EcoFoG Papers -- Query Results

Lauth, J., Ruiz-González, M. X., & Orivel, J. (2011). New findings in insect fungiculture: Have ants developed non-food, agricultural products? Comm & Integr Biol, 4(1942-0889), 728–730. Abstract: The interaction between Allomerus plant-ants and an ascomycete fungus growing on and strengthening their galleries is not opportunistic. We previously demonstrated that this association is highly specific as only one fungal species represented by a few haplotypes was found associated with the ants. We also discovered that the ants' behavior revealed a major investment in manipulating and enhancing the growth of their associated fungus. We have growing evidence that this specificity is consistent with selection by the ants. Here, we discuss this selection within the framework of insect agriculture, as we believe these ants fulfill all of the prerequisites to be considered as farmers. Allomerus ants promote their symbiont's growth, protect it from potential pathogens and select specific cultivars. Taken together, we think that the interaction between Allomerus ants and their cultivar might represent the first case of insect fungiculture used as a means of obtaining building material. http://php.ecofog.gf/refbase/show.php?record=379
Schepaschenko, D., Chave, J., Phillips, O. L., Lewis, S. L., Davies, S. J., Réjou-Méchain, M., et al. (2019). The Forest Observation System, building a global reference dataset for remote sensing of forest biomass. Scientific data, 6(198). Abstract: Forest biomass is an essential indicator for monitoring the Earth's ecosystems and climate. It is a critical input to greenhouse gas accounting, estimation of carbon losses and forest degradation, assessment of renewable energy potential, and for developing climate change mitigation policies such as REDD+, among others. Wall-to-wall mapping of aboveground biomass (AGB) is now possible with satellite remote sensing (RS). However, RS methods require extant, up-to-date, reliable, representative and comparable in situ data for calibration and validation. Here, we present the Forest Observation System (FOS) initiative, an international cooperation to establish and maintain a global in situ forest biomass database. AGB and canopy height estimates with their associated uncertainties are derived at a 0.25 ha scale from field measurements made in permanent research plots across the world's forests. All plot estimates are geolocated and have a size that allows for direct comparison with many RS measurements. The FOS offers the potential to improve the accuracy of RS-based biomass products while developing new synergies between the RS and ground-based ecosystem research communities. http://php.ecofog.gf/refbase/show.php?record=889
Jaouen, G., Fournier, M., & Almeras, T. (2010). Thigmomorphogenesis versus light in biomechanical growth strategies of saplings of two tropical rain forest tree species. Ann. For. Sci., 67(2), 211. Abstract: In the dense tropical rainforest understorey, saplings exhibit different growth strategies aiming at reaching light levels better fitting their ecology. Investing mainly in height growth, at the expense of their width, a lot are close to mechanical instability. Tachigali melinonii, a long living heliophilic tree species, is frequently observed to be extremely slender and supported by neighbours. Such observations suggest an active growth control through the perception of mechanical environment. Mechanical environment or light availability, which one is the most influent on growth and slenderness (H/D)? To test this question, we recorded growth of control and staked saplings of two species with contrasting habits and ecology: T. melinonii, and Dicorynia guianensis, along a natural light gradient. Dicorynia, the more stable, responded more clearly to the staking treatment, showing slenderness increase when light is available, whereas for Tachigali, only light availability governed growth. For Tachigali, growth allocation is mainly governed by light availability and ontogeny, whereas Dicorynia is probably similar to the average tree strategy, using the thigmomorphogenetic physiological process to control its stability. Keywords: biomechanics; thigmomorphogenesis; height growth strategies; tropical rain forest; French Guiana http://php.ecofog.gf/refbase/show.php?record=61
Freycon, V., Krencker, M., Schwartz, D., Nasi, R., & Bonal, D. (2010). The impact of climate changes during the Holocene on vegetation in northern French Guiana. Quat. Res., 73(2), 220–225. Abstract: The impact of climatic changes that occurred during the last glacial maximum and the Holocene on vegetation changes in the Amazon Basin and the Guiana Shield are still widely debated. The aim of our study was to investigate whether major changes in vegetation (i.e. transitions between rainforests and C-4 savannas) occurred in northern French Guiana during the Holocene. We measured variations in the delta C-13 of soil organic matter at eight sites now occupied by forest or savannah. The forest sites were selected to cover two regions (forest refugia and peneplains) which are thought to have experienced different intensities of disturbance during the latest Pleistocene and the Holocene. We found that none of the forest sites underwent major disturbances during the Holocene, i.e. they were not replaced by C-4 savannahs or C-4 forest savannahs for long periods. Our results thus suggest that tropical rainforests in northern French Guiana were resilient to drier climatic conditions during the Holocene. Nevertheless, geographical and vertical variations in the C-13 of SOM were compatible with minor changes in vegetation, variations in soil processes or in soil physical properties. (C) 2009 University of Washington. Published by Elsevier Inc. All rights reserved. Keywords: Holocene; Vegetation change; French Guiana; Carbon isotope composition; Soil organic matter http://php.ecofog.gf/refbase/show.php?record=66
Royer, M., Stien, D., Beauchene, J., Herbette, G., McLean, J. P., Thibaut, A., et al. (2010). Extractives of the tropical wood wallaba (Eperua falcata Aubl.) as natural anti-swelling agents. Holzforschung, 64(2), 211–215. Abstract: Wallaba (Eperua falcata) is a tropical wood that is known to have naturally high moisture related dimensional stability. Samples of wallaba heartwood were subjected to differential solvent extraction. Wood pieces that were extracted with methanol showed significantly greater swelling following rehydration from oven dry to 96% relative humidity than non- extracted samples and samples extracted with other solvents. Methanol soluble wallaba heartwood extract was purified by HPLC and the compounds present were characterized by NMR spectroscopy. The structure of 13 compounds in methanol extract was identified. The relative proportion of polar compounds in methanol extract was found to be high. The compounds identified are proposed to bind to the polymeric cell wall by means of multiple hydrogen bonds restricting the association of water and therefore act as natural anti-swelling agents. http://php.ecofog.gf/refbase/show.php?record=307
Scotti, I., Calvo-Vialettes, L., Scotti-Saintagne, C., Citterio, M., Degen, B., & Bonal, D. (2010). Genetic variation for growth, morphological, and physiological traits in a wild population of the Neotropical shade tolerant rainforest tree Sextonia rubra (Mez) van der Werff (Lauraceae). Tree Genet. Genomes, 6(2), 319–329. Abstract: Quantitative genetic diversity is a fundamental component of the interaction between natural populations and their environment. In breeding programmes, quantitative genetic studies on tropical trees have so far focused on fast-growing, light-demanding species, but no information exists on shade-tolerant, slow-growing species. For this study, 27 3-year-old open-pollinated families of the Neotropical shade-tolerant rainforest tree Sextonia rubra were measured in semicontrolled conditions for 20 morphological, growth, and photosynthesis traits; the effect of genetic relatedness, habitat of provenance, and mother tree status on seedling traits was analysed. Nine traits displayed significant genetic effects, while mother tree status and habitat effects were not significant (P > 0.05) for an y trait. Estimated heritability varied between 0.14 and 0.28, with growth-related traits having the highest values. Additive genetic variation correlated positively with nonheritable variation, suggesting that ecological-evolutionary factors increasing or decreasing additive genetic variance may also affect nonheritable variation in the same direction. Our results suggest that quantitative genetic variability should be taken into account in ecological studies on, and in the management of, natural tropical rainforests; further research is needed to investigate genetic x environment interactions, in particular from the point of view of the genetic response of shade-tolerant plant species to variations in light availability. Keywords: Ecophysiological traits; Heritability; Guiana shield; Amazon; Ecological genetics http://php.ecofog.gf/refbase/show.php?record=68
Schwalm, C. R., Williams, C. A., Schaefer, K., Arneth, A., Bonal, D., Buchmann, N., et al. (2010). Assimilation exceeds respiration sensitivity to drought: A FLUXNET synthesis. Glob. Change Biol., 16(2), 657–670. Abstract: The intensification of the hydrological cycle, with an observed and modeled increase in drought incidence and severity, underscores the need to quantify drought effects on carbon cycling and the terrestrial sink. FLUXNET, a global network of eddy covariance towers, provides dense data streams of meteorological data, and through flux partitioning and gap filling algorithms, estimates of net ecosystem productivity (F-NEP), gross ecosystem productivity (P), and ecosystem respiration (R). We analyzed the functional relationship of these three carbon fluxes relative to evaporative fraction (EF), an index of drought and site water status, using monthly data records from 238 micrometeorological tower sites distributed globally across 11 biomes. The analysis was based on relative anomalies of both EF and carbon fluxes and focused on drought episodes by biome and climatic season. Globally P was approximate to 50% more sensitive to a drought event than R. Network-wide drought-induced decreases in carbon flux averaged -16.6 and -9.3 g C m-2 month-1 for P and R, i.e., drought events induced a net decline in the terrestrial sink. However, in evergreen forests and wetlands drought was coincident with an increase in P or R during parts of the growing season. The most robust relationships between carbon flux and EF occurred during climatic spring for F-NEP and in climatic summer for P and R. Upscaling flux sensitivities to a global map showed that spatial patterns for all three carbon fluxes were linked to the distribution of croplands. Agricultural areas exhibited the highest sensitivity whereas the tropical region had minimal sensitivity to drought. Combining gridded flux sensitivities with their uncertainties and the spatial grid of FLUXNET revealed that a more robust quantification of carbon flux response to drought requires additional towers in all biomes of Africa and Asia as well as in the cropland, shrubland, savannah, and wetland biomes globally. Keywords: biome; carbon cycling; drought; eddy covariance; evaporative fraction; FLUXNET; synthesis http://php.ecofog.gf/refbase/show.php?record=69
Coutand, C., Chevolot, M., Lacointe, A., Rowe, N., & Scotti, I. (2010). Mechanosensing of stem bending and its interspecific variability in five neotropical rainforest species. Ann. Bot., 105(2), 341–347. Abstract: In rain forests, sapling survival is highly dependent on the regulation of trunk slenderness (height/diameter ratio): shade-intolerant species have to grow in height as fast as possible to reach the canopy but also have to withstand mechanical loadings (wind and their own weight) to avoid buckling. Recent studies suggest that mechanosensing is essential to control tree dimensions and stability-related morphogenesis. Differences in species slenderness have been observed among rainforest trees; the present study thus investigates whether species with different slenderness and growth habits exhibit differences in mechanosensitivity. Recent studies have led to a model of mechanosensing (sum-of-strains model) that predicts a quantitative relationship between the applied sum of longitudinal strains and the plant's responses in the case of a single bending. Saplings of five different neotropical species (Eperua falcata, E. grandiflora, Tachigali melinonii, Symphonia globulifera and Bauhinia guianensis) were subjected to a regimen of controlled mechanical loading phases (bending) alternating with still phases over a period of 2 months. Mechanical loading was controlled in terms of strains and the five species were subjected to the same range of sum of strains. The application of the sum-of-strain model led to a dose-response curve for each species. Dose-response curves were then compared between tested species. The model of mechanosensing (sum-of-strain model) applied in the case of multiple bending as long as the bending frequency was low. A comparison of dose-response curves for each species demonstrated differences in the stimulus threshold, suggesting two groups of responses among the species. Interestingly, the liana species B. guianensis exhibited a higher threshold than other Leguminosae species tested. This study provides a conceptual framework to study variability in plant mechanosensing and demonstrated interspecific variability in mechanosensing. Keywords: Mechanosensing; interspecific variability; trees; lianas; rain forest; neotropical species; bending; biomechanics; Bauhinia; Eperua; Symphonia; Tachigali http://php.ecofog.gf/refbase/show.php?record=71
Vedel, V., & Scotti, I. (2011). Promoting the promoter. Plant Sci., 180(2), 182–189. Abstract: Recent evolutionary studies clearly indicate that evolution is mainly driven by changes in the complex mechanisms of gene regulation and not solely by polymorphism in protein-encoding genes themselves. After a short description of the cis-regulatory mechanism, we intend in this review to argue that by applying newly available technologies and by merging research areas such as evolutionary and developmental biology, population genetics, ecology and molecular cell biology it is now possible to study evolution in an integrative way. We contend that, by analysing the effects of promoter sequence variation on phenotypic diversity in natural populations, we will soon be able to break the barrier between the study of extant genetic variability and the study of major developmental changes. This will lead to an integrative view of evolution at different scales. Because of their sessile nature and their continuous development, plants must permanently regulate their gene expression to react to their environment, and can, therefore, be considered as a remarkable model for these types of studies. (C) 2010 Elsevier Ireland Ltd. All rights reserved. Keywords: cis-Regulation; Evolutionary and developmental biology; Integrative evolution; Plant development; Population genetics; Transcription http://php.ecofog.gf/refbase/show.php?record=291
Foucaud, J., Estoup, A., Loiseau, A., Rey, O., & Orivel, J. (2010). Thelytokous parthenogenesis, male clonality and genetic caste determination in the little fire ant: new evidence and insights from the lab. Heredity, 105(2), 205–212. Abstract: Previous studies indicate that some populations of the little fire ant, Wasmannia auropunctata, display an unusual reproduction system polymorphism. Although some populations have a classical haplodiploid reproduction system, in other populations queens are produced by thelytokous parthenogenesis, males are produced by a male clonality system and workers are produced sexually. An atypical genetic caste determination system was also suggested. However, these conclusions were indirectly inferred from genetic studies on field population samples. Here we set up experimental laboratory nests that allow the control of the parental relationships between individuals. The queens heading those nests originated from either putatively clonal or sexual populations. We characterized the male, queen and worker offspring they produced at 12 microsatellite loci. Our results unambiguously confirm the unique reproduction system polymorphism mentioned above and that male clonality is strictly associated with thelytokous parthenogenesis. We also observed direct evidence of the rare production of sexual gynes and arrhenotokous males in clonal populations. Finally, we obtained evidence of a genetic basis for caste determination. The evolutionary significance of the reproduction system polymorphism and genetic caste determination as well as future research opportunities are discussed. Heredity (2010) 105, 205-212; doi: 10.1038/hdy.2009.169; published online 25 November 2009 Keywords: reproduction system; thelytokous parthenogenesis; male clonality; genetic caste determination; Wasmannia auropunctata http://php.ecofog.gf/refbase/show.php?record=78

Lauth, J., Ruiz-González, M. X., & Orivel, J. (2011). New findings in insect fungiculture: Have ants developed non-food, agricultural products? Comm & Integr Biol, 4(1942-0889), 728–730.

Schepaschenko, D., Chave, J., Phillips, O. L., Lewis, S. L., Davies, S. J., Réjou-Méchain, M., et al. (2019). The Forest Observation System, building a global reference dataset for remote sensing of forest biomass. Scientific data, 6(198).

Jaouen, G., Fournier, M., & Almeras, T. (2010). Thigmomorphogenesis versus light in biomechanical growth strategies of saplings of two tropical rain forest tree species. Ann. For. Sci., 67(2), 211.

Freycon, V., Krencker, M., Schwartz, D., Nasi, R., & Bonal, D. (2010). The impact of climate changes during the Holocene on vegetation in northern French Guiana. Quat. Res., 73(2), 220–225.

Royer, M., Stien, D., Beauchene, J., Herbette, G., McLean, J. P., Thibaut, A., et al. (2010). Extractives of the tropical wood wallaba (Eperua falcata Aubl.) as natural anti-swelling agents. Holzforschung, 64(2), 211–215.

Scotti, I., Calvo-Vialettes, L., Scotti-Saintagne, C., Citterio, M., Degen, B., & Bonal, D. (2010). Genetic variation for growth, morphological, and physiological traits in a wild population of the Neotropical shade tolerant rainforest tree Sextonia rubra (Mez) van der Werff (Lauraceae). Tree Genet. Genomes, 6(2), 319–329.

Schwalm, C. R., Williams, C. A., Schaefer, K., Arneth, A., Bonal, D., Buchmann, N., et al. (2010). Assimilation exceeds respiration sensitivity to drought: A FLUXNET synthesis. Glob. Change Biol., 16(2), 657–670.

Abstract: The intensification of the hydrological cycle, with an observed and modeled increase in drought incidence and severity, underscores the need to quantify drought effects on carbon cycling and the terrestrial sink. FLUXNET, a global network of eddy covariance towers, provides dense data streams of meteorological data, and through flux partitioning and gap filling algorithms, estimates of net ecosystem productivity (F-NEP), gross ecosystem productivity (P), and ecosystem respiration (R). We analyzed the functional relationship of these three carbon fluxes relative to evaporative fraction (EF), an index of drought and site water status, using monthly data records from 238 micrometeorological tower sites distributed globally across 11 biomes. The analysis was based on relative anomalies of both EF and carbon fluxes and focused on drought episodes by biome and climatic season. Globally P was approximate to 50% more sensitive to a drought event than R. Network-wide drought-induced decreases in carbon flux averaged -16.6 and -9.3 g C m-2 month-1 for P and R, i.e., drought events induced a net decline in the terrestrial sink. However, in evergreen forests and wetlands drought was coincident with an increase in P or R during parts of the growing season. The most robust relationships between carbon flux and EF occurred during climatic spring for F-NEP and in climatic summer for P and R. Upscaling flux sensitivities to a global map showed that spatial patterns for all three carbon fluxes were linked to the distribution of croplands. Agricultural areas exhibited the highest sensitivity whereas the tropical region had minimal sensitivity to drought. Combining gridded flux sensitivities with their uncertainties and the spatial grid of FLUXNET revealed that a more robust quantification of carbon flux response to drought requires additional towers in all biomes of Africa and Asia as well as in the cropland, shrubland, savannah, and wetland biomes globally.

Keywords: biome; carbon cycling; drought; eddy covariance; evaporative fraction; FLUXNET; synthesis

http://php.ecofog.gf/refbase/show.php?record=69

Coutand, C., Chevolot, M., Lacointe, A., Rowe, N., & Scotti, I. (2010). Mechanosensing of stem bending and its interspecific variability in five neotropical rainforest species. Ann. Bot., 105(2), 341–347.

Abstract: In rain forests, sapling survival is highly dependent on the regulation of trunk slenderness (height/diameter ratio): shade-intolerant species have to grow in height as fast as possible to reach the canopy but also have to withstand mechanical loadings (wind and their own weight) to avoid buckling. Recent studies suggest that mechanosensing is essential to control tree dimensions and stability-related morphogenesis. Differences in species slenderness have been observed among rainforest trees; the present study thus investigates whether species with different slenderness and growth habits exhibit differences in mechanosensitivity. Recent studies have led to a model of mechanosensing (sum-of-strains model) that predicts a quantitative relationship between the applied sum of longitudinal strains and the plant's responses in the case of a single bending. Saplings of five different neotropical species (Eperua falcata, E. grandiflora, Tachigali melinonii, Symphonia globulifera and Bauhinia guianensis) were subjected to a regimen of controlled mechanical loading phases (bending) alternating with still phases over a period of 2 months. Mechanical loading was controlled in terms of strains and the five species were subjected to the same range of sum of strains. The application of the sum-of-strain model led to a dose-response curve for each species. Dose-response curves were then compared between tested species. The model of mechanosensing (sum-of-strain model) applied in the case of multiple bending as long as the bending frequency was low. A comparison of dose-response curves for each species demonstrated differences in the stimulus threshold, suggesting two groups of responses among the species. Interestingly, the liana species B. guianensis exhibited a higher threshold than other Leguminosae species tested. This study provides a conceptual framework to study variability in plant mechanosensing and demonstrated interspecific variability in mechanosensing.

Keywords: Mechanosensing; interspecific variability; trees; lianas; rain forest; neotropical species; bending; biomechanics; Bauhinia; Eperua; Symphonia; Tachigali

http://php.ecofog.gf/refbase/show.php?record=71

Vedel, V., & Scotti, I. (2011). Promoting the promoter. Plant Sci., 180(2), 182–189.

Foucaud, J., Estoup, A., Loiseau, A., Rey, O., & Orivel, J. (2010). Thelytokous parthenogenesis, male clonality and genetic caste determination in the little fire ant: new evidence and insights from the lab. Heredity, 105(2), 205–212.