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Simple sequence repeats (SSR) markers have greater advantages relative to other molecular markers in genetic analysis due to their Mendelian inheritance and co-dominance expression features. Numerous expressed sequence tags (EST) of genus Casuarina, now available from public databases, make it possible to develop EST-SSR markers with high efficiency at low cost. From the analysis of 12,063 EST derived from casuarinas, 367 SSR loci were identified from 352 unigenes, and the distribution frequency of SSR loci was 3.0%. The di- and trinucleotide accounted for 57.77 and 34.06% respectively. They comprised overwhelming majority in five types of repeat motifs of SSR, and AG/CT was the most predominant motif type of SSR. A total of 79 primer pairs were designed based on the non-redundant EST-SSR sequences, but only 21 were successfully amplified and generated polymorphic SSR products in four different Casuarina species and eight clones of C. equisetifolia. Eight primer pairs out of the 21 were applied for paternity analyses of open-pollinated progenies of one female individual of C. equisetifolia. At 95% confidence interval, 76 male individuals were identified as pollen parents of 262 out of 461 progenies, but at 80% confidence interval, 84 male individuals were identified as father trees of 328 out of the 461 progenies. [ABSTRACT FROM AUTHOR]

A field trial to examine growth and wound healing of pruned Corymbia torelliana was established in a 40-month-old plantation in western Guangdong, China. It included: (1) pruning all branches up to stem diameters of 5, 6, 7 or 8 cm, (2) wound protection with wax or paint and (3) a control with no pruning. Measurements of growth and wound occlusion taken at various intervals up to 12 months after pruning showed that pruning generally impeded height growth, promoted diameter at breast height (dbh) growth and slightly increased taper. The optimal pruning intensity for tree growth was pruning up to stem diameter of 8 cm. Lower wound occlusion rates occurred in heavier pruning intensities. The optimal intensity for rapid wound occlusion was pruning up to stem diameter of 7 or 8 cm. Paint resulted in better occlusion than wax. The fastest wound occlusion occurred in stem section of height 2.51 to 5.35 m above the ground. Rate of wound occlusion up to 12 months showed correlations with dbh increment, initial wound size and pruning intensity. [ABSTRACT FROM AUTHOR]

Seven eucalypt species and Acacia mangium from a species trial in southern China were assessed for growth, stem form and wood properties at age 6 years. Differences in growth were highly significant for mean tree volume with the order Eucalyptus urophylla > E. cloeziana > A. mangium > E. grandis > E. urophylla × grandis > E. saligna > E. pellita > E. torelliana. There were also significant differences between species for stem form, height to first live branch and stem straightness. Positive correlations were found between height to first live branch and stem straightness. Pilodyn was used to assess variation in wood density and Fakopp was used to indirectly assess modulus of elasticity (MOE). Eucalyptus cloeziana had the highest wood density and MOE, while E. grandis had the lowest wood density and E. torelliana, the lowest MOE. With regard to growth, stem form and wood properties at age 6 years, the order of species for the purpose of conversion of logs into solid wood products was E. cloeziana > E. urophylla × grandis > E. urophylla > E. pellita > A. mangium > E. grandis > E. saligna > E. torelliana. [ABSTRACT FROM AUTHOR]

In order to examine the effects of global warming on the decomposition of forest leaf litter in Southern China, a reciprocal experiment was designed to decompose forest leaf litter in two sites across climatic zones. One site was located on Mt Jianfengling in the tropical zone and the other, on Mt Dinghushan in the subtropical zone. Both sites were located in NSTEC (North-South Transect in Eastern China), in which the temperature gradient along the transect was the major driver. The two sites had similar altitudes, soil types, annual mean rainfall and dry and wet seasons. The difference of annual mean temperature between sites was 3.7 °C. Leaf litters of 10 native dominant tree species were collected from the two sites and divided into single-species litter and mixed litter, and they were incubated on the forest floor of the two sites reciprocally. The results indicated that litter decomposed in the tropical site 1.36-3.06 times more rapidly than in the subtropical site. Apparent Q10, calculated on the basis of the difference of temperature between sites, ranged from 3.7 to 7.5. The conclusion was that global warming would increase the rate of matter circulation in the subtropical forest ecosystem in China. Mixed litter decomposed more rapidly than single-species litter in subtropical site. Not all dominant species litter could represent mixed litter in decomposition. The variability of decomposition rates among the litter types was less in the tropical site than in the subtropical site. Therefore, the effect of litter quality on litter decomposition was less significant in the warmer conditions of the tropics. [ABSTRACT FROM AUTHOR]