Is the global conservation status assessment of a threatened taxon a utopia?

The signatory countries of the Convention on Biological Diversity agreed to significantly reduce the rate of biodiversity loss by 2010. How will we know, however, if we have achieved this goal? Eight groups of hindrances in evaluating the global conservation status of threatened taxon are identified: (1) the extreme heterogeneity and (2) restricted availability of relevant data; (3) the uncertainty in species number and taxonomic division of the given taxon (Linnean shortfall); (4) the fragmentary distribution knowledge (Wallacean shortfall); (5) the incomplete or incorrect red-listing across the whole distribution area; (6) the lack of homogeneous and exhaustive population trend data; (7) the threat knowledge shortfall; (8) the incomplete general biological knowledge on a given taxon. The Linnean and Wallacean shortfalls lay the foundation of all other hindrances. So long as this dramatic shortfall situation does not change, the adequate assessment of the global status for overwhelming majority of extant taxa will remain a utopi

Eutrophication and endangered aquatic plants: an experimental study on Baldellia ranunculoides (L.) Parl. (Alismataceae)

Anthropogenic enrichment of aquatic ecosystems is an increasingly common phenomenon, resulting from human population growth and the intensification of industrial and agricultural developments. Eutrophication has been considered to be one of the main causes of the decline of many aquatic plants. These observations, however, have rarely been supported by data or explored in detail using an experimental approach. Our experimental study demonstrates, for the first time, a strong direct negative influence of eutrophication on the performance of the endangered aquatic plant Baldelliaranunculoides s.str. (L.) Parl. (Alismataceae). Both morphological and reproductive traits were significantly affected by this phenomenon. Plants growing on eutrophic substrates were much smaller, possessed fewer and smaller leaves, and their biomass was on average half that of plants growing on a mesotrophic substrate. Additionally, plants growing on eutrophic substrates produced fewer inflorescences and flowers, and they had a smaller number of achenes per capitulum. Consequently, they produced only 15% of the seeds produced by plants growing in non-eutrophic conditions. Thus, the chance of long-term subsistence of B.ranunculoides populations in strongly eutrophic habitats will be significantly reduced, and at the same time, the success of any new establishment of viable B.ranunculoides populations in such habitats will be highly restricted. Conservation efforts for B.ranunculoides, either of existing populations or in newly selected re-introduction sites, should start, therefore, with an assessment of the trophic level of those sites. On the other hand, due to its sensitivity to eutrophication, the presence of viable populations of B.ranunculoides can be used as an indicator of valuable aquatic habitats for oligotrophy-dependent organism

Free behind bars: Effects of browsing exclusion on the growth and regeneration of Zelkova abelicea

Abstract Caprine overbrowsing is a main threat to trees of pastoral mountain woodlands in the Mediterranean region of Europe. In this study, we assess the impact of browsing exclusion on the growth and regeneration of the endangered Zelkova abelicea, a Paleogene relict tree endemic to Crete (Greece). Shoot elongation, height growth and natural regeneration were monitored during two to five years in 31 fenced plots across the distribution range of the species. We found that in the absence of browsing pressure, Z. abelicea produces shoots on average two times longer than when browsed, therefore clearly demonstrating the negative impact of current browsing pressure on the growth performance of the species. Shoot elongation and height growth were maximal in most plots during the first two years following fencing, after which growth rates decreased. The proportion of trees that reached a height considered out of reach of caprine browsing had more than doubled already after four years, although this was dependent on initial tree height. Shoot elongation and height growth were positively correlated with tree height, and smaller trees took more time to reach a specific height. Seedlings were only found in three fenced plots as well as in two control browsed areas during a single year and only in western Crete. This underlines the possible strong and concerning impact of climatic factors on seed formation as well as on seedling growth and survival, although site specificities such as stand structure and micro-topography should also be considered. Our findings have important implications for conservation actions, as they can help choose which stands and which individuals to fence in priority for efficient long-term conservation

The Atlantic elements in the Swiss flora: distribution, diversity, and conservation status

The purpose of this study was to examine the composition, distribution, ecology, and conservation status of the Atlantic elements of the Swiss flora. About 195 Atlantic and 80 Mediterranean-Atlantic vascular plant species of the European flora have been used as the basis for our analysis. The complete list of 3,143 taxa has been used as the reference for the Swiss flora. The distributions of the species are illustrated in coincidence maps based on the computer database of the Data Centre of the Swiss Flora in Geneva, Switzerland. Our study demonstrates clearly that the Atlantic flora of Europe requires a new biogeographical appraisal. The Swiss flora comprises 66 Atlantic and Mediterranean-Atlantic taxa, which are taxonomically and ecologically highly diverse. Switzerland contains 44% of all European Sub-Atlantic plants. This confirms the Sub-Atlantic geographical position of Switzerland. Only one Eu-Atlantic species growing in Switzerland, Vicia orobus, can be classified as native with certainty. This species is critically endangered and merits the highest conservation priority. Although a very alpine country, Switzerland has a relatively large number of Mediterranean-Atlantic species. The Atlantic and Mediterranean-Atlantic plants are a very threatened group in Switzerland, with wetland plants the most imperilled ecological grou

Global conservation status assessment of the threatened aquatic plant genus Baldellia (Alismataceae): challenges and limitations

In this study, the aquatic monocot Baldellia (Alismataceae) is used as a model for evaluating the general hindrances and shortfalls in the global conservation status assessment of a threatened taxon. Our study clearly shows that Linnean shortfalls (uncertainty in the number of species and taxonomy) and the Wallacean shortfall (fragmentary knowledge regarding distribution) form the basis for all other hindrances. We demonstrate that even in Europe, which has traditionally been very well investigated, between 60 and 75% of regions or countries possess no detailed distribution maps and/or data banks for Baldellia spp. Furthermore, between 50 and 60% of regions do not have any published red list category. Thus, only general conclusions concerning the global conservation status of the three Baldellia taxa are possible—a global assessment of conservation status for B. ranunculoides subsp. repens is nearly impossible. Baldellia ranunculoides s.str. shows a strong decline in practically all regions of its natural range, and thus it is probably the most threatened species in the genus. Baldellia alpestris is the least threatened species in the genus, even though it is a narrow endemic. Our case study clearly shows the need for reinforced coordination of research and conservation activities as well as an urgent need for data accessibility regarding taxonomic, chorological and conservation studies of endangered specie

Urban aquatic ecosystems: Habitat loss and depletion of native macrophyte diversity during the 20th century in four Swiss cities

Urban areas are among the most affected by human activities. In Europe, urbanization has essentially occurred since the end of the 19th century. However, the influence of this dramatic process on aquatic ecosystems has rarely been quantified and analyzed using historical data. In this study, we investigate the evolution of the hydrological system and native aquatic macrophytes in urban areas between the end of the 19th century and the beginning of the 21st century. Four urban areas in Switzerland were chosen for the analyses, Zürich, Basel, Lausanne and Fribourg, and we analyzed the changes in aquatic plant diversity based on the historical and recent floristic data available for the same areas and the same time periods. Our results show that a significant proportion (∼30%) of aquatic habitats has disappeared from the investigated locales during the last 130years and that the extinction rate of the aquatic plant species is notably higher in the studied cities (28%) than in Switzerland as a whole (2%). Thus, between the end of the 19th and the beginning of the 21st centuries, urban development in Swiss cities has prompted a degradation of aquatic habitats that resulted in a significant reduction of the aquatic biodiversity. However, our study shows that urban areas still have the capacity to shelter a large diversity of aquatic organisms, including some of the most threatened species. Thus, it is important to integrate urban areas in the conservation strategies for these specie

Conservation of threatened relict trees through living ex situ collections: lessons from the global survey of the genus Zelkova (Ulmaceae)

Maintaining living ex situ collections is one of the key conservation methods in botanic gardens worldwide. Despite of the existence of many other conservation approaches used nowadays, it offers for many endangered plants an important insurance policy for the future, especially for rare and threatened relict trees. The aim of this research was to investigate the global extent of living ex situ collections, to assess and discuss their viability and inform the development of conservation approaches that respond to latest global conservation challenges. We used as a model taxon the tree genus Zelkova (Ulmaceae). The genus includes six prominent Tertiary relict trees which survived the last glaciation in disjunct and isolated refugial regions. Our comprehensive worldwide survey shows that the majority of botanic institutions with Zelkova collections are in countries with a strong horticultural tradition and not in locations of their origin. More importantly, the acutely threatened Zelkova species are not the most represented in collections, and thus safeguarded through ex situ conservation. Less than 20% of the ex situ collections surveyed contain plant material of known wild provenance while the majority (90%) of collections are generally very small (1-10 trees). Botanic gardens and arboreta particularly in regions where iconic relict trees naturally occur should play a vital role in the conservation of these species. The coordination of conservation efforts between gardens has to be enhanced to prioritise action for the most threatened relict trees. Large scale genetic studies should be undertaken, ideally at genus level, in order to verify or clarify the provenance of ex situ collections of relict trees in cultivation. For the most threatened relict tree genera, well-coordinated specialist groups should be create

Global Estimation and Mapping of the Conservation Status of Tree Species Using Artificial Intelligence.

Trees are fundamental for Earth's biodiversity as primary producers and ecosystem engineers and are responsible for many of nature's contributions to people. Yet, many tree species at present are threatened with extinction by human activities. Accurate identification of threatened tree species is necessary to quantify the current biodiversity crisis and to prioritize conservation efforts. However, the most comprehensive dataset of tree species extinction risk-the Red List of the International Union for the Conservation of Nature (IUCN RL)-lacks assessments for a substantial number of known tree species. The RL is based on a time-consuming expert-based assessment process, which hampers the inclusion of less-known species and the continued updating of extinction risk assessments. In this study, we used a computational pipeline to approximate RL extinction risk assessments for more than 21,000 tree species (leading to an overall assessment of 89% of all known tree species) using a supervised learning approach trained based on available IUCN RL assessments. We harvested the occurrence data for tree species worldwide from online databases, which we used with other publicly available data to design features characterizing the species' geographic range, biome and climatic affinities, and exposure to human footprint. We trained deep neural network models to predict their conservation status, based on these features. We estimated 43% of the assessed tree species to be threatened with extinction and found taxonomic and geographic heterogeneities in the distribution of threatened species. The results are consistent with the recent estimates by the Global Tree Assessment initiative, indicating that our approach provides robust and time-efficient approximations of species' IUCN RL extinction risk assessments

Analysis of nuclear microsatellites reveals limited differentiation between Colchic and Hyrcanian populations of the wind-pollinated relict tree Zelkova carpinifolia (Ulmaceae)

Premise of the study: The Caucasus represents one of the world’s biodiversity hotspots and includes the climatic refugia Hyrcan on the southern coast of the Caspian Sea and Colchis on the eastern coast of the Black Sea, where different species survived during the Quaternary climatic oscillations. We evaluated the genetic diversity of the relict tree Zelkova carpinifolia shared between the two refugia and distributed throughout the Caucasus and adjacent areas.Methods: Specimens were collected from 30 geographical sites in Azerbaijan, Georgia, Iran, and Turkey and screened for variability at eight nuclear microsatellite loci. The genetic diversity among and within populations was assessed using a set of statistical measures.Key results: We detected 379 different genotypes from a total of 495 individuals with varying degrees of clonal reproduction at the different sites. Low to intermediate levels of genetic diversity were observed at all sites, and strong differentiation between sampling sites was absent. In addition, we observed no clear genetic differentiation between the Colchis and Hyrcan. Bayesian clustering of the genotypes revealed three populations with high levels of admixture between the sampling sites.Conclusions: The lack of strong genetic structure of studied populations of Z. carpinifolia contrasts with a previous study based on chloroplast markers and suggests that long-distance pollen dispersal is an important factor of gene flow among populations of Z. carpinifolia. The present study does not reveal any particular site with particularly isolated genotypes that would deserve more attention for conservation purposes than others, although some sites should be considered for further investigation