VESSEL AND FIBER PROPERTY VARIATION IN EUCALYPTUS-GLOBULUS AND EUCALYPTUS NITENS - SOME PRELIMINARY-RESULTS

Vessel areas and distributions in Eucalyptus globulus and E. nitens va ry in a consistent, significant and predictable way from pith to bark and within annual rings. Trends in vessel areas and distributions can be quantified despite the presence of indistinct annual rings and fals e rings. There is evidence of a vessel free area in first earlywood in E. nitens in which fibre properties are predictably different. At 5% height the vessel free area in the 1991 and 1992 annual rings is 13% a nd 10% respectively. Individual vessel areas increase and vessel numbe rs decrease from pith to bark in both E. globulus and E. nitens. Total vessel area increases slowly across the disc but is markedly influenc ed by position within annual rings - decreasing from latewood (LW) to first earlywood (EW); increasing in midwood (MW) and then decreasing f rom MW to LW. Vessel morphology and fibre morphology follow an EW, MW and LW segmentation in both E. globulus and E. nitens. The transition to latewood vessels is synchronous with the transition to latewood fib res. From EW to MW vessel frequency (per mm(2)) significantly increase s (1- to 2-fold), as does vessel percentage coverage (total vessel are a/total segment area)(1.5- to 2-fold); while fibre lumen diameter and wall thickness increase and decrease respectively. Vessel frequency an d percentage coverage in latewood are significantly less (50% less) th an vessels in MW at 5% height, while fibre lumen diameter and wall thi ckness decrease and increase respectively. Changes in vessel number an d area across the ring conform with changes in fibre morphology produc ing a synchronous partition between latewood (LW) and non-latewood in vessels and fibres in the 1993 ring for both species and in the 1994 r ing in E. nitens.