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Seed, germination and site characteristics: which parameters of arable weeds do explain the change of frequency in Germany?
Summary
For 130 arable weed species occurring in Germany we analysed their combinations of seed, germination and habitat traits by means of Principal Components Analyses. Special attention was paid to species with presently de- or increasing populations. Results did not yield any indication that advantageous strategies like, e. g. a rapid and complete germination of seeds, have a beneficial effect on the present situation of the weed species. Germination rates and the time span needed to reach the peak of germination showed little differentiation between species. Thus, these germination traits are not well suited to explain the success or failure of species. Presently expanding weed species (high ‘tendency of change’-value according to ELLENBERG et al. 1992) were characterised by high optima and wide amplitudes in germination temperature, and high Ellenberg nutrient values.
In general, the tendency of change for arable weeds showed higher correlations with habitat traits (expressed as Ellenberg indicator values) than with seed and germination traits. Expanding species were characterised by high nutrient values, high moisture values and low light values. Remarkably, many species with this combination of traits are considered introduced species in Germany (neophytes). Arable weed species may also profit from modern agronomy with its constant adaptations of cultivation and harvesting practices, which create favourable new site conditions for contemporary crop species. However, our results show that mainly neophytes benefit from modern agriculture, and not the native arable weeds.
Rewarding weeds in arable farming – traits, goals and concepts
Summary
From an agrarian perspective the occurrence of weeds on arable land is predominantly associated with negative side effects: competition for light and nutrients, hampering of the harvest, or reduction of crop quality. On the other hand weeds can also be associated with quite a number of positive side effects. They can contribute to the conservation of abiotic resources and promote beneficial insects. Beside of their ecological values weeds also gain growing importance as genetic resources for the breeding of economic plants. Furthermore, due to an exceptional flowering aspect weeds possess special scenicaesthetical values. Thus, despite of their harmful short and long term effects on crops, there is reason to maintain weed species diversity. Currently arable weeds do not gain much attention in agri-evironmental schemes in Germany. Most conservation concepts have a local, mainly museal character. The success of conservation measures is determined by factors of economic-ecological efficiency, practicability and acceptance. A result-oriented rewarding of arable weeds promises improvements of all three factors. However, it is a critical trait of arable weeds to be simultaneously objective of conservation and of control measures, which should be minimised due to their costs, as well as abiotic and biotic side effects.
The Karlstadt position paper for the preservation of arable field plants
Summary
The complete article is written in German
“Protect Scandix, Legousia, Arnoseris and their relatives!” This is the basic message of the position paper, which tries to draw attention to the situation of endangered arable field plants in Germany. Intensive agriculture and the fusion of small fields on the one hand, but also abandonment and afforesting on the other endanger the last sites of colourful arable field species. Neither standard tools of nature conservation (i.e. nature protection areas) nor the European system of Natura 2000 regions do improve the situation. New solutions have to be found to preserve and to develop diverse rural landscapes with their typical arable field flora and fauna. The position paper points out possibilities of protection and makes claims on citizens, experts and politicians. In the appendix the scientific background is shown.
The Karlstadt position paper was written after the conference for the preservation of arable field plants in Karlstadt/Main at 25./26.6.2004 which had been initiated by Dr Franz-G. Dunkel (Karlstadt). After discussions during the conference the position paper was elaborated by Dr Thomas van Elsen and the authors mentioned above.
Arable plant species as ecological goods – development of a simple method to identify arable fields that are rich in arable plant species
Summary
The complete article is written in German
Plant species diversity has frequently been discussed as an indicator for ecologically sound management methods. Whereas efficient tools for monitoring species diversity already exist in grassland (especially meadows) on which even monetary rewarding systems are based (e.g. Switzerland and Baden-Württemberg, Germany), there is an obvious lack of feasible monitoring and rewarding tools for species diversity in arable land. In the scope of a research project on “simple” indicators for assessing biotic resources on the farm level, a simple method has been developed to assess arable plant species diversity in arable fields. The focus was laid on the feasibility of the method, i.e. the farmers themselves should be able to use the tool. The development of the method and its application are presented. The classification of being rich in plant species is based upon the presence of so called target arable plant species. The chosen method is a “transect-inspection” which consists of three 25 m-sections in the middle of the field. In each 25 m-sample at least 4 target species have to be recorded to characterize the total field as “rich in plant species”. The core set of target species consists of 20 arable plant species that are easily recognized. In 2001 and 2002 „experts“ as well as farmers have tested the method on 42 farms throughout Germany. In 2003 another 39 grain fields have been investigated by using different methods in order to select the best method to deliver accurate and controllable results on species diversity. It is suggested to adjust the core set of target species to different regions and to train the farmers in using the method. The tool that is to be used by the farmers themselves is also regarded as a valuable instrument to promote farmers’ sensibility on the biodiversity in arable fields.
Arable field species on organically and conventionally worked farmland at the Eastern base of the Meißner – Developments throughout the last 30 years
Summary
The complete article is written in German
The Eastern base of the Meißner in North Hessia is known as a particularly species-rich refuge of rare arable field plants. In 2002 new data about the present weed vegetation were gathered in 348 records of vegetation on arable land which was already floristically well examined in the years 1975 and 1990. Differentiated between marginal and inner field areas the phytosociological formation of plant communities and their development is presented. Rare plant communities being typical for limestone soils still exist in that region but they increasingly become impoverished and restricted to field margins. Due to a lack of variety more than 2/3 of the recorded plant species in the inner field areas can no longer be assigned to a vegetation unit. Organic fields show a two to three times higher amount of weed species than conventional ones. Likewise the number of weed species in summer crops is considerably higher than in winter crops. All in all a strong decline of species is detected, especially of rare species which characterize plant societies. Possibilities to improve the protection of species getting rare are discussed.
Changes in the distribution of certain arable weed species in West Hungary – different responses to the modification of agricultural management methods
Summary
The complete article is written in German
By the end of the 20th century West Hungary became a well-developed and intensively managed area, where extensive arable fields survived only in territories of unfavourable site conditions. The changes of the agricultural management methods had different effects on the stands of arable weed species. The changes of the distribution and habitat preference of 7 sample species are discussed as a result of the site and habitat conditions and the agricultural management methods between 1880 and 2005. Due to the intensification Vaccaria hispanica existing only on arable fields disappeared totally. Although Ajuga chamaepitys, Aphanes arvensis, Camelina microcarpa and Valerianella rimosa, which can also be found in fallows and in dry secondary habitats, became rare at different degree, but they still have constant stands in areas having optimal site conditions, moreover Ajuga chamaepitys and Camelina microcarpa exist in naturally dry grasslands as well. The distribution of Montia fontana ssp. chondrosperma is interesting as this species seems to have become more frequent on intensively ploughed fields.
Investigation of weed vegetation on wet segetal fields in South-Western Hungary
Summary
The complete article is written in German
Inland water on soils with bad water balance can lead to serious yield losses. Soil management and plant protection is nearly impossible in these marshy vernal pools, wherefore very special vegetation develops. On the basis of 58 phytocoenological surveys made in South-Western Hungary the vegetation of the vernal pools will be characterised. From phytosociological point of view our surveys stand to Ranunculo sardoi-Alopecuretum geniculati and Myosuro-Ranunculetum sardoi associations the nearest, where the proportion of Nanocyperion elements is significant. The following endangered species occure in these vernal pools: Elatine alsinastrum, Limosella aquatica, Lindernia procumbens, Montia fontana, Peplis portula.
However vernal pools in segetal fields are causing losses from economical aspects, they can contribute to increase agrobiodiversity and have an important role in maintaining numerous threatened and protected plant species (Red Data List, IUCN, Corine Biotopes Project, Bern Convention).
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