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Future Reference Values for Structure and Function in the Habitat Directive Nature Types Dr. Jesper Fredshavn NERI, Aarhus University, Denmark April 26, 2007. Reference values. Setting reference values has scientific as well as political aspects. ”how low can you go”.
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Future Reference Values for Structure and Function in the Habitat Directive Nature Types Dr. Jesper Fredshavn NERI, Aarhus University, Denmark April 26, 2007
Reference values Setting reference values has scientific as well as political aspects ”how low can you go” ”how high will you fly”
The process of future reference values • Select relevant indicators • Monitor indicators • Select a reference set of areas with favourable condition • Compare variation range of reference set with entire monitoring set • Set criterias of individual indicators • Set importance of different indicators • Produce reference value of structure and function from the weighted average of indicators of the reference set
Scientific Criteria for Favourable Conservation Status in Denmark Technical Report from NERI - 462 pp in a Danish version Criteria for 51 habitats Criteria for 36 species Criteria for 75 birds A draft version with 7 habitats, 4 species and 4 birds in English
Monitoring: Intensive sampling stations 201 Sampling stations, monitored yearly Detailed data on year-to-year fluctuations in Natura 2000 areas 6-19 stations pr habitat type (tot. 201 stations covering 18 hab. types) 40 random sampling sites pr station (5-10 ha) • Area: changes in sampling sites with hab. type • Structure/function: registration of vegetation and geo/chemical indicators • Species: sampling site and 5 m circle
Monitoring: Extensive sampling stations 761 Sampling stations, monitored 6-years cycle Specific data on conservation status and trends 50% in N2000 – 50% outside N2000 9-92 stations pr habitat type (tot. 761 stations covering 16 hab. types) 40 random sampling sites pr station (5-10 ha) • Area: changes in sampling sites with hab. type • Structure/function: registration of vegetation and geo/chemical indicators • Species: sampling site and 5 m circle
Indicators - function and structure Observations in the sample plots: • pH in soil/water • Conductivity • C/N - ratio • Phosphorous • Nitrate in soil/water • N in shoots, mosses and lichens Observations in the 5 m circle: • Vegetation height • Pct. cover of woody species • Pct. cover of herbivori • Bog structure 5 m Observations on the station: • Pct. cover of invasive species • Pct. cover of rare typical spec.
The 201 intensive sampling stations Monitoring stations Main nature types Meadow Heath land Calc. Fens Dunes Acid fens Grassland Salt meadow
Sampling Stations Sampling stations are each designated for one habitat type The stations cover the habitat type broadly and often include several habitat types in a mosaic Random sampling sites are used to : • detect changes in area covered by each habitat type • sampling of structure and function indicators
Mapping of Danish habitat types Complete mapping of all 254 Natura 2000 areas and sampled data outside Natura 2000 areas • Stratified Network of Monitoring Stations based on size and quality of the areas • Natura 2000 Management Plans Biological status assessment - • Area: GIS data, field verification • Structure/function: Visual, measurable field indicators • Species: 5 m documentation circle
Mapping the area of habitat types Natura 2000 Designated Area Basic mapping of Habitat types (ortho photo interpretation & field mapping)
Structural indicators in the mapping The structural indicators reflects the pressures on the habitat types All habitat types are evaluated from the same indicators, but the scoring and weighting of the indicators vary from habitat type to habitat type • Vegetation structure • Hydrology and coastal protection • Grassing and nature management • Eutrofication and pesticide spraying • Habitat type specific structures
Species indicators Documentation from a circle of 5 m radius • Species composition of vascular plants The circle is placed in a homogenous area characteristic of the habitat type 5 m
Biological Status Classes 5 quality classes for Biological Status cf. the 5 class frame used by the Water Framework Directive I High nature status II Good nature status III Moderate nature status IV Poor nature status V Bad nature status I & II represents the Habitat Directive’s demands for FCS
Indicators The Biological Status assessment is based on the evaluation of a set of indicators. The Biological Status is assessed on a reference scale between 0 and 1, where 1 is the optimal condition without any negative pressures and 0 is the worst possible condition Each indicator is evaluated separately and given a score between 0 and 1, and the biological status is then calculated from the weighted scores of the indicators
Species scores • The species are assigned scores from 1 to 7 based on how they react on increased antropogenic pressures: -1 = Problem species 1 = Very tolerant 3 = Indifferent 7 = Very susceptible • The species are related to Main Habitat types: 21, coastal dunes; 40, heath land; 62, grass land; 64, meadow; 91, forests etc.
Ecological inertia Disturbed and destroyed habitats can for many years still maintain relicts of the original and rare species, but eventually the species will disappear Newly established natural areas are characterised by high structural indices, but for many years they maintain a low species diversity
Mapping results The mapped areas with habitat types in the Danish NATURA 2000 areas are generally small and of good or low quality. Areas of low biological quality are expected not to meet the demands of favourable conservation status
Reference set of alkaline fens, 7230 hydrology Eutrophication
Reference value The Biological Status is calculated from the weighted scores of the mapping indicators A reference set of high and good nature status would reproduce 0,6 as the reference value An index calculated from the weighted scores of the monitoring indicators, and the selection of a reference set, would produce a national reference value of structure and function
The process of future reference values • Select relevant indicators • Select a reference set of areas with favourable condition • Produce reference values of structure and function
Cost calculations How expensive is it? Mapping: 1.000.000 Euro’s = 16 man years over a 2 years period 254 N2000 areas with a total of 5.700 sites or appr. 16x1400 hours/ 5.700 sites = 4,0 hours/site Monitoring: 201 intensive sampling stations: 1.000.000 Euro/year = 5.000 Euro/Sampling station 761 extensive sampling stations: 800.000 Euro/year = 1.000 Euro/Sampling station