Aubry-Kientz, M., Rossi, V., Wagner, F., & Herault, B. (2015). Identifying climatic drivers of tropical forest dynamics. Biogeosciences, 12(19), 5583–5596.
Abstract: In the context of climate change, identifying and then predicting the impacts of climatic drivers on tropical forest dynamics is becoming a matter of urgency. To look at these climate impacts, we used a coupled model of tropical tree growth and mortality, calibrated with forest dynamic data from the 20-year study site of Paracou, French Guiana, in order to introduce and test a set of climatic variables. Three major climatic drivers were identified through the variable selection procedure: drought, water saturation and temperature. Drought decreased annual growth and mortality rates, high precipitation increased mortality rates and high temperature decreased growth. Interactions between key functional traits, stature and climatic variables were investigated, showing best resistance to drought for trees with high wood density and for trees with small current diameters. Our results highlighted strong long-term impacts of climate variables on tropical forest dynamics, suggesting potential deep impacts of climate changes during the next century. © Author(s) 2015.
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Dejean, A., Ryder, S., Bolton, B., Compin, A., Leponce, M., Azémar, F., et al. (2015). How territoriality and host-tree taxa determine the structure of ant mosaics. Sci Nat, 102(33), 1–9.
Abstract: Very large colonies of territorially dominant arboreal ants (TDAAs), whose territories are distributed in a mosaic pattern in the canopies of many tropical rainforests and tree crop plantations, have a generally positive impact on their host trees. We studied the canopy of an old Gabonese rainforest (ca 4.25 ha sampled, corresponding to 206 Blarge trees) at a stage just preceding forest maturity (the Caesalpinioideae dominated; the Burseraceae were abundant). The tree crowns sheltered colonies from 13 TDAAs plus a codominant species out of the 25 ant species recorded. By mapping the TDAAs' territories and using a null model cooccurrence analysis, we confirmed the existence of an ant mosaic. Thanks to a large sampling set and the use of the self-organizing map algorithm (SOM), we show that the distribution of the trees influences the structure of the ant mosaic, suggesting that each tree taxon attracts certain TDAA species rather than others. The SOMalso improved our knowledge of the TDAAs' ecological niches, showing that these ant species are ecologically distinct from each other based on their relationships with their supporting trees. Therefore, TDAAs should not systematically be placed in the same functional group even when they belong to the same genus.We conclude by reiterating that, in addition to the role played by TDAAs' territorial competition, host trees contribute to structuring ant mosaics through multiple factors, including host-plant selection by TDAAs, the age of the trees, the presence of extrafloral nectaries, and the taxa of the associated hemipterans. © Springer-Verlag Berlin Heidelberg 2015.
Keywords: Africa; Arboreal ants; Distribution; Host-tree selection; Rainforest canopies
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Tritsch, I., Gond, V., Oszwald, J., Davy, D., & Grenand, P. (2012). Territorial dynamics in the wayãpi and teko amerindian communities of the middle oyapock, camopi, French Guiana. Bois Forets Tropiques, 66(311), 49–61.
Abstract: Amerindian populations have been experiencing major socio-economic changes for several decades, in a context of rapid demographic growth. This article addresses the ways in which the Amerindian populations of French Guiana have adapted their land use and natural resource management systems to cope with the pressures exerted on their lands and lifestyles. The aim was to investigate the resilience of their systems for land and natural resource use. The concentration of Amerindian habitats around the town of Camopi, which is linked to the availability of health and school infrastructure and to efforts to promote a sedentary lifestyle, is a factor of increasing natural resource scarcity and social alienation. The system is adapting by fragmenting the Amerindian habitat into peripheral villages and extending farmlands along rivers to access to more space. These villages replicate patterns of spatial organisation that are similar to those found in traditional Wayãpi and Teko villages, except that habitation is sedentary, as families hope to have their villages equipped with at lEast drinking water and electrification. Habitat fragmentation is spatially limited by the time taken for daily journeys to school, and therefore by school bus services (dugout), which means that land use is effectively conditioned by services and infrasrtucture. Other living quarters are maintained at a distance from the village, so that the habitat is bi-local: families have a main home where services and infrastructure are available, and a secondary itinerant home further away, which is chosen according to the quality of farmland, the hunting yield of hunting resources, the history of the location and family networks. These distant homes are kept up by spending income from social assistance on transport. It's thus shown that these Amerindian systems for land and natural resource uses are highly adaptable, in that their sustainability is guaranteed by the reconstruction of a circular pattern of mobility in accordance with the intensity of resource use.
Keywords: Amerindian populations; French Guiana; Protected area; Slash-and-burn cultivation; System of natural resource use; Territorial management
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Abedini, R., Clair, B., Pourtahmasi, K., Laurans, F., & Arnould, O. (2015). Cell wall thickening in developing tension wood of artificially bent poplar trees. IAWA Journal, 36(1), 44–57.
Abstract: Trees can control their shape and resist gravity thanks to their ability to produce wood under tensile stress. This stress is known to be produced during the maturation of wood fibres but the mechanism of its generation remains unclear. This study focuses on the formation of the secondary wall in tension wood produced in artificially tilted poplar saplings. Thickness of secondary wall layer (SL) and gelatinous layer (GL) were measured from cambium to mature wood in several trees sampled at different times after tilting. Measurements on wood fibres produced before tilting show the progressive increase of secondary wall thickness during the growing season. After the tilting date, SL thickness decreased markedly from normal wood to tension wood while the total thickness increased compared to normal wood, with the development of a thick GL. However, even after GL formation, SL thickness continues to increase during the growing season. GL thickening was observed to be faster than SL thickening. The development of the unlignified GL is proposed to be a low cost, efficient strategy for a fast generation of tensile stress in broadleaved trees. © 2015 International Association of Wood Anatomists.
Keywords: developing xylem; Gelatinous layer; maturation stress; secondary wall layer; tree biomechanics
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Zinger, L., Chave, J., Coissac, E., Iribar, A., Louisanna, E., Manzi, S., et al. (2016). Extracellular DNA extraction is a fast, cheap and reliable alternative for multi-taxa surveys based on soil DNA. Soil Biology and Biochemistry, 96, 16–19.
Abstract: DNA metabarcoding on soil samples is increasingly used for large-scale and multi-taxa biodiversity studies. However, DNA extraction may be a major bottleneck for such wide uses. It should be cost/time effective and allow dealing with large sample volumes so as to maximise the representativeness of both micro- and macro-organisms diversity. Here, we compared the performances of a fast and cheap extracellular DNA extraction protocol with a total DNA extraction method in retrieving bacterial, eukaryotic and plant diversity from tropical soil samples of ca. 10 g. The total DNA extraction protocol yielded more high-quality DNA. Yet, the extracellular DNA protocol provided similar diversity assessments although it presented some differences in clades relative abundance and undersampling biases. We argue that extracellular DNA is a good compromise between cost, labor, and accuracy for high-throughput DNA metabarcoding studies of soil biodiversity. © 2016 Elsevier Ltd.
Keywords: DNA extraction protocol; DNA metabarcoding; Multi-taxa biodiversity; Tropical forest
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Houadria, M., Blüthgen, N., Salas-Lopez, A., Schmitt, M. - I., Arndt, J., Schneider, E., et al. (2016). The relation between circadian asynchrony, functional redundancy, and trophic performance in tropical ant communities. Ecology, 97(1), 225–235.
Abstract: The diversity-stability relationship has been under intense scrutiny for the past decades, and temporal asynchrony is recognized as an important aspect of ecosystem stability. In contrast to relatively well- studied interannual and seasonal asynchrony, few studies investigate the role of circadian cycles for ecosystem stability. Here, we studied multifunctional redundancy of diurnal and nocturnal ant communities in four tropical rain forest sites. We analyzed how it was influenced by species richness, functional performance, and circadian asynchrony. In two neotropical sites, species richness and functional redundancy were lower at night. In contrast, these parameters did not differ in the two paleotropical sites we studied. Circadian asynchrony between species was pronounced in the neotropical sites, and increased circadian functional redundancy. In general, species richness positively affected functional redundancy, but the effect size depended on the temporal and spatial breadth of the species with highest functional performance. Our analysis shows that high levels of trophic performance were only reached through the presence of such high- performing species, but not by even contributions of multiple, less- efficient species. Thus, these species can increase current functional performance, but reduce overall functional redundancy. Our study highlights that diurnal and nocturnal ecosystem properties of the very same habitat can markedly differ in terms of species richness and functional redundancy. Consequently, like the need to study multiple ecosystem functions, multiple periods of the circadian cycle need to be assessed in order to fully understand the diversity- stability relationship in an ecosystem. © 2016 by the Ecological Society of America.
Keywords: Diel turnover; Ecosystem functioning; Functional diversity; Multifunctional redundancy; Sampling effect; Temporal partitioning; Tropical rain forests
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Boulogne, I., Constantino, R., Amusant, N., Falkowski, M., Rodrigues, A. M. S., & Houel, E. (2017). Ecology of termites from the genus Nasutitermes (Termitidae: Nasutitermitinae) and potential for science-based development of sustainable pest management programs. Journal of Pest Science, 90(1), 19–37.
Abstract: The genus Nasutitermes is among the most abundant wood-feeding Termitidae and an extremely diverse and heterogeneous group in terms of its biogeography and morphology. Despite the major role of several Nasutitermes species as structural pests, the phylogenetic status of this genus is still unclear, along with a confused taxonomy and species identification remaining difficult. The first aim of this review was thus to gather and discuss studies concerning the taxonomic status of the genus Nasutitermes in order to clarify this crucial point. Then, our goal was to gain new insights into the management of N. corniger, considered to be the most economically detrimental pest of this genus in South America and a Nasutitermes model species, while filtering available information concerning its biology through the prism of termite control, as well as critically examine the existing methods. We indeed strongly believe that increasing our knowledge of this species’ biological strategies is the key to progress in the challenging question of their sustainable management. © 2016, Springer-Verlag Berlin Heidelberg.
Keywords: Antimicrobial and insecticidal botanical extracts; Ipm; Nasutitermes corniger; Sustainable management; Taxonomic history; Termitidae
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Marcon, E., & Puech, F. (2017). A typology of distance-based measures of spatial concentration. Regional Science and Urban Economics, 62, 56–67.
Abstract: Over the last decade, distance-based methods have been introduced and then improved in the field of spatial economics to gauge the geographic concentration of activities. There is a growing literature on this theme including new tools, discussions on their specific properties and various applications. However, there is currently no typology of distance-based methods. This paper fills that gap. The proposed classification helps understand all the properties of distance-based methods and proves that they are variations on the same framework. © 2016 Elsevier B.V.
Keywords: Agglomeration; Aggregation; Economic geography; Point patterns; Spatial concentration
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Hudson, L. N., Newbold, T., Contu, S., Hill, S. L. L., Lysenko, I., De Palma, A., et al. (2017). The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project. Ecology and Evolution, 7(1), 145–188.
Abstract: The PREDICTS project—Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)—has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity. © 2016 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.
Keywords: data sharing; global biodiversity modeling; global change; habitat destruction; land use
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De Souza, F. C., Dexter, K. G., Phillips, O. L., Brienen, R. J. W., Chave, J., Galbraith, D. R., et al. (2016). Evolutionary heritage influences amazon tree ecology. Proceedings of the Royal Society B: Biological Sciences, 283(20161587).
Abstract: Lineages tend to retain ecological characteristics of their ancestors through time. However, for some traits, selection during evolutionary history may have also played a role in determining trait values. To address the relative importance of these processes requires large-scale quantification of traits and evolutionary relationships among species. The Amazonian tree flora comprises a high diversity of angiosperm lineages and species with widely differing life-history characteristics, providing an excellent system to investigate the combined influences of evolutionary heritage and selection in determining trait variation. We used trait data related to the major axes of life-history variation among tropical trees (e.g. growth and mortality rates) from 577 inventory plots in closed-canopy forest, mapped onto a phylogenetic hypothesis spanning more than 300 genera including all major angiosperm clades to test for evolutionary constraints on traits. We found significant phylogenetic signal (PS) for all traits, consistent with evolutionarily related genera having more similar characteristics than expected by chance. Although there is also evidence for repeated evolution of pioneer and shade tolerant lifehistory strategies within independent lineages, the existence of significant PS allows clearer predictions of the links between evolutionary diversity, ecosystem function and the response of tropical forests to global change. © 2016 The Authors.
Keywords: Convergent evolution; Divergent selection; Phylogenetic signal; Trait; Tropical tree
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