Volume 78, Issue 10

Phoebe and Machilus trees, whose wood is known as Nanmu in China, face endangerment owing to long-term manmade destruction and climate change. Therefore, effective and accurate forensic tools to identify Nanmu species are required. This study developed a method for DNA identification of woods from six commonly traded Phoebe and Machilus species. DNA was efficiently extracted from oil cell-rich wood tissues, DNA barcodes were screened, species were compared, and a Nanmu DNA database was constructed. Comparison and analysis involved 26 sets of plastid genomes of Phoebe and Machilus . The five highest variable regions (Pi>0.009; psbA-trnH, psbJ, psbJ-petA, rpl32-trnL, and ycf 1 ) were identified, and three nuclear regions (ITS, LEAFY, and RPB2 ) were compared. Among single DNA fragments, the nuclear DNA region LEAFY proved optimal for identifying Nanmu species, while psbA-trnH + psbJ + ycf1 was the optimal plastid combination locus. Compared with distance-based (TaxonDNA) and machine-learning analyses, the tree-based method had a lower success rate for species identification. Four labelled Nanmu samples were selected to validate the method and clustered with P. zhennan and P. sheareri data based on the LEAFY region and plastid combination locus. These findings will contribute to the conservation, classification, architecture maintenance, and trade monitoring of Nanmu natural resources.

Variability in Eucalyptus wood density and chemical properties is crucial to understanding important factors for the forest-based industry, such as sampling methods and wood suitability as raw material. This study aimed to evaluate the basic density and chemical composition of the radial positions of young wood from the Eucalyptus urophylla clone grown under different precipitation levels. Trees from E. urophylla clonal plantations were collected in Inhambupe, Jandaíra and Itanagra, Bahia State, Brazil. Trees’ basic density and chemical composition (total extractive, lignin, hemicelluloses and α -cellulose) were determined based on the basal log of each tree, at four radial positions (1, 2, 3 and 4). It was found that the basic density and α -cellulose of wood are influenced by the cambial age and the site rainfall. There was greater increase in sections close to the bark (positions 1 and 4) and in more humid environments (sites Itanagra and Jandaríra). This finding highlights the association between wood basic density and chemical composition, mainly in the holocellulose content.

A three-year pot experiment was designed to investigate cadmium (Cd) accumulation in the various parts of poplar ( Populus deltoides Bartr. cv. ‘Lux’ I-69/55) by setting up 5 Cd application treatments (0, 5, 20, 50, and 100 mg/kg dry soil). The results showed that poplar exhibited a high tolerance to Cd stress, with Cd uptake significantly increasing across all plant parts as soil Cd levels rose. In general, leaves exhibited the highest Cd concentration while stems had the lowest. An upward increase trend of the accumulation of Cd in the aboveground parts from the base wood, along the stem to the branch, until the leaves, as well as a radially outward increase of Cd from the wood near the pith, to the wood near the bark, and finally to the bark, were observed. Over the three successive years, poplar trees exhibited a generally increasing extraction ability in terms of Cd concentration and the bioconcentration factor (BCF) in their aboveground parts, attributed to the enhanced leaf transpiration and conducting tissue development. The BCFs of various parts of poplar ranged from 0.09 to 6.30, following the trend of leaf > bark > branch > root > stem.

Wood chips and sawdust are used for cultivating Ganoderma lucidum mushrooms. In Northern Europe, side-streams of Pinus sylvestris are highly abundant, however as cultivation substrate they inhibit the growth of  G. lucidum . To identify the changes in lignocellulosic composition after fungal degradation, the major lignocellulosic components in P. sylvestris and an optimal substrate for  G. lucidum , Populus tremula were analyzed. Populus tremula was evenly degraded while the glucan fraction of P. sylvestris was not degraded and its lignin fraction was consumed almost completely. Despite not being an optimal substrate, P. sylvestris was successfully delignified by G. lucidum .