Abstract: Summary While around 20% of the Amazonian forest has been cleared for pastures and agriculture, one fourth of the remaining forest is dedicated to wood production [1]. Most of these production forests have been or will be selectively harvested for commercial timber, but recent studies show that even soon after logging, harvested stands retain much of their tree-biomass carbon and biodiversity [2,3]. Comparing species richness of various animal taxa among logged and unlogged forests across the tropics, Burivalova et al.[4] found that despite some variability among taxa, biodiversity loss was generally explained by logging intensity (the number of trees extracted). Here, we use a network of 79 permanent sample plots (376 ha total) located at 10 sites across the Amazon Basin [5] to assess the main drivers of time-to-recovery of post-logging tree carbon (Table S1). Recovery time is of direct relevance to policies governing management practices (i.e., allowable volumes cut and cutting cycle lengths), and indirectly to forest-based climate change mitigation interventions. © 2015 Elsevier Ltd.

Abstract: Background and Aims The plant Hirtella physophora, the ant Allomerus decemarticulatus and a fungus, Trimmatostroma sp., form a tripartite association. The ants manipulate both the plant trichomes and the fungus to build galleries under the stems of their host plant used to capture prey. In addition to its structural role, the fungus also improves nutrient uptake by the host plant. But it still remains unclear whether the fungus plays an indirect or a direct role in transferring nutrients to the plant. This study aimed to trace the transfer of N from the fungus to the plant's stem tissue. • Methods Optical microscopy and transmission electron microscopy (TEM) were used to investigate the presence of fungal hyphae in the stem tissues. Then, a 15N-labelling experiment was combined with a nanoscale secondary-ion mass spectrometry (NanoSIMS 50) isotopic imaging approach to trace the movement of added 15N from the fungus to plant tissues. • Key Results The TEM images clearly showed hyphae inside the stem tissue in the cellular compartment. Also, fungal hyphae were seen perforating the wall of the parenchyma cell. The 15N provisioning of the fungus in the galleries resulted in significant enrichment of the 15N signature of the plant's leaves 1 d after the 15N-labelling solution was deposited on the fungus-bearing trap. Finally, NanoSIMS imaging proved that nitrogen was transferred biotrophically from the fungus to the stem tissue. • Conclusions This study provides evidence that the fungi are connected endophytically to an ant-plant system and actively transfer nitrogen from 15N-labelling solution to the plant's stem tissues. Overall, this study underlines how complex the trophic structure of ant-plant interactions is due to the presence of the fungus and provides insight into the possibly important nutritional aspects and tradeoffs involved in myrmecophyte-ant mutualisms. © The Author 2017.

Abstract: The analysis of fine-scale spatial genetic structure (FSGS) within populations can provide insights into eco-evolutionary processes. Restricted dispersal and locally occurring genetic drift are the primary causes for FSGS at equilibrium, as described in the isolation by distance (IBD) model. Beyond IBD expectations, spatial, environmental or historical factors can affect FSGS. We examined FSGS in seven African and Neotropical populations of the late-successional rain forest tree Symphonia globulifera L. f. (Clusiaceae) to discriminate the influence of drift-dispersal vs. landscape/ecological features and historical processes on FSGS. We used spatial principal component analysis and Bayesian clustering to assess spatial genetic heterogeneity at SSRs and examined its association with plastid DNA and habitat features. African populations (from Cameroon and São Tomé) displayed a stronger FSGS than Neotropical populations at both marker types (mean Sp = 0.025 vs. Sp = 0.008 at SSRs) and had a stronger spatial genetic heterogeneity. All three African populations occurred in pronounced altitudinal gradients, possibly restricting animal-mediated seed dispersal. Cyto-nuclear disequilibria in Cameroonian populations also suggested a legacy of biogeographic history to explain these genetic patterns. Conversely, Neotropical populations exhibited a weaker FSGS, which may reflect more efficient wide-ranging seed dispersal by Neotropical bats and other dispersers. The population from French Guiana displayed an association of plastid haplotypes with two morphotypes characterized by differential habitat preferences. Our results highlight the importance of the microenvironment for eco-evolutionary processes within persistent tropical tree populations. © 2017 Torroba-Balmori et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract: Rationale: Studies of wetland eco-hydrology in tropical coastal areas are scarce, and the use of water stable isotopes can be of great help. Key constraints for their analysis are (i) the small difference in delta18O values between seawater and old evaporated freshwater, and (ii) the fact that the presence of old brackish water limits the determination of the water origin and dynamic. Methods: The water from tropical storms displays distinctively depleted heavy stable isotopes, in comparison with usual tropical rainfall without strong convective thunderstorms. During tropical storms, such as Hurricane Rafael in mid-October 2012, the rainfall delta18O signal can be decreased by many units. This effect is called an “isotopic spike”, and it could be used as a temporal marker of the water fluxes. Results: Water samples, with delta18O values as low as −8.9/1000, were collected on the islands of Guadeloupe and Saint-Martin during Hurricane Rafael, whereas the usual range of groundwater or mean rainfall delta18O values is around −2.8 +/- 0.5 /1000, as measured from 2009 to 2012. These water “isotopic spikes” allow us to show a surface freshwater uptake by mangrove trees in Guadeloupe, and in Saint-Martin, to calculate the water renewal of the salt ponds and pools. Conclusions: The “isotopic spikes” generated by tropical storms are generally used to track back past storm events, as recorded in trees and stalagmites. Here, the propagation of isotopic spike is followed to improve the understanding of the freshwater circulation and the water dynamic within coastal ecosystems influenced by seawater.

Abstract: Investigations of basic radial wood density (WD) in tropical trees revealed linear patterns and some curvilinear patterns. Studies usually disregard longitudinal variations, which are often considered to be similar to radial variations. This study aimed to show (1) a new radial curvilinear WD pattern, (2) differences in amplitude between radial and longitudinal gradients and (3) to partition WD variations according to different scales in Parkia velutina, an emergent tree found in Neotropical rain forests. We collected full discs from six felled trees and radial cores from 10 standing trees to check WD variability, plus one dominant axis per tree for analysis of height growth rates. This species showed very high growth rates indicative of heliophilic habits. WD varied from 0.194 to 0.642 g/cm3. Such amplitude is rarely observed within the same tree. Radial variation in WD was curvilinear, with an amplitude generally less than the longitudinal amplitude. Consequently, in mature trees, WD values in the crown were higher than those in the outer trunk. WD variations can be highly significant at different scales. The variance partitioning also revealed that the whole WD range of Parkia velutina is more accurately estimated intra-individually when both longitudinal and radial gradient are covered.