Amazon tree dominance across forest strata

The forests of Amazonia are among the most biodiverse plant communities on Earth. Given the immediate threats posed by climate and land-use change, an improved understanding of how this extraordinary biodiversity is spatially organized is urgently required to develop effective conservation strategies. Most Amazonian tree species are extremely rare but a few are common across the region. Indeed, just 227 'hyperdominant' species account for >50% of all individuals >10 cm diameter at 1.3 m in height. Yet, the degree to which the phenomenon of hyperdominance is sensitive to tree size, the extent to which the composition of dominant species changes with size class and how evolutionary history constrains tree hyperdominance, all remain unknown. Here, we use a large floristic dataset to show that, while hyperdominance is a universal phenomenon across forest strata, different species dominate the forest understory, midstory and canopy. We further find that, although species belonging to a range of phylogenetically dispersed lineages have become hyperdominant in small size classes, hyperdominants in large size classes are restricted to a few lineages. Our results demonstrate that it is essential to consider all forest strata to understand regional patterns of dominance and composition in Amazonia. More generally, through the lens of 654 hyperdominant species, we outline a tractable pathway for understanding the functioning of half of Amazonian forests across vertical strata and geographical locations.

Vascular flora and phytogeographical links of the Carabaya Mountains, Peru

Los estudios sobre la composición florística y riqueza de especies en montañas tropicales apoyan su reconocimiento como áreas de alta diversidad biológica, y, por tanto, de su importancia para la conservación. En este trabajo presentamos datos sobre la flora altoandina de ocho sitios localizados en la Cordillera de Carabaya, proveemos también una comparación florística con otros nueve lugares tanto en Perú como en el norte de Bolivia. El área de estudio incluye 506 especies de plantas vasculares, reconocidas en 203 géneros y 66 familias. Las tasas más altas de riqueza de especies se hallan en dos familias: Asteraceae y Poaceae, que colectivamente abarcan el 37% de todas las especies. Otras familias importantes fueron Caryophyllaceae, Fabaceae, Malvaceae, Brassicaceae, Caprifoliaceae, Gentianaceae, Plantaginaceae y Cyperaceae. Los géneros más diversos fueron Senecio, Calamagrostis, Poa y Nototriche. La forma de crecimiento predominante fueron las hierbas perennes. La flora vascular de la Cordillera Carabaya está muy relacionada con otras regiones del sur de Perú. Además, más de la mitad de todas las plantas vasculares registradas para la Cordillera Carabaya se encuentran en la región andina de Bolivia, lo que demuestra la indudable conexión geofísica y fitogeográfica entre las cordilleras Carabaya y Apolobamba de Bolivia. Este estudio también demuestra la necesidad de una extensa colección botánica y futura exploración, desde que Carabaya, como otras partes de los altos Andes del Perú, están sujetos a cambios dramáticos que amenazan las poblaciones de esas plantas.

An integrated assessment of the vascular plant species of the Americas

The cataloging of the vascular plants of the Americas has a centuries-long history, but it is only in recent decades that an overview of the entire flora has become possible. We present an integrated assessment of all known native species of vascular plants in the Americas. Twelve regional and national checklists, prepared over the past 25 years and including two large ongoing flora projects, were merged into a single list. Our publicly searchable checklist includes 124,993 species, 6227 genera, and 355 families, which correspond to 33% of the 383,671 vascular plant species known worldwide. In the past 25 years, the rate at which new species descriptions are added has averaged 744 annually for the Americas, and we can expect the total to reach about 150,000.

Linking environmental filtering and disequilibrium to biogeography with a community climate framework

We present a framework to measure the strength of environmental filtering and disequilibrium of the species composition of a local community across time, relative to past, current, and future climates. We demonstrate the framework by measuring the impact of climate change on New World forests, integrating data for climate niches of more than 14000 species, community composition of 471 New World forest plots, and observed climate across the most recent glacial-interglacial interval. We show that a majority of communities have species compositions that are strongly filtered and are more in equilibrium with current climate than random samples from the regional pool. Variation in the level of current community disequilibrium can be predicted from Last Glacial Maximum climate and will increase with near-future climate change.

Limited sampling hampers "big data" estimation of species richness in a tropical biodiversity hotspot

Macro-scale species richness studies often use museum specimens as their main source of information. However, such datasets are often strongly biased due to variation in sampling effort in space and time. These biases may strongly affect diversity estimates and may, thereby, obstruct solid inference on the underlying diversity drivers, as well as mislead conservation prioritization. In recent years, this has resulted in an increased focus on developing methods to correct for sampling bias. In this study, we use sample-size-correcting methods to examine patterns of tropical plant diversity in Ecuador, one of the most species-rich and climatically heterogeneous biodiversity hotspots. Species richness estimates were calculated based on 205,735 georeferenced specimens of 15,788 species using the Margalef diversity index, the Chao estimator, the second-order Jackknife and Bootstrapping resampling methods, and Hill numbers and rarefaction. Species richness was heavily correlated with sampling effort, and only rarefaction was able to remove this effect, and we recommend this method for estimation of species richness with “big data” collections.

Functional trait space and the latitudinal diversity gradient

The processes causing the latitudinal gradient in species richness remain elusive. Ecological theories for the origin of biodiversity gradients, such as competitive exclusion, neutral dynamics, and environmental filtering, make predictions for how functional diversity should vary at the alpha (within local assemblages), beta (among assemblages), and gamma (regional pool) scales. We test these predictions by quantifying hypervolumes constructed from functional traits representing major axes of plant strategy variation (specific leaf area, plant height, and seed mass) in tree assemblages spanning the temperate and tropical New World. Alpha-scale trait volume decreases with absolute latitude and is often lower than sampling expectation, consistent with environmental filtering theory. Beta-scale overlap decays with geographic distance fastest in the temperate zone, again consistent with environmental filtering theory. In contrast, gamma-scale trait space shows a hump-shaped relationship with absolute latitude, consistent with no theory. Furthermore, the overall temperate trait hypervolume was larger than the overall tropical hypervolume, indicating that the temperate zone permits a wider range of trait combinations or that niche packing is stronger in the tropical zone. Although there are limitations in the data, our analyses suggest that multiple processes have shaped trait diversity in trees, reflecting no consistent support for any one theory.

Habitat area and climate stability determine geographical variation in plant species range sizes

Despite being a fundamental aspect of biodiversity, little is known about what controls species range sizes. This is especially the case for hyperdiverse organisms such as plants. We use the largest botanical data set assembled to date to quantify geographical variation in range size for ∼ 85 000 plant species across the New World. We assess prominent hypothesised range-size controls, finding that plant range sizes are codetermined by habitat area and long- and short-term climate stability. Strong short- and long-term climate instability in large parts of North America, including past glaciations, are associated with broad-ranged species. In contrast, small habitat areas and a stable climate characterise areas with high concentrations of small-ranged species in the Andes, Central America and the Brazilian Atlantic Rainforest region. The joint roles of area and climate stability strengthen concerns over the potential effects of future climate change and habitat loss on biodiversity.

Beta-diversity in temperate and tropical forests reflects dissimilar mechanisms of community assembly

Site-to-site variation in species composition (β-diversity) generally increases from low- to high-diversity regions. Although biogeographical differences in community assembly mechanisms may explain this pattern, random sampling effects can create this pattern through differences in regional species pools. Here, we compared assembly mechanisms between spatially extensive networks of temperate and tropical forest plots with highly divergent species pools (46 vs. 607 species). After controlling for sampling effects, β-diversity of woody plants was similar and higher than expected by chance in both forests, reflecting strong intraspecific aggregation. However, different mechanisms appeared to explain aggregation in the two forests. In the temperate forest, aggregation reflected stronger environmental correlations, suggesting an important role for species-sorting (e.g. environmental filtering) processes, whereas in the tropics, aggregation reflected stronger spatial correlations, more likely reflecting dispersal limitation. We suggest that biogeographical differences in the relative importance of different community assembly mechanisms contribute to these striking gradients in global biodiversity.

Patient discomfort in bitewing examination with film and four digital receptors

The aim was to compare patient discomfort during bitewing examination using five intra-oral receptors: a conventional film, a storage phosphor plate with a new soft cover, an already manufactured and sold sensor with a wire and two square and two rounded corners, a new version of a previously developed sensor with a wire and four square corners, and a newly developed sensor with a wire and four rounded corners. 60 patients participated in the study. The five receptors [a Kodak paper pack film (Eastman Kodak Company, Rochester, NY), a DIGORA® Optime phosphor plate (Soredex, Tuusula, Finland), and SuniRay (Suni Medical Imaging, Inc., San Jose, CA), DIGORA Toto (Soredex) and Snapshot (Instrumentarium Dental, Tuusula, Finland) complementary metal-oxide-semiconductors] with differences in ergonomic shape were placed in the mouth for a bitewing examination for approximately 10 s. The patients rated their discomfort on a 100 mm visual analogue scale after having had each receptor positioned. There was no significant difference in patient discomfort score between the conventional film and the Snapshot sensor (p > 0.05). Both conventional film and Snapshot were significantly less uncomfortable than the other receptors (p < 0.05). No significant difference was seen between the storage phosphor plate and the SuniRay sensor (p > 0.05). The storage phosphor plate was significantly less uncomfortable than the DIGORA Toto sensor (p < 0.05). There was no significant difference in the perception of discomfort between the conventional film and an ergonomically shaped wired sensor with rounded corners.

Control for recurrences of urinary bladder tumours by transabdominal ultrasonic scanning

By transabdominal ultrasonic scanning of the filled bladder it is possible to examine the surface of the bladder urothelium in the outpatient clinic. In a "blind" study of 129 patients controlled for recurrences of urinary bladder tumours the results of dynamic transabdominal ultrasonography were compared with the results of cystoscopy. The ultrasound could identify the recurrences of 5 mm or above in size significantly. Below 5 mm in dimension, when positioned in the dome of the bladder or at severe trabeculation the ultrasonic scanning lead to a misdiagnosis. No invasive recurrences were overlooked by ultrasonography. We will advocate that transabdominal ultrasonic scanning replace routine cystoscopy in low-risk patients with superficial bladder tumours of the Ta category and a low grade after the primary transurethral treatment and no or few recurrences of the same Ta category at the first control cystoscopy. On the other hand we will recommend to continue cystoscopy of patients with frequently recurring urinary bladder tumours, the high grade Ta tumours, carcinoma in situ because of the risk of invasive growth, and patients with primary invasive tumours including those with the superficial invasion (category T1).