Résumé
We tested the hypothesis that trees have measurable effects on infiltrability, macroporosity, and pref- erential flows in agrosilvopastoral systems. Managing agricultural systems for water conservation is a critical component of sustainable systems. We investigated the relationship between infiltrability and the distance to the nearest tree, and whether differences in macroporosity can account for differences in infiltrability. In both systems, preferential soil water flows were dominant compared to matrix flow. Trees in the pasture landscape improved infiltrability and preferential flow but had no significant effect in the coffee agroforestry system. After comparing rainfall intensity and frequency data to the measured infiltrability values, we conclude that trees in the pasture system reduce surface runoff at the highest observed rainfall intensities (>50 mm h − 1 ). The volcanic soils of the coffee plantation are less degraded and their high natural permeability has been maintained. Since the coffee plants at this site are established (40 years) perennial vegetation with substantial residues and extensive root systems like trees, they improve soil physical properties similarly to trees. Trees increase hydrologic services in pasture lands, a rapidly expanding land use type across Latin America, and therefore may be a viable land management option for mitigating some of the negative environmental impacts associated with land clearing and animal husbandry. However, in land manage- ment practices where understorey perennial vegetation makes up a large proportion of the cover, such as for coffee agroforestry systems, the effect of trees on infiltration-related ecosystem services could be less pronounced
Auteurs, date et publication :
Auteurs L. Benegas , U. Ilstedt , O. Roupsard , J. Jones , A. Malmer
Publication : Agriculture, Ecosystems & Environment
Date : 2025
Volume : 183
Pages : 185-196
Catégorie(s)
#CIRAD #FORET CoffeeFluxRésumé
A basic understanding of nutrition effects on the mechanisms involved in tree response to drought is essential under a future drier climate. A large-scale throughfall exclusion experiment was set up in Brazil to gain an insight into the effects of potassium (K) and sodium (Na) nutrition on tree structural and physiological adjustments to water deficit. Regardless of the water supply, K and Na supply greatly increased growth and leaf area index (LAI) of Eucalyptus grandis trees over the first 3yr after planting. Excluding 37% of throughfall reduced above-ground biomass accumulation in the third year after planting for K- supplied trees only. E.grandis trees were scarcely sensitive to drought as a result of the utilization of water stored in deep soil layers after clear-cutting the previous plantation. Trees coped with water restriction through stomatal closure (isohydrodynamic behavior), osmotic adjustment and decrease in LAI. Additionally, droughted trees showed higher phloem sap sugar concentrations. K and Na supply increased maximum stomatal conductance, and the high water requirements of fertilized trees increased water stress during dry periods. Fertilization regimes should be revisited in a future drier climate in order to find the right balance between improving tree growth and limiting water shortage.
Auteurs, date et publication :
Auteurs P. Battie-Laclau , J.-P. Laclau , J.-C. Domec , M. Christina , J.-P. Bouillet , M.-C. Piccolo , J.-L. de Moraes Goncalves , R. Moreira e Moreira , A.-V. Krusche , J.-M. Bouvet , Y. Nouvellon
Publication : New Phytologist
Date : 2014
Volume : 203
Issue : 2
Pages : 401-413
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 #INRAEAuteurs, 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
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
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