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4 results on '"Chantuma, Arak"'

1. CO2 and water fluxes over a rubber tree ecosystem

Author

Thaler, Philippe, Siripornpakdeekul, Pongpan, Kasempap, Poonpipope, Kunjet, Summit, Chairungsee, Naruenat, Kositsup, Boonthida, Roupsard, Olivier, Chantuma, Arak, Bonnefond, Jean-Marc, Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad), DORAS Center, Kasetsart University, Kasetsart University (KU), Chachoengsao Rubber Research Center (CRRC), Écologie fonctionnelle et physique de l'environnement (EPHYSE), Institut National de la Recherche Agronomique (INRA), and ProdInra, Migration

Subjects
[SDE] Environmental Sciences, Échange gazeux, [SDV]Life Sciences [q-bio], Plantations, F40 - Ecologie végétale, [SDV] Life Sciences [q-bio], F60 - Physiologie et biochimie végétales, Hevea brasiliensis, eau, Biomasse, [SDE]Environmental Sciences, MESURE, Dioxyde de carbone, Écosystème
Abstract

International audience; In Thailand, rubber is the major tree crop covering more than 2 millions hectares. Its impact on environment, and particularly CO2 balance and water use, is a major issue. A complete flux-measuring system has been installed in a 13 years old tubber plantation (clone RRIM 600) in eastern Thailand (Chachoengsao Rubber Research Center, RRIT-DOA) in 2006. Carbon fluxes of rubber plantation ecosystem are continuously measured by eddy-covariance method (CO2 exchanges between the ecosystem and the atmosphere). Evapo-transpiration (ET) are measured by eddy-covariance and water balance together and partitioned between tree transpiration and soil evaporation. Sapflow is measured by heat dissipation method (Granier 1985, 1987) using home-made 20 mm-long radial probes, continuously heated (0.2 W). Meanwhile, amounts of C stored in the trees are evaluated by measuring biomass increment along the life cycle of the plantation, in combination with estimations of the carbon content of the different compartments. These measurements will provide the annual balance of C within plantations at different ages. Results obtained at ecosystem scale by these methods will be compared to gas exchanges measured at the level of the different compartments (canopy, trunk, root system, soil...). Particularly, Farquhar's photosynthesis model (Farquhar et al. 1980) is parameterized across the canopy. Leaf water potential, sapflow and canopy transpiration are computed to calculate canopy conductivity. Thereby, validated CO2 and H2O fluxes will be used to model gas exchanges of rubber plantation ecosystem according to climate and other environmental parameters as well as crop management.

Published
2007

2. Impact of tapping and soil water status on fine root dynamics in a rubber tree plantation in Thailand

Author

Chairungsee, Naruenat, Gay, Frédéric, Thaler, Philippe, Kasemsap, Poonpipope, Thanisawanyangkura, Sornprach, Chantuma, Arak, Jourdan, Christophe, Chairungsee, Naruenat, Gay, Frédéric, Thaler, Philippe, Kasemsap, Poonpipope, Thanisawanyangkura, Sornprach, Chantuma, Arak, and Jourdan, Christophe

Abstract

Fine roots (FR) play a major role in the water and nutrient uptake of plants and contribute significantly to the carbon and nutrient cycles of ecosystems through their annual production and turnover. FR growth dynamics were studied to understand the endogenous and exogenous factors driving these processes in a 14-year-old plantation of rubber trees located in easternThailand. FR dynamicswere observed using field rhizotrons from October 2007 to October 2009.This period covered two complete dry seasons (November to March) and two complete rainy seasons (April to October), allowing us to study the effect of rainfall seasonality on FR dynamics. Rainfall and its distribution during the two successive years showed strong differences with 1500 and 950 mm in 2008 and 2009, respectively. FR production (FRP) completely stopped during the dry seasons and resumed quickly after the first rains. During the rainy seasons, FRP and the daily root elongation rate (RER)were highly variable and exhibited strong annual variations with a total FRP of 139.8 and 40.4mm?2 and an average RER of 0.16 and 0.12 cm day?1 in 2008 and 2009, respectively. The significant positive correlations found between FRP, RER, the appearance of new roots, and rainfall at monthly intervals revealed the impact of rainfall seasonality on FR dynamics. However, the rainfall patterns failed to explain the weekly variations of FR dynamics observed particularly during the rainy seasons. At this time step, FRP, RER, and the appearance of new FR were negatively correlated to the average soil matric potential measured at a depth of between 30 and 60 cm. In addition, our study revealed a significant negative correlation between FR dynamics and the monthly production of dry rubber. Consequently, latex harvesting might disturb carbon dynamics in the whole tree, far beyond the trunk where the tapping was performed. These results exhibit the impact of climatic conditions and tapping system in the carbon budget of rubber plan

Published
2013

4. Effect of tapping activity on the dynamics of radial growth of Hevea brasiliensis trees.

Author

Silpi, Unakorn, Thaler, Philippe, Kasemsap, Poonpipope, Lacointe, Andre, Chantuma, Arak, Adam, Boris, Gohet, Eric, Thaniswanyankura, Sornprach, and Améglio, Thierry

Subjects
HEVEA, TREE growth, TREE physiology, PLANT metabolism, ETHYLENE content of plants, PLANT stems
Abstract

Rubber tree (Hevea brasiliensis Müll. Arg.) radial growth dynamics were monitored with displacement sensors, together with latex production, to investigate three aspects of the dual production of latex and wood: (1) the usefulness of fine-scale dendrometric measurements as a physiological tool to detect water shortage through radial growth; (2) the dynamic aspects, both at the seasonal and at the multi-year scale, of the competition between latex and wood production; and (3) the spatial distribution of radial growth rates around the tapping cut. Radial growth of untapped control trees started with the onset of the rainy season and lasted until the onset of the dry season, ceasing completely during the driest period. Displacement sensors provided a sensitive means of detecting water shortage, with a clear correlation between diameter variations and changes in water availability (both daily evapotranspiration and monthly rainfall) over the whole annual cycle. However, the correlation was significantly disturbed in tapped trees. After resumption of tapping, the radial growth rate dropped sharply within two weeks and the effect persisted throughout the whole season, so that the cumulative growth of tapped trees was about half that of untapped trees, with the cumulative growth deficit reaching 80% for the period from mid-June to November. This long-known negative impact of tapping on growth was much stronger in the second year of tapping than in the first, whereas latex production increased significantly between the first and second year of tapping. The increased latex production, which could not be ascribed to climatic conditions, shows that the establishment of an artificial latex sink is a progressive, long-term process likely involving many aspects of metabolism. As expected, ethylene significantly increased latex production in both years; however, ethylene had no effect on the growth rates of tapped trees. Radial growth was differentially affected at different locations around the tapping cut, with growth rates significantly lower in the tapped panel than in the untapped panel, and higher above the cut than below the cut. Thus, caution is needed when deriving whole stem wood production from girth measurements at one location on the stem, especially from girth measurements made close to the tapping cut. This also provides new evidence for the location of the latex regeneration area in the tapped panel, below the cut. [ABSTRACT FROM PUBLISHER]

Published
2006
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