Tree Species and Epiphyte Taxa Determine the "Metabolomic niche" of Canopy Suspended Soils in a Species-Rich Lowland Tropical Rainforest.

Tropical forests are biodiversity hotspots, but it is not well understood how this diversity is structured and maintained. One hypothesis rests on the generation of a range of metabolic niches, with varied composition, supporting a high species diversity. Characterizing soil metabolomes can reveal fine-scale differences in composition and potentially help explain variation across these habitats. In particular, little is known about canopy soils, which are unique habitats that are likely to be sources of additional biodiversity and biogeochemical cycling in tropical forests. We studied the effects of diverse tree species and epiphytes on soil metabolomic profiles of forest floor and canopy suspended soils in a French Guianese rainforest. We found that the metabolomic profiles of canopy suspended soils were distinct from those of forest floor soils, differing between epiphyte-associated and non-epiphyte suspended soils, and the metabolomic profiles of suspended soils varied with host tree species, regardless of association with epiphyte. Thus, tree species is a key driver of rainforest suspended soil metabolomics. We found greater abundance of metabolites in suspended soils, particularly in groups associated with plants, such as phenolic compounds, and with metabolic pathways related to amino acids, nucleotides, and energy metabolism, due to the greater relative proportion of tree and epiphyte organic material derived from litter and root exudates, indicating a strong legacy of parent biological material. Our study provides evidence for the role of tree and epiphyte species in canopy soil metabolomic composition and in maintaining the high levels of soil metabolome diversity in this tropical rainforest. It is likely that a wide array of canopy microsite-level environmental conditions, which reflect interactions between trees and epiphytes, increase the microscale diversity in suspended soil metabolomes.

Comparable canopy and soil free-living nitrogen fixation rates in a lowland tropical forest.

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.

Habitats shape taxonomic and functional composition of Neotropical ant assemblages.

Determining assembly rules of co-occurring species persists as a fundamental goal in community ecology. At local scales, the relative importance of environmental filtering vs. competitive exclusion remains a subject of debate. In this study, we assessed the relative importance of habitat filtering and competition in structuring understory ant communities in tropical forests of French Guiana. Leaf-litter ants were collected using pitfall and Winkler traps across swamp, slope and plateau forests near Saül, French Guiana. We used a combination of univariate and multivariate analyses to evaluate trait response of ants to habitat characteristics. Null model analyses were used to investigate the effects of habitat filtering and competitive interactions on community assembly at the scale of assemblages and sampling points, respectively. Swamp forests presented a much lower taxonomic and functional richness compared to slope and plateau forests. Furthermore, marked differences in taxonomic and functional composition were observed between swamp forests and slope or plateau forests. We found weak evidence for competitive exclusion based on null models. Nevertheless, the contrasting trait composition observed between habitats revealed differences in the ecological attributes of the species in the different forest habitats. Our analyses suggest that competitive interactions may not play an important role in structuring leaf-litter ant assemblages locally. Rather, habitats are responsible for driving both taxonomic and functional composition of ant communities.

Hospital preparedness for Ebola virus disease: a training course in the Philippines.

OBJECTIVE: To develop, teach and evaluate a training workshop that could rapidly prepare large numbers of health professionals working in hospitals in the Philippines to detect and safely manage Ebola virus disease (EVD). The strategy was to train teams (each usually with five members) of key health professionals from public, private and local government hospitals across the Philippines who could then guide Ebola preparedness in their hospitals. METHODS: The workshop was developed collaboratively by the Philippine Department of Health and the country office of the World Health Organization. It was evaluated using a pre- and post-workshop test and two evaluation forms. χ(2) tests and linear regression analyses were conducted comparing pre- and post-workshop test results. RESULTS: A three-day workshop was developed and used to train 364 doctors, nurses and medical technologists from 78 hospitals across the Philippines in three initial batches. Knowledge about EVD increased significantly (P < 0.009) although knowledge on transmission remained suboptimal. Confidence in managing EVD increased significantly (P = 0.018) with 96% of participants feeling more prepared to safely manage EVD cases. DISCUSSION: The three-day workshop to prepare hospital staff for EVD was effective at increasing the level of knowledge about EVD and the level of confidence in managing EVD safely. This workshop could be adapted for use as baseline training in EVD in other developing countries to prepare large numbers of hospital staff to rapidly detect, isolate and safely manage EVD cases.