader scale in Germany so far) and assuming pollen dispersal radii of 50, 150 and 1000 m. These distances were chosen in dependence on different European buffer zone regulations towards conventional fields (e.g., Spain: 50 m, Germany: 150 m; GENTPFLEV 2008) and recommendations from field trials on maize pollen dispersal.
The following exposure scenarios are generally possible: 1) GMO cultivation on the BDF; 2) the BDF located outside the area of GMO influence; 3) no GMO cultivation on the BDF itself but BDF within the area of direct influence of the GMO based on the three pollen dispersal radii. These scenarios were exemplarily investigated for the federal states of Brandenburg, Hesse, Lower Saxony and Schleswig-Holstein. The further presentation in this summary will focus on the example of Brandenburg where the most intense MON810 cultivation in Germany occurred so far (ca. 1,350 ha in 2007).

Methodology
For the four exemplary federal states the InVeKoS (integrated administration and control system; Integriertes Verwaltungs-und Kontrollsystem) data that identify (GIS based) agriculturally managed lots of land, and the coordinates of BDF on arable land could be used. The BDF sites and the area under MON810 cultivation were plotted in a common map to answer the question to what extent BDF had already been exposed towards MON810. The above mentioned pollen dispersal radii were projected as buffer zones around the lots of land under MON810 cultivation. The result has a residual uncertainty since not every lot of land under MON810 cultivation could be exactly identified beyond doubt. The exposure of the lot of land containing the BDF "Gusow" (blue) within the administrative district of "Märkisch-Oderland" (Brandenburg) towards MON810 cultivation (2005-2008; dark green) assuming a pollen dispersal of 50, 100 and 1000 m (reddish buffer) is depicted below as an example. From this and other examples it became clear that with an intensification of GMO cultivation in Germany more BDF on arable land will likely become exposed towards GMO.

Conclusion: Representativeness of BDF, especially regarding their use for soil biological monitoring programs
There is a generally good representativeness of German BDF for arable land. However, this statement is limited to the basic biotope type "arable and fallow land" ). Due to their life-form, for soil organisms additional site specific parameters (soil properties, nutrient supply, moisture, etc.) are relevant for their distribution. These parameters are reflected in the further subdivision of biotope types (2nd and 3rd level). For an allocation of BDF to certain biotope types often detailed data are missing, e.g. regarding bedrock (lime, silicate, sand, etc.) or general nutrient availability (extensive speciesrich, intensive, nutrient-rich, species-poor, etc). A standardized and detailed data collection should be pursued since the distribution of soil animals shows the strongest correlation at lower levels of site classification (see also ).
The data sets originating from BDF contain little soil biological data and the data inventory fundamentally lacks comprehensive data for most organism groups:  Lumbricidae (best data packet): 97 BDF sites (of 795), representative for grassland, agricultural sites and forests but allocation of BDF to further levels of biotope types only rudimentarily possible, gaps for some federal states;  Enchytraeidae: data from 60 BDF sites; no regional representativeness (e.g., little data from Eastern Germany, Bavaria or Rhineland-Palatinate);  Collembola, Oribatida, and other soil invertebrates in general: no data sets from BDF;  Microbes: thus far no suitable data for biodiversity assessment.
In summary, the results so far indicate that:  the data basis on the occurrence of the most important soil organism groups is not sufficient to be used for a monitoring of GMO;  all BDF need to be classified according to a standardized list of biotope types;  additional sampling on representative BDF is recommended;  the taxonomical determination of soil organisms needs to become simpler and more transparent by using novel (especially genetic) determination methods (e.g., DNAbarcoding);  the basis for a reference system needs to be created in order to be able to evaluate the data generated within the monitoring of GMO.

Formulation of possibilities to expand or adapt the federal permanent soil monitoring and/or complementary monitoring modules for the GMOmonitoring
In the attempt to tackle the lack of soil biological data from BDF sites the data collected in the database Bo-Info were utilized (current content: 1,744 sites with more than 42,000 soil animal records, . In order to facilitate the use of biocoenotical data at the landscape level, a standard frame of reference is needed. For the evaluation of observed changes within the scope of GMO-monitoring a site-specific reference system needs to be developed. It can be described as comprising reference values for the biocoenosis at certain habitat types by evaluating biocoenosis-site-relationships and will ultimately lead to the identification of threshold values with which a significant change of the biocoenosis can be indicated (see figure).
Derivation of threshold values regarding states of preservation (A, B, C; RÖMBKE et al. 2012) related to system stress (EU 1992).
Thus, a reference system for the site-specific diversity of soil organisms consists of:  Reference values: lists of species expected to occur at a certain site with its specific conditions (e.g., climate, soil factors, region etc.);  A quantification of deviations from these reference values that indicate impacted habitat function.
In order to develop reference values that link soil and site parameters with the occurrence of soil organisms, the landscape had to be classified into a limited number of "site categories". The use of the habitat classification concept compiled in the German Red Data Book on endangered habitats ) ensures the compatibility with other monitoring approaches, nature conservation management, and prospectively also pesticide registration. When analyzing different organism groups, correlations between the occurrence of species and the corresponding hierarchical level within the system of biotope types became apparent . Further analysis demonstrated that the composition of communities depends on site properties. A comprehensive ecological assessment of sites requires the integration of different relevant organism groups on the species level thus at the same time covering their function (e.g., organic matter decomposition).