Résumé
Aims Belowground interactions are still poorly understood in mixed-species forests. We investigated the effects of soil fertility on belowground processes in mixed planted forests. Methods The dynamics and traits of Eucalyptus and Acacia mangium fine roots (diameter < 2 mm) in plantations with 50% of each species were studied in a randomized block design established in a nutrient depleted soil. Stands with NPK fertilization applied at planting (F+) were compared to unfertilized stands (F-). Results In the 0-15 cm soil layer, Eucalyptus root mass density (RMD) was higher than Acacia RMD by 50% in F+ and 10% in F-, considering both ages. At 34 months of age, Eucalyptus RMD was 94% higher near Acacia trees than near Eucalyptus trees in F-. In this layer, Eucalyptus specific root length (SRL) was 21% higher than Acacia SRL at 16 months of age and was 10% higher in F- than in F+ at 34 months of age. The cumulative Eucalyptus fine root length production between 16 and 34 months was 66% higher in F- than in F+ in the 0-1 m soil layer. Conclusions Fertilization increased the competition between species and led to a partial exclusion of Acacia fine roots from the nutrient-rich topsoil. Soil exploration by Eucalyptus roots in the vicinity of Acacia trees was higher in F- than in F+, which suggests that unfertilized trees benefited from facilitation through higher soil N availability and direct N transfer from Acacia trees.
Auteurs, date et publication :
Auteurs B. Bordron , A. Germon , J-P Laclau , I. R. Oliveira , A. Robin , C. Jourdan , R. R. Paula , R. C. Pinheiro , J. Guillemot , J. L. M. Goncalves , J-P Bouillet
Publication : PLANT AND SOIL
Date : 2021
Volume : 460
Issue : 1-2
Pages : 559-577
Catégorie(s)
#ANR-Citation #CIRAD #FORET ItatingaRésumé
Soil nutrient availability and functional traits interact in complex ways during the assembly of tree communities hindering our understanding of the implications that this may have for their phylogenetic and functional diversity. We combined abundance, taxonomic, phylogenetic and functional trait data of 222 tree species distributed along nutrient concentration gradients at 24 plots in two tropical forest study sites. We analysed micro and macronutrient concentration in organic and topsoil horizons and tested for the following: (1) nutrient-based species sorting due to contrasting trait–environment relationships, (2) whether nutrient filtering has consequences for phylogenetic and functional diversity, and functional space size and occupancy and (3) we mapped trait distributions across the phylogeny of tree species to track the evolutionary signature of nutrient availability. We found that total nitrogen (N), available phosphorus and total potassium in soil accounted for 68% of the variation in tropical tree species community composition, with strong associations with nutrient concentration for 89% of the tree species included in the analysis. This nutrient-based species selection was mediated by interactions between the three soil nutrient concentrations with leaf nitrogen, leaf thickness and wood density. Soil N concentration was positively associated with the functional space at site level. At plot level, soil N concentration positively correlated with functional evenness and it was negatively associated with the functional space not occupied by any species in the tree community. Despite the phylogenetic conservatism of leaf N across tree lineages even when not considering legumes, many sister-species pairs show contrasting values which match with their habitat preferences thus indicating the evolutionary lability of this trait, particularly within recently diversified clades. Synthesis. Our results demonstrate that soil nutrient-based species selection is a prevalent driver of community assembly in tropical forests, a process mediated by key functional traits within the leaf and wood economics spectrum. Functional space size and its filling increase with soil nutrient concentration, whereas niche vacancy decreases. This selection process has likely influenced tropical tree species diversification patterns via habitat specialization.
Auteurs, date et publication :
Auteurs Guille Peguero , Fernando Coello , Jordi Sardans , Dolores Asensio , Oriol Grau , Joan Llusià , Romà Ogaya , Ifigenia Urbina , Leandro Van Langenhove , Lore T. Verryckt , Clément Stahl , Laëtitia Bréchet , Elodie A. Courtois , Jérôme Chave , Bruno Hérault , Ivan A. Janssens , Josep Peñuelas
Publication : Journal of Ecology
Date : 2025
Volume : 111
Issue : 6
Pages : 1218-1230
Catégorie(s)
#ANR-Citation #CIRAD #CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Oriol Grau , Josep Peñuelas , Bruno Ferry , Vincent Freycon , Lilian Blanc , Mathilde Desprez , Christopher Baraloto , Jérôme Chave , Laurent Descroix , Aurélie Dourdain , Stéphane Guitet , Ivan A. Janssens , Jordi Sardans , Bruno Hérault
Publication : Scientific Reports
Date : 2017
Volume : 7
Pages : 45017
Catégorie(s)
#CIRAD #CNRS #FORET Nouragues #FORET ParacouRésumé
Objectives: Carbon fixed during photosynthesis is exported from leaves towards sink organs as non-structural carbohydrates (NSC), that are a key energy source for metabolic processes in trees. In xylem, NSC are mostly stored as soluble sugars and starch in radial and axial parenchyma. The multi-functional nature of xylem means that cells possess several functions, including water transport, storage and mechanical support. Little is known about how NSC impacts xylem multi-functionality, nor how NSC vary among species and climates. We collected leaves, stem and root xylem from tree species growing in three climates and estimated NSC in each organ. We also measured xylem traits linked to hydraulic and mechanical functioning. Data description: The paper describes functional traits in leaves, stems and roots, including NSC, carbon, nitrogen, specific leaf area, stem and root wood density and xylem traits. Data are provided for up to 90 angiosperm species from temperate, Mediterranean and tropical climates. These data are useful for understanding the trade-offs in resource allocation from a whole-plant perspective, and to better quantify xylem structure and function related to water transportation, mechanical support and storage. Data will also give researchers keys to understanding the ability of trees to adjust to a changing climate.
Auteurs, date et publication :
Auteurs Guangqi Zhang , Pascale Maillard , Zhun Mao , Loic Brancheriau , Julien Engel , Bastien Gérard , Claire Fortunel , Jean Luc Maeght , Jordi Martínez-Vilalta , Merlin Ramel , Sophie Nourissier-Mountou , Stéphane Fourtier , Alexia Stokes
Publication : BMC Research Notes
Date : 2025
Volume : 15
Issue : 1
Pages : 1–4
Catégorie(s)
#CIRAD #FORET ParacouRésumé
Non-structural carbohydrates (NSC) are considered as indicators of the balance between tree carbon sources and sinks and reflect functional strategies throughout different biomes. However, little is known about the contribution of NSC to tree economics, and in particular, whether leaf, stem and coarse root traits co-ordinate together into a whole-tree economics spectrum. Twenty-four functional traits (including NSC content) were measured in leaves, stem and coarse root xylem of up to 90 angiosperm tree species in temperate, Mediterranean and tropical climates. By performing principal component analysis and standardized major axis regression, we explored the relationships between NSC and other functional traits, as well as the effects of climate and phylogeny on these relationships. Our results revealed a covariation between leaf and coarse root NSC content and leaf economic traits, whereas stem NSC content was largely decoupled from the leaf economics spectrum that was mostly driven by leaf nitrogen content and leaf mass per area. Coarse root xylem traits were closely correlated with leaf traits, while most stem xylem traits were independent from the leaf economics spectrum but covaried with coarse root traits. Trade-offs among traits in tropical species opposed those from other climates. Evolutionary history affected relationships among certain traits but did not change overall patterns. We conclude that due to leaf habit, an extended growing season and heightened defences, tropical species form distinct conservative resource acquisition strategies. Across all climates, as the stem must provide an efficient transport route between roots and leaves, while maintaining the display of branch and leaf organs, stem xylem design and NSC storage capacity lead to a stem economics spectrum that is largely independent from the leaf spectrum, but is coupled with that of coarse roots due to anatomical continuity. Read the free Plain Language Summary for this article on the Journal blog.
Auteurs, date et publication :
Auteurs Guangqi Zhang , Zhun Mao , Pascale Maillard , Loïc Brancheriau , Bastien Gérard , Julien Engel , Claire Fortunel , Patrick Heuret , Jean Luc Maeght , Jordi Martínez-Vilalta , Alexia Stokes
Publication : Functional Ecology
Date : 2025
Catégorie(s)
#CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs Sandra Barantal , Heidy Schimann , Nathalie Fromin , Stephan Hättenschwiler
Publication : Ecosystems
Date : 2012
Volume : 15
Issue : 7
Pages : 1039–1052
Catégorie(s)
#CIRAD #FORET ParacouRésumé
An increase in soil N availability by Acacia mangium in pure or mixed-species stands may reduce soil organic matter (SOM) mineralization compared to eucalypt stands. We measured the isotope composition (δ13C) of coarse particulate organic matter (cPOM, 4–0.25 mm), of fine POM (fPOM, 0.25–0.05 mm) and of the remaining organo-mineral fraction (OMF, <0.05 mm), and of the forest floor in plantations established on a tropical C4-grass savannah. In contrast to our hypothesis, the presence of acacia either alone or in mixture did not impact δ13C of the most stable SOM fractions derived from the previous savannah vegetation, which suggests similar rates of native SOM mineralization under acacia and eucalypt trees.
Auteurs, date et publication :
Auteurs D. Epron , Sogni Viviane Tchichelle , Y. Nouvellon , L. Mareschal , L.-S. Koutika
Publication : European Journal of Soil Biology
Date : 2025
Volume : 76
Pages : 92-94
Catégorie(s)
#CIRAD #FORET Itatinga #INRAEAuteurs, date et publication :
Auteurs Benjamin Brede , Louise Terryn , Nicolas Barbier , Harm M Bartholomeus , Renée Bartolo , Kim Calders , Géraldine Derroire , Sruthi Krishna Moorthy , Alvaro Lau , Shaun R Levick , Pasi Raumonen , Hans Verbeeck , Di Wang , Tim Whiteside , Jens Van Der Zee , Martin Herold
Publication : Remote Sensing of Environment
Date : 2025
Volume : 280
Issue : July
Catégorie(s)
#CIRAD #FORET ParacouRésumé
Mixing N-fixing trees with eucalypts is an attractive option to improve the long-term soil N status in fast-growing plantations established in tropical soils. A randomized block design was replicated at four sites in Brazil to compare the biogeochemical cycles in mono-specific stands of Eucalyptus (100E) and Acacia mangium (100A) with mixed species plantations in a proportion of 1:1 (50A50E). Our study aimed to assess the effects of introducing A. rnangium trees in Eucalyptus plantations on atmospheric N-2 fixation, N cycling and soil organic matter stocks. Litterfall and soil N mineralization were measured over the last two years of the rotation (4-6 years after planting). Aboveground N accumulation in the trees and C and N stocks in the forest floor and in the top soil were intensively sampled at harvesting age. N-2 fixation rates were estimated using the natural abundance of N-15 as well as by the difference between total N stocks in 100A and 50A50E relative to 100E (accretion method). While the N-15 natural abundance method was unsuitable, the accretion method showed consistently across the four sites that atmospheric N fixation reached about 250 and 400 kg N ha(-1) rotation(-1) in 50A50E and 100A, respectively. Except at one site with high mortality, N contents within trees at harvesting were approximately 40% higher in 100A than in 100E. Mean N contents in litterfall and N mineralization rates were about 60% higher in 100A than in 100E, with intermediate values in 50A50E. The amounts of N in litterfall were much more dependent on soil N mineralization rates for acacia trees than for eucalypt trees. Soil C and N stocks were dependent on soil texture but not influenced by tree species. N budgets over a 6-year rotation were enhanced by about 65 kg N ha(-1) yr(-1) in 100A and 40 kg N ha(-1) yr(-1) in 50A50E relative to monospecific eucalypt plantations. Introducing N-fixing trees in eucalypt plantations might therefore contribute to reducing the need for mineral N fertilization in the long-term.
Auteurs, date et publication :
Auteurs M. Voigtlaender , C. B. Brandani , D. R. M. Caldeira , F. Tardy , J. -P. Bouillet , J. L. M. Goncalves , M. Z. Moreira , F. P. Leite , D. Brunet , R. R. Paula , J. -P. Laclau
Publication : FOREST ECOLOGY AND MANAGEMENT
Date : 2019
Volume : 436
Pages : 56-67
Catégorie(s)
#ANR-Citation #CIRAD #FORET ItatingaRésumé
Key message Inter-specific interactions with eucalypts in mixed plantations increased N2 fixation rate of acacia trees compared to monocultures. N2 fixation was higher during the wet summer than during the dry winter both in acacia monocultures and in mixed plantations.
Auteurs, date et publication :
Auteurs Ranieri R. Paula , Jean-Pierre Bouillet , José L. de M. Gonçalves , Paulo C. O. Trivelin , Fabiano de C. Balieiro , Yann Nouvellon , Julianne de C. Oliveira , José C. de Deus Júnior , Bruno Bordron , Jean-Paul Laclau
Publication : Annals of Forest Science
Date : 2025
Volume : 75
Issue : 1