Leveraging Signatures of Plant Functional Strategies in Wood Density Profiles of African Trees to Correct Mass Estimations From Terrestrial Laser Data

peer reviewedWood density (WD) relates to important tree functions such as stem mechanics and resistance against pathogens. This functional trait can exhibit high intraindividual variability both radially and vertically. With the rise of LiDAR-based methodologies allowing nondestructive tree volume estimations, failing to account for WD variations related to tree function and biomass investment strategies may lead to large systematic bias in AGB estimations. Here, we use a unique destructive dataset from 822 trees belonging to 51 phylogenetically dispersed tree species harvested across forest types in Central Africa to determine vertical gradients in WD from the stump to the branch tips, how these gradients relate to regeneration guilds and their implications for AGB estimations. We find that decreasing WD from the tree base to the branch tips is characteristic of shade-tolerant species, while light-demanding and pioneer species exhibit stationary or increasing vertical trends. Across all species, the WD range is narrower in tree crowns than at the tree base, reflecting more similar physiological and mechanical constraints in the canopy. Vertical gradients in WD induce significant bias (10%) in AGB estimates when using database-derived species-average WD data. However, the correlation between the vertical gradients and basal WD allows the derivation of general correction models. With the ongoing development of remote sensing products providing 3D information for entire trees and forest stands, our findings indicate promising ways to improve greenhouse gas accounting in tropical countries and advance our understanding of adaptive strategies allowing trees to grow and survive in dense rainforests. © 2020, The Author(s)

Temporal variation of bird assemblages in a wetland: influence of spatial heterogeneity

The temporal variation of bird assemblages at three sites within a wetland of the Parana River was examined. The aim was to obtain an overview of the influence of spatial heterogeneity on communities in such a variable environment as the wetlands. We recorded 1,662 individuals belonging to 139 species from 40 families. There were no significant differences between sites in richness, abundance nor diversity. Species richness in the first year was greater than during the second year. Number of resident and migrant species decreased in the second year. Community composition differed between the two years of study and was significantly different among seasons. Species were grouped into 19 trophic guilds. In this study, number of species and their abundances were not significantly different among sites; there were differences in the composition of birds among sites. Thus, the structure of the environments influenced the composition of assemblages in different areas. Guild composition remained fairly constant between years and among seasons. Geomorphological and hydrological dynamics of the river produce a heterogeneous availability of habitats and resources that affect the composition of bird assemblages. Annual and seasonal changes in meteorological variables can lead to changes in the structure and/or composition of those assemblages.Fil: Ronchi Virgolini, Ana Laura. Universidad Autónoma de Entre Ríos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lorenzón, Rodrigo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Blake, John G.. University of Florida; Estados UnidosFil: Beltzer, Adolfo Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentin