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)

Chirurgie cardiaque au Cameroun. Résultats à un an de la phase pilote.

In the framework of implementation of his national program for control and prevention of cardiovascular diseases, Cameroonian government has set up a cardiac surgery project. We report in this manuscript results of one year follow up of the patients operated during the pilot phase. From September 22 till 26, 2008, 11 patients have been operated in Cameroun. Surgical procedures were 5 mitral mechanic valve replacement, 2 aortic mechanic valve replacement, 1 atrial septal defect closure, 2 pace maker implantation. No intrahospital death was observed. One patient died at 11th month after the operation due to mitral valve thrombosis and attributed to lack of compliance. One patient presented low cardiac output, pneumonia and a pleural effusion. 2 patients presented 2 minor complications consisting of pericarditis and superficial wound infection. The results of the pilot phase of cardiac surgery in Cameroon are effective. However, the sustainability of the program require human, material capacity building, and funding mechanism as well.English AbstractJournal Articleinfo:eu-repo/semantics/publishe