title: How to catch the patch? A dendrometer study of the radial increment through successive cambia in the mangrove Avicennia.
abstract: OBJECTIVE
  Successive vascular cambia are involved in the secondary growth of at least 200 woody species from >30 plant families. In the mangrove Avicennia these successive cambia are organized in patches, creating stems with non-concentric xylem tissue surrounded by internal phloem tissue. Little is known about radial growth and tree stem dynamics in trees with this type of anatomy. This study aims to (1) clarify the process of secondary growth of Avicennia trees by studying its patchiness; and (2) study the radial increment of Avicennia stems, both temporary and permanent, in relation to local climatic and environmental conditions. A test is made of the hypothesis that patchy radial growth and stem dynamics enable Avicennia trees to better survive conditions of extreme physiological drought. Methods Stem variations were monitored by automatic point dendrometers at four different positions around and along the stem of two Avicennia marina trees in the mangrove forest of Gazi Bay (Kenya) during 1 year.
  
  
  RESULTS
  Patchiness was found in the radial growth and shrinkage and swelling patterns of Avicennia stems. It was, however, potentially rather than systematically present, i.e. stems reacted either concentrically or patchily to environment triggers, and it was fresh water availability and not tidal inundation that affected radial increment.
  
  
  CONCLUSIONS
  It is concluded 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. Limited water could be used in a more directive way, investing all the attainable resources in only some locations of the tree stem so that at least at these locations there is enough water to, for example, overcome vessel embolisms or create new cells. As these locations change with time, the overall functioning of the tree can be maintained.
authors: Laboratory of Plant Biology and Nature Management (APNA), Vrije Universiteit Brussel, B-1050 Brussels, Belgium.
authors: Elisabeth M R
authors: EM
authors: Robert
authors: Abudhabi H
authors: AH
authors: Jambia
authors: Nele
authors: N
authors: Schmitz
authors: Dennis J R
authors: DJ
authors: De Ryck
authors: Johan
authors: J
authors: De Mey
authors: James G
authors: JG
authors: Kairo
authors: Farid
authors: F
authors: Dahdouh-Guebas
authors: Hans
authors: H
authors: Beeckman
authors: Nico
authors: N
authors: Koedam
mesh_terms: D032407:Avicennia / Q000033:anatomy & histology / Q000254:growth & development* / Q000502:physiology; D058506:Cambium / Q000033:anatomy & histology / Q000254:growth & development* / Q000502:physiology; D002980:Climate; D004777:Environment; D007630:Kenya; D052585:Phloem / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology; D018547:Plant Stems / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology; D012621:Seasons; D014197:Trees; D014867:Water / Q000502:physiology; D014934:Wood / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology; D052584:Xylem / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology
chemical_list: D014867:Water
keywords: Automatic point dendrometers; Avicennia marina; local climate and environmental conditions; mangrove; patchy growth; pinning analysis; radial tree stem dynamics; successive cambia