广西沿海西部山心、巫头和澫尾岛植被类型初步研究

本文概述了在广西沿海西部山心、巫头和尾岛特殊环境条件下植被的性质及主要类型,初步分析了岛屿上主要森林植被群落的基本特点,并根据岛屿上主要植被类型组合、分布及与环境之间的关系,从植物生态学的角度上提出了森林植被恢复的途径。     

The island rule: An assessment of biases and research trends

Aim

The island rule has been widely applied to a range of taxonomic groups, with some studies reporting supporting evidence but others questioning this hypothesis. To bring more clarity to this debate, we conducted a comparative analysis of the available literature, focussing on potential biases.

Location

Worldwide.

Methods

We performed a systematic review to identify studies testing the island rule and translated these studies’ outcomes, so that they follow a consistent approach. The studies were assessed for differences in their analysis of the island rule. We created an authorship network showing who published studies with whom on the topic and weighted the data based on co‐authorship and number of publications.

Results

We identified 143 relevant studies, finding a significantly lower frequency of supporting studies according to our consistent approach (50%) than the authors’ own statements (59%). Two core‐author groups could be identified with a strong publication record on the island rule. The first group has predominately published studies supporting the rule, whereas the other group has mainly published studies questioning it. According to a subsequent analysis excluding studies with a high risk of HARKing (hypothesizing after the results are known), the frequency of studies supporting the rule further dropped to 42%.

Main conclusions

Empirical support for the island rule is low, especially for non‐mammalian taxa and when using a consistent evaluation approach. Differences among studies in supporting versus questioning this hypothesis seem to be partly due to author‐related biases. Methods to address potential biases in studying ecological hypotheses are urgently needed. We offer such a method here.     

海南和台湾蕨类植物多样性及其大陆性特征

海南和台湾是我国南部和东部两个最重要的大陆性岛屿,具有极为丰富的蕨类植物多样性。特有现象揭示着植物区系和植物多样性的历史,间断分布揭示着与邻近或相关植物区系的联系;特别是在岛屿地区,这种现象和意义尤其明显。海南有蕨类植物区系55科、135属、466种,其中特有种有32种,台湾蕨类植物区系57科、142属、599种,其中特有种达66种。在海南与台湾两地,有共有属104属,共有种仅有176种。台湾海峡出现始于晚白垩世,持续至第四纪;琼州海峡出现于早第四纪,因此,两地的特有现象远少于种子植物(台湾有801种,海南有501种),原因与蕨类植物具有更广的散布性相关,而且在被子植物中起重要作用的物种生物学障碍(机制)在蕨类是缺乏的;形态学的、生殖生物学特征导致蕨类植物具有较缓慢的物种演化历史和较低的灭绝率(Smith,1972)。海南和台湾蕨类植物区系的比较还表明,地理位置和海拔高度对植物区系的物种分化和物种多样性产生了极大的影响。     

Island ecology and contingent theory: the role of spatial scale and taxonomic bias

Scale, the scale dependency of patterns and processes, and the ways that organisms scale their responses to these patterns and processes are central to island and landscape ecology. Here, we take a database of studies in island ecology and investigate how studies have changed over a 40-year period with respect to spatial scale and organisms studied. We demonstrate that there have been changes in the spatial scale of islands studied and that there is taxonomic bias in favour of vertebrates in island ecological studies when compared to scientific publications as a whole. We discuss how such taxonomic bias may have arisen and discuss the implications for ecology and biogeography.     

The insular herpetofauna of Mexico: Composition,conservation, and biogeographic patterns

We compile a Mexican insular herpetofaunal checklist to estimate endemism, conservation status, island threats, net taxonomic turnover among six biogeographic provinces belonging to the Nearctic and Neotropical regions, and the relationships between island area and mainland distance versus species richness. We compile a checklist of insular herpetofaunal through performing a literature and collection review. We define the conservation status according to conservation Mexican law, the Red List of International Union for Conservation of Nature, and Environmental Vulnerability Scores. We determine threat percentages on islands according to the 11 major classes of threats to biodiversity. We estimate the net taxonomic turnover with beta diversity analysis between the Nearctic and Neotropical provinces. The Mexican insular herpetofauna is composed of 18 amphibian species, 204 species with 101 subspecies of reptiles, and 263 taxa in total. Endemism levels are 11.76% in amphibians, 53.57% in reptiles, and 27.91% being insular endemic taxa. Two conservation status systems classify the species at high extinction risk, while the remaining system suggests less concern. However, all systems indicate species lacking assessment. Human activities and exotic alien species are present on 60% of 131 islands. The taxonomic turnover value is high (0.89), with a clear herpetofaunal differentiation between the two biogeographic regions. The species–area and species–mainland distance relationships are positive. Insular herpetofauna faces a high percentage of threats, with the Neotropical provinces more heavily impacted. It is urgent to explore the remaining islands (3,079 islands) and better incorporate insular populations and species in ecological, evolutionary, and systematic studies. In the face of the biodiversity crisis, islands will play a leading role as a model to apply restoration and conservation strategies.     

Bird community patterns in response to the island features of urban woodlots in eastern China

Many studies have demonstrated the changes in the spatial patterns of plant and animal communities with respect to habitat fragmentation.Insular communities tend to exhibit some special patterns in connection with the characteristics of island habitats.In this paper,the relationships between richness,assemblage,and abundance of bird communities with respect to island features were analyzed in 20 urban woodlots in Hangzhou,China.Field investigations of bird communities,using the line transect method,were conducted from January to December,1997.Each woodlot was surveyed 16 times during the year.Results indicated that bird richness was higher,per unit area,in the smaller woodlots than the larger ones,and overall bird density decreased with the increase in the size of woodlot.However,the evenness of species abundance increased with the area,and small woodlots were usually dominated by higher density species and large woodlots by medium density species.Most species occurring in the small woodlots also occurred in larger woodlots.Also,bird communities among urban woodlots showed a nestedness pattern in assemblage.These patterns implied that the main impacts of woodland habitat fragmentation are:(1) species are constricted and thus species number will increase at a given sample size;(2) as surface area decreases,the proportion of forest edge species as to interior species will increase;(3)community abundance will therefore increase per unit area but most individuals will be from a few dominant species;and (4) overall species diversity will decrease at a habitat level as well as at a region level.These patterns of community in response to the island features were therefore summarized as "island effects in community".The underlying processes of such observations were also examined in this paper.Woodlot area,edge ratio,isolation,and habitat nestedness were considered as the important factors forming the island effects in community.High heterogeneity between habitats usually contributed most to the maintenance of regional biodiversity,especially in urban woodlots.     

园林鸟类群落的岛屿性格局

岛屿群落由于受岛屿栖息地特征结构的影响而产生一系列特殊的格局。通过对杭州市园林鸟类群落的研究,分析了园林鸟类群落的物种数、组成和多度与园林岛屿性状的关系,从而确定了园林鸟类群落存在如下与园林的岛屿性状有关的格局:(1)在物种数方面,在相同的取样面积下,园林的物种数随园林面积的增大而减少;(2 )在群落组成上,园林鸟类群落呈现出不完全的嵌套格局,分布于物种数较少的园林中的物种多数也分布在物种数较多的园林中;(3)在物种多度方面,园林鸟类的总密度随面积的增大而减少,园林鸟类多度的均匀度随着面积的增大而提高。群落的岛屿性格局反映了栖息地的岛屿化对群落的影响,总称之为群落的岛屿效应。通过比较全年、繁殖季节、越冬季节和迁徙季节群落岛屿性格局的显著性,分析群落的稳定性与群落岛屿效应之间的关系,认为两者之间没有必然的联系,相对非稳定的群落也可导致显著岛屿效应     

Bird community patterns in response to the island features of urban woodlots in eastern China

Many studies have demonstrated the changes in the spatial patterns of plant and animal communities with respect to habitat fragmentation. Insular communities tend to exhibit some special patterns in connection with the characteristics of island habitats. In this paper, the relationships between richness, assemblage, and abundance of bird communities with respect to island features were analyzed in 20 urban woodlots in Hangzhou, China. Field investigations of bird communities, using the line transect method, were conducted from January to December, 1997. Each woodlot was surveyed 16 times during the year. Results indicated that bird richness was higher, per unit area, in the smaller woodlots than the larger ones, and overall bird density decreased with the increase in the size of woodlot. However, the evenness of species abundance increased with the area, and small woodlots were usually dominated by higher density species and large woodlots by medium density species. Most species occurring in the small woodlots also occurred in larger woodlots. Also, bird communities among urban woodlots showed a nestedness pattern in assemblage. These patterns implied that the main impacts of woodland habitat fragmentation are: (1) species are constricted and thus species number will increase at a given sample size; (2) as surface area decreases, the proportion of forest edge species as to interior species will increase; (3) community abundance will therefore increase per unit area but most individuals will be from a few dominant species; and (4) overall species diversity will decrease at a habitat level as well as at a region level. These patterns of community in response to the island features were therefore summarized as “island effects in community”. The underlying processes of such observations were also examined in this paper. Woodlot area, edge ratio, isolation, and habitat nestedness were considered as the important factors forming the island effects in community. High heterogeneity between habitats usually contributed most to the maintenance of regional biodiversity, especially in urban woodlots. __________ Translated from Acta Ecologica Sinica, 2005, 25(4): 657–663 [译自: 生态学报, 2005, 25(4): 657–663]     

温带次生林的岛屿化对鸟类物种多样性及密度的影响

由于自然事件的影响和人类活动的干扰,越来越多的大片森林破碎成彼此孤立、面积不一的森林岛屿,这种变化无疑会对某些动物的分布模式及行为特征产生影响。于2000和2001年的春夏季,在吉林省左家自然保护区及土门岭地区,采用点样法对18块森林岛屿(面积范围:4.3–76.9hm2)中的鸟类物种多样性及密度进行了调查。主要目的是检测森林岛屿的面积效应是否对鸟类物种多样性及密度产生影响,同时分析经典的岛屿生物地理理论是否可以解释破碎化后的森林岛屿面积与物种的关系。结果表明,鸟类物种多样性在年间没有显著变化,但鸟类的密度在不同年间变化较大。不同面积森林岛屿中的鸟类物种多样性有所差异,所包含的鸟类物种数从12种到43种不等。尽管有些面积较大的斑块所包含的物种数较少,但鸟类物种数的总体趋势是随着斑块面积的增大而增多。不同鸟类对森林岛屿面积的反应并不相同,灰椋鸟(Sturnuscineraceus)、红尾伯劳(Laniuscristatus)、灰头鹀(Embrizaspodocephala)等在面积较小的斑块中密度较大,而山鹡鸰(Dendronanthusindicus)、树鹨(Anthushodg-soni)、灰背鸫(Turdushortulorum)等几乎不分布于小面积斑块之中。森林岛屿中鸟类物种随着面积变化的变异方式符合经典的岛屿生物地理理论的基本模式,但Z值和C值差异较大     

海岛生态保护红线划定技术方法

划定海岛生态保护红线是维护海岛生态安全,协调海岛开发与保护之间矛盾的重要方法。目前,海岛生态保护红线在概念内涵、划定内容、划定方法等方面尚未统一定性,且极易与海洋生态红线的概念混淆,不同类型和形态的海岛红线划定的方法及原则要求也有所区分,例如,单岛、列岛、群岛、有居民和无居民海岛等。论述了海岛生态保护红线概念、海岛生态保护红线与海洋生态红线的区别和联系;结合生态科学、地理科学和管理科学属性,基于发展观点和底线思维阐述了海岛生态保护红线划定原则;海岛生态保护红线类型主要包括:海岛重点生态功能区、海岛生态敏感区/脆弱区和海岛禁止开发区;筛选出海岛生态保护红线划定需要重点考量的指标,提出海岛生态保护红线划定的技术路线,同时针对海岛生态保护红线区划面临的若干问题进行探讨;最后对今后海岛生态保护红线划定研究进行了展望。     

Genetic structure of the critically endangered Red‐headed Wood Pigeon Columba janthina nitens and its implications for the management of threatened island populations

The Red‐headed Wood Pigeon Columba janthina nitens is endemic to the Ogasawara Islands, an oceanic island chain located 1000 km south of the main islands of Japan. The subspecies is at high risk of extinction because of its small population size and restricted habitat range. We undertook genetic analyses of this pigeon using sequences of a portion of the mitochondrial control region and five microsatellite markers to estimate the genetic characteristics of two wild populations from the Bonin and Volcano Islands, as well as one captive breeding population. The genetic diversity of the wild individuals was exceptionally low in both the mitochondria (nucleotide diversity = 0.00105) and at the microsatellite (3.2 alleles per locus and H_E = 0.12) loci. Higher numbers of microsatellite genotypes were observed in the Volcano Islands population than in the Bonin Islands population, which may be because of the relatively low impact of human disturbance. The most common mitochondrial haplotypes and microsatellite alleles observed in the two wild populations were completely fixed in the captive population. Our results suggest that the genetic diversity of the captive population needs to be increased. However, introduction of a wild individual into a captive population can lead to a decreased genetic diversity in the wild population and therefore should be done with caution. The genetic differentiation between the Bonin and the Volcano island groups was low, and the populations of the two island groups should be regarded as a single evolutionarily significant unit. However, special consideration is required for habitat conservation in the Volcano Islands, which may be functioning as a sanctuary for the Red‐headed Wood Pigeon. For the long‐term conservation of threatened bird species that live on remote oceanic islands, determination of management units considering gene flow caused by their flying capacity and maintenance of genetically suitable wild and captive populations are essential.     

千岛湖岛屿特征与节肢动物多样性的关系

采用栅格采样法,于2006年4、5、8和10月对千岛湖库区50个不同大小岛屿中节肢动物的种类与数量进行了调查,分析了岛屿面积、海拔、形状和距离等因素对岛屿节肢动物物种丰富度的影响.结果表明:岛屿上节肢动物总物种丰富度、高扩散力物种丰富度和低扩散力物种丰富度均随岛屿面积的增大而增加,且岛屿面积与物种丰富度之间的关系符合经典岛屿生物地理学模型;节肢动物物种丰富度受岛屿面积、海拔和形状的综合影响,距离对岛屿上物种的丰富度没有显著影响;总的物种丰富度与岛屿形状指数和海拔呈显著正相关,岛屿面积和海拔与高扩散力物种的物种丰富度显著相关,而低扩散力物种与岛屿各地理因素之间的相关性均不显著.     

人类基因组上CpG岛的定位和系统分析

为了研究CpG岛产生和消失机制以及位于基因启动子区域外的CpG岛保守性等问题,我们通过序列比对和进化保守性分析等方法,分析在人类和小鼠中保守的基因上的CpG岛。结果显示已有保守序列的突变以及序列插入删除是CpG岛产生和消失的主要原因,进一步分析发现52%的在小鼠基因组上保守序列完全缺失的CpG岛位于两个转座子之间,提示转座子所介导的序列插入是CpG岛形成和消失的重要原因。人类基因组上在启动子区域外的CpG岛中约有79%为新产生的CpG岛,显著高于启动子区域内新产生的CpG岛比例(41%)。GO分析表明与这些CpG岛相关的部分基因与神经系统发育显著相关,提示新产生的CpG岛参与神经发育过程。     

Body size evolution in insular vertebrates: generality of the island rule

Aim My goals here are to (1) assess the generality of the island rule – the graded trend from gigantism in small species to dwarfism in larger species – for mammals and other terrestrial vertebrates on islands and island‐like ecosystems; (2) explore some related patterns of body size variation in insular vertebrates, in particular variation in body size as a function of island area and isolation; (3) offer causal explanations for these patterns; and (4) identify promising areas for future studies on body size evolution in insular vertebrates. Location Oceanic and near‐shore archipelagos, and island‐like ecosystems world‐wide. Methods Body size measurements of insular vertebrates (non‐volant mammals, bats, birds, snakes and turtles) were obtained from the literature, and then regression analyses were conducted to test whether body size of insular populations varies as a function of body size of the species on the mainland (the island rule) and with characteristics of the islands (i.e. island isolation and area). Results The island rule appears to be a general phenomenon both with mammalian orders (and to some degree within families and particular subfamilies) as well as across the species groups studied, including non‐volant mammals, bats, passerine birds, snakes and turtles. In addition, body size of numerous species in these classes of vertebrates varies significantly with island isolation and island area. Main conclusions The patterns observed here – the island rule and the tendency for body size among populations of particular species to vary with characteristics of the islands – are actually distinct and scale‐dependent phenomena. Patterns within archipelagos reflect the influence of island isolation and area on selective pressures (immigration filters, resource limitation, and intra‐ and interspecific interactions) within particular species. These patterns contribute to variation about the general trend referred to as the island rule, not the signal for that more general, large‐scale pattern. The island rule itself is an emergent pattern resulting from a combination of selective forces whose importance and influence on insular populations vary in a predictable manner along a gradient from relatively small to large species. As a result, body size of insular species tends to converge on a size that is optimal, or fundamental, for a particular bau plan and ecological strategy.