Lowland raised bogs are an important and declining habitat throughout Western Europe. The majority of lowland raised bogs in the UK have been damaged to varying degrees and by various human activities over a very long period. The classification and categorisation of the extent of this damage, the extent of natural or near natural active peat growth and the ability to restore active peat formation is central to the management of remaining sites and the application of appropriate restoration measures on degraded sites.
Existing categorisations are varied and based largely on field inventories and surveys. The adoption of remote sensed techniques allows the potential for consistent assessment of the condition of sites over a wider area. However, such approaches will only be effective if the level of discrimination and classification is appropriate to the determination of the impacts and the indicators of the land cover classes (in terms of degree of degradation). This project seeks to assess the capability of remote sensing to discriminate these classes or to generate classes that approximate closely to those of the Lowland Bog Resource Inventory (LRBI) and EU Habitat Directive classes.
Raised bog surfaces pose a significant challenge to current remote sensing techniques. The areas involved are relatively small, and the spectral differences between plant communities are very subtle and change seasonally. However, in the UK at least, the major part of the raised bog habitat is characterised by a short, open sward that lends itself to detailed analysis using remote-sensing techniques. The habitat is thus more intrinsically amenable to such investigation than more structurally complex habitats such as woodland, scrubland or even tall sedge-fen. Raised bog is also a habitat generally characterised by low surface gradients. Consequently the typical problems associated with remote sensing in upland areas, such as extreme slope angles, markedly differing aspects, and hill shadows, do not generally arise. Indeed there is every reason to believe that as remote sensing becomes more capable, so raised bog sites will yield to the unique advantages that it offers. In particular, remote sensing has the potential to determine the surface extent and configuration of bogs, their species composition, and physical variables such as surface moisture content and the degree of humification of exposed peat. This report describes the results from a contract which set out to achieve three things:
to review the current approaches to raised lowland bog classification and to identify how remote sensing might provide an information source for such classifications;
to develop a cost-effective method of using the best currently available civilian satellite sensor data to produce habitat maps for raised bogs, to a level of accuracy appropriate for management;
to investigate the opportunities offered by advanced airborne sensors currently available for hire in the UK (e.g. ATM, lidar);