Reserves, resilience and dynamic landscapes 20 years later

Abstract

From the 1970s to the 1990s, ecology was dominated by two separate traditions that viewed ecosystems in different ways, and used different concepts and measures in their research. As Lawton (1994) stated, ''For almost three decades, ecosystem and population ecology have ploughed their own independent furrows and developed their own paradigms, approaches and questions''. The population/community ecology paradigm was based on evolutionary theory and looked at changes in numbers and diversity, while ecosystems ecology focused on ecosystem processes like flows of energy and nutrients. During these years, ecology in general also changed in its view of nature, from the early determin-istic concepts of climax, stability and balance of nature towards an appreciation of the spatial and temporal dynamics of populations as well as ecosystem processes. These new views emphasised that change was ubiquitous in ecosystems, and that populations, communities and ecosystems were not closed local entities, but embedded in landscapes that changed both through natural processes and, increasingly, human activities (e.g. Worster 1994; Ihse 1995). In the 1990s, there was a rapidly increasing interest in merging the two perspectives, using bridging concepts like food webs, ecosystem engineers and ecosystem functioning (e.g. Jones and Lawton 1995; Polis and Winemiller 1996), and from another angle the emerging resilience concepts based on Holling's work on ecosystem dynamics (Holling 1973; Folke et al. 1996). Using these concepts, ecologists began asking questions like ''What do species do in ecosystems?'' (Lawton 1994) and ''How does biodiversity matter for ecosystem functioning and ecosystem services?'' (Bengts-son et al. 1997; see also Loreau et al. 2001). It was an exciting time for a young ecologist, and year-by-year the distance between basic science and applied questions about landscape management or biodiversity conservation decreased in both minds and actual research. Our 2003 Ambio paper (Bengtsson et al. 2003) grew out of this intellectual melting pot. We attempted to use the basic knowledge about the links between species and ecosystem functioning, drawing on spatial dynamics of populations, landscape ecology, resilience thinking and ecosystem dynamics , to address the problem that much conservation of biodiversity was focusing on preserving local, usually fairly small, reserves and national parks. This was especially so in the large parts of the world where ecosystems had already been drastically altered by human activities, especially intensified land use (Ellis et al. 2010). In much of Europe, North America, Latin America and Africa, protected areas were like islands in a sea of production ecosystems managed by humans, but management rarely considered natural disturbance regimes and the dynamics of ecosystems in general, which over longer time periods occur at larger scales than most reserves. We also mentioned climate change as a problem, stating that ''the projected global climatic changes make any reliance on internal recolonization (in local reserves) questionable'' (p. 389). Our main conclusion was that for biodiversity and ecosystems in and outside protected areas to reorganise after large-scale disturbances, spatial resilience-which we called ecological memory-in reserves and the surrounding landscape was necessary. We suggested that static reserves should be complemented with dynamic reserves that at the landscape level mimicked the patterns and processes maintained by natural disturbance regimes. 1 1 It could be argued that policymakers implementing the Convention on Biodiversity (CBD) were already working along the lines of landscape management that we were advocating. However, our experience on the ground, both then and now, although mainly from Europe, was that landscape-wide biodiversity management was in practice absent in the agriculture and forestry-dominated landscapes where we worked. We acknowledge that conservation policy may have been experienced differently in other areas, but-as reported in IPBES (2019)-apart from an increased area of protection globally, most conservation goals have failed despite 40 years of policymaking. 123 Ó The Author(s) 2021 www.kva.se/en Ambio 2021, 50:962-966 https://doi.