GenEERA II – Modelling to assess the dispersal behaviour of oilseed rape on a landscape scale – Lower Saxony regional study

(2001 - 2004) University of Vechta, Institute for Environmental Science

Topic

The focus of the research project was on developing a method for assessing the dispersal behaviour of oilseed rape on a landscape scale.

The project was part of the GenEERA joint research project (generic analysis and extrapolation of oilseed rape dispersal) and developed methodological approaches, based on the results of individual part-projects within the network, for the translation of the dispersal dynamics to larger geographical units (geostatistical upscaling).

The project focused on application of the methodology to the region of Lower Saxony. Lower Saxony release experiments and population studies on oilseed rape in the areas around Braunschweig and Bremen were of particular interest.

Summary

Eight representative model areas were selected in Northern Germany to model the dispersal and persistence of genetically modified rape. A large number of point and area data were (geo)statistically processed for the whole region of Northern Germany and linked together. The data included the distribution and start of flowering of the oilseed rape, wind direction and force and climatic conditions. The scenario calculations in the model areas (from part-project 1) were finally applied to the relevant areas of Northern Germany for a period of 10 years in the geographic information system (GIS) and mapped. The results produced by the model showed that with rape cultivation with a GM proportion of 50 per cent, and to a lesser extent with 10 per cent, transgenes can be expected to enter conventional fields and wild rape populations across the area. The extent to which this occurs depends on various factors, details of which are given in part-project GenEERA III.

Experiment description

The objective of the research project was to develop a methodological instrument, which can be used to deduce/predict the dispersal behaviour of oilseed rape for large areas.

In particular, statistical methods were used with the aim of supporting upscaling from the small-scale level to larger areas. They were based on the model results for small-scale conditions from individual part-projects within the GenEERA joint project. The desired result was a regional study of large-scale dispersal behaviour for the region of Northern Germany.

Results

Developing phenological maps and determining climate regions

The focus of the work was initially on compiling comprehensive datasets for climate conditions, land use and soil inventory.

On this basis it was possible in a first step to develop phenological maps for the start of flowering of oilseed rape plants for the region of Northern Germany. These maps were used among other things to select and check satellite photographs, in which oilseed rape cultivation areas are identified for the years 1995 to 2001.

Start of flowering for rape plants

Precipitation regions

Model areas in Northern Germany

On the basis of statistical analyses of climate data (precipitation, temperature, hours of sunshine) for Northern Germany, it was possible in a further step to determine characteristic climatic regions for the model construction.

In order to portray geographical differences in typical wind conditions during the flowering period of the oilseed rape, comprehensive datasets with data on wind speed and direction from 225 stations of the German weather service in Northern Germany were evaluated for the period from 1950 to 2001. Wind conditions are an important factor in the dispersal and outcrossing of oilseed rape pollen.

Designating scenario zones for oilseed rape dispersal

Through the combination of flowering period, climatic regions, wind conditions and landscape ecology, it was finally possible to designate eight representative scenario zones, which were supplemented by agronomical data like crop management, typical crop rotation and cultivation density from part-project 4 (GenEERA IV). The representative zones of Northern Germany designated in this manner were used to carry out the modelling of oilseed rape dispersal planned in part-project 1 (GenEERA I).

Extrapolation of the model calculations

In a final step, the scenario calculations carried out in part-project 1 (GenEERA I) for the dispersal of GM rape for the different model zones were again applied to the areas of Northern Germany and mapped. For the differentiated geographical representation of dispersal scenarios, information on oilseed rape cultivation density and field size and on the potential distribution and abundance of rape crossing partners was also generated.

The results produced by the model are in line with the published studies on the distribution and persistence of rape transgenes. They show that oilseed rape cultivation with a GM proportion of 50 per cent, and to a lesser extent with 10 per cent, can be expected to result in area-wide entry of transgenes into conventional fields and wild rape populations. The extent to which this occurs depends on various factors and is subject to regional self-enhancing effects as a result of the oilseed rape cultivation density in each region.

gmoSafety: More on this topic

Further projects of the GenEERA research association (Generic analysis and extrapolation of oilseed rape dispersal):