Reserve ecological resiliency was examined through an evaluation of reserve ecological stress and integrity. Ecological resiliency in this report is defined as a measure of the ability of an ecological system to return to its original state in a timely manner following an impact. Reserves that have higher ecological integrity and lower ecological stress are likely to be more resilient to the impacts of climate hazards.
Comprehensive direct measures of ecological stress and integrity are not currently available for the reserves, and the collection of novel data that would provide a direct measure of the variables was beyond the scope of this project. Given these constraints, expert input from reserve staff was used to develop an estimated measure of ecological stress and integrity.
The expert input process provided insights into staff perceptions of 1) the current level of ecological integrity at the reserves, 2) the overall ecological stress that reserves are experiencing, 3) the key ecological stressors impacting the reserves, 4) the relative contributions of key ecological stressors to overall ecological stress levels, and 5) causal factors related to the key ecological stressors. In addition, the responses were used to examine reserve resiliency.
KEY FINDINGS
Examining the underlying stressors leading to lowered resiliency can offer insights into management strategies that would reduce overall vulnerability to climate change. The key ecological stressors most frequently identified as impacting reserves included:
- Toxic contaminants
- Storm impacts (not including flooding)
- Invasive species
- Habitat fragmentation
- Sediment loading, and
- Coastal shoreline erosion
When percent contribution to overall ecological stress at reserves is also considered, the largest contributors, on average, to reserve ecological stress include the stressors already listed plus nutrient loading/eutrophication and habitat loss. This suggests that while nutrient loading/eutrophication and habitat loss may not be an issue at as many reserves as the other listed stressors, they are having a substantial relative impact at the reserves where they are occurring.
The most frequently identified causal factors contributing to key stressors included:
- Residential development
- Past land use
- Population growth
- Wastewater treatment, and
- Sea level rise
The identified causal factors underscore the considerable impact that anthropogenic activities are having on reserves.
It is expected that reserves with lower integrity ratings and higher stress would be less resilient and, therefore, have greater vulnerability to climate change. This suggests that sites with low ecological resiliency are at higher risk of climate change impacts when all other factors are considered equal. Our analysis indicates that the least ecologically resilient sites in the NERRS include:
- Tijuana River Reserve
- San Francisco Bay Reserve
- Waquoit Bay Reserve
- Elkhorn Slough Reserve
- Old Woman Creek Reserve
- Weeks Bay Reserve
And, the most ecologically resilient sites include:
- Guana Tolomato Matanzas Reserve
- Sapelo Island Reserve
- North Inlet-Winyah Bay Reserve