天童森林植被的群落稳定性与物种多样性关系的研究

本文依据天童森林群落样地的数据,分析了群落稳定性与物种多样性的关系。结果表明不能单纯以物种多样性的高低来判断某具体群落的稳定性,使用群落各层次的物种多样性指数和群落优势种群的年龄结构来衡量群落的稳定性较为合适     

群落生态学的中性理论

生物多样性的分布格局和维持机制一直是群落生态学研究的核心问题,其中的关键是物种的共存机制。长期以来,生态位分化的思想在这一研究领域占据着主导地位。然而这一理论在解释热带雨林很高的物种多样性时遇到了困难。而以Hubbell为代表提出的群落中性漂变理论则假定在同一营养级物种构成的群落中不同物种的不同个体在生态学上可看成是完全等同的;物种的多度随机游走,群落中的物种数取决于物种灭绝和物种迁入/新物种形成之间的动态平衡。在这一假定之下,该理论预言了两种统计分布。一种是集合群落在点突变形成新物种的模式下其各个物种相对多度服从对数级数分布,而受扩散限制的局域群落以及按照随机分裂为新物种模式形成的集合群落则服从零和多项式分布。与生态位理论相反,中性理论不以种间生态位差异作为研究群落结构的出发点,而是以物种间在个体水平上的对等性作为前提。该理论第一次从基本生态学过程(出生、死亡、迁移、物种分化)出发,给出了群落物种多度分布的机理性解释,同时其预测的物种多度分布格局在实际群落中也得到了广泛的印证。因此,中性理论自诞生以来便在生态学界引发了极大的反响,也包括一些反对的声音。该文重点综述了关于中性理论的假设、预测和物种形成模式等方面的最新研究进展,包括中性理论本身的发展、关于中性理论的假设和预测的合理性检验以及在集合群落尺度上物种分化模式的讨论;并指出未来发展方向可能是在生态位理论和中性理论之间架起一座桥梁,同时发展包含随机性的群落生态位模型,以及允许种间差异的近中性模型。     

光皮桦天然林群落结构及物种多样性分析

对福建省光皮桦（Betula luminifera H．Winkl）天然林群落结构和物种多样性进行了调查分析。结果表明,光皮桦天然林群落的物种多样性丰富,与光皮桦混生的植物种类有46科78属117种。9个光皮桦天然林群落乔木层中,武平县梁野山自然保护区的Simpson多样性指数最高,邵武卫闽的最低。较原生的森林群落中,以壳斗科植物为基本建群种,物种多样性较丰富,光皮桦重要值较低。在原生森林遭到破坏后的演替过程中,光皮桦重要值增高,成为落叶阔叶林类型之一。光皮桦天然林渐危的主要原因是人为破坏,应加强现有天然林资源的保护、注重遗传资源的收集和保存以及人工林资源的培育。     

山西庞泉沟自然保护区森林群落物种多样性

在对山西庞泉沟自然保护区森林群落进行数量分类的基础上,运用丰富度指数、物种多样性指数和均匀度指数对保护区内森林群落的物种多样性进行了研究,并对森林群落各层片之间的物种多样性进行了相关性分析.结果表明:(1)森林群落15个群丛的丰富度指数、物种多样性指数和均匀度指数能很好地反映各群丛多样性变化规律.(2)各群丛的丰富度指数和物种多样性指数总体上呈现草本层＞灌木层＞乔木层,草本层的均匀度最小,大多数森林群落乔木层和灌木层的均匀度比较接近.(3) Patrick指数、Simpson指数、Shannon指数以及Pielou指数和Alatalo指数之间表现极显著差异性(P＜0.01).(4)群丛3(华北落叶松-土庄绣线菊+美蔷薇-东方草莓群丛)灌木层和草本层之间呈显著负相关(r=-0.643,P＜0.05);群丛8(白桦+山杨-灰栒子+美蔷薇-中亚苔草群丛)乔木层和灌木层呈显著负相关(r=-0.458,P＜0.05),灌木层和草本层则呈显著正相关(r=0.404,P＜0.05);群丛11(白杄-中亚苔草+烟管头草)的乔木层和草本层之间呈显著负相关(r=-0.949,P＜0.05).     

地带性森林群落物种多样性的比较研究

在群落调查以及文献收集的基础上,对暖温带地区、暖温带和亚热带过渡地区、亚热带地区以及热带地区的典型地带笥植被不同群落类型群落多样性进行了分析和研究。结果发现这４类地区物种多样性的变化具有一定的规律性,具体表现在热带地区群落乔木层的物种丰富度和多样性为最高,然后依次是亚热带地区、秦蛉地区和东灵山地区;灌木层的物种丰富度和多样性则以亚热带地区为最高,其次是秦岭地区,热带地区的则仍高于东灵山地区;灌木层     

安徽皇甫山黄檀群落物种多样性初步研究

分析了安徽皇甫山黄檀（Dalbergia hupeana）群落乔木层、灌木层、草本层物种多样性指数,表明群落物种多样性较低.乔木层物种多样性指数最低,灌木层、草本层物种多样性指数较高.黄檀在群落中优势度明显.     

长沙黄花国际机场鸟类群落物种多样性分析

为了获得长沙黄花国际机场鸟击防范工作所需的鸟类基础性资料,从2005年9月~2006年8月,通过对机场地区5种生境类型鸟类群落的调查与监测,记录到鸟类112种,属16目32科。其中46种属东洋界种类、45种属古北界种类、21种属广布种;留鸟46种、夏候鸟25种、冬候鸟29种、旅鸟12种。经RB频率指数测算,鸟类群落的优势种为白头鹎(Pycnonotus sinensis)、乌鸫(Turdus merula)和树麻雀(Passer montanus)。按鸟类生境分布系数划分,广布型的鸟类有44种,是该区鸟类群落组成的主体。鸟类群落的Shannon-Weiner物种多样性指数为1.607,均匀性指数为0.784。     

草坪无脊椎动物群落物种多样性及功能群研究

本文采用扫网和样方法对草坪固定样地无脊椎动物群落进行了调查,根据不同种类的营养情况进行了功能群的划分,并采用物种丰富度、Shannon-Wiener指数、Hulbert种间相遇概率、Pielou均匀度指数等四种多样性指数对群落及功能群的物种多样性进行了测度和分析,结果表明：草坪无脊椎动物功能群组成具有一定的垂直分化;不同植被生长情况下功能群的组成及多样性具有一定的差异,但无明显的规律性;各功能群中,捕食寄生性功能群的多样性最高,而植食性功能群的种类、数量最多,但由于个别种数量的异常,其多样性反而较低,植食性功能群与捕食寄生性功能群在多样性、种类数及数量上呈现一定的互为消长关系。     

石蒜生长对杂草群落组成及物种多样性的影响

通过野外调查,研究了石蒜（Lycoris radiata）对群落杂草组成和物种多样性的影响。结果表明：石蒜的生长能减少群落中物种的种类,降低群落中杂草的密度,并减少商陆（Phytolacca aeinosa）、蹄盖蕨（Athyrium fricellia）及禾本科（Granmeae）几个物种的数量,群落的物种多样性指数降低,群落均匀度提高。群落相似度与没有石蒜分布的群落相比显著降低。说明石蒜改变了杂草的群落结构,有利于限制杂草的发生危害。     

不同强度旅游干扰对黄山松群落物种多样性的影响

研究天柱山国家森林公园不同强度旅游干扰下黄山松群落的物种多样性,用物种丰富度指数S、Simpson指数D、ShannonWiener指数日和Pialou均匀度J比较分析了不同层次物种多样性变化。结果表明：乔木层中,低度干扰下多样性指数较大;其他层次中,中度干扰下多样性指数最高。整个群落分析表明,低度干扰下几种多样性指数分别为38、3．0976、0．9326、0．7515;中度干扰下,多样性指数最高,分别为44、3．2519、0．9421、O．8594,其中灌木层和草本层所起的作用较大;高度干扰下,多样性指数有很大程度的下降,分别为34、3．0095、0．9289、0．7834。利用群落优势度（C）衡量了不同干扰下黄山松群落的稳定性。结果发现中度干扰下的群落稳定性最低。表明中度干扰能一定程度增加群落的物种多样性,但可能会导致群落稳定性降低。     

Neutral theory in community ecology

One of the central goals of community ecology is to understand the forces that maintain species diversity within communities. The traditional niche-assembly theory asserts that species live together in a community only when they differ from one another in resource uses. But this theory has some difficulties in explaining the diversity often observed in specie-rich communities such as tropical forests. As an alternative to the niche theory, Hubbell and other ecologists introduced a neutral model. Hubbell argues that the number of species in a community is controlled by species extinction and immigration or speciation of new species. Assuming that all individuals of all species in a trophically similar com-munity are ecologically equivalent, Hubbell's neutral theory predicts two important statistical distributions. One is the asymptotic log-series distribution for the metacommunities under point mutation speciation, and the other is the zero-sum multinomial distribution for both local communities under dispersal limitation and metacommunities under random fission speciation. Unlike the niche-assembly theory, the neutral theory takes similarity in species and individuals as a starting point for investigating species diversity. Based on the fundamental processes of birth, death, dispersal and spe-ciation, the neutral theory provided the first mechanistic explanation of species abundance distribution commonly observed in natural communities. Since the publication of the neutral theory, there has been much discussion about it, pro and con. In this paper, we summarize recent progress in the assumption, prediction and speciation mode of the neutral theory, including progress in the theory itself, tests about the assumption of the theory, prediction and speciation mode at the metacommunity level. We also suggest that the most important task in the future is to bridge the niche-assembly theory and the neutral theory, and to add species differences to the neutral theory and more stochasticity to the niche theory.     

Neutral theory in community ecology

One of the central goals of community ecology is to understand the forces that maintain species diversity within communities. The traditional niche-assembly theory asserts that species live together in a community only when they differ from one another in resource uses. But this theory has some difficulties in explaining the diversity often observed in specie-rich communities such as tropical forests. As an alternative to the niche theory, Hubbell and other ecologists introduced a neutral model. Hubbell argues that the number of species in a community is controlled by species extinction and immigration or speciation of new species. Assuming that all individuals of all species in a trophically similar community are ecologically equivalent, Hubbell’s neutral theory predicts two important statistical distributions. One is the asymptotic log-series distribution for the metacommunities under point mutation speciation, and the other is the zero-sum multinomial distribution for both local communities under dispersal limitation and metacommunities under random fission speciation. Unlike the niche-assembly theory, the neutral theory takes similarity in species and individuals as a starting point for investigating species diversity. Based on the fundamental processes of birth, death, dispersal and speciation, the neutral theory provided the first mechanistic explanation of species abundance distribution commonly observed in natural communities. Since the publication of the neutral theory, there has been much discussion about it, pro and con. In this paper, we summarize recent progress in the assumption, prediction and speciation mode of the neutral theory, including progress in the theory itself, tests about the assumption of the theory, prediction and speciation mode at the metacommunity level. We also suggest that the most important task in the future is to bridge the niche-assembly theory and the neutral theory, and to add species differences to the neutral theory and more stochasticity to the niche theory. __________ Translated from Journal of Plant Ecology, 2006, 30(5): 868–877 [译自:植物生态学报]     

Neutral community dynamics, the mid-domain effect and spatial patterns in species richness

The mid‐domain effect (MDE) aims to explain spatial patterns in species richness invoking only stochasticity and geometrical constraints. In this paper, we used simulations to show that its main qualitative prediction, a hump‐shaped pattern in species richness, converges to the expectation of a spatially bounded neutral model when communities are linked by short‐distance migration. As these two models can be linked under specific situations, neutral theory may provide a mechanistic population level basis for MDE. This link also allows establishing in which situations MDE patterns are more likely to be found. Also, in this situation, MDE models could be used as a first approximation to understand the role of both stochastic (ecological drift and migration) and deterministic (adaptation to environmental conditions) processes driving the spatial structure of species richness.     

Erosion of community diversity and stability by herbivore removal under warming

Climate change has the potential to influence the persistence of ecological communities by altering their stability properties. One of the major drivers of community stability is species diversity, which is itself expected to be altered by climate change in many systems. The extent to which climatic effects on community stability may be buffered by the influence of species interactions on diversity is, however, poorly understood because of a paucity of studies incorporating interactions between abiotic and biotic factors. Here, I report results of a 10-year field experiment, the past 7 years of which have focused on effects of ongoing warming and herbivore removal on diversity and stability within the plant community, where competitive species interactions are mediated by exploitation through herbivory. Across the entire plant community, stability increased with diversity, but both stability and diversity were reduced by herbivore removal, warming and their interaction. Within the most species-rich functional group in the community, forbs, warming reduced species diversity, and both warming and herbivore removal reduced the strength of the relationship between diversity and stability. Species interactions, such as exploitation, may thus buffer communities against destabilizing influences of climate change, and intact populations of large herbivores, in particular, may prove important in maintaining and promoting plant community diversity and stability in a changing climate.     

鄱阳湖湿地大型底栖无脊椎动物多样性对群落次级生产力及稳定性的影响

理解生物多样性对生态系统功能及稳定性的影响对于制定有效的保护管理策略有重要意义。然而,目前生物多样性与群落生产力、稳定性的关系仍存在争议。在鄱阳湖湿地布设30个采样点,于2019年秋季开展大型底栖无脊椎动物群落野外调查。基于底栖动物群落数据,采用广义加性模型分析物种、谱系、功能多样性对鄱阳湖湿地底栖动物群落次级生产力与稳定性的影响。结果表明:底栖动物群落的次级生产力与反映物种多样性的指数(Simpson多样性指数、Shannon-Wiener多样性指数、Pielou均匀度指数)、分类多样性指数、平均分类差异指数、功能丰富度指数等呈显著的负相关,其中Pielou均匀度指数与次级生产力的相关度最高(r²=0.33)。功能多样性对群落次级生产力的空间分异有最高的解释度(r²=0.75)。P/B值(次级生产力与生物量之比代表群落稳定性)与物种、谱系、功能多样性指数均呈正相关,其中功能丰富度与P/B值的相关度最高(r²=0.22)。反映物种多样性的三个指数总体上对P/B值的空间分异解释度最高(r²=0.37)。谱系多样性与次级生产力、P/B值的相关性相对较弱。生物多样性指数总体分别解释了次级生产力和群落稳定性中81.9%、54.8%的变异。上述研究结果表明,生物多样性与群落生产力、稳定性的关系可能因具体的生物群落而异。研究结果对于鄱阳湖湿地的底栖生物多样性保护有参考价值。     

Shotgun mitogenomics across body size classes in a local assemblage of tropical Diptera: Phylogeny,species diversity and mitochondrial abundance spectrum

Mitochondrial genomes can be assembled readily from shotgun‐sequenced DNA mixtures of mass‐trapped arthropods (“mitochondrial metagenomics”), speeding up the taxonomic characterization. Bulk sequencing was conducted on some 800 individuals of Diptera obtained by canopy fogging of a single tree in Borneo dominated by small (<1.5 mm) individuals. Specimens were split into five body size classes for DNA extraction, to equalize read numbers across specimens and to study how body size, a key ecological trait, interacts with species and phylogenetic diversity. Genome assembly produced 304 orthologous mitochondrial contigs presumed to each represent a different species. The small‐bodied fraction was the by far most species‐rich (187 contigs). Identification of contigs was through phylogenetic analysis together with 56 reference mitogenomes, which placed most of the Bornean community into seven clades of small‐bodied species, indicating phylogenetic conservation of body size. Mapping of shotgun reads against the mitogenomes showed wide ranges of read abundances within each size class. Ranked read abundance plots were largely log‐linear, indicating a uniformly filled abundance spectrum, especially for small‐bodied species. Small‐bodied species differed greatly from other size classes in neutral metacommunity parameters, exhibiting greater levels of immigration, besides greater total community size. We suggest that the established uses of mitochondrial metagenomics for analysis of species and phylogenetic diversity can be extended to parameterize recent theories of community ecology and biodiversity, and by focusing on the number mitochondria, rather than individuals, a new theoretical framework for analysis of mitochondrial abundance spectra can be developed that incorporates metabolic activity approximated by the count of mitochondria.     

Plant diversity and community history shift colonization success from early- to mid-successional species

Aims Functional traits are supposed to play an important role in determining the colonization success of new species into established communities. Short-term experimental studies have documented higher resistance of more diverse grasslands against colonization by new species. However, little is known about which traits colonizers should have to successfully invade diverse plant communities in the longer term and how community history may modify the resistance of diverse communities against colonization.Methods In a grassland biodiversity experiment (Jena Experiment) established with different species richness (SR; 1, 2, 4, 8 and 16) and functional group (FG) number and composition (1 to 4; legumes, grasses, small herbs, tall herbs), we studied colonization of naturally dispersed species in split-plots (i) with different duration of weeding (never weeded, weeded for 3 or 6 years and then un-weeded for 1 year) and (ii) with different duration of colonization (7 years, 4 years and 1 year after cessation of weeding).Important findings Resistance against colonization by new species declined with increased duration of weeding (on average 13, 17 and 22 colonizer species in 1-, 4- and 7-year-old communities, respectively). Communities established at low diversity accumulated more colonizer species with a longer duration of weeding than more diverse communities. Duration of colonization had only small effects on the number of colonizer species. Colonizers with early successional traits, i.e. annual life cycle, reproduction by seeds, small seeds, long-lived seeds and an earlier start of a longer flowering period, were favoured in species-poor newly established experimental plant communities (short duration of weeding) and early after cessation of weeding (short duration of colonization). A change from early- to mid-successional traits, i.e. taller growth, perennial life cycle, vegetative reproduction, characterized colonization at increased plant diversity and in communities with legumes or without grasses. Legume absence/grass presence and increased duration of weeding led to a shift in colonizer strategies from rapid nutrient uptake and cycling (higher specific leaf area) to nutrient retention and symbiotic N 2 fixation. Our study shows that non-random trait spectra of naturally dispersed colonizers encompass trade-offs between different functions (reproduction, persistence, growth) reflected in a change from early- to mid-successional traits at increasing plant diversity, with a longer duration of weeding and a longer time of colonization.     

Experimental evidence that soil heterogeneity enhances plant diversity during community assembly

Aims Environmental heterogeneity is a primary mechanism explaining species coexistence and extant patterns of diversity. Despite strong theoretical support and ample observational evidence, few experimental studies in plant communities have been able to demonstrate a causal link between environmental heterogeneity and plant diversity. This lack of experimental evidence suggests that either fine-scale heterogeneity has weak effects on plant diversity or previous experiments have been unable to effectively manipulate heterogeneity. Here, we utilize a unique soil manipulation to test whether fine-scale soil heterogeneity will increase plant richness through species sorting among experimental patch types.Methods This experiment was conducted in the tallgrass prairie region of south-central Kansas, USA. We utilized the inherent variation found in the vertical soil profile, which varied in both biotic and abiotic characteristics, and redistributed these strata into either homogeneous or heterogeneous spatial arrangements in 2.4×2.4 m plots. After the soil manipulation, 34 native prairie species were sown into all plots. We conducted annual censuses at peak biomass to quantify species composition and plant density by species within the experimental communities.Important findings After 2 years, species richness was significantly higher in heterogeneous relative to homogeneous plots and this pattern was independent of total plant density. In the heterogeneous plots, 13 species had higher establishment in a specific patch type representing one of the three soil strata. Conversely, no species had greater establishment in the mixed stratum, which comprised the homogeneous plots, relative to the heterogeneous strata. These species sorting patterns suggest that fine-scale heterogeneity creates opportunities for plant establishment due to niche differences, which translates into increased plant diversity at the plot scale. Species richness was more strongly related to plant density among patches comprising homogenous plots—where fine-scale heterogeneity was minimized, but weak in heterogeneous plots. This pattern is consistent with the idea that richness–density relationships dominate when neutral processes are important but are weak when niche processes operate. Unlike many previous attempts, our results provide clear, experimental evidence that fine-scale soil heterogeneity increases species richness through species sorting during community assembly.     

Predicting community structure in snakes on Eastern Nearctic islands using ecological neutral theory and phylogenetic methods

Predicting species presence and richness on islands is important for understanding the origins of communities and how likely it is that species will disperse and resist extinction. The equilibrium theory of island biogeography (ETIB) and, as a simple model of sampling abundances, the unified neutral theory of biodiversity (UNTB), predict that in situations where mainland to island migration is high, species-abundance relationships explain the presence of taxa on islands. Thus, more abundant mainland species should have a higher probability of occurring on adjacent islands. In contrast to UNTB, if certain groups have traits that permit them to disperse to islands better than other taxa, then phylogeny may be more predictive of which taxa will occur on islands. Taking surveys of 54 island snake communities in the Eastern Nearctic along with mainland communities that have abundance data for each species, we use phylogenetic assembly methods and UNTB estimates to predict island communities. Species richness is predicted by island area, whereas turnover from the mainland to island communities is random with respect to phylogeny. Community structure appears to be ecologically neutral and abundance on the mainland is the best predictor of presence on islands. With regard to young and proximate islands, where allopatric or cladogenetic speciation is not a factor, we find that simple neutral models following UNTB and ETIB predict the structure of island communities.     

刈割、施肥对高寒草甸物种多样性与生态系统功能关系的影响及群落稳定性机制

植物群落中不同“功能身份”物种的多样性与特定生态系统功能之间具有何种关系及其作用机制尚不明确。通过在高寒矮嵩草(Kobresia humilis)草甸为期5年的刈割(不刈割、留茬3 cm、留茬1 cm)、施肥(施肥、不施肥)和浇水(浇水、不浇水)控制实验, 研究了刈割与土壤资源获得性梯度上不同“功能身份”物种(群落中所有物种、响应物种、作用物种和共有物种)的多样性变化与群落地上净初级生产力和稳定性的关系以及稳定性机制。研究结果显示: 群落中响应物种、作用物种和共有物种数分别占全部物种数的36.6%、18.3%和64.8%, 物种多样性对生态系统功能具有不同的效应, 净初级生产力主要受响应物种和作用物种的多样性变化影响, 而稳定性则主要由共有物种的多样性变化决定; 群落稳定性的维持主要依赖于共有物种的多样性增加, 其作用机制是投资组合效应, 而超产效应和异步性效应对稳定性并无作用; 刈割和施肥对物种多样性、稳定性和净初级生产力具有相反的影响, 前者能增加物种多样性和稳定性, 并降低净初级生产力, 而后者的作用正相反。这与群落中全部物种的多样性变化受刈割影响较大, 而作用物种的多样性变化受资源获得性影响较大有关。上述结果表明高寒草甸生态系统地上净初级生产力主要由少数影响生产力的作用物种的多样性决定, 而稳定性则由大量共有物种的多样性所掌控。投资组合效应是物种多样性导致稳定性的机制。由于群落中不同物种的多样性效应具有分异性, 对于特定的生态系统功能而言, 物种的“功能身份”可能比物种多样性本身更重要, 不加区别地笼统定义物种多样性与生态系统功能的关系可能欠妥。