This chapter concludes that, in combination with additional environmental data sets, it is now possible to model quantitatively the spatial extent of widespread habitats and landscapes on the basis of land cover information derived from satellite imagery. Although it is now possible to model the spatial extent of widespread European habitats, these patterns cannot be directly translated into area estimates. The retrieval of accurate land cover information is not only crucial for the spatial modelling of European landscapes and habitats, but also for their monitoring. Operational remote sensing enables land cover characterization at various scales but the classification accuracies are still insufficient at continental and global scales for monitoring purposes. Instead, the use of continuous thematic fraction layers, as derived from linear unmixing, provides a good basis for monitoring land cover changes of Europe’s complex landscapes. However, gradual and small changes in habitats and their quality are not easily detected from space by satellite imagery, and therefore, additional information from field surveys is needed. Protocols for rapid field surveying of habitats have been developed that can provide a European baseline based on a sampling design across European landscapes. The information from the field samples (e.g. square kilometres) can be used for the validation and calibration of the obtained distribution maps of European habitats. The field surveying method is amongst others based on the estimation of the main plant life forms, which are highly correlated with vegetation structure. The latter has been shown to have a good relationship with satellite imagery. Field surveys are always limited to relatively small areas in Europe, and therefore, the spatial modelling of habitats and landscapes with the help of remotely sensed information remains important for providing a synoptic overview.
Top1. Introduction
During the last two centuries in particular, the world population grew rapidly, in conjunction with technological developments, which led to a significant expansion of industrialisation, urbanisation and agricultural activity (Stanners & Bordeaux, 1995; Moran et al., 2004; EEA, 2005). As a result, land use and associated land cover changed at an increasing rate, intensifying the pressures on landscapes, habitats and biodiversity in general. A global analysis by Klein Goldewijk & Ramankutty (2004) showed that between 1700 and 1990 the area of arable land increased by approximately 500%, from 3 million km2 to 15 million km2, and that of grassland by approximately 600%, from 5 million km2 to 31 million km2, both at the expense of semi-natural vegetation and forests. Over the same period, forest area decreased by approximately 17%, from 53 million km2 to 44 million km2. Types and rates of land cover change vary over time and space. Europe, for example, has experienced an opposite trend over the last 40 years, which included a net forest increase of approximately 10%, a net loss of arable land of about 11% and a net loss of permanent grassland of about 11% (source: FAO land use statistics). The EU project BIOPRESS showed, by analysis of historical aerial photographs over the period 1950-1990-2000, that of these land cover changes urbanisation was predominant. Alarmingly, the project showed that in the 59 transects across Europe the rate of land cover change remained almost constant; respectively, 15% and 14% per decade over the periods 1950-1990 and 1990-2000 (Köhler et al., 2006; Gerard et al., 2010). In The Netherlands, between 1950-1990, in parallel with a net loss of agricultural land and a net increase of forest and urbanisation, there was a dramatic 44% decline of natural areas (Van Duuren et al., 2003). The amount of heathland was reduced by 68%, of salt marshes by 60%, of raised bogs (moors and peat-land) by 81% and of inland sand dunes by 52%. Only wetlands increased, by 9% (http://www.pbl.nl/nl/publicaties/mnp/2003/Natuurcompendium_2003.html) due to land reclamation from the sea resulting in the creation of new wetlands (e.g., Oostvaardersplassen).
Global biodiversity is declining, and habitat destruction and degradation are caused mainly by changes in land use which, next to climate change, remains the most important driver of biodiversity loss (Hansen et al., 2004). Changes in land use that are related to intensification and marginalization in agriculture are seen as major threats to European landscapes and their biodiversity (Jongman, 1996).
Therefore, there is an increasing need for reliable, up-to-date, Europe-wide data on land use and land cover to inform current environmental policies and nature conservation planning (Stanners & Bourdeaux, 1995). The impact of land use change is widely recognised and has forced national and international agencies to take policy measures to afford a higher degree of protection to our landscapes and habitats, in association with an increasing demand for monitoring and identification of potential sites for nature conservation. In Europe, the Convention on the Conservation of European Wildlife and Natural Habitats (the Bern Convention) that was adopted in Bern, Switzerland, in 1979 was a step forwards. The principal aim of the Convention is to ensure conservation and protection of wild plant and animal species and their natural habitats. To implement the Bern Convention in Europe, the European Community adopted Council Directive 79/409/EEC on the Conservation of Wild Birds (the EC Birds Directive), in 1979, and Council Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora (the EC Habitats Directive), in 1992. The Directives facilitate, among other things, the establishment of a European network of protected areas (Natura, 2000), to tackle the continuing losses of European biodiversity due to human activities.