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Aim To determine whether life‐history characters that affect population persistence (e.g. habit and life span) and those that influence reproductive success (e.g. sexual system and fruit type) are non‐randomly correlated with extinction risk (i.e. threat category) in the Australian flora (c. 19,000 species, of which c. 14% is threatened). To identify patterns that present useful conservation directions. To understand patterns of extinction risk in the Australian flora at a broad scale. Location Continental Australia. Methods A country‐wide exploration of four life‐history characters in the Australian flora (n = 18,822 species) was undertaken using reference texts, expert opinion, herbarium records and field work. For each character and threat‐category combination, a G‐test (using a log‐linear model) was performed to test the null hypothesis that the two factors were independent in their effects on count. A generalized linear model (GLM) with a logit link and binomial error distribution was constructed with the proportion of taxa in each extinction risk category as the response variable and the habit, sex and fruit‐type characters as explanatory terms. In a separate approach, we investigated patterns across the threat categories of non‐endangered extant, endangered, and extinct using a multinomial model. We examined whether or not species‐poor genera were more likely to contain threatened or extinct species than species‐rich genera. A GLM with a binomial error distribution and logit link function was constructed to obtain a weighted regression on the proportion of species listed as extinct or endangered within a genus versus the log of the size of the genus. We also used a supertree analysis and character tracing to investigate the role of phylogeny on extinction risk. Results We found that the Australian flora is primarily composed of bisexual shrubs with dry‐dehiscent fruits. Dioecious breeding systems (separate female and male flowers on separate plants) in many floras are the predominant unisexual system, but in Australia there are unexpectedly high levels of monoecy (separate female and male flowers on the same plant). Within the extinct data set of 31 species we detected a significant departure from that expected for habit but not for life span, sexual system or fruit type. There are significantly fewer trees on the extinct list than expected. This may reflect the greater resilience of trees than of other growth habits to extinction processes as well as the observation time‐frame. Within the endangered data set of 450 species we found significant differences in the representation of the observed characters from that expected within sex systems and fruit types. We show that, depending on the life form, unisexual breeding systems can be significantly and positively associated with endangered species compared with non‐threatened species. For example, there are more monoecious species than expected by chance among the tree species listed as endangered but fewer among the herbaceous life forms. Threat category was found to be non‐randomly clustered in some clades. Main conclusions Life‐history characters in certain combinations are predictive of extinction risk. Phylogeny is also an important component of extinction risk. We suggest that specific life‐history characters could be used for conservation planning and as an early warning sign for detecting vulnerability in lists of species.  相似文献   

3.
In this study, the urban bryophyte flora of the city of Cologne (W. Germany) was studied. A total of 143 bryophyte taxa (17 hepatics and 126 mosses) were recorded within the metropolitan area of Cologne. Three species were newly recorded for North Rhine‐Westphalia: Hannediella heimii, Schistidium helveticum and Tortula schimperi. Thirteen species red‐listed in NRW were recorded, among them hardly endangered: Bryum intermedium and Syntrichia laevipila and extinction endangered: Syntrichia papillosa. The temperate biogeographic element prevails among Cologne bryophytes. According to frequency of recordance, only 11 species are widespread over the urban area of which three are hepatics.  相似文献   

4.
《Comptes rendus biologies》2014,337(12):695-708
Six temporary wetlands in the region of Sejenane (Mogods, NW Tunisia) were studied in order to characterize the aquatic flora and fauna and to quantify their spatio-temporal variability. Samplings of aquatic fauna, phytosociological relevés, and measurements of the physicochemical parameters of water were taken during four different field visits carried out during the four seasons of the year (November 2009–July 2010). Despite the strong anthropic pressures on them, these temporary wetlands are home to rich and diversified biodiversity, including rare and endangered species. Spatial and temporal variations affect fauna and flora differently, as temporal variability influences the fauna rather more than the plants, which are relatively more dependent on spatial factors. These results demonstrate the interest of small water bodies for maintaining biodiversity at the regional level, and thus underscore the conservation issues of Mediterranean temporary wetlands that are declining on an ongoing basis currently.  相似文献   

5.
Four percent of the Australian flora is rare and endangered with over 100 taxa presumed extinct. Western Australia contains a large proportion of the endangered flora of Australia with 238 taxa in a critical state of conservation and 70 species presumed extinct. Kings Park and Botanic Garden in south-west Australia is responsible for developing specialized collections of rare and endangered indigenous flora. Macro-and micropropagation procedures are used including conventional cutting and seed propagation, grafting and in thein vitro programme whole seeds (asymbiotic and symbiotic germination), excised seed embryos, shoot apices and inflorescence sections. Wherever possible explants are collected from major provenances of the species and a wide cross section of a species population. Although many of the rare flora of Western Australia are now in theex situ collection maintained by Kings Park and Botanic Garden attempts are being made to develop slow growth storage forin vitro cultures and cryostorage. Trial recovery programmes have commenced with a number of species including the rare and endangered Purdie's donkey orchid (Diuris purdiei). Results of these recovery programmes will guide future efforts in conserving and recovering rare Australian species.  相似文献   

6.
Landscape and aquatic environments have suffered increasing threats over the last century with major impacts on lentic waters and, presumably, on its inhabiting life. This study aims to evaluate changes in occurrence of aquatic macrophyte flora in lentic waters in Catalonia (NE Spain), emphasizing the last 20 years, with particular reference to vulnerable species. We conducted a survey (2005–2009) identifying macrophytes from 215 lentic water bodies (from eight different geomorphological typologies) and compared the data obtained with a historical compilation (1879–2006) from the Biodiversity Data Bank of Catalonia (BDBC). Vascular hydrophyte species were present in 53.5% of the sampled water bodies and only 69.7% of species cited in the BDBC were re-sampled in the recent survey. Significant changes in species occurrence were also found, particularly for those endangered macrophytes where the ratio of re-sampling was lower (52%). Hydrophyte flora of 36 water bodies has changed over the last 20 years and richness clearly tends to decrease. However, trends are different in each typology; while richness is stable in alpine lakes, it drops for coastal lagoons, ponds and karstic lakes. The threats most correlated with hydrophyte disappearance are water extraction and regulation and desiccation/drainage. To sum up, we detect a loss of hydrophyte diversity at a local and regional scale. Conservation actions are needed to preserve remaining water bodies and flora.  相似文献   

7.
Human disturbance and climate change have increased the risk of extinction for rare and endangered wild plant species.One effective way to conserve these rare and endangered species is through reintroduction.In this review,we summarize the advances in wild plant reintroduction from five perspectives:the establishment of reintroduction biology as an important tool for biodiversity conservation;the importance of genetic diversity in reintroduction;reintroduction under global climate change;recruitment limitation in reintroduction;and reintroduction and ecological restoration.In addition,we consider the future of plant reintroduction strategies.  相似文献   

8.
福建省南平茫荡山有木本植物102科,272属,719种,隶属于13个分布区类型,占我国分布区类型的86.7%,具有区系成分复杂、种类繁多、起源古老和珍稀树种丰富的特点。  相似文献   

9.
We made a comparison between life history and reproductive characteristics of a group of Dutch rare (30) and common (105) plant species, all dicotyledonous and insect-visited forbs. The traits life span, clonality, breeding system, seed production, seed dispersal, and soil seed bank longevity are considered. All trait values have been ranked according to their possible effect on the vulnerability of a species for extinction, where low values indicate a low risk and high values a high risk for a species. Rare and common plants differed significantly in four traits: seed production, breeding system, seed bank longevity and clonality. The discriminant analysis showed that 79% of the 135 species was correctly classified in the group they presently belong to. Especially species that are rare now but were much more common 50–100 years ago were classified as being common species, pointing at the detrimental effect of habitat loss these species encountered at which they have not yet been able to adapted to. The data set include eight hemiparasitic plant species (familyOrobanchaceae), of which six are endangered in The Netherlands and two more common. Both rare and common hemiparasites scored high traits values, indicating that they are vulnerable for extinction. The hemiparasites had several characteristics in common: they are all annuals or biennials that have no means of clonal reproduction. They all have non-clustered, zygomorphic flowers that produce nectar and have a precise pollen presentation and are mainly visited by (bumble) bees. Mean life span was significantly shorter in the eight hemiparasiticOrobanchaceae than in the non-hemiparasiticScrophulariaceae used for comparison (4 species). Overall, we concluded that hemiparasitic plants have a special combination of life history traits which makes them vulnerable for local and regional extinction.  相似文献   

10.
The current paper presents four lichen associations, including rare and endangered lichen species found in Lithuanian oak-woods. The structure of communities on the oak, characteristic of these localities, and geographical and sociological evaluation of communities are presented. Main reasons causing the extinction of rare species in the communities are mentioned as well.  相似文献   

11.
Modena, founded by the Romans (183 BC), has always been conditioned by water in all its urban history. In the city, numerous archaeobotanical investigations have been carried out in order to reconstruct the natural landscape and human–environment interactions over time. During these investigations, four archaeological sites (two Roman and two medieval) have revealed deposits with a marked character of palaeobiocoenosis, largely resulting from the natural environment surrounding the sites, due to natural “seed rain”. These deposits are characterized by widespread evidence of plants related to water, constituting a valuable archive to investigate habitats which currently have become very rare and threatened, if they have not completely disappeared. The present paper aims to reveal the peculiarities of the Roman/medieval archaeocarpological floristic lists (through a comparison with the flora over the last two centuries in the area of Modena) and highlight the possible causes explaining the presence or the demise of several taxa, considering also the palaeoecological reconstruction of the environment in which they have been found.  相似文献   

12.
We present the first global assessment of extinction risk for a major group of freshwater invertebrates, caridean shrimps. The risk of extinction for all 763 species was assessed using the IUCN Red List criteria that include geographic ranges, habitats, ecology and past and present threats. The Indo-Malayan region holds over half of global species diversity, with a peak in Indo-China and southern China. Shrimps primarily inhabit flowing water; however, a significant subterranean component is present, which is more threatened than the surface fauna. Two species are extinct with a further 10 possibly extinct, and almost one third of species are either threatened or Near Threatened (NT). Threats to freshwater shrimps include agricultural and urban pollution impact over two-thirds of threatened and NT species. Invasive species and climate change have the greatest overall impact of all threats (based on combined timing, scope and severity of threats).  相似文献   

13.
A freshwater diatom flora has been shown to exist on sand grains. The species have been determined from samples of four bodies of water. This epipsammic flora is composed of minute diatoms, many of which require electron microscope study before their identification can be made certain. The chemistry of the water undoubtedly influences the association of species.  相似文献   

14.
海南鹦哥岭自然保护区的珍稀濒危植物与保育   总被引:1,自引:0,他引:1  
对鹦哥岭的珍稀濒危植物进行野外调查表明,本区共有野生分布的珍稀濒危植物79种,隶属于47科71属。其中属于1999年国家重点一级保护4种,如海南苏铁(Cycas hainansis)、坡垒(Hopea hainansis)、台湾苏铁(Cy-cas taiwaniana)和伯乐树(Bretschneidera sinensis),国家二级保护14种。建议将18种列入国家保护名录中,20种列入省级保护名录,其中有30种为海南特有种。鹦哥岭珍稀濒危植物面临的威胁主要有原始森林面积的减少、人为毁林开荒和分布区限制。针对珍稀濒危植物的现状和受到的威胁,提出了应重点加强保护的6个地点及相应的保护对策和建议。  相似文献   

15.
浙江珍稀濒危保护植物的地理分布及其区系特征   总被引:13,自引:0,他引:13  
本文分析了浙江珍稀濒危保护植物56种的地理分布和51属的分布区类型及其区系特征,其结果如下: 1.本区存在较多的我国特有属,单型属、少型属的事实,说明浙江省的珍稀濒危植物区系的古老性和相对原始性。2.根据51属的分布区类型的分析,其属具有明显的温带性质,而56种的地理分布则以亚热带区系成分为主,它们与华中亚热带区系植物关系密切。  相似文献   

16.
九宫山自然保护区珍稀濒危植物调查研究   总被引:3,自引:1,他引:2  
据估计 ,在我国约 3 0 0 0 0种高等植物中至少有3 0 0 0种处于受威胁或濒临灭绝的境地[1] 。保护植物的多样性 ,特别是保护珍稀濒危植物等工作已被世界上许多国家的政府、学术组织和有关机构以及科学家们所普遍重视。湖北九宫山自然保护区分布有许多珍稀濒危植物 ,不仅是宝贵的种质资源 ,具有十分重要的经济意义 ,而且在植物分类学与地理学研究中具有重要价值。杨春锋等[2 ] 曾对九宫山自然保护区的植被进行了调查研究 ,目前对九宫山自然保护区的珍稀濒危植物尚未见报道。九宫山自然保护区的珍稀濒危植物由于多种原因日趋枯竭。因此 ,有必要…  相似文献   

17.
黄土高原地区种子植物区系中的珍稀濒危植物研究   总被引:7,自引:0,他引:7  
黄土高原地区植物区系是南北和东西区系成分的交汇 ,也是旱生、中生和湿生植物聚集的地区 ,生长着比较丰富的植物种类 ,有种子植物 32 2 4种 ,其中珍稀濒危植物 78种 ,分别隶属于 4 3科 6 6属 ,国家一类保护植物 2种 ,国家二类保护植物 10种 ,国家三类保护植物 15种 .地理成分分析表明 ,在属一级水平上以北温带成分、中国特有成分、东亚成分为主 ,种一级水平上以华北区系成分为主 .另外 ,在分析黄土高原珍稀濒危植物致濒机制的基础上 ,进一步提出了保护对策  相似文献   

18.
Parrots (Psittaciformes) are among the most threatened bird orders with 28 % (111 of 398) of extant species classified as threatened under IUCN criteria. We confirmed that parrots have a lower Red List Index (higher aggregate extinction risk) than other comparable bird groups, and modeled the factors associated with extinction risk. Our analyses included intrinsic biological, life history and ecological attributes, external anthropogenic threats, and socio-economic variables associated with the countries where the parrot species occur, while we controlled for phylogenetic dependence among species. We found that the likelihood of parrot species being classified as threatened was less for species with larger historical distribution size, but was greater for species with high forest dependency, large body size, long generation time, and greater proportion of the human population living in urban areas in the countries encompassing the parrots’ home ranges. The severity of extinction risk (from vulnerable to critically endangered) was positively related to the per capita gross domestic product (GDP) of the countries of occurrence, endemism to a single country, and lower for species used as pets. A disproportionate number of 16 extinct parrot species were endemic to islands and single countries, and were large bodied, habitat specialists. Agriculture, hunting, trapping, and logging are the most frequent threats to parrots worldwide, with variation in importance among regions. We use multiple methods to rank countries with disproportionately high numbers of threatened parrot species. Our results promote understanding of global and regional factors associated with endangerment in this highly threatened taxonomic group, and will enhance the prioritization of conservation actions.  相似文献   

19.
Tenebrionid beetle records from 55 sites in urban Rome (Italy) were used to study the influence of structural parameters (area, isolation, forest cover, and shape) of green spaces on species richness and extinction trends. In line with biogeographical predictions, species richness correlated positively with area size of green spaces, extinction was enhanced by isolation and hindered by area size, but, in contrast with common findings, forest extent had a negative impact on tenebrionid persistence. This is explained by the fact that most of tenebrionid species from Rome are associated with open habitats typical of the landscape that characterized the study area before modern urbanization. In contrast with results obtained in other studies of urban ecology, distance to city centre (which expresses the urban–rural gradient) was never recovered as an important correlate of tenebrionid richness or extinction, which may be explained by the fact that tenebrionids include both urban avoider and urban adapter species. These results warn against making generalizations on urban diversity patterns and conservation strategies without reference to past land-use and species characteristics.  相似文献   

20.
Abstract. The native flora of tropical oceanic islands is known to be particularly susceptible both to displacement and extinction, following the invasion of alien organisms. Miconia calvescens DC. (Melastomataceae), first introduced to Tahiti (French Polynesia, South Pacific Ocean) in 1937 as an ornamental plant, now covers over two-thirds of the Island. As it forms dense monotypic stands which have progressively overwhelmed the native forests, this plant pest is a direct threat to the rich Tahitian indigenous flora. Between 40 and 50 species of the 107 species endemic to Tahiti are thought to be on the verge of extinction. M. calvescens was finally declared a'noxious species in French Polynesia'in 1990. Without efficient control efforts and effective endangered plant conservation and protection legislation, M. calvescens could cause Tahiti and all the high islands of French Polynesia to become ecological deserts.  相似文献   

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