Inner bark vs sapwood is the main driver of nitrogen and phosphorus allocation in stems and roots across three tropical woody plant communities.

Nutrient allocation is central to understanding plant ecological strategies and forest roles in biogeochemical cycles. Thought to be mainly driven by environmental conditions, nutrient allocation to woody organs, especially to living tissues, is poorly understood. To examine the role of differences in living tissues (sapwood, SW, vs inner bark, IB), organs, ecological strategies, and environmental conditions in driving nutrient allocation and scaling in woody plants, we quantified nitrogen and phosphorus in main stems and coarse roots of 45 species from three tropical ecosystems with contrasting precipitation, fire regime, and soil nutrients. Nutrient concentration variation was mostly explained by differences between IB and SW, followed by differences between species and, in the case of phosphorus, soil nutrient availability. IB nutrient concentrations were four times those of SW, with root tissues having slightly higher concentrations than stem tissues. Scaling between IB and SW, and between stems and roots, was generally isometric. In cross-sections, IB contributed half of total nutrients in roots and a third in stems. Our results highlight the important role of IB and SW for nutrient storage, the coordination in nutrient allocation across tissues and organs, and the need to differentiate between IB and SW to understand plant nutrient allocation.

Metabonomics Analysis of Stem Extracts from Dalbergia sissoo.

Dalbergia sissoo is a woody plant with economic and medicinal value. As the pharmacological qualities and properties of the wood from this plant primarily depend on its extractives, in this study, the metabolomic analysis of extractives from its stems was carried out using UPLC-MS/MS. A total of 735 metabolites were detected from two groups of samples, heartwood and sapwood, with the largest number of terpenoids in type and the largest number of flavonoids in quantity. The PCA and cluster analysis showed significant differences in the metabolite composition between the two groups. The differential metabolites were mainly organic oxygen compounds, flavonoids, and isoflavones. Among the 105 differential metabolites, 26 metabolites were significantly higher in relative content in sapwood than in heartwood, while the other 79 metabolites were significantly higher in relative content in heartwood than in sapwood. KEGG metabolic pathway enrichment analysis showed that these differential metabolites were mainly enriched in three metabolic pathways: Flavonoid biosynthesis, isoflavonoid biosynthesis, and flavonoid and flavonol biosynthesis. This study provides a reference for metabolomics studies in Dalbergia and other woody plants.

An extensive study on the chemical diversity of lipophilic extractives from Eucalyptus globulus wood.

Three mature Eucalyptus globulus trees with 40 years of age were studied at three height levels (0%, 35%, and 60% of total tree height) and at three radial regions (sapwood, inner and outer heartwood). The composition of lipophilic extracts was evaluated and an extensive list of 202 compounds was reported for the first time. The fatty acids were the major chemical family, representing 40.8% of the total compounds, followed by phytosterols (19.0%), aromatics (10.5%) and triterpenes (10.4%). Saturated fatty acids accounted for 74.2% of total compounds (C16:0, C24:0 and C26:0 were predominant), ß-Sitosterol and stigmastanol were the main sterols (80 and 7% respectively), while aromatics were mainly represented by syringic acid, 4-hydroxy-3,5-dimethoxybenzaldehyde, vanillic acid, and vanillin. The main triterpenes were asiatic and arjunolic acids.