Résumé
Natural rubber is a valuable source of income in many tropical countries and rubber trees are increasingly planted in tropical areas, where they contribute to land-use changes that impact the global carbon cycle. However, little is known about the carbon balance of these plantations. We studied the soil carbon balance of a 15-year-old rubber plantation in Thailand and we specifically explored the seasonal dynamic of soil CO2 efflux (FS) in relation to seasonal changes in soil water content (WS) and soil temperature (TS), assessed the partitioning of FS between autotrophic (RA) and heterotrophic (RH) sources in a root trenching experiment and estimated the contribution of aboveground and belowground carbon inputs to the soil carbon budget. A multiplicative model combining both TS and WS explained 58 % of the seasonal variation of FS. Annual soil CO2 efflux averaged 1.88 kg C m−2 year−1 between May 2009 and April 2011 and RA and RH accounted for respectively 63 and 37 % of FS, after corrections of FS measured on trenched plots for root decomposition and for difference in soil water content. The 4-year average annual aboveground litterfall was 0.53 kg C m−2 year−1 while a conservative estimate of belowground carbon input into the soil was much lower (0.17 kg C m−2 year−1). Our results highlighted that belowground processes (root and rhizomicrobial respiration and the heterotrophic respiration related to belowground carbon input into the soil) have a larger contribution to soil CO2 efflux (72 %) than aboveground litter decomposition.
Auteurs, date et publication :
Auteurs Duangrat Satakhun , Frédéric Gay , Naruenat Chairungsee , Poonpipope Kasemsap , Pisamai Chantuma , Sornprach Thanisawanyangkura , Philippe Thaler , Daniel Epron
Publication : Ecological Research
Date : 2025
Volume : 28
Issue : 6
Pages : 969-979
Catégorie(s)
#CIRAD #FORET RubberfluxRésumé
Soil CO2 flux (Fs) can be measured either manually or automatically. While manual measurements are well suited to capture the spatial variability of Fs, automated measurements are able to capture its temporal variability at fine time scales. The manual method is the most commonly used method to estimate annual carbon budgets. However, such estimates can be biased depending on the measurement frequency, the time at which measurements are made, and the method used to interpolate Fs between two measurements. In this study, we investigated the effects of within-day measurement frequency and of the time of measurement on the estimation of daily Fs. We also investigated the effects on cumulative Fs estimates of weekly and fortnightly sampling frequencies over several months and of the interpolation method used to cumulate Fs. We based our analyses on two complete datasets of automated measurements (one 12-month and one 4-month) recorded in two contrasting ecosystems (a tropical eucalypt plantation and a temperate poplar plantation). Low-frequency time step within a day (every 360 min for the eucalypt and every 180 min for the poplar plantations) was sufficient to capture mean daily Fs accurately. Furthermore, in the tropical site, measurements averaged over any 6h period provided good estimates of the daily flux. By contrast, biases were observed in the temperate site. With one measurement per week, linear interpolation methods provided accurate cumulative fluxes at both sites. However, all interpolation methods failed to produce robust estimates of cumulative Fs in the temperate plantation with one measurement every two weeks. Automated measurements will help to select the best time slot for manual measurements or to correct manual measurements from the apparent deviation between measurements collected during the sampling period and the 24 h-mean CO2 flux. It will also be useful to elaborate empirical equations used to cumulate Fs obtained manually. Combining manual and automated methods will enhance the accuracy of annual soil carbon budgets in forest plantations. (Résumé d'auteur)
Auteurs, date et publication :
Auteurs Cécilia Gana , Yann Nouvellon , Nicolas Marron , Jose Luiz Stape , Daniel Epron
Publication : Journal of Plant Nutrition and Soil Science
Date : 2025
Volume : 181
Issue : 1
Pages : 12-20
Catégorie(s)
#CIRAD #FORET AgroTCR #FORET Itatinga #FORET RubberfluxRésumé
Our knowledge of the rhizosphere bacterial communities in deep soils and the role of Eucalyptus and Acacia on the structure of these communities remains very limited. In this study, we targeted the bacterial community along a depth profile (0 to 800 cm) and compared community structure in monospecific or mixed plantations of Acacia mangium and Eucalyptus grandis. We applied quantitative PCR (qPCR) and sequence the V6 region of the 16S rRNA gene to characterize composition of bacterial communities. We identified a decrease in bacterial abundance with soil depth, and differences in community patterns between monospecific and mixed cultivations. Sequence analysis indicated a prevalent effect of soil depth on bacterial communities in the mixed plant cultivation system, and a remarkable differentiation of bacterial communities in areas solely cultivated with Eucalyptus. The groups most influenced by soil depth were Proteobacteria and Acidobacteria (more frequent in samples between 0 and 300 cm). The predominant bacterial groups differentially displayed in the monospecific stands of Eucalyptus were Firmicutes and Proteobacteria. Our results suggest that the addition of an N2-fixing tree in a monospecific cultivation system modulates bacterial community composition even at a great depth. We conclude that co-cultivation systems may represent a key strategy to improve soil resources and to establish more sustainable cultivation of Eucalyptus in Brazil. (Résumé d'auteur)
Auteurs, date et publication :
Auteurs Arthur Prudêncio de Araujo Pereira , Pedro Avelino Maia de Andrade , Daniel Bini , Ademir Durrer , Agnès Robin , Jean-Pierre Bouillet , Fernando Dini Andreote , Elke Jurandy Bran Nogueira Cardoso
Publication : PloS One
Date : 2025
Volume : 12
Issue : 7
Pages : e0180371 (15 p.)
Catégorie(s)
#CIRAD #FORET Itatinga #FORET Rubberflux #INRAERésumé
The soil microbial activity is a key parameter in numerous studies aiming to assess soil quality in agricultural plots. Basal Soil Respiration (BSR) has been extensively used as an indicator of this soil microbial activity. However, available methods to measure BSR remain time- and labor- consuming and must be performed in the laboratory which may lead to result distortion due to the needed soil pre-treatments. The SituResp® method was developed to assess BSR in a time- and cost-effective way. This method was adapted from a laboratory methodology, the MicroResp™ method, in order to be implemented in the field on fresh soil samples. It is based on the color change of a pH-sensitive gel in reaction to the CO2 concentration change in the headspace of a soil sample over the 24-h incubation. This study presents the calibration and validation of the SituResp® method in laboratory conditions, and a comparison in the field with the Solvita® tool, a comparable method used by agricultural scientists and advisors. The results of the calibration showed a high correlation between the air CO2 concentration and the absorbance variation of the gel at 570 nm (R2 = 0.95). The validation against the titration alkali-trap method, on 21 soil samples, showed a strong correlation between the two methods (R2 = 0.90). In the field test on 9 agricultural-plots, the SituResp® method yielded similar results to the Solvita® tool. The SituResp® method is therefore a reliable method for performing a cheap, rapid but efficient assessment of soil microbial activity in the field which could be included in soil quality monitoring.
Auteurs, date et publication :
Auteurs Alexis Thoumazeau , Frédéric Gay , Pascal Alonso , Nopmanee Suvannang , Audjima Phongjinda , Phantip Panklang , Tiphaine Chevallier , Cécile Bessou , Alain Brauman
Publication : Applied Soil Ecology
Date : 2025
Volume : 121
Pages : 223-230
Catégorie(s)
#CIRAD #FORET Itatinga #FORET RubberfluxRésumé
Although large amounts of potassium (K) are applied in tropical crops and planted forests, little is known about the interaction between K nutrition and water supply regimes on water resources in tropical regions. This interaction is a major issue because climate change is expected to increase the length of drought periods in many tropical regions and soil water availability in deep soil layers is likely to have a major influence on tree growth during dry periods in tropical planted forests. A process-based model (MAESPA) was parameterized in a throughfall exclusion experiment in Brazil to gain insight into the combined effects of K deficiency and rainfall reduction (37% throughfall exclusion) on the water used by the trees, soil water storage and water table fluctuations over the first 4.5 years after planting Eucalyptus grandis trees. A comparison of canopy transpiration in each plot with the values predicted for the same soil with the water content maintained at field capacity, made it possible to calculate a soil-driven tree water stress index for each treatment. Compared to K-fertilized trees with undisturbed rainfall (+K+W), canopy transpiration was 40% lower for K deficiency (−K+W), 20% lower for W deficit (+K−W) and 36% lower for combined K deficiency and W deficit (−K−W) on average. Water was withdrawn in deeper soil layers for −W than for +W, particularly over dry seasons. Under contrasted K availability, water withdrawal was more superficial for −K than for +K. Mean soil water content down to 18 m below surface (mbs) was 24% higher for −K+W than for +K+W from 2 years after planting (after canopy closure), while it was 24% lower for +K−W and 12% lower for −K−W than for +K+W. The soil-driven tree water stress index was 166% higher over the first 4.5 years after planting for −W than for +W, 76% lower for −K than for +K, and 14% lower for −K−W than for +K+W. Over the study period, deep seepage was higher by 371 mm yr−1 (+122%) for −K than for +K and lower by 200 mm yr−1 (−66%) for −W than for +W. Deep seepage was lower by 44% for −K−W than for +K+W. At the end of the study period, the model predicted a higher water table for −K (10 mbs for −K+W and 16 mbs for −K−W) than for +K (16 mbs for +K+W and 18 mbs for +K−W). Our study suggests that flexible fertilization regimes could contribute to adjusting the local trade-off between wood production and demand for soil water resources in planted forests.
Auteurs, date et publication :
Auteurs M. Christina , G. le Maire , Y. Nouvellon , R. Vezy , B. Bordon , P. Battie-Laclau , J.L.M. Gonçalves , J.S. Delgado-Rojas , J.-P. Bouillet , J.-P. Laclau
Publication : Forest Ecology and Management
Date : 2025
Catégorie(s)
#CIRAD #FORET Itatinga #FORET Rubberflux #INRAERésumé
The rapid expansion of perennial crops is a major threat to biodiversity in Southeast Asia. The biodiversity losses related to the conversion of forest lands to oil palm or rubber plantations (RP) are well documented by recent studies. However, the impact of the conversion from intensively managed annual crops to perennial crops on soil biodiversity has not yet been addressed. This study aims at assessing the impact on soil biodiversity of a) the short-term effect of land use conversion from cassava crop to RP, and b) the long-term effect of RP ageing. Soil biodiversity (bacterial, fungal and macrofaunal), microbial activities and pedoclimatic characteristics were measured over a chronosequence of 1–25 years old of RP compared to cassava fields, the former crop, in Thailand. The conversion from cassava to young RP (1–3 yr) had a significant effect on microbial biomass and activities and fungal composition, but did not impact the bacterial and macrofaunal diversity. This effect of land use conversion could be explained by the change in land management due to the cultivation of pineapple in the inter-row of the young RP. Canopy closure appeared to be the main driver of soil biota shifts, as most of the biotic parameters, composition, abundance and activities were significantly modified after 7 years of RP. The changes of composition in older rubber plantations originated from the dominance of Trichoderma (fungi), Firmicutes (bacteria), and earthworms. Old rubber plantations (23–25 yr) harboured the highest microbial and macrofaunal biomass; however, they were also characterised by a significant decrease in bacterial richness. The change in pedoclimatic conditions across the rubber chronosequence, i.e. increase in soil moisture, litter and organic carbon content, was a stronger driver of soil biota evolution than land use conversion. The macrofaunal composition was more resistant to land use conversion than the bacterial composition, whereas the microbial biomass was sensitive to land use conversion, but showed resilience after 20 years. However, bacterial, fungal and macrofaunal diversity, macrofaunal and microbial biomass and microbial activities were all sensitive to RP ageing.
Auteurs, date et publication :
Auteurs Monrawee Peerawat , Aimeric Blaud , Jean Trap , Tiphaine Chevallier , Pascal Alonso , Frederic Gay , Philippe Thaler , Ayme Spor , David Sebag , Chutinan Choosai , Nopmanee Suvannang , Kannika Sajjaphan , Alain Brauman
Publication : Agriculture, Ecosystems & Environment
Date : 2018
Volume : 257
Pages : 92-102
Catégorie(s)
#CIRAD #FORET RubberfluxRésumé
Biofunctool® is a new framework for assessing the impact of land management on soil quality – defined as the capacity of the soil to function. Biofunctool® uses a set of twelve indicators to monitor changes in three key soil functions: carbon transformation, nutrient cycling and structure maintenance (part A). Information from all the indicators is integrated in a Soil Quality Index using multivariate analysis (PCA) weighting. We used Biofunctool® to assess the impact of land use, land use change and agricultural practices on soil quality. The Biofunctool® index was measured for soils in Thailand within rubber plantations, forests and intensive cash crops (cassava and sugar cane). The results demonstrate that the Biofunctool® index provides an aggregated synthetic soil functioning score that is sensitive to land management and is robust in various pedo-climatic contexts. Firstly, the index revealed the impact on soil of land conversion from annual cropping to rubber plantations and ranked the effect on soil with respect to a natural forest reference. Secondly, it showed the positive effect of legume cover-crops on soil functioning. Thirdly, it highlighted a trend of improving soil quality with increasing age of rubber plantations, in contrasted pedo-climatic contexts. It is concluded that the Biofunctool® index is a reliable and relevant descriptor of integrated soil functioning (i.e. soil quality) that could be useful for environmental impact assessment at regional to global scales.
Auteurs, date et publication :
Auteurs Alexis Thoumazeau , Cécile Bessou , Marie-Sophie Renevier , Phantip Panklang , Porntip Puttaso , Monrawee Peerawat , Pusanisa Heepngoen , Prapatsorn Polwong , Nitjaporn Koonklang , Sayan Sdoodee , Pisamai Chantuma , Phrueksa Lawongsa , Prakaijan Nimkingrat , Philippe Thaler , Frédéric Gay , Alain Brauman
Publication : Ecological Indicators
Date : 2019
Volume : 97
Pages : 429-437
Catégorie(s)
#CIRAD #FORET RubberfluxRésumé
The assessment of soil quality is a scientific issue that has been widely debated in the literature for the last twenty years. We developed the Biofunctool® framework to assess soil quality based on an integrative approach that accounts for the link between the physico-chemical properties and the biological activity of soils. Biofunctool® consists in a set of twelve in-field, time- and cost-effective indicators to assess three main soil functions: carbon transformation, nutrient cycling and structure maintenance. The indicators were applied in a network of mostly rubber plantations compared with three other land uses in Thailand. We collected 1952 indicators values in 180 sampling points over a wide range of pedo-climatic and agronomic contexts in order to assess the validity of the indicators. A reliability, redundancy and sensitivity analysis was performed to validate the capacity of the set of indicators to assess the impact of land management on soil quality. The results showed the relevance and consistence of each of the twelve indicators to assess the soil functioning. Improvements are finally discussed to guide further implementation of the indicators in various contexts and build a soil quality index.
Auteurs, date et publication :
Auteurs Alexis Thoumazeau , Cécile Bessou , Marie-Sophie Renevier , Jean Trap , Raphaël Marichal , Louis Mareschal , Thibaud Decaëns , Nicolas Bottinelli , Benoît Jaillard , Tiphaine Chevallier , Nopmanee Suvannang , Kannika Sajjaphan , Philippe Thaler , Frédéric Gay , Alain Brauman
Publication : Ecological Indicators
Date : 2019
Volume : 97
Pages : 100-110
Catégorie(s)
#CIRAD #FORET RubberfluxRésumé
The rapid expansion of rubber tree plantations in recent decades has been accompanied by dramatic negative ecological and social impacts. Rubber sector stakeholders consequently engaged in sustainable production of rubber. Despite the lack of harvest during the immature stage following planting, this period plays a key role in future yields. Management practices, particularly fertilization regimes, are used by farmers to shorten the immature period as much as possible. This entails maintaining or even improving the productivity of existing plantations to face the demand for natural rubber. This review focuses specifically on the immature period of rubber tree plantations, as it is the most critical period for nutrient management. We reviewed available knowledge on fertilization practices, soil management, and nutrient dynamics in rubber plantations with the goal of developing a nutrient balance approach for this crop. Our review revealed (1) a notable difference between fertilizer recommendations made by technical institutes and those reported in the scientific literature; (2) that even though nutrient diagnostic methods could help growers adapt the fertilization of rubber trees more than 3 years of age, further studies are needed to adapt current methods to the wide range of cultivation areas; and (3) that the nutrient budget approach may be the best way to incorporate the variety of rubber tree cultivation conditions. In conclusion, the nutrient budget method is a promising way to improve the sustainability of rubber plantations through fertilization making it possible to increase nutrient use efficiency. A comprehensive approach based on nutrient budgets requires further in-depth studies to examine nutrient dynamics in a wide range of conditions, including intercropping and logging residue management between clearcutting and replanting.
Auteurs, date et publication :
Auteurs Sylvain Vrignon-Brenas
Publication : Agron. Sustain. Dev.
Date : 2025
Pages : 21
Catégorie(s)
#CIRAD #FORET RubberfluxRésumé
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