Continua and Umwelt: novel perspectives on viewing landscapes

The concept of habitat fragmentation has been central to conservation research and practice since the 1970s (Diamond 1975, Bunnell 1999, Haila 2002). The consequences of fragmentation have been researched worldwide (Saunders et al. 1991, Haila 2002). One of the original fragmentation models was adapted from the island biogeography theory developed by MacArthur and Wilson (1967) to explain differences in species richness on oceanic islands. The early fragmentation models applied the analogy of oceanic islands to terrestrial habitat ‘‘islands’’ resulting from the breaking up of formerly continuous habitat (Haila 2002). By the early 1990s it was recognised that these early models failed to describe the range of possible landscape configurations found in reality (Lord and Norton 1990, McIntyre and Barrett 1992, McIntyre and Hobbs 1999). These ‘‘schematic’’ fragmentation models have been extensively criticised for failing to reflect ‘‘multi-faceted empirical reality’’ (Haila 2002; summary in Table 1). In this paper we discuss two key concepts that have major implications for the understanding of landscapes and landscape ecology (1) the concept of continua in nature; (2) the concept of Umwelt / individual species perception and response. We also outline the landscape continuum model proposed by McIntyre and Hobbs (1999) as an alternative to the fragmentation model. Finally, we conclude that there is a need to revise how we view landscapes and how we research, understand and manage those landscapes.