Patchy radial increment in the mangrove Avicennia

In the mangrove genus Avicennia successive vascular cambia are organized in patches, creating stems with non-concentric xylem tissue surrounded by internal phloem tissue. Robert et al. monitor stem variations in A. marina trees in a natural mangrove forest over the course of one year, and find that patchiness occurs in both the radial growth and the shrinkage and swelling patterns of the stems. Radial increment is affected by fresh water availability rather than tidal inundation. They conclude that the ability to develop successive cambia in a patchy way enables Avicennia trees to adapt to changes in the prevailing environmental conditions, enhancing its survival in the highly dynamic mangrove environment.