Multi‐stemmed trees in subtropical coastal dune forest: Survival strategy in response to chronic disturbance

Abstract

AbstractQuestions: Is multi‐stemming a survival strategy in response to chronic disturbance? Is multi‐stemming under phylogenetic control? What environmental factors are associated with multi‐stemming? When do trees initiate growth of multiple stems? Do multi‐stemmed trees have limited stature?Location: Subtropical Indian Ocean coastal dune forest at Cape Vidal in the Greater St. Lucia Wetland Park, northeastern South Africa.Methods: Tree physiognomy and environmental conditions were sampled in 20 transects that were 300 m long and 5 m wide.Results: 38.9 % of trees were multi‐stemmed, with no correlation between multi‐stemming and taxonomic grouping. The multi‐stemming trait was most associated with stem decumb‐ency and substrate erosion and multi‐stemmed individuals were less common in protected dune slacks. Trees at Cape Vidal appear to facultatively produce multiple stems from an early stage. There was no trade‐off between tree height and stem number.Conclusions: Coastal winds and the unstable dune substrate are important environmental correlates of multi‐stemming. Both short stature and the high incidence of multi‐stemming are related to the tree‐disturbance interaction. The taxonomically widespread phenotypic plasticity in this trait indicates the importance of multi‐stemming to tree survival even under low levels of disturbance.