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Biodiversity monitoring is an almost inconceivable challenge at the scale of the entire Earth. The current (and soon to be flown) generation of spaceborne and airborne optical sensors (i.e., imaging spectrometers) can collect detailed information at unprecedented spatial, temporal, and spectral resolutions. These new data streams are preceded by a revolution in modeling and analytics that can utilize the richness of these datasets to measure a wide range of plant traits, community composition, and ecosystem functions. At the heart of this framework for monitoring plant biodiversity is the idea of remotely identifying species by making use of the 'spectral species' concept. In theory, the spectral species concept can be defined as a species characterized by a unique spectral signature and thus remotely detectable within pixel units of a spectral image. In reality, depending on spatial resolution, pixels may contain several species which renders species-specific assignment of spectral information more challenging. The aim of this paper is to review the spectral species concept and relate it to underlying ecological principles, while also discussing the complexities, challenges and opportunities to apply this concept given current and future scientific advances in remote sensing.

Positive plant–plant interactions are thought to drive vegetation patterns in harsh environments, such as semi-arid areas. According to the stress-gradient hypothesis (SGH), the role of positive interactions between species (facilitation) is expected to increase with harshness, predicting associated variation in species composition along environmental gradients. However, the relation between stress and facilitation along environmental gradients is debated. Furthermore, differentiating facilitative interactions from other underlying mechanisms, such as microtopographic heterogeneity, is not trivial. We analysed the spatial co-occurrence relationships of vascular plant species that form patchy vegetation in arid lapilli fields (tephra) from recent volcanic eruptions on La Palma, Canary Islands. Assuming a harshness gradient negatively correlated with elevation because the lower elevations are more arid and water availability is considered the most limiting resource, and that an outcome of facilitation is plants co-occurring in the same patch, from the SGH we expected a greater degree of co-occurrence at lower elevation. We tested this at both the species and the individual plant level. We analysed the species composition of 1277 shrubby vegetation patches at 64 different sampling points, ranging from the coast to around 700 m a.s.l. Patch morphology and microtopographic heterogeneity variables were also measured, to account for their potential effects on the species composition of patches. We used generalized linear models and generalized mixed-effects models to analyse species richness, number of individuals in patches and percentage of patches with positive co-occurrences, and a pairwise co-occurrence analysis combined with a graphical network analysis to reveal positive links between 13 of the species. We found that the percentage of patches with positive co-occurrences increased at higher elevations, in contrast to the predictions of the SGH, but in accordance with a refined stress-gradient hypothesis for arid sites, in which characteristics of the interacting species are incorporated.

Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.

Topography influences evolutionary and ecological processes by isolating populations and enhancing habitat diversity. While the effects of large-scale topography on patterns of species richness and endemism are increasingly well documented, the direct effect of local topography on endemism is less understood. This study compares different aspects of topographic isolation, namely the isolating effect of deep barrancos (ravines) and the effect of increasing isolation with elevation in influencing patterns of plant endemism within a topographically diverse oceanic island (La Palma, Canary Islands, Spain). We collected plant presence–absence data from 75 plots in 8 barrancos on the northern coast of La Palma, spanning an elevation gradient from 95 to 674m a.s.l. Using mixed-effects models, we assessed the effect of barranco depth and elevation on the percentage of single-island endemics, multi-island endemics, and archipelago endemics. We found that percent endemism was not significantly correlated with barranco depth and correlated negatively with elevation within barrancos (rather than the expected positive relationship). The topographic barriers associated with the deep island barrancos thus appear insufficient to drive speciation through isolation in oceanic island plants. The decrease in endemism with elevation contradicts findings by previous broader-scale studies and it may reflect local influences, such as high habitat heterogeneity at low elevations.

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Aim: Biodiversity on islands is commonly explained by a set of natural drivers such as area, isolation and habitat heterogeneity. However, constant human impact has led to considerable changes in island floras worldwide. This is reflected, among others, in increased numbers of non‐native species. Barrier islands are discrete land units, strongly influenced by humans and not displaying significant evolutionary dynamics. This makes them highly suitable for studying contemporary patterns of species richness and underlying processes. We aim to disentangle the effects of established natural and anthropogenic drivers on native and non‐native plant species richness at the example of 31 European barrier islands. Location: 31 North Sea barrier islands located off the Dutch, German and Danish coast. Taxon: Native and non‐native plant species (spermatophytes and ferns). Methods: Individual relationships of natural and anthropogenic drivers with native and non‐native plant species richness are analysed with generalised linear models (GLMs). We use structural equation models (SEMs) to additionally account for interrelations between drivers. Results: Island area was the strongest predictor of native and non‐native plant species richness but affected richness mostly indirectly through habitat heterogeneity (non‐native species) and island inhabitants (native species). Isolation had a slight negative effect on native and non‐native plant species numbers on islands. Main Conclusions: The richness of native and non‐native plant species on islands is associated with different drivers, that is, habitat heterogeneity and island inhabitants respectively. This might be caused by distinct underlying processes forming native and non‐native richness patterns. Area was confirmed to be the most important driver of species richness but acting primarily through other natural and anthropogenic drivers of plant species richness. We encourage considering both natural and anthropogenic drivers and their interrelatedness to explain contemporary biogeographic patterns of species richness. [ABSTRACT FROM AUTHOR]

Are we entering a new ‘Golden Age’ of biogeography, with continued development of infrastructure and ideas? We highlight recent developments, and the challenges and opportunities they bring, in light of the snapshot provided by the 7th biennial meeting of the International Biogeography Society (IBS 2015). We summarize themes in and across 15 symposia using narrative analysis and word clouds, which we complement with recent publication trends and ‘research fronts’. We find that biogeography is still strongly defined by core sub-disciplines that reflect its origins in botanical, zoological (particularly bird and mammal), and geographic (e.g., island, montane) studies of the 1800s. That core is being enriched by large datasets (e.g. of environmental variables, ‘omics’, species’ occurrences, traits) and new techniques (e.g., advances in genetics, remote sensing, modeling) that promote studies with increasing detail and at increasing scales; disciplinary breadth is being diversified (e.g., by developments in paleobiogeography and microbiology) and integrated through the transfer of approaches and sharing of theory (e.g., spatial modeling and phylogenetics in evolutionary–ecological contexts). Yet some subdisciplines remain on the fringe (e.g., marine biogeography, deep-time paleobiogeography), new horizons and new theory may be overshadowed by popular techniques (e.g., species distribution modelling), and hypotheses, data, and analyses may each be wanting. Trends in publication suggest a shift away from traditional biogeography journals to multidisciplinary or open access journals. Thus, there are currently many opportunities and challenges as biogeography increasingly addresses human impacts on, and stewardship of, the planet (e.g., Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services). As in the past, biogeographers doubtless will continue to be engaged by new data and methods in exploring the nexus between biology and geography for decades into the future. But golden ages come and go, and they need not touch every domain in a discipline nor affect subdisciplines at the same time; moreover, what appears to be a Golden Age may sometimes have an undesirable ‘Midas touch’. Contexts within and outwith biogeography—e.g., methods, knowledge, climate, biodiversity, politics—are continually changing, and at times it can be challenging to establish or maintain relevance. In so many races with the Red Queen, we suggest that biogeography will enjoy greatest success if we also increasingly engage with the epistemology of our discipline.

Knowledge of the habitat requirements and temporal stability of populations of extinct aurochs (Bos primigenius) is surprisingly scarce. Reliable reports of this species, which by its domestication remains tremendously important for humans, are rare. As the species became extinct about 400 years ago and regionally disappeared much earlier, its behaviour and morphology are also under debate. Aurochs is also a crucial component of the mega-herbivore theory in nature conservation, but in fact its natural habitat and behaviour are unknown. Here, I report records of aurochs for the time period of Ancient Egypt. They are found in archaeological sites and literature, and in collections. Records of the species continue through all the periods of Ancient Egypt. In particular, hunting scenes illustrating the merits of high-ranking persons, in their graves (mastabas) and temples, provide insights into the behaviour and ecology of the depicted game. Here, special attention is given to one outstanding hunting scene that is documented in a relief at the mortuary temple of Ramesses III (1175 BC, Medinet Habu, Egypt). Assisted by a group of hunters, the pharaoh kills three specimens of aurochs. The whole scene is stunningly realistic.  The adult specimen is fleeing towards the reed belt of the River Nile, suggesting that the species’ habitat was probably in large valley bottoms, where open grassland is regularly created by flooding. Endemic species of fish and game confirm that this scene took place in Lower Egypt. The regional populations of the North-African subspecies of aurochs probably went extinct shortly after this piece of art was produced. Records of species in ancient art can be very informative in terms of ecology and behaviour of species, especially when extinct species are addressed. In addition, the dating of old pieces of art containing biological information can be very precise, for instance when these refer to a historic personage.

The processes underlying species’ dominance patterns and community composition are insufficiently investigated for springs, yet these systems, which are believed to be very stable environments, represent an important interface between aquatic and terrestrial habitats contributing significantly to local and regional diversity. We studied the dominance patterns and plant community composition of 238 springs in Central Europe. According to the conventional ecological belief we hypothesized (1) a positive relationship between local abundance and regional distribution of spring plant species, as well as between species commonness and species’ realized breadth and (2) the occurrence of oligarchic species similar to other stable environments like tropical forests. Based on previous studies on this springs, we furthermore hypothesized (3) that water pH—essentially a proxy for nutrient availability—is the major driver of spatial compositional dissimilarity, i.e. beta-diversity. We tested these three hypotheses by using species commonness estimates, realized niche space and generalized dissimilarity modelling based on hydrochemistry. In line with conventional wisdom, we report a positive relationship between local abundance, species commonness and regional distribution for the majority of the species. In contradiction to other systems, we found both specialist and generalist species to be locally dominant and regionally widespread, thus common, while species with intermediate niche breadth showed the lowest commonness values. However, we detected three oligarchic species, exceeding all other species in local abundance and regional distribution, which did not follow these relationships. Both dominance relations (oligarchy) and community composition were mainly driven by water temperature and concentration of elements related to acidity regime (Al, Cd, Ca and Mg), although much of the variation in both remained unexplained. Thus, further research should focus on biotic interactions, which are likely to be important drivers of plant community composition in springs.