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1.
The Floristic Quality Analysis (FQA) is a method to assess the quality of a flora based on the assignment of scores to plant species and subsequent calculation of indices. This method is widely applied, but inadequate investigation has been devoted to test its potential problems due to human factors. This work is aimed to specifically test how the human factor can affect the calculation of the FQA indices, by addressing three questions: (i) Are the scores given to plant species consistent among different experts?; (ii) Are the floristic quality indices calculated by different experts consistent in ordering individual sites?; and (iii) Does the use of an appropriate statistics change the ordering of individual sites? To answer these questions, a list of species obtained in 136 plots in central Italy was submitted to nine experts, who scored each species. The FQA indices were then calculated from the scores of each of the experts. The results showed that: (i) the scores given to the species by the experts were not consistent and the derived floristic quality indices were statistically different; (ii) the floristic quality indices calculated for each plot were significantly different among experts, but the ranking of these plots based on their floristic quality was rather consistent; and (iii) the use of ordinal statistics, which is more adequate for this type of data, did not change the results. This study demonstrated that the Floristic Quality Analysis does not provide reliable and objective tools to assess the quality of the flora in a human-managed ecosystem. The application of these indices should be preceded with resolution of the methodological problems associated with the use of inappropriate statistics, and by procedures to reduce the degree of subjectivity in assigning the CC scores.  相似文献   

2.
    
Abstract How to maximize the conservation of biodiversity is critical for conservation planning, particularly given rapid habitat loss and global climatic change. The importance of preserving phylogenetic diversity has gained recognition due to its ability to identify some influences of evolutionary history on contemporary patterns of species assemblages that traditional taxonomic richness measures cannot identify. In this study, we evaluate the relationship between taxonomic richness and phylogenetic diversity of angiosperms at genus and species levels and explore the spatial pattern of the residuals of this relationship. We then incorporate data on historical biogeography to understand the process that shaped contemporary floristic assemblages in a global biodiversity hotspot, Yunnan Province, located in southwestern China. We identified a strong correlation between phylogenetic diversity residuals and the biogeographic affinity of the lineages in the extant Yunnan angiosperm flora. Phylogenetic diversity is well correlated with taxonomic richness at both genus and species levels between floras in Yunnan, where two diversity centers of phylogenetic diversity were identified (the northwestern center and the southern center). The northwestern center, with lower phylogenetic diversity than expected based on taxonomic richness, is rich in temperate‐affinity lineages and signifies an area of rapid speciation. The southern center, with higher phylogenetic diversity than predicted by taxonomic richness, contains a higher proportion of lineages with tropical affinity and seems to have experienced high immigration rates. Our results highlight that maximizing phylogenetic diversity with historical interpretation can provide valuable insights into the floristic assemblage of a region and better‐informed decisions can be made to ensure different stages of a region's evolutionary history are preserved.  相似文献   

3.
Protected areas (PAs) are at the forefront of conservation efforts, and yet despite considerable progress towards the global target of having 17% of the world''s land area within protected areas by 2020, biodiversity continues to decline. The discrepancy between increasing PA coverage and negative biodiversity trends has resulted in renewed efforts to enhance PA effectiveness. The global conservation community has conducted thousands of assessments of protected area management effectiveness (PAME), and interest in the use of these data to help measure the conservation impact of PA management interventions is high. Here, we summarize the status of PAME assessment, review the published evidence for a link between PAME assessment results and the conservation impacts of PAs, and discuss the limitations and future use of PAME data in measuring the impact of PA management interventions on conservation outcomes. We conclude that PAME data, while designed as a tool for local adaptive management, may also help to provide insights into the impact of PA management interventions from the local-to-global scale. However, the subjective and ordinal characteristics of the data present significant limitations for their application in rigorous scientific impact evaluations, a problem that should be recognized and mitigated where possible.  相似文献   

4.
Plant species richness, endemism, and genetic resources in Namibia   总被引:1,自引:0,他引:1  
Namibia is a floristically diverse, arid to mesic country, with several highly distinct taxa. Including naturalized plants, there are about 4334 vascular plant species and infraspecific taxa within the country's borders, a substantial increase from the existing major reference work. Dominant families are the Poaceae (422species), Fabaceae (377), Asteraceae (385) and Mesembryanthemaceae (177). Freshwater algae and most other groups of lower plants remain poorly known. Concentrations of plant species richness are found in the Succulent Karoo biome, Kaokoveld, Otavi highland/Karstveld area, Okavango Basin, and Khomas highlands. Recent studies have led to a new estimate of 687 endemic plant species, defined as those contained wholly within Namibia's borders, amounting to about 17% of the Namibian flora. At least a further 275 species are Namib Desert endemics shared between the Kaokoveld and southern Angola (75spp.) and between the Succulent Karoo and northwestern South Africa (200spp.). Research on plant genetic resources is focused on species of potential or actual agricultural importance, such as pearl millet, Pennisetum glaucum, and cucurbits. Many wild plants have considerable genetic diversity and development potential. Primary threats to plant diversity fall in the category of poor land management and inappropriate development.  相似文献   

5.
云南蕨类植物的物种多样性和区系组成   总被引:1,自引:0,他引:1       下载免费PDF全文
在一定实地调查和分类的基础上,采用统计分析及区系地理分析法,对云南地区蕨类植物进行研究。结果表明:云南地区共有蕨类植物60科193属1 530种(包括变种和变型),科、属、种分别占中国蕨类植物科总数的58.8%,属的83.9%和种的95.2%;在这60个科中含30种以上的有13个,含5个属以上的有11个,分别占该蕨类植物区系属、种数的56.5%和79.2%,特别是鳞毛蕨科、蹄盖蕨科、水龙骨科和金星蕨科,这4个科共拥有70属761种,分别占总属数、总种数的36.3%、49.7%;193属中含30种以上的有11个,分别占总属、总种数的5.7%和41.7%,最具优势的是鳞毛蕨属和耳蕨属、蹄盖蕨属、铁角蕨属、卷柏属,这5个属共有403种,占总种数的26.3%;该区系中无云南特有科,但具有4个亚洲特有科:雨蕨科、稀子蕨科、柄盖蕨科和骨碎补科;该区系以热带、亚热带性质为主,科的区系成分中热带亚热带分布的科占66.6%,热带成分的属有112个,占68.7%(除世界分布类型);该区系是东亚地区蕨类植物区系的重要组成部分,东亚分布31属和中国特有分布6属,分别占总属数(除世界分布属外)的19.0%和3.7%;该地区蕨类植物区系与西藏、台湾具有共同的区系起源和物种分化形成的背景,属的相似性系数约为70%,种的相似性系数约为30%,均起源于热带亚热带地区;属的热带区系成分与温带区系成分所占比例分别为68.7%和27.6%,存在一定的区系过渡性;该区系科的分化强度为3.2,属的分化强度为7.9,在科、属水平上均表现出较强的区系分化特征。  相似文献   

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The present work aims to study the effect of deferring grazing on the floristic diversity of Stipa tenacissima Loefl. ex L. rangelands in the central Algerian steppe in two different bioclimatic stages, namely semi‐arid and arid. This work is part of a perspective to know the floristic characteristics of an area excluded from grazing and an unrestricted rangeland, in two different environments in order to highlight the factors that are conceivably responsible for the diversification of flora in the steppe ecosystems. In the present study, a number of 96 floristic surveys were performed during the spring season of the years 2014, 2015 and 2016. The methodology adopted is a subjective sampling. The minimum area retained is 100 m2 defined by the method of Braun Blanquet and de Bolos (1957, Annales Estacion Experimental de Aula Dei, 5, 266). This method has been used to study the floristic diversity represented by the floristic richness, Shannon index, the equitability, the biological and the phytochoric type. The climatic correction according to the altitudinal gradient was applied to determine the bioclimatic stage. The results from the surveys indicate that the rangelands at the studied sites contain 109 species, 27 families and 63 genera out of which 79 species and 22 families are in the semi‐arid bioclimatic stage. A two‐way analysis of variance was employed to examine the effect of the bioclimatic stage and the pasture land put at rest. Variance analysis of the diversity indices showed that the bioclimatic stage has a significant impact on the floristic richness and flora diversity of the S. tenacissima steppe (p ≤ 0.01) with a 5% threshold; on the other hand, the protection of these ecosystems does not have a remarkable influence on the floristic diversity (p > 0.05). In recent years, climatic disturbances have resulted in changes in vegetation, even in rested areas located between the study localities.  相似文献   

7.
该研究于2019-2021年4次对安徽大别山北坡进行苔藓植物野外考察和标本采集,对采集到的1 517份标本鉴定以及文献整理,统计分析该区苔藓植物物种组成、区系地理组成;并与华东、华中、华北等地的苔藓植物区系地理组成进行比较,以明确大别山北坡苔藓植物区系的归属问题。结果表明:(1)安徽大别山北坡共有苔藓植物80科180属482种(包括种以下单位);该次调查增加了12科40属206种,其中安徽省新记录种9个。(2)发现受威胁苔藓植物2种——滇西高领藓(Glyphomitrium minutissimum)属于极危(CR),瘤根真藓(Bryum bornholmense)属于易危(VU)。(3)大别山北坡苔藓植物区系拥有3个世界性单种科,14个世界性单种属,且有34个世界性寡种属(2~6种),该区单种属和寡种属(48属)占该区总属数的26.67%,表明该区苔藓植物起源古老。(4)大别山北坡苔藓植物区系地理成分复杂多样,以北温带成分(26.43%)和东亚成分(24.89%)为主,热带亚洲成分(14.54%)次之。(5)安徽大别山北坡苔藓植物区系与华东(西天目山、清凉峰、阳际峰)区系的关系最为密...  相似文献   

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The Species Catalogue of China: Volume 1: Plants (SCCP) is a new, comprehensive, hardcopy inventory of Chinese higher plants that combines several datasets and references to recent taxonomic treatments. The database, with all attached additional information, is freely accessible via the internet (http://www.sp2000.org.cn/) and on CD-ROM, and will be updated yearly. It includes bryophytes (157 families, 599 genera, and 3167 specific and infraspecific taxa), lycophytes and ferns (41 families, 181 genera, and 2336 specific and infraspecific taxa), gymnosperms (10 families, 45 genera, and 311 specific and infraspecific taxa), and angiosperms (270 families, 3227 genera, and 35 873 specific and infraspecific taxa); in total 478 families, 4052 genera, and 41 687 specific and infraspecific taxa. Several other important statistics can also be drawn from the database, such as the distribution pattern of the four major groups of higher plants, as well as number of endemic and naturalized or cultivated genera/taxa. Entries in SCCP are also compared with Flora of China, and Flora reipublicae popularis Sinicae at the genus level. The SCCP will not only be a useful reference for floristic or biodiversity studies in China, but will also serve as a key resource to direct action and monitor progress. It is intended to be a useful resource for achieving Target 1 of the Global Strategy for Plant Conservation (GSPC).  相似文献   

9.
    
  1. Analysis of the structure, diversity, and demographic dynamics of tree assemblages in tropical forests is especially important in order to evaluate local and regional successional trajectories.
  2. We conducted a long‐term study to investigate how the structure, species richness, and diversity of secondary tropical forests change over time. Trees (DBH ≥ 5 cm) in the Atlantic Forest of southern Brazil were sampled twice during a 10‐year period (2007 and 2017) in six stands (1 ha each) that varied in age from their last disturbance (25, 60, 75, 90, and more than 100 years). We compared forest structure (abundance and basal area), species richness, alpha diversity, demographic rates (mortality, recruitment, and loss or gain in basal area), species composition, spatial beta diversity, and temporal beta diversity (based on turnover and nestedness indices) among stand ages and study years.
  3. Demographic rates recorded in a 10‐year interval indicate a rapid and dynamic process of species substitution and structural changes. Structural recovery occurred faster than beta diversity and species composition recovery. The successional gradient showed a pattern of species trade‐off over time, with less spatial dissimilarity and faster demographic rates in younger stands. As stands grow older, they show larger spatial turnover of species than younger stands, making them more stochastic in relation to species composition. Stands appear to split chronologically to some extent, but not across a straightforward linear axis, reflecting stochastic changes, providing evidence for the formation of a nonequilibrium community.
  4. Policy implications. These results reiterate the complexity and variability in forest succession and serve as a reference for the evaluation and monitoring of local management and conservation actions and for defining regional strategies that consider the diversity of local successional trajectories to evaluate the effectiveness of restoration measures in secondary forests of the Atlantic Forest biome.
  相似文献   

10.
This study provides a checklist of the Caesalpinioideae (Leguminosae) present in Equatorial Guinea, comprising 52 genera and 124 taxa. Seven species are known from Annobón, 33 from Bioko and 109 from Río Muni. The best represented genus is Senna with eight species. In addition, bibliographic references for Caesalpinioideae (Leguminosae) from Equatorial Guinea have been gathered and checked. Fourteen species are included based on literature records, because their distribution ranges suggest they may occur in Equatorial Guinea, 11 introduced species could be naturalized, and 45 taxa are recorded for the first time from the country. This represents an increase of over 35% in the floristic knowledge of Caesalpinioideae from Equatorial Guinea. A statistical summary is presented at the end of the checklist.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 541–562.  相似文献   

11.
报道了广东省始兴县车八岭国家级自然保护区及其邻近地区木兰科植物种群特点及保护现状。木兰科植物通常位于人为破坏较轻 ,林相保存较好 ,以壳斗科、樟科、茶科为主要建群种的中亚热带常绿阔叶林中。共设置了 9个面积为 4 0 0 m2的样方。在样方中共记录了 3种木兰科植物 :观光木 ( Tsoongiodendron odor-um Chun)、深山含笑 ( Michelia maudiae Dunn)和金叶含笑 ( M.foveolata Merr.ex Dandy)。其中 ,深山含笑的种群较大 ,呈稳定结构 ,但主要局限于保护区内保护较好的地域 ;金叶含笑种群面临濒危 ,种群小 ,在保护区呈零星分布 ;观光木的分布区域相对较广 ,在保护区内外均见分布 ,但种群较小 ,特别是在保护区外的种群 ,由于人为的干扰 ,种群在急剧减少。大多数木兰科植物的种群在原生境均表现出自然更新不良 ,必须加以保护。分析了影响车八岭及其邻近地区木兰科植物种群及其群落发展的主要限制因素 ,建议加强自然保护知识的宣传和木兰科植物的人工保育 ,促进该区域木兰科植物资源的管理和发展  相似文献   

12.
Exploitation of deep-sea resources is now underway and there is economic pressure to renew and expand currently restricted waste disposal in that environment. Since the deep sea is noted for very high species diversity, it is appropriate that diversity conservation be initiated. Review of current concepts of diversity maintenance finds that the ideas have evolved more through increasing information about sources of heterogeneity than through rigorous testing. This history weakens the immediate value of these concepts for the development of conservation strategies and demonstrates the need for additional investigation. Such inquiry might focus upon the rare component of overall species richness. A comparison of box core samples at 2100m in the western Atlantic and the Gulf of Mexico continental shelf reveals that deep soft bottoms are not unique in having many rare species. The rare component at depth is largely comprised of species more common at other locations near and far. The rare component on the shelf is comprised mostly of species which are consistently rare and restricted in distribution. These observations suggest a shallow–deep difference that is more one of degree than fundamental in nature; the deep having larger regions and regional species pools.  相似文献   

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Grazing is one of the key processes in terrestrial ecosystems and this can be provided by both indigenous and domestic ungulates. However, a question remains whether or not traditional forms of land use such as the grazing of domestic animals support the maintenance of biodiversity. If it does not, then the second question becomes to what extent does grazing of domestic animals alter the systems and processes that support biodiversity? This study demonstrates that in attempting to answer this question, small organisms like dung beetles are ideal indicators that can be used to express significant differences between conserved (indigenous) and non‐conserved (domestic) land. As a general trend, studies that investigated these differences displayed differences through analysis of the diversity indices. This method has in most cases demonstrated a lack of contrast between conserved and non‐conserved land. In the existence of such uncertainty this study has demonstrated that in such cases, where the analysis of biodiversity indices fail to demonstrate significant differences a closer examination of actual species such as guilds and functional groups could confirm significant differences between conserved and non‐conserved land. These apparently conflicting findings reflect the need to consider the actual elements of biodiversity (e.g. species) when assessing conservation issues rather than just the statistical measures of biodiversity.  相似文献   

15.
张梅 《西北植物学报》2015,35(8):1669-1675
采用植物区系谱、排序分析、聚类模型和相关性等方法,研究了辽西白狼山植物区系属的地理组成以及与其它山地的相似关系,以揭示多个山地植物区系的相互关系及分布格局。结果表明:(1)白狼山自然保护区野生种子植物多样而丰富,共有101科394属790种;被子植物占总种数的98.35%,优势科现象明显,寡种属和单种属占优势,呈现一定残遗性;(2)属的地理成分以温带成分为主,共有273属,占总属数的81.3%,处于中国-日本森林植物亚区暖温带-温带过渡范围内,植物区系划归于华北植物区系平原山地亚地区。(3)相关分析表明,白狼山与努鲁儿虎山(r=0.999)、东灵山(r=0.998)之间的植物区系具有极显著相关关系;主坐标排序和聚类分析表明,白狼山种子植物属的分布区类型与努鲁儿虎山、东灵山、小五台山以及雾灵山等有着较大的相似性,不同纬度水热条件可能是影响植物区系地理分布格局的重要因素。  相似文献   

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Continuous livestock grazing can have negative effects on biodiversity and landscape function in arid and semi‐arid rangelands. Alternative grazing management practices, such as rotational grazing, may be a viable option for broad‐scale biodiversity conservation and sustainable pastoral management. This study compared ground cover, plant species composition and floristic and functional diversity along gradients of grazing intensity between a pastoral property rotationally grazed by goats and an adjacent nature reserve (ungrazed by commercial livestock) in semi‐arid south‐eastern Australia. Understorey plant species composition differed significantly between the rotationally grazed property and the nature reserve, with a greater proportion and frequency of palatable species recorded in the nature reserve. Understorey plant species richness, diversity, functional biodiversity measures and ground cover declined with increasing grazing pressure close to water points under commercial rotational grazing management. However, at a whole‐paddock scale, there were few differences in plant biodiversity and ground cover between the rotationally grazed property and the nature reserve, despite differences in overall plant species composition. Flexible, adaptive, rotational grazing should be investigated further for its potential to achieve both socio‐economic and biodiversity conservation outcomes in semi‐arid rangelands to complement existing conservation reserves.  相似文献   

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退化草原冷蒿群落13年不同放牧强度后的植物多样性   总被引:16,自引:0,他引:16       下载免费PDF全文
刘振国  李镇清 《生态学报》2006,26(2):475-482
放牧过程通过家畜的啃食、践踏干扰草原环境,使草原的物种组成发生变化,植物种群的优势地位发生更替。对退化草原中的冷蒿群落在经历13a不同放牧强度——无牧(0.00只羊,hm^2)、轻牧(1.33只羊/hm^2)、中牧(4.00只羊/hm^2)、重牧(6.67只羊,hm^2)的围栏放牧后的植物群落多样性进行研究,结果表明:经过13a的演替变化,(1)无牧处理下植被密度显著低于其它3个放牧处理下的植被密度,而其它3个放牧处理之间的植被密度差异不显著;(2)无牧处理下羊草成为群落的优势种,轻牧和中牧处理下冷蒿依然是群落的优势种。这3种处理下寸草苔的种群密度最大;重牧处理下优势种变为星毛委陵菜,并且其种群密度最大;随着放牧强度增加,不同放牧退化阶段指示植物的种群密度的变化趋势是:冷蒿为先增大后减小,而星毛委陵菜为先急剧增大,然后平缓增大,最后再急剧增大;(3)植物多样性和均匀度指数在中牧处理下最大,在无牧处理下最小,说明中牧处理下群落的多样性最高,无牧处理下群落的多样性最小。而优势度指数正相反。植物群落结构和多样性的变化主要是由放牧家畜选择性采食、不同植物对放牧响应的不同策略、植物种间的竞争、动植物协同进化以及由放牧改变的土壤理化性质等因素综合决定的。此研究有助于进一步认识退化草原在继续放牧干扰下的演替规律以及为退化草原的保护和恢复提供理论依据。  相似文献   

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