Auteurs, date et publication :
Auteurs Vinicius Resende Castro , Paula Gabriella Surdi , Carlos Roberto Sette Junior , Mario Tomazello Filho , Gilles Chaix , Jean Paul Laclau
Publication : Ciência Florestal
Date : 2017
Volume : 27
Issue : 3
Pages : 1017
Catégorie(s)
#CIRAD #FORET Itatinga #INRAERésumé
Considerable areas of forest plantations of fast-growing of eucalyptus in Brazil and in other regions of the world are under the influence of climate change, water stress and low soil fertility, affecting the growth and the quality of the wood from the trees. This study aimed to evaluate the growth of the trunk of Eucalyptus grandis trees for 24 months, evaluating the reduction in rainfall and potassium and sodium nutrition. The treatments were defined by two water treatments (100 and 66% of rainfall, with artificial exclusion with polyethylene sheeting) and three types of nutrition: K (K - 4.5 kmol/ha), Na (Na - 4.5 kmol/ha) and control. 54 eucalyptus trees per treatment were selected and installed with a dendrometric band at DAP height. The results showed the effect of the climatic seasonality in the increase in diameter of the trunk of the tree, with maximum and minimum periods of growth rate and the cambial meristem and, therefore, the measurement of the diameter of the trunk with the dendrometers indicate that the response to a given climatic event is expressed after the period of 15, 30 and up to 45 days. Tree treatments with 100% of rainfall had higher cumulative growth, as well as treatments with application K. The results may be used as subsidies for the adoption of silvicultural practices in forest plantations in areas with water stress, as well as replacement part of K by Na.
Auteurs, date et publication :
Auteurs Vinicius Resende Castro , Paula Gabriella Surdi , Mario Tomazello Filho , Gilles Chaix , Jean Paul Laclau
Publication : Scientia Forestalis
Date : 2017
Volume : 45
Issue : 113
Catégorie(s)
#CIRAD #FORET Itatinga #INRAEAuteurs, date et publication :
Auteurs J.-P. Bouillet , M. Voigtlaender , J.-P. Laclau , J.-L. de Moraes Gonçalves , J.-L. Gava , F. Palha Leite , R. Eiji Hakamada , L. Mareschal , A. Mabiala , Y. Nouvellon
Publication : Série Técnica IPEF
Date : 2025
Volume : 18
Issue : 39
Pages : 26-36
Catégorie(s)
#CIRAD #FORET Itatinga #INRAEAuteurs, date et publication :
Auteurs C.-R. Sette Jr , I.-R. Oliveira , M.-T. Filho , F.-M. Yamajie , J. P. Laclau
Publication : Revista Arvor, Viçosa-MG
Date : 2025
Volume : 36
Pages : 1183-1190
Catégorie(s)
#CIRAD #FORET Itatinga #INRAERésumé
The impact of increases in drought frequency on the Amazon forest's composition, structure and functioning remain uncertain. We used a process‐ and individual‐based ecosystem model (ED2) to quantify the forest's vulnerability to increased drought recurrence. We generated meteorologically realistic, drier‐than‐observed rainfall scenarios for two Amazon forest sites, Paracou (wetter) and Tapajós (drier), to evaluate the impacts of more frequent droughts on forest biomass, structure and composition. The wet site was insensitive to the tested scenarios, whereas at the dry site biomass declined when average rainfall reduction exceeded 15%, due to high mortality of large‐sized evergreen trees. Biomass losses persisted when year‐long drought recurrence was shorter than 2–7 yr, depending upon soil texture and leaf phenology. From the site‐level scenario results, we developed regionally applicable metrics to quantify the Amazon forest's climatological proximity to rainfall regimes likely to cause biomass loss textgreater 20% in 50 yr according to ED2 predictions. Nearly 25% (1.8 million km2) of the Amazon forests could experience frequent droughts and biomass loss if mean annual rainfall or interannual variability changed by 2σ. At least 10% of the high‐emission climate projections (CMIP5/RCP8.5 models) predict critically dry regimes over 25% of the Amazon forest area by 2100.
Auteurs, date et publication :
Auteurs Marcos Longo , Ryan G. Knox , Naomi M. Levine , Luciana F. Alves , Damien Bonal , Plinio B. Camargo , David R. Fitzjarrald , Matthew N. Hayek , Natalia Restrepo-Coupe , Scott R. Saleska , Rodrigo da Silva , Scott C. Stark , Raphael P. Tapajós , Kenia T. Wiedemann , Ke Zhang , Steven C. Wofsy , Paul R. Moorcroft
Publication : New Phytologist
Date : 2018
Catégorie(s)
#CIRAD #FORET ParacouRésumé
1The stoichiometry of resources is increasingly acknowledged as a major control of consumer activity and abundance. Chemical properties of litter, the main source of food for decomposers, are likely to be important drivers of decomposer activity.2Theory predicts a high control of resource stoichiometry on the abundance of consumer organisms that maintain strict homeostasis, due to costs associated with the regulation of nutrient balance in their body tissue. Decomposer efforts in nutrient acquisition should be related to imbalances in resource stoichiometry.3A 21 year old experimental plantation of monospecific plots of trees with leaves of contrasting chemistry was used to test four hypotheses: (i) soil and litter nutrient stoichiometry (C, N, P) are linked; (ii); soil enzyme activity ratios and stoichiometry are linked; (iii) earthworms' tissue stoichiometry does not depend on soil and litter stoichiometry (homeostasis); (iv) earthworm density is dependent upon phosphorus availability, the most limiting nutrient in soils at this site, and, to a lesser extent, to nitrogen availability.4We found (i) no relationship between litter and soil stoichiometry, (ii) microbial activity was linked to soil stoichiometry, (iii) earthworms showed strict homeostasis in their tissue and (iv) earthworm abundance increased with P availability.5We discuss the mechanisms that might lead to these patterns.
Auteurs, date et publication :
Auteurs R. Marichal , J. Mathieu , M.-M. Couteaux , P. Mora , J. Roy , P. Lavelle
Publication : Soil Biology and Biochemistry
Date : 2011
Volume : 43
Issue : 7
Pages : 1528–1535
Catégorie(s)
#CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs J.-P. Laclau , E.-A. da Silva , G. Rodrigues Lambais , M. Bernoux , G. Le Maire , J.-L. Stape , J.-P. Bouillet , J.-L.-M. Goncalves , C. Jourdan , Y. Nouvellon
Publication : Frontiers in Plant Science
Date : 2025
Volume : 4
Pages : 243-243
Catégorie(s)
#CIRAD #FORET Itatinga #INRAERésumé
Climate change is predicted to increase the occurrence of extreme droughts, which are associated with elevated mortality rates in tropical trees. Drought-induced mortality is thought to occur by two main mechanisms: hydraulic failure or carbon starvation . This chapter focuses on the strategies that plants use to survive these two drought-induced mortality mechanisms and how these mechanisms are distributed among the immense diversity of tropical tree species. The traits that tropical trees may use to survive drought include (1) xylem that is resistant to drought-induced cavitation , (2) high sapwood capacitance that protects xylem from critically low water potentials , (3) drought deciduousness, (4) photosynthetic stems that have the potential to assimilate carbon at greater water-use efficiency than leaves, (5) deep roots, (6) regulation of gas exchange to reduce leaf water loss or to maintain photosynthesis at low leaf water potential and (7) when all else fails, low cuticular conductance from exposed tissues during extended drought. To date, most research has focused on deciduousness, resistant xylem, soil water, gas exchange behavior and sapwood capacitance, whereas little is known about the role of photosynthetic stems or cuticular conductance during extreme extended drought, making these processes a high priority for a complete understanding of tropical tree physiology during drought.
Auteurs, date et publication :
Auteurs Louis S. Santiago , Damien Bonal , Mark E. De Guzman , Eleinis Ávila-Lovera , Guillermo Goldstein , Louis S. Santiago
Date : 2025
Pages : 243-258
Catégorie(s)
#CIRAD #FORET ParacouRésumé
1. Amazonian droughts are predicted to become increasingly frequent and intense, and the vulnerability of Amazonian trees has become increasingly documented. However, little is known about the physiological mechanisms and the diversity of drought tolerance of tropical trees due to the lack of quantitative measurements. 2. Leaf water potential at wilting or turgor loss point (πtlp) is a determinant of the tolerance of leaves to drought stress, and contributes to plant-level physiological drought tolerance. Recently, it has been demonstrated that leaf osmotic water potential at full hydration (π0) is tightly correlated with πtlp. Estimating πtlp from osmometer measurements of π0 is much faster than the standard pressure-volume curve approach of πtlp determination. We used this technique to estimate πtlp for 165 trees of 71 species, at three sites within forests in French Guiana. Our dataset represents a significant increase in available data for this trait for tropical tree species. 3. Tropical trees showed a wider range of drought tolerance than previously found in the literature, πtlp ranging from -1.4 to -3.2 MPa. This range likely corresponds in part to adaptation and acclimation to occasionally extreme droughts during the dry season. 4. Leaf-level drought tolerance varied across species, in agreement with the available published observations of species variation in drought-induced mortality. On average, species with a more negative πtlp (i.e., with greater leaf-level drought tolerance) occurred less frequently across the region than drought-sensitive species. 5. Across individuals, πtlp correlated positively but weakly with leaf toughness (R2=0.22, Accepted Article P=0.04) and leaf thickness (R2=0.03, P=0.03). No correlation was detected with other functional traits (leaf mass per area, leaf area, nitrogen or carbon concentrations, carbon isotope ratio, sapwood density or bark thickness). 6. The variability in πtlp among species indicates a potential for highly diverse species responses to drought within given forest communities. Given the weak correlations between πtlp and traditionally measured plant functional traits, vegetation models seeking to predict forest response to drought should integrate improved quantification of comparative drought tolerance among tree species
Auteurs, date et publication :
Auteurs Isabelle Maréchaux , Megan K. Bartlett , Lawren Sack , Christopher Baraloto , Julien Engel , Emilie Joetzjer , Jérôme Chave , Kaoru Kitajima
Publication : Functional Ecology
Date : 2015
Volume : 29
Issue : 10
Pages : 1268–1277
Catégorie(s)
#ANR-Citation #CIRAD #CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Laëtitia Bréchet , Stéphane Ponton , Tancrède Alméras , Damien Bonal , Daniel Epron
Publication : Plant and Soil
Date : 2011
Volume : 347
Issue : 1-2
Pages : 293–303