Tension wood and opposite wood in 21 tropical rain forest species: 1. Occurrence and efficiency of the G-layer.

摘要

Wood samples were taken from the upper and lower sides of 21 naturally tilted trees from 18 families of angiosperms in the tropical rain forest in French Guiana. The 21 tree species were Guatteria schomburgkiana, Oxandra asbeckii, Lacmellea aculeata, Protium opacum, Licania membranacea, Symphonia globulifera, Casearia javitensis, Goupia glabra, Hebepetalum humiriifolium, Dendrobangia boliviana, Ocotea indirectinervia, Eschweilera sagotiana, Lecythis poiteaui, Trichilia schomburgkii, Inga marginata, Myrcia decorticans, Ormosia bolivarensis, Ormosia coutinhoi, Cassipourea guianensis, Cupania scrobiculata and Talisia simaboides. The measurement of growth stresses ensured that the two samples were taken from wood tissues in different mechanical state: highly tensile stressed wood on the upper side, called tension wood, and lower tensile stressed wood on the lower side, called opposite wood. Eight species had tension wood fibres with a distinct gelatinous layer (G-layer). The distribution of gelatinous fibres varied from species to species. One of the species, Casearia javitensis (Flacourtiaceae), showed a peculiar multilayered secondary wall in its reaction wood. Comparison between the stress level and the occurrence of the G-layer indicates that the G-layer is not a key factor in the production of high tensile stressed wood..