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Aim Concern about climate change, with the subsequent emergence of carbon markets and policy initiatives such as REDD (reducing carbon emissions by decreasing deforestation and forest degradation), have focused attention on assessing and monitoring terrestrial carbon reserves. Most effort has focused on above-ground forest biomass. Soil has received less attention despite containing more carbon than above-ground terrestrial biomass and the atmosphere combined. Our aim was to explore how well soil carbon concentration could be estimated on three continents from existing climate, topography and vegetation-cover data. Location Peru, Brazil, Argentina, Australia, China. Methods Soil carbon concentration and leaf area index ( LAI) as well as GIS-derived climate and topography variables for 65 temperate and 43 tropical, forest and woodland ecosystems, were either directly measured or estimated from freely available global datasets. We then used multiple regressions to determine how well soil carbon concentration could be predicted from LAI, climate and topography at a given site. We compared our measurements with top soil carbon estimates from the Food and Agriculture Organization of the United Nations ( FAO) harmonized world soil map. Results Our empirical model based on estimates of temperature, water availability and plant productivity provided a good estimate of soil carbon concentrations ( R2 = 0.79). In contrast, the values of topsoil carbon concentrations from the FAO harmonized world soil map correlated poorly with the measured values of soil carbon concentration ( R2 = 0.0011). Main conclusions The lack of correlation between the measured values of soil carbon and the values from the FAO harmonized world soil map indicate that substantial improvements in the production of soil carbon maps are needed and possible. Our results demonstrate that the inclusion of freely available GIS data offers improved estimates of soil carbon and will allow the creation of more accurate soil carbon maps. [ABSTRACT FROM AUTHOR]

Aim To determine the relationship between the distribution of climate, climatic heterogeneity and pteridophyte species richness gradients in Australia, using an approach that does not assume potential relationships are spatially invariant and allows for scale effects (extent of analysis) to be explicitly examined. Location Australia, extending from 10° S to 43° S and 112° E to 153° E. Method Species richness within 50 × 50 km grid cells was determined using point distribution data. Climatic surfaces representing the distribution and availability of water and energy at 1 km and 5 km cell resolutions were obtained. Climate at the 50 km resolution of analysis was represented by their mean and standard deviation in that area. Relationships were assessed using geographically weighted linear regression at a range of spatial bandwidths to investigate scale effects. Results The parameters and the predictive strength of all models varied across space at all extents of analysis. Overall, climatic variables representing water availability were more highly correlated to pteridophyte richness gradients in Australia than those representing energy. Their variance in cells further increased the strength of the relationships in topographically heterogeneous regions. Relationships with water were strong across all extents of analysis, particularly in the tropical and subtropical parts of the continent. Water availability explained less of the variation in richness at higher latitudes. Main conclusions This study brings into question the ability of aspatial and single-extent models, searching for a unified explanation of macro-scaled patterns in gradients of diversity, to adequately represent reality. It showed that, across Australia, there is a positive relationship between pteridophyte species richness and water availability but the strength and nature of the relationship varies spatially with scale in a highly complex manner. The spatial variance, or actual complexity, in these relationships could not have been demonstrated had a traditional aspatial global regression approach been used. Regional scale variation in relationships may be at least as important as more general relationships for a true understanding of the distribution of broad-scale diversity. [ABSTRACT FROM AUTHOR]

Aim: A key ecological debate is whether ecosystem functions are distinctly influenced by biological diversity across broad scales. Although recent work has emphasized the importance of links between ecosystem functions and measures of ecological specialization as proxies of biodiversity, few studies have analysed macroecological relationships empirically in diverse environments. We tested whether gross primary productivity (GPP) in the Australian Wet Tropics (WT) was distinctly related to community‐level measures of the ecological specialization of component tree species across climate space, after accounting for climate drivers. Location: Wet Tropics, Australia. Time period: 1976–2012. Major taxa studied: Nine hundred and forty‐eight WT tree species. Methods: Using all geographically valid herbarium records for WT trees, we quantified the realized climatic niche widths using continental surfaces for maximum temperature of the warmest period and total annual rainfall. The median realized niche width for all tree species occurring at 510 sites was used to approximate ecological specialization within communities. To separate climatic effects on GPP, we applied a novel analysis using the difference in GPP and the difference in median community realized niche width between site pairs with similar climatic conditions. Linear models were then run on the difference in GPP between site pairs (response) and the difference in climatic niche widths (predictor). Results: For climatically similar sites in drier areas, GPP was higher in sites composed of species with narrower temperature niches (average R2 = 0.087, average t‐statistic = −3.45). Conversely, for climatically similar sites in drier areas, GPP was lower in sites composed of species with narrower rainfall niches (average R2 = 0.171, average t‐statistic = 5.06). Main conclusions: Wet Tropics sites with more thermal specialists had higher productivity, whereas sites with more moisture specialists had lower productivity. These findings suggest that physiological specialization across climate space can influence primary productivity at broad scales, but in inconsistent ways. [ABSTRACT FROM AUTHOR]

Motivation We generated a novel database of Neotropical snakes (one of the world's richest herpetofauna) combining the most comprehensive, manually compiled distribution dataset with publicly available data. We assess, for the first time, the diversity patterns for all Neotropical snakes as well as sampling density and sampling biases. Main types of variables contained We compiled three databases of species occurrences: a dataset downloaded from the Global Biodiversity Information Facility (GBIF), a verified dataset built through taxonomic work and specialized literature, and a combined dataset comprising a cleaned version of the GBIF dataset merged with the verified dataset. Spatial location and grain Neotropics, Behrmann projection equivalent to 1° × 1°. Time period Specimens housed in museums during the last 150 years. Major taxa studied Squamata: Serpentes. Software format Geographical information system (GIS). Results The combined dataset provides the most comprehensive distribution database for Neotropical snakes to date. It contains 147,515 records for 886 species across 12 families, representing 74% of all species of snakes, spanning 27 countries in the Americas. Species richness and phylogenetic diversity show overall similar patterns. Amazonia is the least sampled Neotropical region, whereas most well-sampled sites are located near large universities and scientific collections. We provide a list and updated maps of geographical distribution of all snake species surveyed. Main conclusions The biodiversity metrics of Neotropical snakes reflect patterns previously documented for other vertebrates, suggesting that similar factors may determine the diversity of both ectothermic and endothermic animals. We suggest conservation strategies for high-diversity areas and sampling efforts be directed towards Amazonia and poorly known species. [ABSTRACT FROM AUTHOR]

Aim Ecosystem functions such as productivity may be influenced not only by the biological diversity at each location (α-diversity) but also by the biological turnover between locations (β-diversity). We perform a continental-scale test of the strength and direction of relationships between gross primary productivity (GPP) and both α- and β-diversity. Location Continental Australia. Methods Species occurrence records were used to quantify the taxonomic α-diversity of vascular plants in approximately 11,000 1 km × 1 km grid cells across Australia, and to calculate the average β-diversity within a 10-km radius around each cell. The magnitude and variability of monthly, MODIS-derived remotely sensed GPP (2001-12) were summarized for continental Australia, as were rainfall and temperature over the same period. Generalized additive models were then used to test whether the magnitude or variability of GPP were distinctly influenced by either biodiversity measure, over and above the influence of environmental conditions. Results Precipitation and temperature explained large proportions of deviance in the magnitude (75.6%) and variability (38.3%) of GPP across the Australian continent. GPP was marginally more strongly related to species richness than it was to species turnover. However, neither diversity measure provided substantial increases in the explanatory power of GPP models over and above that of environment-only models (always < 1%). Main conclusions The relationship between primary productivity and taxonomic α- and β-diversity was weak for the Australian flora. Our findings question the generality of key assumptions, predictions and results in the literature regarding the strength of empirical relationships between productivity and biodiversity across multiple biological levels (α-, β- and γ-diversity) at macroecological scales. [ABSTRACT FROM AUTHOR]

Aim The idea that species are generally more colourful at tropical latitudes has held great appeal among biologists since the days of exploration by early naturalists. However, advances in colour quantification and analysis only now allow an objective test of this idea. We provide the first quantitative analysis of the latitudinal gradient in colour on a broad scale using data from both animals and plants, encompassing both human-visible and ultraviolet colours. Location Australia. Methods We collected spectral reflectance data from 570 species or subspecies of birds, adult forms of 424 species or subspecies of butterflies and the flowers of 339 species of plants, from latitudes ranging from tropical forests and savannas at 9.25° S, to temperate forests and heathlands at 43.75° S. Colour patch saturation, maximum contrast between patches, colour diversity and hue disparity between patches were calculated for all species. Latitudinal gradients in colour were analysed using both regression analyses and comparisons of categorically temperate and tropical regions. We also provide phylogenetically independent contrast analyses. Results The analyses which compared the colour traits of communities and the phylogenetically independent contrasts both show that species in the tropics are not more colourful than those at higher latitudes. Rather, the cross-species analyses indicate that species further away from the equator possess a greater diversity of colours, and their colours are more contrasting and more saturated than those seen in tropical species. These results remain consistent regardless of whether the mean or the maximum of coloration indices are considered. Main conclusions We demonstrate that birds, butterflies and flowers display similar gradients of colourfulness across latitudes, indicating strong ecological and evolutionary cohesion. However, our data do not support the idea that tropical latitudes contain the most colourful species or house the more colourful biological communities. [ABSTRACT FROM AUTHOR]