20
• The reclassification algorithms to convert a vegetation map into a habitat map
also had to be further developed. Reclassification rules were added or adapted to
deal with the known habitats that occurred on the new study sites. Furthermore,
the rules for delineating ‘relevant’ habitat patches (based on the BIOHAB
method; Bunce et al. 2008) were extended to work not only in a heathland context, but (at least in theory) in all European ecosystems.
It is important to notice that in the tests, we did not strive for success at all cost.
It was our intention to evaluate what could be done with the method in – what we
considered – a realistic timeframe. We therefore limited the available time to
approximately 2 weeks of work per case. If, after that time, we did not feel yet we
were on track to a result in the very near future, we would stop the test.
Transfer Test Case 1: To Later Dates
Study Site
The heathland of Kalmthoutse Heide is part of a cross-border Natura 2000 site in
Belgium and the Netherlands, located some 20 km northeast of the city of Antwerp
(Belgium), in the Atlantic Biogeographical Region of Europe. It consists of a core
area of over 1000 ha of open heathland and inland dunes, surrounded by broadleaved forests (oak, birch) and pine plantations. Prevailing Natura 2000 habitat
types are wet (4010) and dry heathland (4030) and open habitats on inland dunes
(2310 and 2330). The area is also home to a wide range of heathland-associated
birds, reptiles, amphibians and invertebrates.
The site’s location, amidst an intensively used agricultural area (especially
fertilizer- demanding maize culture) and in the vicinity of the port of Antwerp’s
industry, makes it extremely prone to nutrient enrichment from atmospheric depositions. This results in the encroachment of Purple moorgrass (Molinia caerulea) at
the expense of the ericoid dwarf shrub vegetation (Calluna vulgaris and Erica tetralix) that is typical of heathlands. Other pressures include dune fixation by an invasive exotic moss species (Campylopus introflexus), desiccation from drinking water
extraction, recreational use, and uncontrolled wildfires. The management primarily
aims at counteracting the negative effects of nutrient accumulation, through grazing,
mowing and sod-cutting, and restoring the natural dynamics of the inland dunes.
Method Application
The original application of our method was on a Airborne Hyperspectral Scanner
(AHS) image acquired on 2nd June 2007 by the Spanish National Institute of
Aeronautics (INTA). The same method was then applied (the transfer case) to several hyperspectral images of the same area acquired by the German Aerospace
Centre’s (DLR) Airborne Prism Experiment (APEX) in 2010, 2011 and 2012. The
same hierarchical classification scheme (Table 1) and the same reference dataset
J. Vanden Borre et al.
• The reclassification algorithms to convert a vegetation map into a habitat map
also had to be further developed. Reclassification rules were added or adapted to
deal with the known habitats that occurred on the new study sites. Furthermore,
the rules for delineating ‘relevant’ habitat patches (based on the BIOHAB
method; Bunce et al. 2008) were extended to work not only in a heathland context, but (at least in theory) in all European ecosystems.
It is important to notice that in the tests, we did not strive for success at all cost.
It was our intention to evaluate what could be done with the method in – what we
considered – a realistic timeframe. We therefore limited the available time to
approximately 2 weeks of work per case. If, after that time, we did not feel yet we
were on track to a result in the very near future, we would stop the test.
Transfer Test Case 1: To Later Dates
Study Site
The heathland of Kalmthoutse Heide is part of a cross-border Natura 2000 site in
Belgium and the Netherlands, located some 20 km northeast of the city of Antwerp
(Belgium), in the Atlantic Biogeographical Region of Europe. It consists of a core
area of over 1000 ha of open heathland and inland dunes, surrounded by broadleaved forests (oak, birch) and pine plantations. Prevailing Natura 2000 habitat
types are wet (4010) and dry heathland (4030) and open habitats on inland dunes
(2310 and 2330). The area is also home to a wide range of heathland-associated
birds, reptiles, amphibians and invertebrates.
The site’s location, amidst an intensively used agricultural area (especially
fertilizer- demanding maize culture) and in the vicinity of the port of Antwerp’s
industry, makes it extremely prone to nutrient enrichment from atmospheric depositions. This results in the encroachment of Purple moorgrass (Molinia caerulea) at
the expense of the ericoid dwarf shrub vegetation (Calluna vulgaris and Erica tetralix) that is typical of heathlands. Other pressures include dune fixation by an invasive exotic moss species (Campylopus introflexus), desiccation from drinking water
extraction, recreational use, and uncontrolled wildfires. The management primarily
aims at counteracting the negative effects of nutrient accumulation, through grazing,
mowing and sod-cutting, and restoring the natural dynamics of the inland dunes.
Method Application
The original application of our method was on a Airborne Hyperspectral Scanner
(AHS) image acquired on 2nd June 2007 by the Spanish National Institute of
Aeronautics (INTA). The same method was then applied (the transfer case) to several hyperspectral images of the same area acquired by the German Aerospace
Centre’s (DLR) Airborne Prism Experiment (APEX) in 2010, 2011 and 2012. The
same hierarchical classification scheme (Table 1) and the same reference dataset
J. Vanden Borre et al.