Using environmental heterogeneity to plan for sea-level rise.

Area of Science:

• Ecology
• Conservation Biology
• Climate Change Adaptation

Background:

• Environmental heterogeneity is a key factor in selecting conservation areas for future biodiversity under climate change.
• The conserving nature's stage (CNS) approach assumes environmental features change slower than biological communities.
• The effectiveness of CNS is questioned when environmental features change rapidly, such as in coastal salt marshes experiencing sea level rise (SLR).

Purpose of the Study:

• To test the effectiveness of CNS for salt marsh conservation in coastal Georgia, USA, considering rapid environmental changes due to SLR.
• To evaluate two methods for selecting sites based on environmental heterogeneity: environmental diversity (ED) and environmental richness (ER).
• To assess the performance of selected sites in predicting species diversity, resilience to SLR, and habitat provision for threatened species.

Main Methods:

• Calculated species diversity for 7 bird species in Georgia salt marshes.
• Assessed environmental heterogeneity across six landscape gradients (elevation, salinity, patch area).
• Used ED and ER approaches to select conservation sites and compared their effectiveness against random selection.

Main Results:

• ER-selected sites predicted present-day species diversity better than random sites (up to 8.1% improvement).
• ER-selected sites showed resilience to SLR (1.0% average areal loss by 2050 vs. 0.9% for random sites) and provided better habitat for a threatened species.
• ED-selected sites did not predict species diversity better than random sites and were less resilient to SLR (2.9% average areal loss by 2050).

Conclusions:

• The ER approach within CNS is a viable strategy for salt marsh conservation site selection, demonstrating success in predicting diversity and SLR resilience.
• CNS, particularly the ER method, has potential for other coastal areas impacted by SLR, though performance may vary with geological change magnitude.
• Coastal ecosystems, including low-lying coasts, should be considered in regional conservation strategies using CNS planning.