Can forest management based on natural disturbances maintain ecological resilience?

Given the increasingly global stresses on forests, many ecologists argue that managers must maintain ecological resilience: the capacity of ecosystems to absorb disturbances without undergoing fundamental change. In this review we ask: Can the emerging paradigm of natural-disturbance-based management (NDBM) maintain ecological resilience in managed forests? Applying resilience theory requires careful articulation of the ecosystem state under consideration, the disturbances and stresses that affect the persistence of possible alternative states, and the spatial and temporal scales of management relevance. Implementing NDBM while maintaining resilience means recognizing that (i) biodiversity is important for long-term ecosystem persistence, (ii) natural disturbances play a critical role as a generator of structural and compositional heterogeneity at multiple scales, and (iii) traditional management tends to produce forests more homogeneous than those disturbed naturally and increases the likelihood of unexpected catastrophic change by constraining variation of key environmental processes. NDBM may maintain resilience if silvicultural strategies retain the structures and processes that perpetuate desired states while reducing those that enhance resilience of undesirable states. Such strategies require an understanding of harvesting impacts on slow ecosystem processes, such as seed-bank or nutrient dynamics, which in the long term can lead to ecological surprises by altering the forest's capacity to reorganize after disturbance

Roads, Railroads, and Floodplain Fragmentation Due to Transportation Infrastructure Along Rivers

River floodplains comprise about 7 percent of the land area of the United States and are areas of great biodiversity and ecological productivity, much of which is due to the many connections between terrestrial and aquatic systems in these settings. The flat topography of floodplains, however, means that they are also ideal sites for transportation infrastructure that can disconnect the river from the surrounding landscape. Few studies have examined the role of roads and railroads as components of river system structure and function at landscape scales. In this study, we use geographic information systems (GIS) and easily obtainable data to map the extent of floodplain disconnection caused by transportation infrastructure across two river basins in Washington State. Digital geologic or soils data, along with digital elevation data, provide the extent of total floodplain area, and transportation data define the extent of disconnection. Our results show that 44 percent to 58 percent of the total floodplain area in the three study basins is disconnected by these roads and railroads. Transportation infrastructure disconnected between 17 percent and 64 percent of the floodplain area in the individual study reaches. Federal Emergency Management Agency floodplain data often show where floodplains are truncated by infrastructure, particularly by large features or in urban areas, but do not capture the loss of total floodplain area. Relatively simple broad-scale documentation of infrastructure and floodplain disconnection has potential for guiding further study of floodplain fragmentation at multiple scales, providing an impetus for improving infrastructure design and repair and helping inform aquatic and floodplain management activities