Wood density (WD) is a key functional trait for its importance in tree performance and in biomass calculations of forests. Yet, the variation of WD among different woody tree parts, how this varies across ecosystems, and how this influences estimates of forest carbon stocks remains little understood, particularly for diverse tropical forests such as the Amazon. We assembled a dataset on stem and twig wood density from 119 tree species in three different Amazonian ecosystem types that differ considerably in soil nutrition and flooding: non-flooded forest (Terra Firme), white-water floodplain forest (V & aacute;rzea) and black-water floodplain forest (Igap & oacute;) to investigate (i) variation of stem and twig wood density across ecosystems, (ii) the relationships between stem and twig wood density and how these relationships vary across ecosystems. Wood density varied substantially across ecosystems. V & aacute;rzea species showed lower mean WD for stems compared to Terra firme, while Igap & oacute; species showed higher WD for twigs compared to the other ecosystems. Twig and stem wood density were positively related (R2adj = 0.47) with similarly increasing rates across ecosystems, although average WD values differed between Terra firme and Igap & oacute;. For any given twig density, stem density tends to be lower in floodplain environments but higher in Terra firme, a habitat-specific pattern of wood density variation within trees that may emerge from differences in the function of stem and twig wood for growth and survival in ecologically differentiated environments. Our results show how ecosystem has strong impacts on how trees allocate resources to different woody tissues, suggesting contrasting ecological strategies linked to ecosystem constraints. Our results suggest that greater consideration of the variation of WD within trees and how these changes across ecosystems might lead to more accurate estimates of above-ground biomass in Amazonia.Read the free Plain Language Summary for this article on the Journal blog. A densidade da madeira (WD) & eacute; um tra & ccedil;o funcional chave devido a sua import & acirc;ncia na performance das & aacute;rvores e para os c & aacute;lculos de biomassa em florestas. Entretanto, pouco se conhece sobre a varia & ccedil;& atilde;o da WD entre diferentes partes das plantas, se tal varia & ccedil;& atilde;o muda entre ecossistemas, e como isto influencia as estimativas de estoque de carbono, principalmente em florestas tropicais muito diversas como a Amaz & ocirc;nia. N & oacute;s utilizamos um conjunto de dados de densidade da madeira do tronco e do ramo de 119 esp & eacute;cies de & aacute;rvores de tr & ecirc;s tipos de ecossistemas amaz & ocirc;nicos: florestas de terra firme, florestas alag & aacute;veis de & aacute;guas brancas (V & aacute;rzea) e florestas alag & aacute;veis de & aacute;guas pretas (Igap & oacute;s) e investigamos (i) a variabilidade da densidade da madeira do tronco e do ramo entre ecossistemas, (ii) e a rela & ccedil;& atilde;o entre a densidade da madeira do tronco e a do ramo, e como esta rela & ccedil;& atilde;o varia entre os ecossistemas. A densidade da madeira variou consideravelmente entre os ecossistemas. As esp & eacute;cies de V & aacute;rzea tiveram WD m & eacute;dia do tronco menor comparada a Terra firme, enquanto as esp & eacute;cies de Igap & oacute; tiveram WD m & eacute;dia do ramo maior comparada aos outros ecossistemas. A densidade do ramo e do tronco tiveram correla & ccedil;& atilde;o positiva (R(2)adj = 0.47) e taxas de aumento similares entre os ecossistemas, mas com diferen & ccedil;a nos valores m & eacute;dios de densidade entre Terra firme e Igap & oacute;. Para um dado valor de WD do ramo, a WD do tronco tende a ser menor nas florestas alag & aacute;veis, por & eacute;m maior na Terra firme, um padr & atilde;o de varia & ccedil;& atilde;o na densidade das & aacute;rvores espec & iacute;fico do habitat, que pode surgir de diferen & ccedil;as nas fun & ccedil;& otilde;es do tronco e do ramo para o crescimento e sobreviv & ecirc;ncia das esp & eacute;cies em ambientes ecologicamente distintos. N & oacute;s mostramos como os ecossistemas impactam a aloca & ccedil;& atilde;o de recursos das & aacute;rvores em diferentes tecidos da madeira, sugerindo a exist & ecirc;ncia de estrat & eacute;gias ecol & oacute;gica contrastantes associadas as restri & ccedil;& otilde;es ambientais. Nossos resultados sugerem que considerar a varia & ccedil;& atilde;o da WD de uma & aacute;rvore e como tal varia & ccedil;& atilde;o muda entre ecossistemas pode propiciar estimativas mais acuradas de biomassa na Amaz & ocirc;nia. Read the free Plain Language Summary for this article on the Journal blog.image

Key messageThe high-wood-density species displays greater water limitation tolerance, as it maintains leaf transpiration under drought conditions.AbstractThe relationship between environmental conditions and plant hydraulic safety is essential to understand species' strategies to minimize damage to their hydraulic structure yet maintain function. In the Brazilian semi-arid, the relationships between rainfall seasonality, hydraulic conductivity, wood density, stomatal conductance, and phenology in different species still needs to be clarified. To better understand these relationships, we selected two deciduous trees species with contrasting wood density: (1) Commiphora leptophloeos (Mart.) J.B. Gillett (low wood density) and (2) Cenostigma pyramidale (Tul.) E. Gagnon & G. P. Lewis (high wood density) from the Caatinga dry forest of northeast Brazil. We tracked monthly measurements of whole-tree hydraulic conductivity, leaf stomatal conductance, leaf transpiration rate, xylem water potential, and phenology. We found that the low-wood-density species had a higher whole-tree hydraulic conductivity and an early leaf flush and fall. In addition, lower leaf transpiration rate and higher water storage capacity maintained high xylem water potential and stomatal conductance values, especially in the rainy season. On the other hand, the high-wood-density species had a lower whole-tree hydraulic conductivity and higher leaf transpiration rate, even during the dry season. These results point to the divergent hydraulic strategies employed by each species, further suggesting opposing hydraulic safety pathways during drought.

This study analyzed the diversity of physical properties and mechanical properties of white jabon (Neolamarckia cadamba (Roxb.) Bosser) from various locations and ecological conditions in West Java and Banten Indonesia. White jabon wood samples were taken from 8 locations in West Java and the Banten region. Tree ages ranged from 5 to 6 years. This wood was then tested to compare physical characteristics (density or specific gravity) and mechanical characteristics (modulus of rupture (MOR) and modulus of elasticity (MOE)). The results showed that wood density ranged from 0.29 to 0.43 g.cm-3, MOR ranged from 361 to 641 kg.cm-2, and MOE ranged from 31,117 to 58,910 kg.cm-2. The highest density average (0.43 +/- 0.004 g.cm-3) was produced from Cianjur, and the lowest density average (0.29 +/- 0.010 g.cm-3) was from Tanjungsari Sumedang. Environmental factors (precipitation and altitude) affect the density of wood. Separately, rainfall has a low effect and a negative relationship to jabon wood density, while altitude has a high influence and a negative relationship to jabon wood density. Andosol soil types tend to produce low density wood.