Edinburgh Napier University

  Despite the environmental stresses that mangrove forests experience – including fluctuating salinity, low soil oxygen and buffeting by waves – they can be highly productive. Facilitation, defined here as the benefits to an organism by the minimisation by neighbouring organisms of biotic or physical stress, may help explain this. Theory suggests that facilitation is likely in stressful environments, and trees and shrubs have been found to be particularly likely to exhibit facilitation. Hence, we should find facilitation in mangrove forests, and this chapter summarises new and published evidence for its existence. Facilitation occurs at a wide range of scales and during all different points in a mangrove tree's life. Amelioration of hydrodynamic and dessicative stresses can be important during seedling establishment and early growth. Interactions with fauna, including crabs and ants, can sustain tree production and help defend against herbivores. Ecosystem-scale facilitation helps ensure resilience in the face of changes such as sea-level rise. Hence facilitation is common in mangroves, and the challenge now is to gain a theoretical understanding of when and where to expect it.