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Author Levionnois, S.; Jansen, S.; Wandji, R.T.; Beauchêne, J.; Ziegler, C.; Coste, S.; Stahl, C.; Delzon, S.; Authier, L.; Heuret, P. doi  openurl
  Title Linking drought-induced xylem embolism resistance to wood anatomical traits in Neotropical trees Type Journal Article
  Year 2021 Publication New Phytologist Abbreviated Journal New Phytol.  
  Volume 229 Issue 3 Pages 1453-1466  
  Keywords bordered pits; drought-induced embolism; pit membrane; transmission electron microscopy; tropical trees; vessel grouping; xylem anatomy  
  Abstract Drought-induced xylem embolism is considered to be one of the main factors driving mortality in woody plants worldwide. Although several structure–functional mechanisms have been tested to understand the anatomical determinants of embolism resistance, there is a need to study this topic by integrating anatomical data for many species. We combined optical, laser, and transmission electron microscopy to investigate vessel diameter, vessel grouping, and pit membrane ultrastructure for 26 tropical rainforest tree species across three major clades (magnoliids, rosiids, and asteriids). We then related these anatomical observations to previously published data on drought-induced embolism resistance, with phylogenetic analyses. Vessel diameter, vessel grouping, and pit membrane ultrastructure were all predictive of xylem embolism resistance, but with weak predictive power. While pit membrane thickness was a predictive trait when vestured pits were taken into account, the pit membrane diameter-to-thickness ratio suggests a strong importance of the deflection resistance of the pit membrane. However, phylogenetic analyses weakly support adaptive coevolution. Our results emphasize the functional significance of pit membranes for air-seeding in tropical rainforest trees, highlighting also the need to study their mechanical properties due to the link between embolism resistance and pit membrane diameter-to-thickness ratio. Finding support for adaptive coevolution also remains challenging. © 2020 The Authors New Phytologist © 2020 New Phytologist Foundation  
  Address UMR BIOGECO, INRAE, Université de Bordeaux, Pessac, 33615, France  
  Corporate Author Thesis  
  Publisher Blackwell Publishing Ltd Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0028646x (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number EcoFoG @ webmaster @ Serial 997  
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Author Aubry-Kientz, Mélaine ; Laybros, Anthony ; Weinstein, Ben ; Ball, James G. C. ; Jackson, Toby ; Coomes, David ; Vincent, Grégoire doi  openurl
  Title Multisensor data fusion for improved segmentation of individual tree crowns in dense tropical forests Type Journal Article
  Year 2021 Publication IEEE Journal of Selected topics in Applied Earth Observations and Remote Sensing Abbreviated Journal  
  Volume 14 Issue Pages 3927-3936  
  Keywords  
  Abstract Automatic tree crown segmentation from remote sensing data is especially challenging in dense, diverse, and multilayered tropical forest canopies, and tracking mortality by this approach is even more difficult. Here, we examine the potential for combining airborne laser scanning (ALS) with multispectral and hyperspectral data to improve the accuracy of tree crown segmentation at a study site in French Guiana. We combined an ALS point cloud clustering method with a spectral deep learning model to achieve 83% accuracy at recognizing manually segmented reference crowns (with congruence >0.5). This method outperformed a two-step process that involved clustering the ALS point cloud and then using the logistic regression of hyperspectral distances to correct oversegmentation. We used this approach to map tree mortality from repeat surveys and show that the number of crowns identified in the first that intersected with height loss clusters was a good estimator of the number of dead trees in these areas. Our results demonstrate that multisensor data fusion improves the automatic segmentation of individual tree crowns and presents a promising avenue to study forest demography with repeated remote sensing acquisitions.  
  Address  
  Corporate Author Thesis  
  Publisher IEEE Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number EcoFoG @ webmaster @ Serial 1008  
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Author Dejean, Alain ; Petitclerc, Frédéric ; Azémar, Frédéric ; Rossi, Vivien doi  openurl
  Title Nutrient provisioning of its host myrmecophytic tree by a temporary social parasite of a plant-ant Type Journal Article
  Year 2021 Publication Biological Journal of the Linnean Society Abbreviated Journal  
  Volume 133 Issue 3 Pages 744-750  
  Keywords  
  Abstract One of the most advanced ant–plant mutualisms is represented by myrmecophytes sheltering colonies of some plant-ant species in hollow structures called domatia. In turn, the myrmecophytes benefit from biotic protection and sometimes nutrient provisioning (myrmecotrophy). Furthermore, over the course of evolution, some ant species have become social parasites of others. In this general context, we studied the relationship between its host trees and Azteca andreae (Dolichoderinae), a temporary social parasite of the plant-ant Azteca ovaticeps, and, as such, obligatorily associated with myrmecophytic Cecropia obtusa trees (Urticaceae). A first experiment showed that the δ15N values of the young leaves of Cecropia sheltering a mature A. andreae colony were very similar to those for trees sheltering Azteca alfari or A. ovaticeps, two typical Cecropia mutualists for which myrmecotrophy is known. In a second experiment, by injecting a 15N-labelled glycine solution into locusts given as prey to A. andreae colonies, we triggered an increase in δ15N in the young leaves of their host Cecropia. Thus, 15N passed from the prey to the host trees, explaining the outcomes of the first experiment. We discuss these results in light of the notion of ‘by-product benefits’.  
  Address  
  Corporate Author Thesis  
  Publisher Oxford Academy Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number EcoFoG @ webmaster @ Serial 1009  
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Author Amani, Bienvenu H.K. ; N'Guessan, Anny E. ; Derroire, Géraldine ; N'dja, Justin K. ; Elogne, Aka G. M. ; Traoré, Karidia ; Zo-Bi, Irie C. ; Hérault, Bruno doi  openurl
  Title The potential of secondary forests to restore biodiversity of the lost forests in semi-deciduous West Africa Type Journal Article
  Year 2021 Publication Biological Conservation Abbreviated Journal  
  Volume 259 Issue Pages  
  Keywords  
  Abstract In West Africa, more than 80% of the original forest cover has disappeared due to the exponential growth of human populations in a recurrent search for new agricultural land. Once the fertility of the land is exhausted, these areas are abandoned and left to be reforested through natural succession. Despite the widespread presence of secondary forests of various ages in West African landscapes, little is known about the trajectories of recovery and the environmental factors that influence recovery rates. We set up 96 0.2 ha forest plots, along a chronosequence of 1 to 40 years and including 7 controls, on which all trees larger than 2.5 cm in diameter at breast height were inventoried. We modelled the recovery trajectories of four complementary dimensions of biodiversity (richness, diversity, composition, indicators of old-growth forest) in a Bayesian framework. Our results show that the four dimensions of biodiversity recover at different rates, with composition recovering much faster than floristic diversity. Among the local, landscape, and historical factors studied, the number of remnants and proximity to old-growth forests have a positive impact on recovery rates, with, under good environmental conditions, the composition, richness, and diversity being almost completely recovered in less than 25 years. Our results demonstrate the very high resilience of the composition of the semi-deciduous forests of West Africa, but also suggest that the management of these post-forest areas must be differentiated according to the landscape context and the presence of isolated trees, which are the last vestiges of the former forest. In unfavourable conditions, natural dynamics should be assisted by agroforestry practices and local tree planting to allow for a rapid restoration of forest goods and services to local populations.  
  Address  
  Corporate Author Thesis  
  Publisher Elsevier B.V. Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number EcoFoG @ webmaster @ Serial 1010  
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Author Urbina, Ifigenia ; Grau, Oriol ; Sardans, Jordi ; Margalef, Olga ; Peguero, Guillermo ; Asensio, Dolores ; Llusia, Joan ; Ogaya, Roma ; Gargallo-Garriga, Albert ; Van Langenhove, Leandro ; Verryckt, Lore T. ; Courtois, Elodie A. ; Stahl, Clement ; Soong, Jennifer L. ; Chave, Jérome ; Hérault, Bruno ; Janssens, Ivan A. ; Sayer, Emma ; Penuelas, Josep doi  openurl
  Title High foliar K and P resorption efficiencies in old-growth tropical forests growing on nutrient-poor soils Type Journal Article
  Year 2021 Publication Ecology and Evolution Abbreviated Journal  
  Volume 11 Issue 13 Pages 8969-8982  
  Keywords  
  Abstract Resorption is the active withdrawal of nutrients before leaf abscission. This mechanism represents an important strategy to maintain efficient nutrient cycling; however, resorption is poorly characterized in old-growth tropical forests growing in nutrient-poor soils. We investigated nutrient resorption from leaves in 39 tree species in two tropical forests on the Guiana Shield, French Guiana, to investigate whether resorption efficiencies varied with soil nutrient, seasonality, and species traits. The stocks of P in leaves, litter, and soil were low at both sites, indicating potential P limitation of the forests. Accordingly, mean resorption efficiencies were higher for P (35.9%) and potassium (K; 44.6%) than for nitrogen (N; 10.3%). K resorption was higher in the wet (70.2%) than in the dry (41.7%) season. P resorption increased slightly with decreasing total soil P; and N and P resorptions were positively related to their foliar concentrations. We conclude that nutrient resorption is a key plant nutrition strategy in these old-growth tropical forests, that trees with high foliar nutrient concentration reabsorb more nutrient, and that nutrients resorption in leaves, except P, are quite decoupled from nutrients in the soil. Seasonality and biochemical limitation played a role in the resorption of nutrients in leaves, but species-specific requirements obscured general tendencies at stand and ecosystem level.  
  Address  
  Corporate Author Thesis  
  Publisher Wiley Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number EcoFoG @ webmaster @ Serial 1011  
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Author Bonhomme, Camille ; Céréghino, Régis ; Carrias, Jean-François ; Compin, Arthur ; Corbara, Bruno ; Jassey, Vincent E.J. ; Leflaive, Joséphine ; Farjalla, Vinicius F. ; Marino, Nicholas A.C. ; Rota, Thibault ; Srivastava, Diane S. ; Leroy, Celine doi  openurl
  Title In situ resistance, not immigration, supports invertebrate community resilience to drought intensification in a neotropical ecosystem Type Journal Article
  Year 2021 Publication Journal of Animal Ecology Abbreviated Journal  
  Volume 90 Issue 9 Pages 2015-2026  
  Keywords  
  Abstract While future climate scenarios predict declines in precipitations in many regions of the world, little is known of the mechanisms underlying community resilience to prolonged dry seasons, especially in ‘naïve’ Neotropical rainforests. Predictions of community resilience to intensifying drought are complicated by the fact that the underlying mechanisms are mediated by species' tolerance and resistance traits, as well as rescue through dispersal from source patches. We examined the contribution of in situ tolerance-resistance and immigration to community resilience, following drought events that ranged from the ambient norm to IPCC scenarios and extreme events. We used rainshelters above rainwater-filled bromeliads of French Guiana to emulate a gradient of drought intensity (from 1 to 3.6 times the current number of consecutive days without rainfall), and we analysed the post-drought dynamics of the taxonomic and functional community structure of aquatic invertebrates to these treatments when immigration is excluded (by netting bromeliads) or permitted (no nets). Drought intensity negatively affected invertebrate community resistance, but had a positive influence on community recovery during the post-drought phase. After droughts of 1 to 1.4 times the current intensities, the overall invertebrate abundance recovered within invertebrate life cycle durations (up to 2 months). Shifts in taxonomic composition were more important after longer droughts, but overall, community composition showed recovery towards baseline states. The non-random patterns of changes in functional community structure indicated that deterministic processes like environmental filtering of traits drive community re-assembly patterns after a drought event. Community resilience mostly relied on in situ tolerance-resistance traits. A rescue effect of immigration after a drought event was weak and mostly apparent under extreme droughts. Under climate change scenarios of drought intensification in Neotropical regions, community and ecosystem resilience could primarily depend on the persistence of suitable habitats and on the resistance traits of species, while metacommunity dynamics could make a minor contribution to ecosystem recovery. Climate change adaptation should thus aim at identifying and preserving local conditions that foster in situ resistance and the buffering effects of habitat features.  
  Address  
  Corporate Author Thesis  
  Publisher British Ecological Society Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number EcoFoG @ webmaster @ Serial 1012  
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Author Sayer, E.J.; Rodtassana, C.; Sheldrake, M.; Bréchet, L.M.; Ashford, O.S.; Lopez-Sangil, L.; Kerdraon-Byrne, D.; Castro, B.; Turner, B.L.; Wright, S.J.; Tanner, E.V.J. doi  openurl
  Title Revisiting nutrient cycling by litterfall—Insights from 15 years of litter manipulation in old-growth lowland tropical forest Type Journal Article
  Year 2020 Publication Advances in Ecological Researc Abbreviated Journal Adv. Ecol. Res.  
  Volume 62 Issue Pages 173-223  
  Keywords Forest floor; Litter addition; Litter removal; Litterfall; Nutrient cycling; Nutrient use efficiency; Soil fertility; Trace elements; Tropical lowland forest  
  Abstract The crucial role of tropical forests in the global carbon balance is underpinned by their extraordinarily high biomass and productivity, even though the majority of tropical forests grow on nutrient-poor soils. Nutrient cycling by litterfall has long been considered essential for maintaining high primary productivity in lowland tropical forests but few studies have tested this assumption experimentally. We review and synthesise findings from the Gigante Litter Manipulation Project (GLiMP), a long-term experiment in lowland tropical forest in Panama, Central America, in which litter has been removed from or added to large-scale plots for 15 years. We assessed changes in soil and litter nutrient concentrations in response to the experimental treatments and estimated nutrient return and nutrient use efficiency to indicate changes in nutrient cycling. The soil concentrations of most nutrients increased with litter addition and declined with litter removal. Litter removal altered nitrogen, potassium, manganese and zinc cycling, demonstrating the importance of litter inputs for maintaining the availability of these elements to plants. By contrast, litter addition only altered nitrogen cycling and, despite low concentrations of available soil phosphorus, the effects of litter manipulation on phosphorus cycling were inconsistent. We discuss potential mechanisms underlying the observed changes, and we emphasise the importance of decomposition processes in the forest floor for retaining nutrient elements, which partially decouples nutrient cycling from the mineral soil. Finally, by synthesising GLiMP studies conducted during 15 years of litter manipulation, we highlight key knowledge gaps and avenues for future research into tropical forest nutrient cycling. © 2020 Elsevier Ltd  
  Address Teagasc, Johnstown Castle, Wexford, Ireland  
  Corporate Author Thesis  
  Publisher Academic Press Inc. Place of Publication Editor Dumbrell A.J.; Turner E.C.; Fayle T.M.  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title Advances in Ecological Research  
  Series Volume 62 Series Issue Edition  
  ISSN 00652504 (Issn); 9780128211342 (Isbn) ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number EcoFoG @ webmaster @ Serial 1001  
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Author Peguero, Guille ; Ferrin, Miquel ; Sardans, Jordi ; Verbruggen, Erik ; Ramirez-Rojas , Irène ; Van Langenhove, Leandro ; Verryckt, Lore T. ; Murienne, Jérôme ; Iribar, Amaia ; Zinger, Lucie ; Grau, Oriol ; Orivel, Jérome ; Stahl, Clement ; Courtois, Elodie A. ; Asensio, Dolores ; Gargallo-Garriga, Albert ; Llusia, Joan ; Margalef, Olga ; Ogaya, Roma ; Richter, Andreas ; Janssens, Ivan A. ; Penuelas, Josep doi  openurl
  Title Decay of similitary across tropical forest communities: integrating spatial distance with soil nutrients Type Journal Article
  Year 2021 Publication Ecology Abbreviated Journal  
  Volume 103 Issue 2 Pages e03599  
  Keywords  
  Abstract Understanding the mechanisms that drive the change of biotic assemblages over space and time is the main quest of community ecology. Assessing the relative importance of dispersal and environmental species selection in a range of organismic sizes and motilities has been a fruitful strategy. A consensus for whether spatial and environmental distances operate similarly across spatial scales and taxa, however, has yet to emerge. We used censuses of four major groups of organisms (soil bacteria, fungi, ground insects, and trees) at two observation scales (1-m2 sampling point vs. 2,500-m2 plots) in a topographically standardized sampling design replicated in two tropical rainforests with contrasting relationships between spatial distance and nutrient availability. We modeled the decay of assemblage similarity for each taxon set and site to assess the relative contributions of spatial distance and nutrient availability distance. Then, we evaluated the potentially structuring effect of tree composition over all other taxa. The similarity of nutrient content in the litter and topsoil had a stronger and more consistent selective effect than did dispersal limitation, particularly for bacteria, fungi, and trees at the plot level. Ground insects, the only group assessed with the capacity of active dispersal, had the highest species turnover and the flattest nonsignificant distance−decay relationship, suggesting that neither dispersal limitation nor nutrient availability were fundamental drivers of their community assembly at this scale of analysis. Only the fungal communities at one of our study sites were clearly coordinated with tree composition. The spatial distance at the smallest scale was more important than nutrient selection for the bacteria, fungi, and insects. The lower initial similarity and the moderate variation in composition identified by these distance-decay models, however, suggested that the effects of stochastic sampling were important at this smaller spatial scale. Our results highlight the importance of nutrients as one of the main environmental drivers of rainforest communities irrespective of organismic or propagule size and how the overriding effect of the analytical scale influences the interpretation, leading to the perception of greater importance of dispersal limitation and ecological drift over selection associated with environmental niches at decreasing observation scales.  
  Address  
  Corporate Author Thesis  
  Publisher Ecological Society of America Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number EcoFoG @ webmaster @ Serial 1022  
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Author Vergne, Antoine ; Darbot, Vincent ; Bardot, Corinne ; Enault, François ; Le Jeune, Anne-Hélène ; Carrias, Jean-François ; Corbara, Bruno ; Céréghino, Régis ; Leroy, Celine ; Jeanthon, Christian ; Giraud, Eric ; Mary, Isabelle ; Lehours, Anne-Catherine doi  openurl
  Title Assemblages of anoxygenic phototrophic bacteria in tank bromeliads exhibit a host-specific signatureit Type Journal Article
  Year 2021 Publication Journal of Ecology Abbreviated Journal  
  Volume 109 Issue 7 Pages 2550-2565  
  Keywords  
  Abstract Anoxygenic phototrophic bacteria (APB) are a very significant metabolic functional group in the phytotelmata of tank-forming Bromeliaceae plants. Considering the close relationships existing between the bromeliad and its tank microbiota, the dominance of APB raises the question of their role in the ecology and evolution of these plants. Here, using pufM gene sequencing for taxonomic profiling, we investigated the structure of APB communities in the tanks of five bromeliad species exhibiting different habitat characteristics (i.e. physicochemical factors associated with the host), and occurring in different localities of French Guiana.
We found that APB assemblages were specific to plant species and were less dependent on location or on bromeliad habitat characteristics. This convergence suggests that the identity of the bromeliad species per se is more important than habitat filtering or dispersal to control specific assembly rules for APB. The pufM OTUs were affiliated with five orders of Alpha- and Beta-proteobacteria (Rhodobacterales, Sphingomonadales, Rhizobiales, Burkholderiales and Rhodospirillales), and we assume that they may be major components of the core microbiota of plant-held waters. Our findings also revealed that up to 79% of the sequences were affiliated with APB clades possessing nitrogen-fixing genes suggesting that this metabolic capability is widespread within the APB community inhabiting tank bromeliads. We hypothesized that bromeliads may benefit nutritionally from associations with free-living APB capable to fix atmospheric nitrogen. Synthesis. Understanding the dominance of APB in tank bromeliads and determining whether a potential interplay exists between these partners is an intriguing aspect of possible mutualistic and coevolving interactions between the two existing forms of chlorophototrophy (i.e. bacteriochlorophyll-based anoxygenic and chlorophyll-based oxygenic phototrophy). In the present study, we found that bromeliad species was the main factor that explained variance in APB community composition. These findings suggest that APB and tank bromeliads may have a close, mutualistic relationship and we hypothesize according to our genomic analyses that APB may promote the bromeliad growth by provisioning essential nutrients like nitrogen.
 
  Address  
  Corporate Author Thesis  
  Publisher British Ecological Society Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number EcoFoG @ webmaster @ Serial 1023  
Permanent link to this record
 

 
Author Heu, Katy ; Romoli, Ottavia ; Schonbeck, Johan Claes ; Ajenoe, Rachel ; Epelboin, Yanouk ; Kircher, Verena ; Houel, Emeline ; Estevez, Yannick ; Gendrin, Mathilde doi  openurl
  Title The Effect of Secondary Metabolites Produced by Serratia marcescens on Aedes aegypti and Its Microbiota Type Journal Article
  Year 2021 Publication Frontiers in Microbiology Abbreviated Journal  
  Volume 12 Issue Pages 645701  
  Keywords  
  Abstract Serratia marcescens is a bacterial species widely found in the environment, which very efficiently colonizes mosquitoes. In this study, we isolated a red-pigmented S. marcescens strain from our mosquito colony (called S. marcescens VA). This red pigmentation is caused by the production of prodigiosin, a molecule with antibacterial properties. To investigate the role of prodigiosin on mosquito- S. marcescens interactions, we produced two white mutants of S. marcescens VA by random mutagenesis. Whole genome sequencing and chemical analyses suggest that one mutant has a nonsense mutation in the gene encoding prodigiosin synthase, while the other one is deficient in the production of several types of secondary metabolites including prodigiosin and serratamolide. We used our mutants to investigate how S. marcescens secondary metabolites affect the mosquito and its microbiota. Our in vitro tests indicated that S. marcescens VA inhibits the growth of several mosquito microbiota isolates using a combination of prodigiosin and other secondary metabolites, corroborating published data. This strain requires secondary metabolites other than prodigiosin for its proteolytic and hemolytic activities. In the mosquito, we observed that S. marcescens VA is highly virulent to larvae in a prodigiosin-dependent manner, while its virulence on adults is lower and largely depends on other metabolites  
  Address  
  Corporate Author Thesis  
  Publisher Frontiers Media Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes (up) Approved no  
  Call Number EcoFoG @ webmaster @ Serial 1024  
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