Richness and species composition of arboreal arthropods affected by nutrients and predators: a press experiment

A longstanding goal for ecologists is to understand the processes that maintain biological diversity in communities, yet few studies have investigated the combined effects of predators and resources on biodiversity in natural ecosystems. We fertilized nutrient limited plots and excluded insectivorous birds in a randomized block design, and examined the impacts on arthropods associated with the dominant tree in the Hawaiian Islands, Metrosideros polymorpha (Myrtaceae). After 33 months, the species load (per foliage mass) of herbivores and carnivores increased with fertilization, but rarified richness (standardized to abundance) did not change. Fertilization depressed species richness of arboreal detritivores, and carnivore richness dropped in caged, unfertilized plots, both because of the increased dominance of common, introduced species with treatments. Herbivore species abundance distributions were more equitable than other trophic levels following treatments, and fertilization added specialized native species without changing relativized species richness. Overall, bird removal and nutrient addition treatments on arthropod richness acted largely independently, but with countervailing influences that obscured distinct top-down and bottom-up effects on different trophic levels. This study demonstrates that species composition, biological invasions, and the individuality of species traits may complicate efforts to predict the interactive effects of resources and predation on species diversity in food webs.     

Species richness in soil bacterial communities: a proposed approach to overcome sample size bias

Estimates of species richness based on 16S rRNA gene clone libraries are increasingly utilized to gauge the level of bacterial diversity within various ecosystems. However, previous studies have indicated that regardless of the utilized approach, species richness estimates obtained are dependent on the size of the analyzed clone libraries. We here propose an approach to overcome sample size bias in species richness estimates in complex microbial communities. Parametric (Maximum likelihood-based and rarefaction curve-based) and non-parametric approaches were used to estimate species richness in a library of 13,001 near full-length 16S rRNA clones derived from soil, as well as in multiple subsets of the original library. Species richness estimates obtained increased with the increase in library size. To obtain a sample size-unbiased estimate of species richness, we calculated the theoretical clone library sizes required to encounter the estimated species richness at various clone library sizes, used curve fitting to determine the theoretical clone library size required to encounter the "true" species richness, and subsequently determined the corresponding sample size-unbiased species richness value. Using this approach, sample size-unbiased estimates of 17,230, 15,571, and 33,912 were obtained for the ML-based, rarefaction curve-based, and ACE-1 estimators, respectively, compared to bias-uncorrected values of 15,009, 11,913, and 20,909.     

梵争山和张家界地区蜘蛛群落结构及多样性研究

1990年8月对梵净山和张家界两个自然保护区内蜘蛛群落进行调查,结果表明:自然保护区内蜘蛛资源极为丰富,经初步鉴定,计有蜘蛛27科85属180种,其中主要成分依次为肖蛸、园蛛、狼蛛、球蛛和皿蛛等。蜘蛛发生量折合每亩为17,585—54,000头。八个不同生境类型蜘蛛群落的种类数和密度存在明显差异;各种蜘蛛分布群在群落内的比例随栖息地结构变化而改变,因而也导致蜘蛛群落的Shannon-Wiener多样性指数,Simpson优势度和均等度等参数的变化。     

群落均匀度分形分析

修正了Frontier和Ricotta等关于有效物种丰富度指数A与物种丰富度指数S之间幂律关系的定义．探讨了A与S之间分形关系的生态学意义．认为分形维数D是群落均匀度测度值在物种数S不断增加的过程中．向其逼近的一个理论值;提出了利用双对数坐标上建立的A与S拟合直线的方程．对群落均匀度的4种变化趋势进行描述的方法。以广东黑石顶自然保护区森林演替系列为例．研究了针阔叶混交林和常绿阔叶林样带上．随着样带观察长度的逐渐增加群落均匀度的变化情况。结果表明．230m长的混交林样带只存在一个线性无标度区间．群落均匀度随样带长度的不断增加而逐渐降低．向分形维数D=0．810趋近。170m长的常绿阔叶林样带存在两个线性无标度区问．在0～25m的尺度域内．随着样带长度的逐渐增加均匀度不断降低．向分形维数D=0．525逼近;在30～170m的尺度域内．随着样带观察长度的增加．群落均匀度也逐渐增加．向分形维数D=0．920趋近。     

Influence of Salinity Concentration on Aquatic Insect Community Structure: A Mesocosm Experiment in the Dead Sea Basin Region

Salinity varies considerably among temporary pools in the Dead Sea Basin, Israel. We experimentally assessed the effects of four salinity levels (0, 10, 20 and 30 g NaCl per liter) on the aquatic insect community in this basin in an artificial pool experiment. Each salinity level was randomly assigned to six pools (total=24 pools). Salinity did not affect total insect abundance but strongly affected abundance and distributions of different species, and consequently, community structure. Of 13 taxa colonizing the pools, 12 were Diptera including 10 mosquito species. Five taxa were sufficiently common to assess abundance in relation to salinity. Polypedilum nubiferum Skuse (Diptera: Chironomidae) was largely salinity intolerant being abundant only in the freshwater. Ephydra flavipes Macquart (Diptera: Ephydridae) was most abundant at the highest salinity level and was rare in freshwater. Ochlerotatus caspius Pallas (Diptera: Culicidae) abundance tended to be highest at 10 g/l and lowest at 30 g/l although the differences were not statistically significant. Anopheles multicolor Cambouliu (Diptera: Culicidae) was relatively euryhaline although numbers dropped significantly at the highest salinity. Cleon dipterum Linnaeus (Baetidae: Ephemeroptera) was also euryhaline and showed no significant differences in abundance across salinities. For the mosquito species, we also estimated survival to pupation. Survival to pupation was significantly lower for O. caspius in freshwater, but was not statistically significantly different across salinities for A.␣multicolor. Species diversity was highest at the two lowest salinities tested and then dropped with increasing salinity. Evenness was not significantly different across salinities. Community similarity generally decreased with increasing salinity differences though dissimilarity was greatest when comparing freshwater to other salinities. Thus, regional diversity is likely increased when there is a range of salinities among pools.     

稻田节肢动物群落物种丰富度及多样性的研究(英文)

本文根据田间调查的资料和群落多样性指数的测定,比较了不同稻田和水稻不同生育期节肢动物群落物种丰富度及多样性。田间调查于1994年在福建省福州市郊区选择3种具有代表性的水稻种植区进行,在此基础上,作者运用Shannon－Wiener（1949）的平均信息（H）、Hurlbert（1971）的种间相遇机率（PIE）和Pielou（1966）的均匀度（E）指数来测定和分析稻田生态系统中节肢动物群落的丰富度及多样性。结果表明,由于受到稻田生境中各种环境因素及水稻不同生育期营养状况的影响,稻田节肢动物群落的丰富度及多样性不仅因田而异,而且随着水稻的生长发育过程有较大的波动。作者认为,稻田节肢动物群落丰富度及多样性的研究结果,可为水稻害虫的预测预报和综合治理提供重要的科学依据。文中还就群落丰富度及多样性的测定方法问题进行了讨论。     

高寒草甸不同草地群落物种多样性与生产力关系研究

生态系统的结构和功能、生物多样性与生产力的关系问题是近年来群落生态学中研究的中心问题,其中,生态系统生产力水平是其功能的重要表现形式,用4种不同草地类型探讨自然群落的物种多样性与生产力关系.结果表明,矮嵩草草甸、小嵩草草甸和金露梅灌丛群落中物种多样性与生产力的关系呈线性增加关系,藏嵩草沼泽化草甸群落中线性增加关系不显著,这表明群落生产力除受物种多样性的影响外,也受物种本身特征和环境资源的影响.不同的环境资源和环境异质性是形成群落结构特征、物种多样性分布格局差异的主要原因之一.     

大兴安岭绰纳河保护区植物多样性特征

探究林分结构、立地条件、保护强度与植物多样性之间存在的耦合关系,有助于提升保护区植物多样性保护效果。基于此,该研究选择大兴安岭绰纳河国家级自然保护区森林群落作为研究对象,调查乔木层、灌木层、草本层植物多样性和林分结构特征,并采集土壤样品测定土壤理化性质。利用频率分布、冗余排序与方差分解分析等方法,揭示该区域植物多样性特征及其与影响因素间的耦合关系。结果表明：（1）绰纳河保护区乔木层主要树种为落叶松（Larix gmelinii）,相对多度为64.35%,其次为白桦（Betula platyphylla）;灌木以越橘（Vaccinium vitis-idaea）占比最高,达到72.70%;草本共记录77种,其中羊须草（Carex callitrichos）占比最大（23.72%）。（2）乔、灌、草丰富度与多样性指数由大到小排序依次为草本层、乔木层、灌木层,均匀度指数以灌木层最高。（3）方差分解分析和冗余分析结果表明,林分结构的独立效应对植物多样性变化解释量最大;草本层盖度、灌木密度、乔木树高和土壤容重与植物多样性变化关系最为紧密。通过调整林分结构来提升植物多样性是简单而又可靠的途径,上述结果为大兴安岭地区林分管理提供了数据支撑。     

特殊生境中丛枝菌根真菌多样性

丛枝菌根真菌(AMF)是生态系统的重要组分之一,不仅具有丰富的遗传、物种和功能多样性,而且还具有生态系统多样性,即该真菌的分布与栖息生境复杂多样.AMF侵染植物根系形成菌根,营专性活体共生营养,生态适应性强,除了森林、草原和农田生态系统外,还广泛分布于保护地、盐碱地、矿区污染地、石化与农药污染地、荒漠地、干旱地、湿地、沼泽地、火山地、高原、低温与极地等植物多样性匮乏的特殊生境,形成独特的群落结构,发挥着不可替代的生理生态功能.本文总结了上述生境中AMF物种多样性与菌根发育特点,旨在为进一步开展这些特殊生境和极端环境下的AMF研究提供基本信息.     

Coral and sea urchin assemblage structure and interrelationships in Kenyan reef lagoons

Patterns of hard coral and sea urchin assemblage structure (species richness, diversity, and abundance) were studied in Kenyan coral reef lagoons which experienced different types of human resource use. Two protected reefs (Malindi and Watamu Marine National Parks) were protected from fishing and coral collection, but exposed to heavy tourist use. One reef (Mombasa MNP) received protection from fishermen for one year and was exploited for fish and corals prior to protection and was defined as a transitional reef. Three reefs (Vipingo, Kanamai, and Diani) were unprotected and experienced heavy fishing and some coral collection. Protected and unprotected reefs were distinct in terms of their assemblage structure with the transitional reef grouping with unprotected reefs based on relative and absolute abundance of coral genera. Protected reefs had slightly higher (p<0.01) coral cover (23.6 ± 8.3 % ± S.D.) than unprotected reefs (16.7 ± 8.5), but the transitional reef had the highest coral cover (30.8 ± 6.4) which increased by 250% since measured in 1987: largely attributable to a large increase inPorites nigrescens cover. Protected reefs had higher coral species richness and diversity and a greater relative abundance ofAcropora, Montipora andGalaxea than unprotected reefs. The transitional reef had high species richness, but lower diversity due to the high dominance ofPorites. Sea urchins showed the opposite pattern with highest diversity in most unprotected reefs. Coral cover, species richness, and diversity were negatively associated with sea urchin abundance, but the relative abundance ofPorites increased with sea urchin abundance to the point wherePorites composed >90% of the coral cover at sites with the highest sea urchin abundance. Effects of coral overcollection was only likely for the genusAcropora (staghorn corals). A combination of direct and indirect effects of human resource use may reduce diversity, species richness, and abundance of corals while increasing the absolute abundance of sea urchins and the relative cover ofPorites.     

烟地节肢动物群落研究

本文根据田间系统调查所获材料对烟地节肢动物群落的动态进行分析。已鉴定出的种类分属于昆虫、蜘蛛、螨类及多足纲等类群共７９种。其中植食性昆虫以蚜虫为优势种·捕食性天敌以蜘蛛类群的拟环纹狼蛛、拟水狼蛛、草间小黑蛛及食虫瘤胸蛛为优势种,寄生性无敌种类单一,以烟蚜茧蜂为主。在烟草的不同生育期,物种丰富度、多样性指数、均匀性指数及个体密度都有一定程度的差异,存在从烟苗期到成熟期上升的趋势。杀虫剂的使用与烟地节肢动物群落的结构与动态有较密切的关系。     

深圳梧桐山风景区昆虫资源调查及群落结构分析

2012年7月-2013年7月,对深圳梧桐山风景区昆虫资源进行系统调查,并对其群落结构进行分析。期间共采集昆虫标本2934号,鉴定出166种,隶属17目98科。通过对不同生境昆虫物种丰富度和多样性指数统计分析得出,亚热带常绿阔叶林昆虫物种多样性指数最高,为3.29;南亚热带常绿灌丛昆虫多样性指数最低,为1.88。各种生境昆虫物种多样性指数从大到小排列为:亚热带常绿阔叶林南亚热带针阔叶混交林南亚热带人工常绿阔叶林南亚热带常绿灌丛。不同生境昆虫群落相似性系数在0.0889-0.2690之间,随着植被构成和环境小气候的差别越大相似性系数越小,说明梧桐山风景区各个生境之间昆虫群落具有一定的独立性。通过对不同垂直地带昆虫物种多样性指数统计分析得出,海拔介于300-600 m地带昆虫物种多样性指数最高,为3.30,海拔900 m以上地带昆虫多样性指数最低,为1.06。不同垂直地带昆虫多样性指数从大到小排列顺序为:海拔300-600 m海拔600-900 m海拔100-300 m海拔900 m以上。     

环境梯度下蒙古栎群落的物种多样性特征

通过样地法研究了东北地区处于不同经度、纬度和海拔的 13个地点蒙古栎群落的物种丰富度、Gini指数、PIE指数、Shannon指数和 Pielou指数 ,利用相关和回归的统计方法分析了不同地点物种的丰富度指数、Simpson多样性指数和 Shannon多样性指数与各地所处的经度、纬度和海拔的关系。结果发现 :不仅不同地点 (较大尺度 )的物种丰富度和多样性指数均有差异 ,即使在相同的地点 (较小尺度 ) ,物种丰富度及多样性指数也有差异 ,有时还具有很大的差异 ,呈现空间异质性分布的特征 ;因为影响这些多样性指数的环境因子更加复杂 ,不仅受经度、纬度和海拔的影响 ,也受地形、群落的年龄、干扰史等多种生态因子影响。不同地点的物种丰富度与海拔和纬度都具有明显的相关性 (p<0 .0 5 ) ,物种丰富度随海拔和纬度的升高而降低 ,依据显著度的大小可以推测物种丰富度与海拔的相关性比与纬度的相关性更密切 ;蒙古栎群落不同类群的植物种的丰富度具有不同的分布格局 ,木本植物的丰富度与当地纬度具有明显的相关性 (p<0 .0 5 ) ,而与所在地的海拔没有显著的关系 (p>0 .0 5 ) ,而草本植物受海拔的影响更显著 (p<0 .0 5 ) ,而与纬度之间没有显著的关系 (p>0 .0 5 )。群落的 Gini指数、PIE指数、Shannon指数和Pielou指数未发现与海     

青藏高原高寒灌丛植被对长期放牧强度试验的响应特征

在青藏高原中国科学院海北高寒草甸生态系统定位研究站对金露梅高寒灌丛草场植被开展了长期不同放牧强度试验,分别在短期(4年)、中期(11年)和长期(18年)放牧阶段研究不同放牧干扰强度对草地植物物种多样性、群落结构、地上生物量和草场质量的影响.研究表明,在不同放牧阶段,随着放牧强度增加植物群落的高度和盖度都降低.在中期放牧干扰阶段,物种多样性数和均匀度指数随着放牧强度增加呈现典型的单峰曲线模式;在长期放牧干扰阶段,随着放牧强度增加,占优势地位的灌木和禾草被典型杂类草替代,其中的重度放牧干扰简化了高寒灌丛植被群落结构,减少了地上现存生物量,特别是可食优良牧草生物量.植被对放牧的响应除了与放牧强度和放牧时间阶段密切相关外,还与该地区水热条件的变化有一定的相关性.针对长期放牧干扰的反应特性可将金露梅灌丛草场中植物划分为增加型、敏感型、忍耐型和无反应型4种类型.除了丰富度指数、多样性指数和均匀度指数外,其它一些特征参数并不支持著名的中度干扰假说.本研究发现,长期重度放牧促进了青藏高原高寒草地退化,适度放牧有利于高寒灌丛草场的生物多样性保护和牧草利用;\"取半留半\"的放牧原则在青藏高原草场放牧管理实践中值得推荐,它将有利于防止草场退化,提高牧草利用率和维持较高的生物多样性.