Table 1 Important factors for consideration in developing conservation strategy in small islands (adapted from ref. ⁴¹).

1. Ecological heterogeneity

The quality and quantity of distinct resource types varies between islands. Properly informed conservation policy will require monitoring to build baselines throughout the multi-island system. Rather than a blanket policy, successful island governance will require the assessment of the conservation status of each island’s biological community to be made available to decision makers.

2. Social heterogeneity

Local island communities differ in the structure and strength of their economies, and the beliefs and values of their peoples. These differences affect a number of socio-economic and cultural aspects, including livelihoods, identities, and trade. Policies that do not take island diversity at the social level into account might face great challenge and opposition from local communities. National-level policies would benefit from increased alignment with local needs.

3. Ecological spillovers

In population dynamics, ecological spillovers can lead to increases in abundances beyond what resource limits can dictate, leading to species with the dispersal capability to colonize other islands⁴⁶. In the same vein, governance actions on one island can lead to changes in another since they form interlinked social-ecological systems⁴⁰. Conservation actions may lead to unplanned consequences. For example, hasty restoration of mangroves on islands and coastal areas of Eastern Samar in the Philippines after Typhoon Haiyan (2013) used the less laboriously cultivated but higher-mortality Rhizophora mangroves instead of the naturally-dominant species Sonneratia alba and Avicennia marina. Typhoon survivors began clearing defoliated (but live) trees and surviving seedlings to avail of cash grants⁴⁷. Many post-Haiyan rehabilitation initiatives continue to use Rhizophora propagules and encroach on other sensitive coastal habitats like seagrass meadows across different islands⁴⁸. In line with the precautionary principle, contingencies should be taken into account when planning ecological restoration in order to avoid unfavorable outcomes.

4. Social spillovers

These can occur when management actions on one island affect the cultural, human, physical, and natural capital of other islands. Island distribution can affect available amenities and transport systems; thus, the economy, human health, livelihoods and, cultural aspects of local communities might already be significantly different⁴⁹ where changes can quickly cascade from one island community to another. This means that actions can also have impacts beyond a single island community.

5. Uncertainty and irreversibility

Stochastic events are a property of all social-ecological systems, and interconnected small island systems are no exception. However, because of the unique traits and small size of ecological communities on island systems, they are especially vulnerable to unforeseen catastrophic events. The challenge for governance lies in development planning that accounts for these uncertainties, such as in disaster risk reduction and climate change adaptation.