Ecological management in the context of rapid global climate change: Running with the Red Queen along the Gulf coast

Background/Question/Methods Restoration goals often focus on reassembly of ecological systems historically present on a site. Trajectories of change towards historical states are attempted based on reintroduction of historical components and reinstitution of historical ecological processes. Global climate change and associated effects are producing environmental conditions not previously experienced by historical ecological systems. Establishing restoration targets based on historical conditions is unlikely to result in accomplishment of goals. Alternative restoration goals could be based on changes expected in intact, non-degraded ecological systems as a result of global climate change. Given sufficient time, restoration-induced shifts in degraded systems might produce convergence with non-degraded ecological systems, maintain some semblance of historical conditions, and conserve biodiversity. Along the Gulf of Mexico coastline, for example, effects of climate change (e.g., flooding, increased salinity associated with sea level rise) are producing slow, steady changes along downslope ends of coastal transitions between marine and terrestrial habitats. Models for responses tend to be based in upslope migration of species and communities over time. Given human actions upslope (e.g., development, fire suppression), the net effect predicted is squeezing of coastal transition communities into progressively smaller sections of elevation gradients until they disappear.

Results/Conclusions This quasi-historical approach may not be possible in areas where global climate change is generating punctuated changes in ecological systems. For example, ecosystems in the middle of Gulf coastal transition elevation gradients experiencing pronounced storm surges during Hurricane Katrina have undergone rapid disassembly without concomitant reassembly. Dominant graminoid and tree species in freshwater marshes, wet pine savannas, and hydric forests have been lost. These communities are not reassembling in situ, nor have they gained dominant graminoid species from downslope fresh, brackish and salt marshes. Nonetheless, some salt-tolerant species, both native and exotic shrubs and herbs have migrated along the elevation gradient, forming new communities with in situ species resistant or resilient to storm surge damage. Such resistance will depend on the ability to survive sudden changes, such as salinity pulses, and resilience will depend on the ability to respond quickly, such as inland migration by hydrochory during hurricanes and establishment in saline conditions. Concepts to guide restoration when running with the Red Queen are likely to be based on assembly of functional landscapes, irrespective of history, biodiversity, and species origin and to focus on assembly of ecosystems whose components are capable of resistance or resilience to sudden changes in environments.