Summary
In Europe we are facing the situation that farming has become a threatening factor for biodiversity. As part of the MacSharry reform of 1992 agrienvironmental schemes (AES) were introduced to encourage farmers to adopt or continue production methods serving the protection and enhancement of biodiversity. Scientific studies only confirm them mixed success, though. The payments by results approach (outcome-oriented AES) is in discussion for being a promising way to improve the effectiveness and efficiency of AES. In this thesis, options improving the effectiveness and efficiency of and by the payments by results approach are investigated. Starting points are the design and the implementation of such an approach. For this purpose an existing method for the derivation of regional, outcome-oriented environmental services is analyzed and further developed. Case study region is the regional district Doberan in Mecklenburg-Western Pomerania. Also, the suitability of standardized fixed payments for outcome-based environmental services on arable land is investigated.

Chapter 3 provides a conceptual framework of how to conserve and promote arable weeds as an environmental service of farming. The success of AES is determined by their cost-effectiveness, acceptability and practicability. The article concludes that outcome-oriented payments for arable weeds promise improvements of all three factors.

In Chapter 4 it is postulated that a combination of outcome-oriented AES for the promotion of arable weeds with a scaling of payments for environmental services (PES) might be more efficient than a combination with standardized fixed payments. On the basis of management data of conventional cropping farms farmers´ individual Opportunity Costs of participation in an outcome-oriented approach are estimated. The results showed wide fluctuations of individual Opportunity Costs (-36 € to 430 €), depending on the cultivated crops, site conditions, and management strategies. Site conditions generated higher GM deviations as temporal market price and costs fluctuations (2003, 2007). From the results of the study the following conclusions can be drawn: we recommend providing outcome-oriented AES for arable land and introducing a scaling of PES (e.g. by auctions) that provides for sufficient participation incentives in regionally differing environmental and economic settings. Besides, farmers should be allowed producing a defined quantity and quality of weeds within their arable land without a need for producing them in a multi-year approach on a specific plot.

Outcome-oriented AES for arable weeds cannot be transferred offhand from one region to another. They require a regional adjustment of the criteria selecting plots worth rewarding. In chapter 5 the outcome-oriented scheme taken as a basis was therefore transferred from the regional district Northeim, Lower Saxony, to the regional district Doberan. The eligibility of a specific plot of arable land is determined by the quantity (number) and quality (threat status) of weeds occurring within defined control units on the plot. Crucial factor for the transferability of the quality levels of the ecological good between regions is the comparability of the mean number of species of typical regional weed communities. In Doberan exists a weed community that is characterized by relatively few species, Sclerantho annui-Arnoseridetum minima. Due to its specific habitat requirements it is exceptionally rare and worthy of protection. In order for this community to be comparable with other regional weed communities the required number of weed species for the quality levels had to be reduced. As a necessary criterion for the occurrence of the community a low soil pH value was determined. Apart from that, the underlying AES is suitable for being transferred from Northeim to Doberan. In terms of the quality criterion it was found that the Red-list species Centaurea cyanus occurred in almost every third vegetation survey. The relatively frequent occurrence of this species led to a significantly increased number of “high-quality plots”.

In chapter 6 the ecological good grassland of the underlying AES is transferred from the district Northeim to the district Doberan. The aim was to gain new insights into the possibilities and limits of a regional transfer of outcome-oriented approaches rewarding ecological services in agriculture. We tested a method that selects the appropriate indicator species by means of existing vegetation data. The study showed that up to a certain extent it is possible to carry out a regional adaptation of the scheme using vegetation databases. Despite the presence of criteria for species selection expert knowledge is absolutely essential, though, to create an indicator species list. The criteria for selecting indicator species and the quality levels of the ecological good grassland should be regionally adapted, if certain decisive characteristics of grasslands in the transfer region (mean number of species per control unit, dicots non-dicots ratio) are significantly different from those in the source region, or if characteristics of the grassland communities within a region differ greatly. Otherwise, a comparable quality of the rewarded grassland is not guaranteed. In the case of the district Doberan it was therefore recommended to implement a separate agrienvironmental measure for the community Juncetea maritimi. What is more, a mosaic-like vegetation structure as it occurs in salt marshes makes it more difficult to implement the plot control system of the underlying AES concept (several circular control units per grassland plot). In this case the practicality of the method is limited. The results of the study also show that the use of indicator species allows a more precise plot selection, as the definition of a non-specific minimum number of species.

In chapter 7 the promotion of grazing is proposed as a new field of application for the outcome-oriented approach. The study shows that the approach can be a very flexible tool for rewarding voluntary services of agriculture. However, it pushes its limits when the indicator species cannot securely indicate the achievement of the schemes goal. The goal ‘indication of grazing’ sets a very tight framework for selecting appropriate indicator species, especially since there are no pure ‘pasture-indicator species’. The indicator species should be capable of indicating grazing despite different local conditions (trophic level, soil moisture). The use of existing data only enabled the establishment of an indicator species list with limited validity. For their verification and validation for different site conditions additional field tests are necessary. In relation to the control costs our approach seems superior to an action-oriented approach, as only one inspection walk is necessary to verify the species inventory, but several to verify a regular grazing of animals.

In this work it can be shown that the techniques developed by Bertke (2005) to operationalize the objective "maintaining regionally occurring plant communities" are suitable for application in other regions in Germany. The most significant amendment from this work to Bertke´s (2005) method is the observation that if the regionally occurring plant commu-nities are not equally able to meet the differentiated quality criteria, separate rule additions or quality criteria must be developed to ensure a comparable quality of the extracted and rewarded grassland. The objective "maintaining" can be effectively achieved with outcome-oriented compensation payments. However, for the objective "grassland restoration", which is pursued on many grassland areas of Doberan, it is questionable whether outcome-orientation would give a real gain in effectiveness and efficiency.

Outcome-oriented payments for extensive grazing offers efficiency advantages compared to action-orientated payments. The effectiveness of the approach is, however, at most equal to action-oriented AES.

Regarding farmers already willing to participate in AES on arable land the conservation of weeds by outcome-oriented AES can be expected to produce efficiency and effectiveness gains in comparison to action-oriented AES. However, it is questionable whether the outcome-oriented approach is generally able to increase the willingness to participate of farmers in AES on arable land and with that to improve their efficiency and effectiveness. The decisive factor is the individual assessment of the risk situation (income and production risk) in participance.

It has also been found that database relevés cannot replace, but complement field work, and thus can reduce compilation costs, enabling increased efficiency in the implementation of regionalized outcome-oriented AES. However, due to a lack of adequate databases in many regions, field work will be indispensable in order to produce indicator-species lists.