Search

Endemism and species richness are highly relevant to the global prioritization of conservation efforts in which oceanic islands have remained relatively neglected. When compared to mainland areas, oceanic islands in general are known for their high percentage of endemic species but only moderate levels of species richness, prompting the question of their relative conservation value. Here we quantify geographic patterns of endemism-scaled richness ("endemism richness") of vascular plants across 90 terrestrial biogeographic regions, including islands, worldwide and evaluate their congruence with terrestrial vertebrates. Endemism richness of plants and vertebrates is strongly related, and values on islands exceed those of mainland regions by a factor of 9.5 and 8.1 for plants and vertebrates, respectively. Comparisons of different measures of past and future human impact and land cover change further reveal marked differences between mainland and island regions. While island and mainland regions suffered equally from past habitat loss, we find the human impact index, a measure of current threat, to be significantly higher on islands. Projected land-cover changes for the year 2100 indicate that land-use-driven changes on islands might strongly increase in the future. Given their conservation risks, smaller land areas, and high levels of endemism richness, islands may offer particularly high returns for species conservation efforts and therefore warrant a high priority in global biodiversity conservation in this century. [ABSTRACT FROM AUTHOR]

We present the first global map of vascular plant species richness by ecoregion and compare these results with the published literature on global priorities for plant conservation. In so doing, we assess the state of floristic knowledge across ecoregions as described in floras, checklists, and other published documents and pinpoint geographical gaps in our understanding of the global vascular plant flora. Finally, we explore the relationships between plant species richness by ecoregion and our knowledge of the flora, and between plant richness and the human footprint– a spatially explicit measure of the loss and degradation of natural habitats and ecosystems as a result of human activities. Global. Richness estimates for the 867 terrestrial ecoregions of the world were derived from published richness data of c. 1800 geographical units. We applied one of four methods to assess richness, depending on data quality. These included collation and interpretation of published data, use of species–area curves to extrapolate richness, use of taxon-based data, and estimates derived from other ecoregions within the same biome. The highest estimate of plant species richness is in the Borneo lowlands ecoregion (10,000 species) followed by nine ecoregions located in Central and South America with≥ 8000 species; all are found within the Tropical and Subtropical Moist Broadleaf Forests biome. Among the 51 ecoregions with≥ 5000 species, only five are located in temperate regions. For 43% of the 867 ecoregions, data quality was considered good or moderate. Among biomes, adequate data are especially lacking for flooded grasslands and flooded savannas. We found a significant correlation between species richness and data quality for only a few biomes, and, in all of these cases, our results indicated that species-rich ecoregions are better studied than those poor in vascular plants. Similarly, only in a few biomes did we find significant correlations between species richness and the human footprint, all of which were positive. The work presented here sets the stage for comparisons of degree of concordance of plant species richness with plant endemism and vertebrate species richness: important analyses for a comprehensive global biodiversity strategy. We suggest: (1) that current global plant conservation strategies be reviewed to check if they cover the most outstanding examples of regions from each of the world's major biomes, even if these examples are species-poor compared with other biomes; (2) that flooded grasslands and flooded savannas should become a global priority in collecting and compiling richness data for vascular plants; and (3) that future studies which rely upon species–area calculations do not use a uniform parameter value but instead use values derived separately for subregions. [ABSTRACT FROM AUTHOR]

Islands harbour a significant portion of all plant species worldwide. Their biota are often characterized by narrow distributions and are particularly susceptible to biological invasions and climate change. To date, the global richness pattern of islands is only poorly documented and factors causing differences in species numbers remain controversial. Here, we present the first global analysis of 488 island and 970 mainland floras. We test the relationship between island characteristics (area, isolation, topography, climate and geology) and species richness using traditional and spatial models. Area is the strongest determinant of island species numbers ( R2 = 0.66) but a weaker predictor for mainlands ( R2 = 0.25). Multivariate analyses reveal that all investigated variables significantly contribute to insular species richness with area being the strongest followed by isolation, temperature and precipitation with about equally strong effects. Elevation and island geology show relatively weak yet significant effects. Together these variables account for 85% of the global variation in species richness. [ABSTRACT FROM AUTHOR]

Global conservation assessments require information on the distribution of biodiversity across the planet. Yet this information is often mapped at a very coarse spatial resolution relative to the scale of most land-use and management decisions. Furthermore, such mapping tends to focus selectively on better-known elements of biodiversity (e.g., vertebrates). We introduce a new approach to describing and mapping the global distribution of terrestrial biodiversity that way help to alleviate these problems. This approach focuses on estimating spatial pattern in emergent properties of biodiversity (richness and compositional turnover) rather than distributions of individual species, making it well suited to lesser-known, yet highly diverse, biological groups. We have developed a global biodiversity model linking these properties to mapped ecoregions and fine-scale environmental surfaces. The model is being calibrated progressively using extensive biological data sets for a wide variety of taxa. We also describe un analytical approach to applying our model in global conservation assessments, illustrated with a preliminary analysis of the representativeness of the world's protected-area system. Our approach is intended to complement, not compete with, assessments based on individual species of particular conservation concern. [ABSTRACT FROM AUTHOR]