Geographic distribution patterns and status assessment of threatened plants in China

Large scale heterogeneous distribution of biodiversity has become a hot topic for ecologists and conservationists. A threat status assessment combined with geographic distribution patterns of threatened plants in China has been conducted at a national scale in this study based upon a distribution database that refers to both specimen records and published references. Currently, 302 threatened plant species are cataloged in the “National Protected Key Wild Plants” in China belonging to 92 families and 194 genera. Results of the assessment according to the Categories and Criteria system of The World Conservation Union (IUCN) Red List indicate that three species have been assessed as Extinct in Wild (EW) while a further 79, 99 and 112 species have been assessed as Critically Endangered (CR), Endangered (EN), and Vulnerable (VU), respectively. Distribution patterns of threatened plants were analyzed with GIS to identify areas of high species diversity. It was found that threatened plant species occur unevenly within counties and are concentrated in the following eight hotspots: the central and southern Hengduanshan mountain area; the southeast regions of Yunnan as well as Xishuangbanna and southwestern Guangxi; the southern Hainan island; the border mountainous regions of Guizhou, Hunan and Guangxi provinces; the mountainous regions of southwestern Hubei and northern Hunan; southwestern Zhejiang and western Fujian; central Sichuan and southern Gansu; and the western mountains of Guangdong. Moreover, the 12 counties with the greatest number of threatened plant species represent cumulatively more than 50% of the total listed species and, therefore, are the regions in China that should be prioritized for conservation efforts. By overlapping the map of threatened plant species with the distribution of national nature reserves, a gap was identified in protected areas. This research will ultimately provide insights for prioritizing biodiversity conservation as well as processing the mechanisms of distribution patterns.     

Achieving Target 2 of the Global Strategy for Plant Conservation: building a preliminary assessment of vascular plant species using data from herbarium specimens

The Global Strategy for Plant Conservation calls for a preliminary assessment of the conservation status of all known plant species by the year 2010. To date insufficient progress has been made on meeting this target. New efforts to develop a preliminary list beyond using the full IUCN criteria in plant assessments are needed. Here we present an algorithm that provides a preliminary assessment of the conservation status of plant species using data from herbarium specimens. We use Hawaiian specimen data from the United States National Herbarium to calibrate the parameters of the algorithm and then use specimen data from the Arecaceae, Commelinaceae, Gesneriaceae and Heliconiaceae as examples of the application of the algorithm. The algorithm was calibrated to insure 95% accuracy in placing the Hawaiian plant species into previously and independently determined threatened categories. Our results indicate that 28% of the Hawaiian taxa, 27% of the species of Arecaceae, 45% of the species of Commelinaceae, 32% of the species of Gesneriaceae, and 35% of the species of Heliconiaceae are Not Threatened and will not need any further evaluation for the preliminary assessment. Species identified here as Potentially Extinct and Potentially Threatened can be further assessed by additional herbarium material and/or conservation specialists for final evaluation using other assessment strategies (e.g., regional and national lists, taxonomic expert assessment, etc.).     

Biogeography, current knowledge and conservation of threatened vascular plants characteristic of Mexican temperate forests

The main goal of this study is to document the biogeographical patterns, current status and conservation of 24 species of vascular plants in Mexico, all of them recorded in some risk category in the Mexican official publication named ‘Norma Oficial Mexicana 059’ (NOM-059) and some of them in the IUCN red lists (the World Conservation Union) and CITES (Convention on International Trade in Endangered Species); many of these species are linked to Mexican cloud forests and other temperate vegetation types. Distribution maps of these 24 species were generated with information obtained from specialized literature, herbarium specimens, institutional databases, and field work; with this information, the patterns of richness and endemism of these species were obtained. For this, the Mexican territory was divided using a grid system based on a chart index (scale 1:50,000 system composed by grids of 15' × 20'). Also, we up to date the knowledge of these species and their populations and current habitats, and evaluate their geographic distribution in relation to the current Mexican National Parks and Reserves System and Mexican Priority Regions for Conservation. We also discuss some changes of categories in the NOM-059 and suggest the urgent incorporation of some of the species in the recent IUCN Red Data List of Threatened Species (2003). Most of the species studied require special policies for their conservation due to problems that affect their natural populations; also we consider that these taxa are underrepresented in the current Mexican System of Natural Protected Areas, especially those with restricted distributions.     

Cryptic species complexes,widespread species and conservation: lessons from Amazonian frogs of the Leptodactylus marmoratus group (Anura: Leptodactylidae)

Morphologically cryptic species act as a wild card when it comes to biodiversity assessments and conservation, with the capacity to dramatically alter our understanding of the biological landscape at the taxonomic, ecological, biogeographic, evolutionary, and conservation levels. We discuss the potential effects that cryptic species may have on biodiversity assessments and conservation, as well as some of the current issues involving the treatment of cryptic species both at taxonomic and conservation levels. In addition, using a combination of advertisement call and morphological data, we describe a new species of the Leptodactylus marmoratus group from the upper Amazon basin, and we assess how cryptic species can affect conservation assessments of species in the Leptodactylus marmoratus group by examining how recent findings affect our understanding of the distribution of what is assumed to be a widespread Amazonian species, Leptodactylus andreae.     

Bird communities in habitats along a successional gradient: Divergent patterns of species richness,specialization and threat

The long history of human influence on northern temperate landscapes has created a mosaic of successional stages, from closed forest to open grassland. Various species thus adapted to different habitats and it is interesting to explore how these differences in species composition among particular successional stages translate into differences at the community level. For this purpose, we surveyed breeding birds in 233 patches of five different habitats covering a gradient from bare ground to forest in 29 abandoned military training sites scattered throughout the Czech Republic. Linear mixed effects modelling revealed that late-successional habitats (dense scrubland and forest) were the most species-rich, whereas early-successional stages hosted bird communities with the highest habitat specialization and threat level. These results suggest that the habitats of late-successional stages are important for the maintenance of high bird species richness, but that early-successional habitats are essential for highly specialized and threatened bird species. Given the highly adverse impacts of agricultural intensification and land abandonment on open habitats, it is necessary to promote factors creating initial successional stages suitable for specialized and threatened species.     

Diversity and genetic structure of the endangered cycad Dioon sonorense (Zamiaceae) from Sonora, Mexico: Evolutionary and conservation implications

The diversity and genetic structure of the cycad Dioon sonorense (De Luca, Sabato & Vázq. Torres) Chemnick, T.J. Greg. & S. Salas-Mor. were evaluated from the four known populations in tropical dry forests of Sonora, Mexico. The estimates of genetic diversity in the 19 loci analysed were: mean number of alleles per locus (A = 2.0), percentage of polymorphic loci (P = 81.6) and expected heterozygosity (H_E = 0.314). The subpopulations were found to be in Hardy–Weinberg equilibrium at the local level (F_is), even though we found a global excess of homozygotes (F_it = 0.13). Genetic variation attributed to differences among populations was 15%. Our results indicate that the geographical isolation caused by the historical effects of the Pleistocene among populations has probably generated clinal variation of the allelic frequencies at two loci, in relation to their latitudinal distribution. We compare our results with the long-lived southern hemisphere trees Fitzroya and Nothofagus in relationship to the Pleistocene glaciations. We also infer that the populations have become fragmented recently due to increasing pressure of habitat conversion, disturbance and illegal extraction of plants and seeds for the international horticultural trade. We therefore recommend three aspects: (i) propagation of this species for reintroduction, (ii) declare the localities of its northern distribution as a protected area, and (iii) an amendment of the current International Union for Conservation of Nature Red List categorisation for this species to ‘Critically Endangered’.     

Defining a role for herbarium data in Red List assessments: a case study of Plectranthus from eastern and southern tropical Africa

Red Lists are widely used to indicate species at risk of extinction. Specimen sheets in herbaria provide an important source of data relevant for Red List assessments. The aims of this paper are to establish which data can be sourced from specimen information to satisfy IUCN Red Data List criteria and to identify the specific criteria that can be used. Red List parameters are measured within a Geographical Information System (GIS), as this provides an objective and repeatable methodology which is less subjective than manual methods. Data used to explore this were gathered during the course of preparing a monograph on Plectranthus (Lamiaceae). Criteria relating to distribution (extent of occurrence, area of occupancy and fragmentation) and population profile (projected continuing decline and number of subpopulations) proved most suitable for assigning categories of threat. Estimates of mature individuals, generation length, population size, population reduction, extreme fluctuation and number of locations could not be derived from herbarium material without making inconsistent subjective decisions. In addition to comprehensively databased specimen information, extensive field knowledge is required to produce better estimates for assessing extinction risk. In order to enhance the usefulness of specimen information in the future, improvements in recording additional botanical data at the time of collection would be beneficial. Overall, herbaria provide a useful starting point for conservation-related work and can help to guide future work.     

Molecular genetic analysis of virus isolates from wild and cultivated plants demonstrates that East Africa is a hotspot for the evolution and diversification of Sweet potato feathery mottle virus

Sweet potato feathery mottle virus (SPFMV, genus Potyvirus) is globally the most common pathogen of cultivated sweet potatoes (Ipomoea batatas; Convolvulaceae). Although more than 150 SPFMV isolates have been sequence‐characterized from cultivated sweet potatos across the world, little is known about SPFMV isolates from wild hosts and the evolutionary forces shaping SPFMV population structures. In this study, 46 SPFMV isolates from 14 wild species of genera Ipomoea, Hewittia and Lepistemon (barcoded for the matK gene in this study) and 13 isolates from cultivated sweet potatoes were partially sequenced. Wild plants were infected with the EA, C or O strain, or co‐infected with the EA and C strains of SPFMV. In East Africa, SPFMV populations in wild species and sweet potato were genetically undifferentiated, suggesting inter‐host transmission of SPFMV. Globally, spatial diversification of the 178 isolates analysed was observed, strain EA being largely geographically restricted to East Africa. Recombination was frequently detected in the 6K2‐VPg‐NIaPro region of the EA strain, demonstrating a recombination ‘hotspot’. Recombination between strains EA and C was rare, despite their frequent co‐infections in wild plants, suggesting purifying selection against strain EA/C recombinants. Positive selection was predicted on 17 amino acids distributed over the entire coat protein in the globally distributed strain C, as compared to only four amino acids in the coat protein N‐terminus of the EA strain. This selection implies a more recent introduction of the C strain and a higher adaptation of the EA strain to the local ecosystem. Thus, East Africa appears as a hotspot for evolution and diversification of SPFMV.     

Assessment of interaction between sheep and poorly palatable grass: a key tool for grassland management and restoration

Invasion of poorly palatable grasses due to abandonment or improper grazing management decreases pastures feeding value and biodiversity. With the aim to control their spread, we assessed the relationship between sheep foraging behavior and changes in aboveground phytomass, leaf traits, and chemical features of the tall grass Brachypodium rupestre and evaluated the effects of a B. rupestre-based diet on epithelium keratinization of rumen. Our results demonstrated that sheep became less selective throughout the experimental trials and B. rupestre decreased its aboveground phytomass. Some leaf traits showed significant changes (LDMC, LA, and ADL were higher in ungrazed areas; leaf nitrogen content was higher in the grazed ones). In addition, we detected an increase of the degree of epithelium keratinization of sheep. Thus high grazing pressure can be used to control the spread of B. rupestre, but negative effects on animal welfare due to the increase of rumen keratinization might be expected.     

Acid growth effects in maize roots: Evidence for a link between auxin-economy and proton extrusion in the control of root growth

The role of proton excretion in the growth of apical segments of maize roots has been examined. Growth is stimulated by acidic buffers and inhibited by neutral buffers. Organic buffers such as 2[N-morpholino] ethane sulphonic acid (MES) — 2-amino-2-(hydroxymethyl)propane-1,3 diol (Tris) are more effective than phosphate buffers in inhibiting growth. Fusicoccin(FC)-induced growth is also inhibited by neutral buffers. The antiauxins 4-chlorophenoxyisobutyric acid (PCIB) and 2-(naphthylmethylthio) propionic acid (NMSP) promote growth and H⁺-excretion over short time periods; this growth is also inhibited by neutral buffers. We conclude that growth of maize roots requires proton extrusion and that regulation of root growth by indol-3yl-acetic acid (IAA) may be mediated by control of this proton extrusion.Abbreviations IAA indol-3yl-acetic acid - ABA abscisic acid - FC fusicoccin - PCIB 4-chlorophenoxy-isobutyric acid - MES 2(N-morpholino)ethane sulphonic acid - Tris 2-amino-2-(hydroxymethyl) propane-1,3-diol - NMSP 2-(naphthylmethylthio)propionic acid     

Overstorey tree species regulate colonization by native and exotic plants: a source of positive relationships between understorey diversity and invasibility

The North American woody species, Prunus serotina Ehrh., is an aggressive invader of forest understories in Europe. To better understand the plant invasion process, we assessed understorey plants and Prunus serotina seedlings that have colonized a 35-year-old replicated common-garden experiment of 14 tree species in south-western Poland. The density and size of established (> 1 year old) P. serotina seedlings varied among overstorey species and were related to variation in light availability and attributes of the understorey layer. In a multiple regression analysis, the density of established P. serotina seedlings was positively correlated with light availability and understorey species richness and negatively correlated with understorey species cover. These results suggest that woody invader success is adversely affected by overstorey shading and understorey competition for resources. Simultaneously, however, invader success may generally be positively associated with understorey species richness because both native and invasive plant colonization respond similarly to environmental conditions, including those influenced by overstorey tree species. Identification of characteristics of forests that increase their susceptibility to invasion may allow managers to target efforts to detect invasives and to restore forests to states that may be less invasible.     

Relationship between plant species diversity and soil microbial functional diversity along a longitudinal gradient in temperate grasslands of Hulunbeir,Inner Mongolia,China

Numerous experiments have been established to examine the effect of plant diversity on the soil microbial community. However, the relationship between plant diversity and microbial functional diversity along broad spatial gradients at a large scale is still unexplored. In this paper, we examined the relationship of plant species diversity with soil microbial biomass C, microbial catabolic activity, catabolic diversity and catabolic richness along a longitudinal gradient in temperate grasslands of Hulunbeir, Inner Mongolia, China. Preliminary detrended correspondence analysis (DCA) indicated that plant composition showed a significant separation along the axis 1, and axis 1 explained the main portion of variability in the data set. Moreover, DCA-axis 1 was significantly correlated with soil microbial biomass C (r = 0.735, P = 0.001), microbial catabolic activity (average well color development; r = 0.775, P < 0.001) and microbial functional diversity (catabolic diversity: r = 0.791, P < 0.001 and catabolic richness: r = 0.812, P < 0.001), which suggested thatsome relationship existed between plant composition and the soil microbial community along the spatial gradient at a large scale. Soil microbial biomass C, microbial catabolic activity, catabolic diversity and catabolic richness showed a significant, linear increase with greater plant species richness. However, many responses that we observed could be explained by greater aboveground plant biomass associated with higher levels of plant diversity, which suggested that plant diversity impacted the soil microbial community mainly through increases in plant production.     

The interactive effects of elevated CO<Subscript>2</Subscript>, temperature and initial size on growth and competition between a native C<Subscript>3</Subscript> and an invasive C<Subscript>3</Subscript> grass

A controlled environment experiment was conducted to determine the impact of enhanced carbon dioxide and temperature on competition between the C₃ grasses Austrodanthonia eriantha and Vulpia myuros. Plants were grown in mixtures and monocultures to compare the responses both with and without an interspecific competitor. Temperature and CO₂ were set at current levels (350 ppm CO₂; 20 °C day and 10 °C night temperature), in factorial combination with enhanced levels (700 ppm CO₂; 23 °C day and 13 °C night temperature). To examine the potential impact of initial seedling size on competition under elevated CO₂ and temperature, the two species were combined in mixtures of differing initial sizes. Above-ground growth of all plants was enhanced by increased CO₂ and temperature alone, however the combined temperature and CO₂ treatment showed a sub-additive effect, where growth was less than expected based on the responses to each factor independently. Austrodanthonia in mixture with Vulpia plants of the same initial size experienced a 27 reduction in growth. Austrodanthonia grown in the presence of an initially larger Vulpia plant experienced a 58 reduction in growth. When the Vulpia plant was initially smaller than Austrodanthonia, growth of the Austrodanthonia was reduced by 16%. The growth of Vulpia appeared to be largely unaffected by the presence of Austrodanthonia. Variation in the CO₂ and temperature environment did not affect the pattern of these interspecific interactions, although there was some evidence to suggest that the degree of suppression of Austrodanthonia by Vulpia was less under elevated CO₂. These results do not support the initial advantage hypothesis, as Vulpia was always able to suppress Austrodanthonia, regardless of the initial relative sizes of the competitors. Furthermore, the lack of an effect of changing the CO₂ or temperature environment on the direction of interspecific competition suggests that the competitiveness of the invasive Vulpia will be minimally affected by changes in atmospheric CO₂ concentration or temperature.