The global extent and distribution of forest trees is central to our understanding of the terrestrial biosphere. We provide the first spatially continuous map of forest tree density at a global scale. This map reveals that the global number of trees is approximately 3.04 trillion, an order of magnitude higher than the previous estimate. Of these trees, approximately 1.39 trillion exist in tropical and subtropical forests, with 0.74 trillion in boreal regions and 0.61 trillion in temperate regions. Biome-level trends in tree density demonstrate the importance of climate and topography in controlling local tree densities at finer scales, as well as the overwhelming effect of humans across most of the world. Based on our projected tree densities, we estimate that over 15 billion trees are cut down each year, and the global number of trees has fallen by approximately 46% since the start of human civilization.

Aim To compare theoretical approaches towards estimating risks of plant species loss to anthropogenic climate change impacts in a biodiversity hotspot, and to develop a practical method to detect signs of climate change impacts on natural populations.Results A loss of Fynbos biome area of between 51% and 65% is projected by 2050 (depending on the climate scenario used), and roughly 10% of the endemic Proteaceae have ranges restricted to the area lost. Species range projections suggest that a third could suffer complete range dislocation by 2050, and only 5% could retain more than two thirds of their range. Projected changes to individual species ranges could be sufficient to detect climate change impacts within ten years. Main conclusionsThe biome-level approach appears to underestimate the risk of species diversity loss from climate change impacts in the Fynbos Biome because many narrow range endemics suffer range dislocation throughout the biome, and not only in areas identified as biome contractions. We suggest that targeted vulnerable species could be monitored both for early warning signs of climate change and as empirical tests of predictions.

Summary Projected climate change has been suspected of affecting the biota of conserved nature areas in different and significant ways. Nevertheless, strategic management within some nature conservation agencies appears relatively unprepared for the possible consequences of climate change. National level planning of reserve design networks has also tended to skirt the issue, possibly owing to insufficient analysis. This paper provides a first assessment of the possible effects of climate change on plant diversity within the protected area network of South Africa. A climate change scenario of increased temperature but no change in precipitation resulted in derived optimum growth days increasing in some reserves through increased temperature extending the growing season. In some other reserves optimum growth days declined through greater evapotranspiration. We concentrated on the larger reserves of the latter group for which conditions that are more limiting were predicted. Plant species were evaluated in terms of their critical limits in growth days and minimum temperature. Over a third of the species analysed for one reserve (Augrabies Falls National Park and Melkbosrand) was indicated to become locally extinct with climate change. Another reserve in the region showed fewer than 1% local extinctions. It is clear that although a certain magnitude of climate change is a prerequisite for these extinctions, the rate and number of extinctions depend strongly on the different environmental tolerances of the specific biotic components of the conserved area. Potential immigration of other species to Augrabies Falls/Melkbosrand required to balance the projected extinctions with climate change would need migration abilities and conditions that are unlikely to be met. A net decrease in plant diversity may thus be expected. The results confirm that with the climate change scenario used, the concept of sustaining species through fixed protected areas may be fundamentally flawed, at least in certain areas.

Questions How does heavy grazing change plant community structure, composition and species richness and diversity in an ecotone between grassland and semi‐arid shrub steppe‐type vegetation? Does grazing favour plants with arid affinity over those with less arid affinity? Does the grazing‐induced transformation constitute a switch to the equivalent of a shrub‐dominated biome? Location Central South Africa. Methods Using systematic scanning of SPOT 5 imagery and ground‐truthing, a grazing treatment area was selected that met criteria of intensity of grazing, sampling requirements, and biogeographical position within a broad ecotonal zone. Differential vegetation responses to heavy grazing were tested for significant differences in plant traits, vegetation structure, and species diversity, richness and evenness. Gamma diversity was calculated for the whole study site, whereas, independent beta diversity was calculated across the treatments assuming the additive partitioning of diversity. In addition, the biogeographical association of grazing‐induced species shifts was determined using a range of available databases. Results Canopy cover and height of woody shrubs increased significantly with heavy grazing whereas that of graminoid plants declined. The resultant species turnover was modest, apparent extinctions of local species were minimal, species richness was maintained and species diversity was significantly enhanced. There was a significant increase in species evenness, through possible suppression of dominant species. Significant increases in species cover were those associated with mainly the Nama‐Karoo biome indicating that species from more arid areas are more resistant to grazing as would be expected by the convergence model of aridity and grazing resistance. Conclusions The significant increase in shrub cover in heavily grazed semi‐arid grassland followed general global expectations. The study confirmed that the supposed former large shift of grassland to shrubby Nama‐Karoo in the eastern upper Karoo can indeed be readily affected by heavy grazing. The negative connotations for biodiversity that have often been associated with intense grazing seem, in terms of the positive responses of plant species diversity in this study, to perhaps be exaggerated. The elevated species diversity with grazing of vegetation with a long evolutionary grazing history in a low resource area may require a reappraisal of the application of certain grazing hypotheses.

Southern Africa has been recognised as one of the most interesting and important areas of the world from an ecological and evolutionary point of view. The establishment and development of the National Vegetation Database (NVD) of South Africa enabled South Africa to contribute to environmental planning and conservation management in this floristically unique region. In this paper, we aim to provide an update on the development of the NVD since it was last described, near its inception, more than a decade ago. The NVD was developed using the Turboveg software environment, and currently comprises 46 697 vegetation plots (relevés) sharing 11 690 plant taxa and containing 968 943 species occurrence records. The NVD was primarily founded to serve vegetation classification and mapping goals but soon became recognised as an important tool in conservation assessment and target setting. The NVD has directly helped produce the National Vegetation Map, National Forest Type Classification, South African National Biodiversity Assessment and Forest Type Conservation Assessment. With further development of the NVD and more consistent handling of the legacy data (old data sets), the current limitations regarding certain types of application of the data should be significantly reduced. However, the use of the current NVD in multidisciplinary research has certainly not been fully explored. With the availability of new pools of well-trained vegetation surveyors, the NVD will continue to be purpose driven and serve the needs of biological survey in pursuit of sustainable use of the vegetation and flora resources of the southern African subcontinent.