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To develop an understanding of observed greater diameter increments responses to thinning in less shade-tolerant Eucalyptus dunnii with lower green crown ratio than more shade-tolerant Corymbia citriodora spp.variegata with higher green crown ratio,we investigated into structural relationships between tree leaf area and sapwood area following thinning in 11-year-old E.dunnii and C.citriodora plantations established in high rainfall sites.Changes in specific leaf area (SLA),leaf area (Al)-sapwood area (As) relationships and Al/As were examined in both species after thinning.There was no significant difference in SLA between thinned and unthinned stands of E.dunnii,while significant reductions in SLA in both the lower and upper crown were found in C.citriodora following thinning.At the whole-tree level thinning did not influence Al-As relationships and the best point of predicting leaf area based on As appeared at the crown base in both species.At the within-crown level relationships between Al and As were affected by thinning in E.dunnii due to the significant increase in Al/As ratios at upper crown.For C.citriodora thinning did not affect Al-As relationships,while Al/As ratios at lower crown did increase as a result of thinning.Al/As ratios did not decrease with tree height on crown level,and conversely the maximum occurred at the upper crown despite thinning regime and tree species.These results testified the hypotheses that (i) greater increases in the amount of leaf area supported per unit sapwood area would occur in less shade-tolerant E.dunnii compared with more shade-tolerant C.variegate as a result of thinning,and (ii) for both species Al/As was not decreased with tree height on crown level in high rainfall sites.Furthermore the observed variations also suggest that for less shade-tolerant E.dunnii upper crown leaves appear to be driving growth response to thinning,while for more shade-tolerant C.citriodora lower crown leaves appear to be driving it.