| Records |
| 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 |
| 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 |
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| Volume |
11 |
Issue |
13 |
Pages |
8969-8982 |
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| 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. |
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| Publisher |
Wiley |
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no |
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EcoFoG @ webmaster @ |
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1011 |
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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 |
| 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 |
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| Volume |
259 |
Issue |
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Pages |
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| Keywords |
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| 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. |
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Elsevier B.V. |
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no |
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EcoFoG @ webmaster @ |
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1010 |
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| Author |
Dejean, Alain ; Petitclerc, Frédéric ; Azémar, Frédéric ; Rossi, Vivien |
| 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 |
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| Volume |
133 |
Issue |
3 |
Pages |
744-750 |
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| 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’. |
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Oxford Academy |
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no |
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EcoFoG @ webmaster @ |
Serial |
1009 |
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Aubry-Kientz, Mélaine ; Laybros, Anthony ; Weinstein, Ben ; Ball, James G. C. ; Jackson, Toby ; Coomes, David ; Vincent, Grégoire |
| 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 |
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| Volume |
14 |
Issue |
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Pages |
3927-3936 |
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| 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. |
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IEEE |
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no |
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EcoFoG @ webmaster @ |
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1008 |
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| Author |
Brosse, Sébastien ; Baglan, Antoine ; Covain, Raphael ; Lalague, Hadrien ; Le Bail, Pierre-Yve ; Vigouroux, Régis ; Quartarollo, Grégory |
| Title |
Aquarium trade and fish farms as a source of non-native freshwater fish introductions in French Guiana |
Type |
Journal Article |
| Year |
2021 |
Publication |
Annales de Limnologie – International Journal of Limnology |
Abbreviated Journal |
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| Volume |
57 |
Issue |
4 |
Pages |
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| Keywords |
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| Abstract |
Rivers of French Guiana are still little invaded by non-native fish, but several fish introductions were recently recorded through the development of aquarium fish trade and fish farms. Here we report records of 11 non-native fish species. Among them, four (Cichla monoculus, Heros efasciatus, Mesonauta guyanae and Poecilia reticulata) are established and one of them (Heros efasciatus) is rapidly increasing its spatial range. Two species (Hyphessobrycon eques and Pterophyllum scalare) were not retrieved in recent records and are probably extinct from French Guiana. The establishment status of the five other species (Arapaima gigas, Colossoma macropomum, Cyprinus carpio, Oreochromis mossambicus and Osteoglossum bicirrhosum) is uncertain and only a few specimens were observed in the wild. Nevertheless, these species, intensively reared in nearby countries, belong to highly invasive species able to cause detrimental impacts on recipient ecosystems. Those first occurrences of invasive fish species in French Guiana should therefore act as an early warning for both researchers and environmental managers. |
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EDP SCIENCES S A |
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Anglais |
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no |
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EcoFoG @ webmaster @ |
Serial |
1007 |
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Van Langenhove, Leandro ; Depaepe, Thomas ; Verryckt, Lore T. ; Fuchslueger, Lucia ; Donald, Julian ; Celine, Leroy ; Krishna Moorthy, Sruthi M. ; Gargallo-Garriga, Albert ; Farnon Ellwood, M. D.; Verbeeck, Hans ; Van Der Straeten, Dominique ; Penuelas, Josep ; Janssens, Ivan A. |
| Title |
Comparable canapy and soil free living nitrogen fixation rates in e lowland tropical forest |
Type |
Journal Article |
| Year |
2021 |
Publication |
Science of the total environment |
Abbreviated Journal |
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| Volume |
754 |
Issue |
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Pages |
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| Keywords |
Biodiversité ; Systématique ; phylogénie ; taxonomie ; Ecologie, Environnement ; Ecosystèmes ; Biologie végétale ; Botanique ; Biodiversité |
| Abstract |
Biological nitrogen fixation (BNF) is a fundamental part of nitrogen cycling in tropical forests, yet little is known about the contribution made by free-living nitrogen fixers inhabiting the often-extensive forest canopy. We used the acetylene reduction assay, calibrated with 15N2, to measure free-living BNF on forest canopy leaves, vascular epiphytes, bryophytes and canopy soil, as well as on the forest floor in leaf litter and soil. We used a combination of calculated and published component densities to upscale free-living BNF rates to the forest level. We found that bryophytes and leaves situated in the canopy in particular displayed high mass-based rates of free-living BNF. Additionally, we calculated that nearly 2 kg of nitrogen enters the forest ecosystem through free-living BNF every year, 40% of which was fixed by the various canopy components. Our results reveal that in the studied tropical lowland forest a large part of the nitrogen input through free-living BNF stems from the canopy, but also that the total nitrogen inputs by free-living BNF are lower than previously thought and comparable to the inputs of reactive nitrogen by atmospheric deposition. |
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Elsevier |
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Anglais |
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no |
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EcoFoG @ webmaster @ |
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1006 |
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Duplais, Christophe ; Sarou-Kanian, Vincent ; Massiot, Dominique ; Hassan, Alia ; Perrone, Barbara ; Estevez, Yannick ; Wertz, John; Martineau, Estelle ; Farjon, Jonathan ; Giraudeau, Patrick, Moreau, Carrie S. |
| Title |
Gut bacteria are essential for normal cutile development in herbivorous turtle ants |
Type |
Journal Article |
| Year |
2021 |
Publication |
Nature Communication |
Abbreviated Journal |
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| Volume |
12 |
Issue |
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Pages |
1-6 |
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| Abstract |
Across the evolutionary history of insects, the shift from nitrogen-rich carnivore/omnivore diets to nitrogen-poor herbivorous diets was made possible through symbiosis with microbes. The herbivorous turtle ants Cephalotes possess a conserved gut microbiome which enriches the nutrient composition by recycling nitrogen-rich metabolic waste to increase the production of amino acids. This enrichment is assumed to benefit the host, but we do not know to what extent. To gain insights into nitrogen assimilation in the ant cuticle we use gut bacterial manipulation, 15N isotopic enrichment, isotope-ratio mass spectrometry, and 15N nuclear magnetic resonance spectroscopy to demonstrate that gut bacteria contribute to the formation of proteins, catecholamine cross-linkers, and chitin in the cuticle. This study identifies the cuticular components which are nitrogen-enriched by gut bacteria, highlighting the role of symbionts in insect evolution, and provides a framework for understanding the nitrogen flow from nutrients through bacteria into the insect cuticle. |
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NATURE PUBLISHING GROUP |
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Anglais |
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no |
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EcoFoG @ webmaster @ |
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1005 |
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Bréchet, Laëtitia M.; Daniel Warren; Stahl, Clément; Burban, Benoït; Goret, Jean-Yves; Salomon, Roberto L.; Janssens, Ivan A.o |
| Title |
Simultaéneous tree stem and soil greenhouse gas (CO2, CH4, N2O) flux measurements: a novel design for continuous monitoring towards improving flux estimates and temporal resolution |
Type |
Journal Article |
| Year |
2021 |
Publication |
New Phytologist |
Abbreviated Journal |
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| Volume |
230 |
Issue |
6 |
Pages |
2487-2500 |
| Keywords |
système de chambre automatisé ; efflux de dioxyde de carbone ; flux de méthane ; flux d'oxyde nitreux ; tige d'arbre ; forêt tropicale |
| Abstract |
Tree stems and soils can act as sources and sinks for the greenhouse gases (GHG) carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Since both uptake and emission capacities can be large, especially in tropical rainforests, accurate assessments of the magnitudes and temporal variations of stem and soil GHG fluxes are required. We designed a new flexible stem chamber system for continuously measuring GHG fluxes in a French Guianese rainforest. Here, we describe this new system, which is connected to an automated soil GHG flux system, and discuss measurement uncertainty and potential error sources. In line with findings for soil GHG flux estimates, we demonstrated that lengthening the stem chamber closure time was required for accurate estimates of tree stem CH4 and N2O flux but not tree stem CO2 flux. The instrumented stem was a net source of CO2 and CH4 and a weak sink of N2O. Our experimental setup operated successfully in situ and provided continuous tree and soil GHG measurements at a high temporal resolution over an 11-month period. This automated system is a major step forward in the measurement of GHG fluxes in stems and the atmosphere concurrently with soil GHG fluxes in tropical forest ecosystems. |
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New Phytologist Foundation |
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no |
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EcoFoG @ webmaster @ |
Serial |
1004 |
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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. |
| Title |
Revisiting nutrient cycling by litterfall—Insights from 15 years of litter manipulation in old-growth lowland tropical forest |
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Journal Article |
| Year |
2020 |
Publication |
Advances in Ecological Researc |
Abbreviated Journal |
Adv. Ecol. Res. |
| Volume |
62 |
Issue |
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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 |
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Academic Press Inc. |
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Editor |
Dumbrell A.J.; Turner E.C.; Fayle T.M. |
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Abbreviated Series Title |
Advances in Ecological Research |
| Series Volume |
62 |
Series Issue |
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Edition |
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| ISSN |
00652504 (Issn); 9780128211342 (Isbn) |
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no |
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EcoFoG @ webmaster @ |
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1001 |
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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. |
| 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 |
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Blackwell Publishing Ltd |
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0028646x (Issn) |
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no |
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EcoFoG @ webmaster @ |
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997 |
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