Abstract: Mangroves, a unique flora, have high primary productivity in the intertidal environments. Mangrove species are more efficient in energy use than most of forest species when facing the harsh conditions, e.g., waterlogging, high salinity, and tidal flushing. How to balance the energy allocation among propagation, survival, stress-resilience and competition is the key driver for their successful settlement. From seedlings to mature plants, the main energy investment objects shift from roots to stems. Although the relative biomass of leaf decreases with plant growth, the calorific value in leaf is constantly higher than other organs. Due to the additional energy consumption for environmental resistance, the slow-return investments of energyuse strategy are favored by most species. Under this situation, the investment to leaf is reduced, and the newly absorbed energy is concentrated on roots and stems to maintain the survival. Viviparous mangrove species invest more energy to propagules, while non-viviparous species have higher specific leaf area and nitrogen concentration but lower cost of construction, leading to faster investment return. The energy-use strategy is closely related to leaf economic spectrum, while both are important to the adaptive strategy and invasiveness of mangrove species under stressful environment.

Key words: mangrove, calorific value, vivipary, propagule, energy.