Mangrove interaction with saltmarsh varies at different life stages.

Mangroves and saltmarshes are two of the most relevant coastal habitats for humans. These ecosystems offer several services like coastal protection, climate mitigation, and nursery habitats for many artisanal and commercially exploited fish, crabs, and shellfish. They mostly dominate different latitudinal ranges but in several places around the world they co-occur and interact. Here, we summarize the current scientific knowledge on mangrove-saltmarsh ecological interactions and propose a conceptual model. We screened 1410 articles from 1945 to 2022 and selected 29 experiments that assessed mangrove-saltmarsh ecological interactions. Both positive and negative interactions are observed but there is variation along different mangrove life stages. Higher retention and establishment of mangrove propagules are found inside saltmarshes than on bare flats, i.e. facilitation, and these effects are higher at grass than at succulent saltmarsh species. Mangrove seedlings, saplings, or trees mostly compete with saltmarshes, negatively affecting mangrove growth. We propose a model with different outcomes considering the interaction between different mangrove's life stages and saltmarsh forms and discussed these interactions in the light of anthropogenic threats and climate change.