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Fromin, N.; Porte, B.; Lensi, R.; Hamelin, J.; Domenach, A.-M.; Buatois, B.; Roggy, J.-C. |
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Spatial variability of the functional stability of microbial respiration process: A microcosm study using tropical forest soil |
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2012 |
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Journal of Soils and Sediments |
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J. Soils Sed. |
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12 |
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7 |
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1030-1039 |
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Disturbance; Diversity-stability relationship; Microbial diversity; Substrate-induced respiration |
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Purpose: Understanding the ability of ecosystem processes to resist to and to recover from disturbances is critical to sustainable land use. However, the spatial variability of the stability has rarely been addressed. Here, we investigated the functional stability of a soil microbial process for 24 soils collected from adjacent locations from a 0. 3 ha tropical rainforest plot in Paracou, French Guiana. Materials and methods: The 24 locations were characterized regarding soil chemical and biological (microbial diversity) parameters and forest structure. The corresponding soils were submitted to an experimental transient heat disturbance during a microcosm experiment. The response of the respiration process was followed using substrate-induced respiration (SIR). Results and discussion: The response of soil SIR to heat disturbance varied widely between samples. The variability of the SIR response increased just after the disturbance, and a global rather homogeneous decrease in SIR rates was observed 15 and 30 days after. The stability of SIR in response to heat disturbance could not be related to either the genetic or the metabolic diversity of the microbial community. The initial level of SIR before the disturbance was the soil variable that best correlated with the impact of the disturbance: the soil locations with the highest initial SIR rates were the most affected 15 and 30 days after the heat disturbance. Conclusions: Such a heterogeneous response suggests that the response of soil processes to a disturbance will be difficult to assess from only local-scale analyses and highlights the need for spatial explicitness in understanding biogeochemical processes. © 2012 Springer-Verlag. |
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UMR EcoFoG, BP 709, 97387 Kourou, French Guiana |
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Export Date: 30 July 2012; Source: Scopus; doi: 10.1007/s11368-012-0528-7; Language of Original Document: English; Correspondence Address: Fromin, N.; CEFE, CNRS UMR 5175, 1919 Route de Mende, 34293 Montpellier cedex 5, France; email: nathalie.fromin@cefe.cnrs.fr |
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EcoFoG @ webmaster @ |
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415 |
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Fromin, N.; Saby, N.P.A.; Lensi, R.; Brunet, D.; Porte, B.; Domenach, A.-M.; Roggy, J.-C. |
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Spatial variability of soil microbial functioning in a tropical rainforest of French Guiana using nested sampling |
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2013 |
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Geoderma |
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197-198 |
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98-107 |
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Denitrification; Respiration; Scale dependent process; Soil microbial processes; Soil organic matter; Tree influence potential |
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Understanding the pattern in spatial distribution of soil microbial processes is critical to understand the environmental factors that regulate them as well as to scale up these processes to ecosystem. Soil samples from a 1. ha tropical rainforest plot (Paracou, French Guiana) were analyzed according a nested sampling approach using different separation distances ranging from 0.4 to 40. m. The variability of substrate induced respiration (SIR) and of denitrification enzyme activity (DEA) was characterized in relation to various soil properties (total C and N contents, NIRS related index of soil organic matter quality, SOMQ, and index of tree influence potential, IP). The variability of SIR and DEA was higher than that of environmental properties. The patterns of accumulated variance as a function of distance varied among the soil properties. The variability of SIR and DEA mainly occurred at small (1. m) scale (and at the 10-40. m-scales for SIR), probably reflecting the quality of litter input that results of the influence of local assemblage of different tree species, though changes in the soil N and C contents. Indeed, total soil C and N contents explained the microbial properties at every scale. Coefficients of codispersion showed that neither SOMQ nor IP did correlate with SIR and DEA, and confirmed that total C and N contents explained microbial properties in a scale dependent and complex manner. Such spatial dependency underlines the importance of soil heterogeneity in this tropical forest with implications for sampling strategies when studying the microbial processes and their response to disturbances. © 2012 Elsevier B.V. |
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UMR EcoFoG, BP 709, 97387 Kourou, GUF, France |
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Export Date: 13 February 2013; Source: Scopus |
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EcoFoG @ webmaster @ |
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466 |
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Guitet, S.; Herault, B.; Molto, Q.; Brunaux, O.; Couteron, P. |
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Spatial structure of above-ground biomass limits accuracy of carbon mapping in rainforest but large scale forest inventories can help to overcome |
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2015 |
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PLoS ONE |
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PLoS ONE |
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10 |
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9 |
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e0138456 |
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Precise mapping of above-ground biomass (AGB) is a major challenge for the success of REDD+ processes in tropical rainforest. The usual mapping methods are based on two hypotheses: a large and long-ranged spatial autocorrelation and a strong environment influence at the regional scale. However, there are no studies of the spatial structure of AGB at the landscapes scale to support these assumptions.We studied spatial variation in AGB at various scales using two large forest inventories conducted in French Guiana. The dataset comprised 2507 plots (0.4 to 0.5 ha) of undisturbed rainforest distributed over the whole region. After checking the uncertainties of estimates obtained from these data, we used half of the dataset to develop explicit predictive models including spatial and environmental effects and tested the accuracy of the resulting maps according to their resolution using the rest of the data. Forest inventories provided accurate AGB estimates at the plot scale, for a mean of 325 Mg.ha-1. They revealed high local variability combined with a weak autocorrelation up to distances of no more than10 km. Environmental variables accounted for a minor part of spatial variation. Accuracy of the best model including spatial effects was 90 Mg.ha-1 at plot scale but coarse graining up to 2-km resolution allowed mapping AGB with accuracy lower than 50 Mg.ha-1. Whatever the resolution, no agreement was found with available pan-tropical reference maps at all resolutions.We concluded that the combined weak autocorrelation and weak environmental effect limit AGB maps accuracy in rainforest, and that a trade-off has to be found between spatial resolution and effective accuracy until adequate “wall-to-wall” remote sensing signals provide reliable AGB predictions. Waiting for this, using large forest inventories with low sampling rate (<0.5%) may be an efficient way to increase the global coverage of AGB maps with acceptable accuracy at kilometric resolution. Copyright: © 2015 Guitet et al. |
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Institut de Recherche Pour le Développement (IRD), UMR Amap, Montpellier, France |
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Export Date: 25 November 2015 |
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EcoFoG @ webmaster @ |
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639 |
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Dejean, A.; Fisher, B.L.; Corbara, B.; Rarevohitra, R.; Randrianaivo, R.; Rajemison, B.; Leponce, M. |
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Spatial Distribution of Dominant Arboreal Ants in a Malagasy Coastal Rainforest: Gaps and Presence of an Invasive Species |
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2010 |
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PLoS One |
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PLoS One |
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5 |
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2 |
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e9319 |
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We conducted a survey along three belt transects located at increasing distances from the coast to determine whether a non-random arboreal ant assemblage, such as an ant mosaic, exists in the rainforest on the Masoala Peninsula, Madagascar. In most tropical rainforests, very populous colonies of territorially dominant arboreal ant species defend absolute territories distributed in a mosaic pattern. Among the 29 ant species recorded, only nine had colonies large enough to be considered potentially territorially dominant; the remaining species had smaller colonies and were considered non-dominant. Nevertheless, the null-model analyses used to examine the spatial structure of their assemblages did not reveal the existence of an ant mosaic. Inland, up to 44% of the trees were devoid of dominant arboreal ants, something not reported in other studies. While two Crematogaster species were not associated with one another, Brachymyrmex cordemoyi was positively associated with Technomyrmex albipes, which is considered an invasive species-a non-indigenous species that has an adverse ecological effect on the habitats it invades. The latter two species and Crematogaster ranavalonae were mutually exclusive. On the other hand, all of the trees in the coastal transect and at least 4 km of coast were occupied by T. albipes, and were interconnected by columns of workers. Technomyrmex albipes workers collected from different trees did not attack each other during confrontation tests, indicating that this species has formed a supercolony along the coast. Yet interspecific aggressiveness did occur between T. albipes and Crematogaster ranavalonae, a native species which is likely territorially dominant based on our intraspecific confrontation tests. These results suggest that the Masoala rainforest is threatened by a potential invasion by T. albipes, and that the penetration of this species further inland might be facilitated by the low density of native, territorially dominant arboreal ants normally able to limit its progression. |
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[Dejean, Alain] CNRS, Unite Mixte Rech 8172, Kourou, France, Email: alain.dejean@wanadoo.fr |
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PUBLIC LIBRARY SCIENCE |
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1932-6203 |
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ISI:000274923700021 |
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EcoFoG @ eric.marcon @ |
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81 |
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Leponce, Maurice ; Corbara, Bruno ; Delabie, Jacques H.C. ; Orivel, Jérome ; Aberlenc, Henri-Pierre ; Bail, Johannes ; Barrios, Hector ; Campos, Ricardo I. ; Cardoso do Nascimento, Ivan ; Compin, Arthur ; Didham, Raphaël K. ; Floren, Andreas ; Medianero, Enrique ; Ribeiro, Sérvio P. ; Roisin, Yves ; Schmidl, Juergen ; Tishechkin, Alexey K. ; Winchester, Neville N. ; Basset, Yves ; Dejean, Alain |
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Spatial and functional structure of an entire ant assemblage in a lowland Panamanian rainforest |
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2021 |
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Basic and Applied |
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56 |
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32-44 |
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Ants are a major ecological group in tropical rainforests. Few studies in the Neotropics have documented the distribution of ants from the ground to the canopy, and none have included the understorey. A previous analysis of an intensive arthropod study in Panama, involving 11 sampling methods, showed that the factors influencing ant β diversity (i.e., changes in assemblage composition) were, in decreasing order of importance, the vertical (height), temporal (season), and horizontal (geographic distance) dimensions. In the present study, we went one step further and aimed (1) to identify the best sampling methods to study the entire ant assemblage across the three strata, (2) to test if all strata show a similar horizontal β diversity and (3) to analyze the functional structure of the entire ant assemblage. We identified 405 ant species from 11 subfamilies and 68 genera. Slightly more species were sampled in the canopy than on the ground; they belonged to distinct sub-assemblages. The understorey fauna was mainly a mixture of species found in the other two strata. The horizontal β diversity between sites was similar for the three strata. About half of the ant species foraged in two (29%) or three (25%) strata. A single method, aerial flight interception traps placed alongside tree trunks, acting as arboreal pitfall traps, collected half of the species and reflected the vertical stratification. Using the functional traits approach, we observed that generalist species with mid-sized colonies were by far the most numerous (31%), followed by ground- or litter-dwelling species, either specialists (20%), or generalists (16%), and arboreal species, either generalists (19%) or territorially dominant (8%), and finally army ants (5%). Our results reinforce the idea that a proper understanding of the functioning of ant assemblages requires the inclusion of arboreal ants in survey programs. |
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1026 |
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Levionnois, S.; Tysklind, N.; Nicolini, E.; Ferry, B.; Troispoux, V.; Le Moguedec, G.; Morel, H.; Stahl, C.; Coste, S.; Caron, H.; Heuret, P. |
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Soil variation response is mediated by growth trajectories rather than functional traits in a widespread pioneer Neotropical tree |
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2020 |
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bioRxiv, peer-reviewed by Peer Community in Ecology |
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351197 |
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v4 |
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Trait-environment relationships have been described at the community level across tree species. However, whether interspecific trait-environment relationships are consistent at the intraspecific level is yet unknown. Moreover, we do not know how consistent is the response between organ vs. whole-tree level.We examined phenotypic variability for 16 functional leaf (dimensions, nutrient, chlorophyll) and wood traits (density) across two soil types, Ferralitic Soil (FS) vs. White Sands (WS), on two sites for 70 adult trees of Cecropia obtusa Trécul (Urticaceae) in French Guiana. Cecropia is a widespread pioneer Neotropical genus that generally dominates early successional forest stages. To understand how soil types impact resource-use through the processes of growth and branching, we examined the architectural development with a retrospective analysis of growth trajectories. We expect soil types to affect both, functional traits in relation to resource acquisition strategy as already described at the interspecific level, and growth strategies due to resource limitations with reduced growth on poor soils.Functional traits were not involved in the soil response, as only two traits-leaf residual water content and K content-showed significant differences across soil types. Soil effects were stronger on growth trajectories, with WS trees having the slowest growth trajectories and less numerous branches across their lifespan.The analysis of growth trajectories based on architectural analysis improved our ability to characterise the response of trees with soil types. The intraspecific variability is higher for growth trajectories than functional traits for C. obtusa, revealing the complementarity of the architectural approach with the functional approach to gain insights on the way trees manage their resources over their lifetime. Soil-related responses of Cecropia functional traits are not the same as those at the interspecific level, suggesting that the effects of the acting ecological processes are different between the two levels. Apart from soil differences, much variation was found across sites, which calls for further investigation of the factors shaping growth trajectories in tropical forests. |
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EcoFoG @ webmaster @ |
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931 |
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Soong, J.L.; Janssens, I.A.; Grau, O.; Margalef, O.; Stahl, C.; Van Langenhove, L.; Urbina, I.; Chave, J.; Dourdain, A.; Ferry, B.; Freycon, V.; Herault, B.; Sardans, J.; Peñuelas, J.; Verbruggen, E. |
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Soil properties explain tree growth and mortality, but not biomass, across phosphorus-depleted tropical forests |
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2020 |
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Scientific reports |
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Sci Rep |
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10 |
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2302 |
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We observed strong positive relationships between soil properties and forest dynamics of growth and mortality across twelve primary lowland tropical forests in a phosphorus-poor region of the Guiana Shield. Average tree growth (diameter at breast height) increased from 0.81 to 2.1 mm yr-1 along a soil texture gradient from 0 to 67% clay, and increasing metal-oxide content. Soil organic carbon stocks in the top 30 cm ranged from 30 to 118 tons C ha-1, phosphorus content ranged from 7 to 600 mg kg-1 soil, and the relative abundance of arbuscular mycorrhizal fungi ranged from 0 to 50%, all positively correlating with soil clay, and iron and aluminum oxide and hydroxide content. In contrast, already low extractable phosphorus (Bray P) content decreased from 4.4 to <0.02 mg kg-1 in soil with increasing clay content. A greater prevalence of arbuscular mycorrhizal fungi in more clayey forests that had higher tree growth and mortality, but not biomass, indicates that despite the greater investment in nutrient uptake required, soils with higher clay content may actually serve to sustain high tree growth in tropical forests by avoiding phosphorus losses from the ecosystem. Our study demonstrates how variation in soil properties that retain carbon and nutrients can help to explain variation in tropical forest growth and mortality, but not biomass, by requiring niche specialization and contributing to biogeochemical diversification across this region. |
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Institut National Polytechnique Félix Houphouët-Boigny, Ivory CoastYamoussoukro, Cote d'Ivoire |
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NLM (Medline) |
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20452322 (Issn) |
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Van Langenhove, Leandro ; Verryckt, Lore T. ; Stahl, Clement ; Courtois, Elodie A. ; Urbina, Ifigenia ; Grau, Oriol ; Asensio, Dolores ; Peguero, Guille ; Margalef, Olga ; Freycon, Vincent ; Penuelas, Josep ; Janssens, Ivan A. |
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Soil nutrient variation along a shallow catena in Paracou, French Guiana |
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2021 |
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Soil Research |
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59 |
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130 |
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French Guiana, lowland tropical forest, Paracou, phosphorus, topography, water drainage. |
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Tropical forests are generally considered to stand upon nutrient-poor soils, but soil nutrient concentrations and availabilities can vary greatly at local scale due to topographic effects on erosion and water drainage. In this study we physically and chemically characterised the soils of 12 study plots situated along a catena with a shallow slope in a tropical rainforest in French Guiana both during the wet and the dry season to evaluate seasonal differences. Soils along the catena were all Acrisols, but differed strongly in their water drainage flux. Over time, this differential drainage has led to differences in soil texture and mineral composition, affecting the adsorption of various nutrients, most importantly phosphorus. The more clayey soils situated on the slope of the catena had higher total concentrations of carbon, nitrogen, phosphorus and several micronutrients, while extractable nutrient concentrations were highest in the sandiest soils situated at the bottom of the catena. We found that carbon, nitrogen and extractable nutrients all varied seasonally, especially in the surface soil layer. These results are interesting because they show that, even at the local scale, small differences in topography can lead to large heterogeneity in nutrient concentrations, which can have large impacts on plant and microbial community organisation at the landscape level. |
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CSIRO Publishing |
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1042 |
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Petitjean, C.; Hénault, C.; Perrin, A.-S.; Pontet, C.; Metay, A.; Bernoux, M.; Jehanno, T.; Viard, A.; Roggy, J.-C. |
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Soil N2O emissions in French Guiana after the conversion of tropical forest to agriculture with the chop-and-mulch method |
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2015 |
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Agriculture, Ecosystems and Environment |
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Agriculture, Ecosystems and Environment |
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208 |
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64-74 |
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Chop-and-mulch method; Fire-free deforestation; French Guiana; Land use change; Soil N<inf>2</inf>O emissions |
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In French Guiana, the population growth will result in an increase in demand for agricultural products and thus, will lead to an increase in the amount of tropical forests converted into cropland or pasture. Impacts of different agricultural systems on greenhouse gas (GHG) fluxes have not been studied in French Guiana. In this context, the fire-free chop-and-mulch method was used to convert a tropical forest site to agriculture. This study focused on soil nitrous oxide (N<inf>2</inf>O) emissions and we compared four land uses: (1) the undisturbed tropical forest, (2) recently converted grassland and recently converted croplands (fertilized soybean/maize rotation) with either (3) disk tillage or (4) no tillage.N<inf>2</inf>O measurements were obtained through the chamber technique and conducted over a 1-year period (measurements began 19 months after the forest was cleared). N<inf>2</inf>O fluxes were related to soil parameters measured at each sampling date: nitrate and ammonium contents, gravimetric water content (GWC) and temperature. Through the entire period, the mean (± standard error) and median N<inf>2</inf>O fluxes were 3.8 ± 0.5 and 2.7 gNha-1day-1, respectively for undisturbed tropical forest and 2.4 ± 0.9 and 0.8gNha-1day-1, respectively for grassland (mowed Brachiaria ruziziensis). For croplands, no significant difference was found for N<inf>2</inf>O emissions between both agricultural practices. The mean (± standard error) and median N<inf>2</inf>O fluxes were 8.5 ± 1.2 and 4.0 gNha-1day-1, respectively for disk tillage plots and 8.5 ± 1.3 and 3.6gNha-1day-1, respectively for no tillage plots. Nitrogen inputs (due to the application of fertilizer or due to the mineralization of crop residues) led to higher N<inf>2</inf>O fluxes, resulting in significantly higher mean N<inf>2</inf>O emissions from croplands compared to the forest, when only considering land use effect on N<inf>2</inf>O fluxes in a statistical model. The soil nitrate content, GWC and temperature had a significant positive effect on N<inf>2</inf>O fluxes. Taking into account these soil parameters in another statistical model, N<inf>2</inf>O emissions from croplands were not higher than the natural N<inf>2</inf>O emissions from tropical forest soils. Our results suggest that, if more forest will have to be converted in the course of the expected population growth in French Guiana, it could have low impact on the soil N<inf>2</inf>O fluxes (similar to natural fluxes from forest) with the improving of farming techniques (for example modification of the splitting of N-fertilizer) in the cropping plots. © 2015 Elsevier B.V. |
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INRA, UMR EcoFoG, Campus agronomiqueKourou, Guyane Française, France |
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Export Date: 18 May 2015 |
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EcoFoG @ webmaster @ |
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601 |
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Soong, J.L.; Marañon-Jimenez, S.; Cotrufo, M.F.; Boeckx, P.; Bodé, S.; Guenet, B.; Peñuelas, J.; Richter, A.; Stahl, C.; Verbruggen, E.; Janssens, I.A. |
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Soil microbial CNP and respiration responses to organic matter and nutrient additions: Evidence from a tropical soil incubation |
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2018 |
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Soil Biology and Biochemistry |
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141-149 |
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13c; Cnp; Microbial stoichiometry; Priming; Soil respiration; Tropics |
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Soil nutrient availability has a strong influence on the fate of soil carbon (C) during microbial decomposition, contributing to Earth's C balance. While nutrient availability itself can impact microbial physiology and C partitioning between biomass and respiration during soil organic matter decomposition, the availability of labile C inputs may mediate the response of microorganisms to nutrient additions. As soil organic matter is decomposed, microorganisms retain or release C, nitrogen (N) or phosphorus (P) to maintain a stoichiometric balance. Although the concept of a microbial stoichiometric homeostasis has previously been proposed, microbial biomass CNP ratios are not static, and this may have very relevant implications for microbial physiological activities. Here, we tested the hypothesis that N, P and potassium (K) nutrient additions impact C cycling in a tropical soil due to microbial stoichiometric constraints to growth and respiration, and that the availability of energy-rich labile organic matter in the soil (i.e. leaf litter) mediates the response to nutrient addition. We incubated tropical soil from French Guiana with a 13C labeled leaf litter addition and with mineral nutrient additions of +K, +N, +NK, +PK and +NPK for 30 days. We found that litter additions led to a ten-fold increase in microbial respiration and a doubling of microbial biomass C, along with greater microbial N and P content. We found some evidence that P additions increased soil CO2 fluxes. Additionally, we found microbial biomass CP and NP ratios varied more widely than CN in response to nutrient and organic matter additions, with important implications for the role of microorganisms in C cycling. The addition of litter did not prime soil organic matter decomposition, except in combination with +NK fertilization, indicating possible P-mining of soil organic matter in this P-poor tropical soil. Together, these results point toward an ultimate labile organic substrate limitation of soil microorganisms in this tropical soil, but also indicate a complex interaction between C, N, P and K availability. This highlights the difference between microbial C cycling responses to N, P, or K additions in the tropics and explains why coupled C, N and P cycle modeling efforts cannot rely on strict microbial stoichiometric homeostasis as an underlying assumption. |
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INRA, UMR Ecology of Guiana Forests (Ecofog), AgroParisTech, Cirad, CNRS, Université de Guyane, Université des Antilles, Kourou, France |
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Export Date: 16 May 2018 |
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EcoFoG @ webmaster @ |
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804 |
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