Scale, the dynamic stability of forest ecosystems, and the persistence of biodiversity

Abstract

Even as ecologists documented the importance of disturbance and non-equilibrium in vegetation dynamics, they began to ask whether the dramatic changes at the local, patch scale, would contribute to an equilibrium at larger spatial scales. Heinselman (1973) hypothesized a ‘shifting mosaic’ for the dynamics of boreal forests in which the spatial location of recent burns and stands of various successional ages would shift, but each would continue to be present within the larger landscape at some relatively constant frequency. The ‘mosaic-cycle concept of ecosystems’ (Remmert 1991) also conjectured that an overall dynamic equilibrium would be maintained in spite of local dynamic changes. Recent studies of disturbance focused on functional resilience, biodiversity and landscape equilibrium (e.g. Romme 1982, Turner et al.1993, Peterson et al. 1998, Engelmark et al. 1999, Frehlich and Reich 1999, White et al. 1999, Walker et al. 1999, White and Jentsch 2001). We defi ne function as the product of an ecological unit (e.g. an organism, a successional sere) and an ecological process (e.g. photosynthesis, nitrogen fi xation). Thus, functional stability and Scale, the Dynamic Stability of Forest Ecosystems, and the Persistence of Biodiversity