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No. 226: Development and testing of methodology for modeling ecosystem services and biodiversity indicators - for the purpose of mapping synergies and conflicts in areas

Termansen, M., Konrad, M., Levin, G., Hasler, B., Thorsen, B.J., Aslam, U., Andersen, H.E., Bojesen, M., Lundhede, T.H., Panduro, T.E. & Strange, N. 2017. Udvikling og afprøvning af metode til modellering af økosystemtjenester og biodiversitetsindikatorer - med henblik på kortlægning af synergier og konflikter ved arealtiltag. Aarhus Universitet, DCE – Nationalt Center for Miljø og Energi, 81 s. - Videnskabelig rapport fra DCE - Nationalt Center for Miljø og Energi nr. 226. http://dce2.au.dk/pub/SR226.pdf

 

Summary

The report presents and tests a tool developed for analysing the changes in provision of a range of different ecosystem services resulting from setting aside land in agricultural or forestry production. In particular, the tool is developed to enable the analysis of synergies and trade-offs between services. If it is possible to identify areas where significant synergetic effects can be obtained across several important ecosystem services, it will be possible to develop a tool supporting multi-objective land use planning. Furthermore, identification of potential conflicts is also important in land use planning. The analyses in the report are based on a case study of the Limfjord catchment. A set of core ecosystem services is identified for the case study area, and subsequently a number of stylized scenarios are generated in order to facilitate the analysis of interactions between the included ecosystem services.

The analyses in the report include the following ecosystem services: food production, timber production, water quality regulation in the form of nitrogen retention, climate regulation in the form of carbon sequestration, hunting and recreation. In addition, the analyses also encompass the impacts of the land use changes on biodiversity indicators, i) coverage of areas important for protection of rare species, ii) spatial connectivity of habitats and habitat structure.

The report follows a scenario approach where each scenario represents a hypothetical change in land use. The scenarios consider three different types of land use change:

1.       Conversion of agricultural land to semi-natural areas

2.       Conversion of agricultural land to forest land

3.       Conversion of productive forest land to semi-natural un-managed forest land

 

The scenarios are described geographically with a map, which specifies the location of the areas selected for conversion.

The project is based on a case study of the Limfjord catchment. The size of the catchment area is 7.597 km2 which is equivalent to approximately 1/6 of the total area of Denmark. The catchment area is characterised by a long coastline and environmental challenges caused by intensive agricultural production. The case study serves to illustrate the potential for conducting more general analyses of nature protection and use in Denmark.

Seven different scenarios of land use change are analysed in the report. In the first 6 scenarios focus is on maximising the supply of one specific ecosystem service. Each of these 6 scenarios is run for three different acreage restrictions (1 %, 3% and 5 % of the productive area in the catchment). The 6 scenarios are: 1) a water scenario where the conversion of agricultural land to semi-natural areas is prioritised in order to maximise N-retention, 2) a climate scenario where the conversion of agricultural land to forest is prioritised in order to optimise carbon sequestration, 3) a recreation scenario where conversion of agricultural land to mixed forest and semi-natural areas is prioritised to increase the number of recreational visits to the new recreational areas, 4) a biodiversity scenario where the conversion of productive forest land is targeted towards areas of high species score, 5) a habitat connectivity scenario where the conversion of agricultural land to semi-natural areas is prioritised to improve the connectivity of areas with high species scores, and 6) a habitat structure scenario where the conversion of agricultural land to semi-natural areas is targeted at improving the structure of existing habitats. The final scenario focuses on several services by simultaneously maximising several ecosystem services. More specifically this scenario has been developed to prioritise food and timber production together with climate and water quality regulation. The importance of the weighting between the different ecosystem services is illustrated by repeating the scenario calculations for different sets of relative prices.

The report presents, for each of the identified scenarios, the expected changes in ecosystem services and their values. The report also includes a mapping and an assessment of the interactions between ecosystem services and biodiversity indicators in the different scenarios.

The analyses of the different scenarios are focused on the effects of the land use changes. The effects are measured in terms of changes in ecosystem services and biodiversity indicators assessed in biophysical units. When possible the assessment in biophysical units is supplemented with an assessment of economic value. The results of the scenario analyses can be summarised in a scenario-effect matrix.

If the scenarios are analysed jointly the scenario-effect matrix can be used to quantify the interactions between the different ecosystem services in the different scenarios. This analysis is conducted by comparison across the columns of the matrix based on the quantitative biophysical units or indicators, as well as on the economic values of the ecosystem services.

The scenario-effect matrix can also be used to quantify synergies and conflicts between different types of land use change. This analysis is conducted by comparison across the rows of the matrix, and it makes it possible to identify the consequences of targeting land use changes at specific services or indicators.

The chosen method is static. Consequently, it does not take account of the fact that the production of ecosystem services often will develop over time. As an example the method does not reflect that it takes several years before newly established recreational areas will actually become attractive for recreation. The time-frame within which the ecosystem services are analysed in this report can be realised in practice is likely to vary significantly across the different services. Therefore, it is relevant to direct future efforts towards developing dynamic models. The primary contribution of the present analyses is to develop geographically specific models for quantifying and valuing ecosystem services. By adopting this focus, the analyses make a contribution to the development of ES modelling methodologies and to improved understanding of synergies and conflicts between provision of individual ecosystem services and biodiversity conservation.

The analysis of the water scenario shows that the water quality improvement targets in the waters to which the area drains becomes the most important determinant of the location of the areas that are taken out of production. The N reduction requirement is relatively high for one of the inlets in the catchment, Hjarbæk Fjord, and accordingly the catchment to this inlet is highly prioritised in the solutions. Areas characterised by low retention coefficients are also seen to be highly prioritised in the solutions. On a more local level differences in soil types and crop composition are important determinants of which areas are designated for conversion. The analysis also illustrates that the positive interactions with other ecosystem services are limited. In relative terms the most significant positive interactions are seen in relation to hunting, recreation and habitat connectedness. The effects on the remaining ecosystem services are very modest. In particular the coverage of areas with a high species score is negligible.

The analysis of the climate scenario shows that areas for afforestation primarily are identified based on the carbon sequestration potential of the trees and the soil. Afforestation on carbon rich soils is very effective in terms of climate regulation. Accordingly, the soils richest in carbon are prioritised higher than other soils regardless of their productivity. The timber production in the scenario is significant and there is a strong positive interaction with hunting. There is also a significant positive interaction with water quality whereas the positive interaction with areas with a high species score is quite modest.

For the recreation scenario the analysis shows that the effect on the number of visits to nature areas in the catchment is relatively small. This is partly due to the fact that a significant effect of introducing new recreation areas is to shift visits from existing areas to the new areas. Hence even though the new areas are expected to attract many visitors the net-effect in terms of total number of visits is small. The economic modelling shows that the distance to forests and nature areas will be reduced for many people. This implies that the new areas represent potentially significant recreational values. The scenario shows that conversion of agricultural land based on prioritisation of recreation primarily result in positive interactions with timber production and hunting. The interaction with water quality and the indicator for habitat connectedness is modest, although positive. Again the effect in terms of biodiversity score is very modest.

The analysis of the biodiversity hot-spot scenario shows that it primarily is productive forest that is converted. It is also seen that it is possible to protect a significant share of the productive areas with a high biodiversity value even if the conversion area is relative small. Increasing the conversion area only leads to minor increases in biodiversity values. This is perhaps not surprising considering that areas representing high biodiversity value are quite rare in areas characterised by intense agricultural production such as the Limfjord catchment. As the dominant land use change in this scenario is conversion of productive forest to natural un-managed forest the primary effect of the scenario is a decrease in timber production. The effects in terms of all the other services are very modest. It should however be noted that the analysis does not account for the potential implications of the changed land use in relation to recreation and hunting values. Likewise potential long-term effects in relation to carbon storage have not been accounted for either. These potential effects are however expected to be modest.

In the habitat connectedness scenario focus is on establishing connections between all nature areas in the catchment. The scenario is very different from the habitat structure scenario, and the geographical imprint of the two scenarios is very different. Thus there is limited overlap between the scenarios in terms of which areas are converted. Despite this, the analyses show that the two habitat scenarios have strikingly similar effects on the considered services. Except for the biodiversity scenario, where the effect is limited, all other scenarios have an effect on habitat connectedness. The limited effect in the biodiversity scenario is caused by the fact that existing forests constitute a significant share of the areas designated for conversion in the scenario. This implies that the land use change will have no impact on how habitats are connected. The scenarios which result in conversion of more and larger aggregate areas, which are also closely linked to natural characteristics such as soil type and topography (water, climate and biodiversity), have a larger effect on habitat structure than the scenarios which are not linked to natural characteristics (recreation) or which are comprised of many but small new nature areas (habitat connectedness).

In conclusion, the analyses show that the positive interactions between ecosystem services are surprisingly modest when the location of the land use change is determined based on a single ecosystem service. Therefore, the magnitude of side benefits is limited. This indicates that it is necessary to specifically include all the ecosystem services that should be prioritised in the planning of land use changes. With an increasing area designated for regulating or cultural ecosystem services the positive side effects in terms of other ecosystem services is increasing. The analyses of the scenarios where several services (food and timber production, water quality and climate regulation) are included simultaneously in the optimisation illustrate that it is possible to increase the level of interactions by expanding the focus to include several services. However, the analysis of the importance of the weighting between the services (determined by the relative value of the services) illustrates that the interactions between the services very much depends on the relative weights attached to the individual services.

The analysis illustrates that it is very effective to target land use changes towards an increase of a specific ecosystem service. Accordingly, scenarios which focus on optimising a given ecosystem service will have a much larger effect on the provision of this service than other scenarios will. This is especially the case for ecosystem services, which can only be supplied at a high level in few and very specific types of areas. In the present analyses this is particularly evident for land conversions motivated by biodiversity protection and climate regulation. If significant increases in the supply of these services are to be realised through land conversion, it is necessary to target the land use changes at the areas where the potential for these ecosystem services (carbon sequestration or biodiversity protection) is highest. However, this also means that the side effects in terms of increased provision other ecosystem services will be modest. This result has direct relevance in relation to land use planning and ecosystem service management.

Another implication of the observations presented above is, that if land use policies aim to increase several services, then it is necessary to explicitly include all services in the prioritisation and to agree the relative weighting between the services. It should not be expected that numerous services will be delivered at any significant level as side effects of policy processes targeting one or two services. However, the analyses of the scenario where several weighted ecosystem services enter simultaneously show that it is possible to achieve increased synergy between services. More specifically the analysis shows that a relatively high weight ascribed to climate regulation result in a positive interaction with recreation and hunting. This is because conversion motivated by climate regulation result in large spatially connected areas with a high degree of afforestation.

Over all, the project has shown that it is possible to combine existing spatial data layers and models thereby facilitating analyses of the effects of land use changes across many ecosystem services and biodiversity indicators. Moreover, it has been shown that it is possible to combine bio-physical modelling of ecosystem services with spatially specific data and economic valuation data. The joint inclusion of ecosystem services and biodiversity indicators provides a tool for analysing land management in a common framework. Accordingly the modelling tool makes it possible to analyse the consequences of land use management in situations where different production, environmental and biodiversity considerations need to be integrated and analysed in a consistent data and modelling framework.