Wood density is central for estimating vegetation carbon storage and a plant functional trait of great ecological and evolutionary importance. However, the global extent of wood density variation is unclear, especially at the intraspecific level. We assembled the most comprehensive wood density collection to date, including 109 626 records from 16 829 plant species across woody life forms and biomes (GWDD v.2, available here: doi: 10.5281/zenodo.16919509). Using the GWDD v.2, we explored the sources of wood density variation within individuals, within species and across environmental gradients. Intraspecific variation accounted for c. 15% of overall wood density variation (SD = 0.068 g cm-3). Variance was 50% smaller in sapwood than heartwood, and 30% smaller in branchwood than trunkwood. Individuals in extreme environments (dry, hot and acidic soils) had higher wood density than conspecifics elsewhere (+0.02 g cm-3, c. 4% of the mean). Intraspecific environmental effects strongly tracked interspecific patterns (r = 0.83) but were 70-80% smaller and varied considerably among taxa. Individual plant wood density was difficult to predict (root mean square error > 0.08 g cm-3; single-measurement R2 = 0.59). We recommend: (1) systematic sampling of multiple individuals and tissues for local applications; and (2) expanded taxonomic coverage combined with integrative models for robust estimates across ecological scales.
Nutrition is a fundamental aspect of human well-being, yet persistent deficiencies remain prevalent among vulnerable populations. In Madagascar, smallholder farmers experience chronic nutritional insecurity driven by limited dietary diversity and low resilience to shocks. These vulnerabilities were exacerbated by COVID-19-related disruptions to food access and fragile supply chains. Despite the presumed buffering role of home-based food production, its contribution to nutritional adequacy, and the temporal variability of nutritional supply during this period, remains insufficiently documented, with limited local evidence and few global parallels. This study analyzes primary data collected over six survey rounds from June 2019 to June 2021, covering 548 lowland rice-farming households in rural Madagascar. It has two objectives. First, it examines the changes in food consumption and nutrient supply before and after the COVID-19 outbreak period. We assess and compare food consumption patterns by food group and nutrient supply per adult male equivalent (AME) using the Wilcoxon matched-paired signed-rank test. Second, we investigate the impact of home-based food production, which is represented by the energy-based food self-sufficiency ratio (FSSR), on the nutrient supply, using a fixed effects regression model. The results indicated a dietary shift toward increased vegetable consumption and a reduced intake of animal-sourced foods after the COVID-19 outbreak. It caused an increased supply of vitamin A and calcium and decreased supply of vitamin B12, which is primarily derived from animal-sourced foods. Regarding the impact of home-based food production, the results suggest that approximately half of the study population’s energy requirements are met through home-based food production, with significant seasonal fluctuations. Fixed effects regression analysis demonstrated that the FSSR had a significant positive effect on energy and nutrient supply per AME, except for vitamin B12, and that this effect diminished after the shock. These findings highlight the importance of strengthening and intensifying home-based food production as a key strategy for nutritional improvement. However, additional factors such as increased income, which is related to animal-sourced food consumption, should be considered to address deficiencies, particularly vitamin B12 supply.
Black rice is cultivated in Southeast Asia’s upland and lowland area, where yields are often limited by low soil fertility, phosphorus (P) deficiency, and limited external inputs. Phytic acid (PA)—the principal storage form of P in rice seeds—represents more than 70% of the total seed P. Data on the effects of seed PA levels on the agronomic performance of black rice, especially under upland field conditions, are scarce. This study explored the effect of seed PA concentration on the early growth, nutrient uptake, and yield performance of black rice under both pot and upland field conditions. In pot experiments, we tested three levels of seed PA (low, moderate, and high) at different soil P applications (control, low P, and high P). A complementary field trial in Luang Prabang, Laos, evaluated the effects of seed PA and nitrogen (N) application (0 or 30 kg N ha-1) under rainfed conditions. Results demonstrated that high-PA seeds significantly improved early seedling vigor, shoot and root biomass, and nutrient uptake, particularly under conditions of low or no external P supply. At maturity, high-PA plants yielded 35% more grain than that yielded by low-PA plants in pots and exhibited a 47% yield advantage in upland fields. Low N input did not affect grain yield but notably reduced grain PA levels under upland conditions. Overall, the findings indicate that seed PA concentration is a key physiological trait that enhances the adaptation and productivity of black rice in nutrient-poor upland systems.
