Patterns of tree buttressing at Lawachara National Park, Bangladesh

摘要

We describe patterns of buttress formation and development in eleven tree species at Lawachara National Park,Bangladesh.Forty-five percent of trees of these 11 species had buttresses.Artocarpus chaplasha Roxb.showed maximum (87％) buttress formation,whereas Alstonia scholaris (L.) R.Br.did not show any buttress.Buttresses were recorded in 20％-40％ of trees of six species and 40％-60％ of trees in three species.Mean length and height of buttress varied among the species and ranged from 0.37-1.37 m and 0.71-2.13 m,respectively.Buttress height,mean buttress length,total buttress length,and total length plus length of secondaries increased with DBH (diameter at breast height) and tree height.Buttress number did not increase with DBH or tree height.Under-storey and mid-canopy trees produced less developed buttresses than did emergent trees (p＜0.01).Wood density showed moderate effects on buttress characters (p＜0.05),while the slope of the land did not.Canopy category was a primary regulating factor for tree buttressing,suggesting that buttresses are mechanical adaptations of trees to counter physical stresses.