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黑龙江省东部森林群落β多样性的研究 总被引：5，自引：0，他引：5
以连续带指数和集合环境梯度作为植物群落演替动态和环境质量的定量指标,探讨了黑龙江省东部森林群落β多样性随环境梯度和演替动态的变化规律．结果表明,森林群落中植物种的β多样性βＺ和昆虫种的β多样性βＫ都随环境梯度的增加而升高,即随着环境质量升高群落间物种更替速率降低,且βＫ的变化滞后于βＺ．βＺ和βＫ与连续带指数（ＣＩ）呈非线性相关,在演替初期群落间物种更替速率较高,在演替中后期群落间物种的更替速率最小．βＫ曲线的峰值出现滞后于βＺ曲线,说明森林昆虫群落多样性变化对植物群落多样性变化的依赖性 相似文献
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以连续带指数和集合环境梯度作为植物群落演替动态和环境质量的定量指标,探讨了黑龙江省东部森林群落β多样性随环境梯度和演替动态的变化规律。结果表明,森林群落中植物种的β多样性βZ和昆虫种的β多样性βK都随环境梯度的增加而升高,即随着环境质量升高群落间物种更替速率降低,且βK的变化滞后于βZ.βZ和βK与连续带指数(CI)呈非线性相关,在演替初期群落间物种更替速率较高,在演替中后期群落间物种的更替速率最小。βK曲线的峰值出现滞后于βZ曲线,说明森林昆虫群落多样性变化对植物群落多样性变化的依赖性. 相似文献
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长白山北坡森林群落结构组成及其海拔变化 总被引：10，自引：2，他引：10
对长白山北坡海拔700～1900m的13个森林群落进行了群落组成、结构随海拔上升变化情况的研究。结果表明,随着海拔的升高,群落的建群种组成、层次结构等,都表现出由复杂多样逐渐向简单单一过渡的变化趋势,从700m至1700m,针叶树所占的比例随海拔的升高呈明显的增加趋势,阔叶树比例随之减少,到林线时针阔叶树种均急剧减少,沿海拔梯度存在明显的树种更替现象。从群落的平均胸径及胸高断面积和可知。最大值出现于900～1100m及1600m,这2个海拔段正是不同森林群落类型间的过渡区。除海拔1800m的岳桦林之外,其它群落径级结构都呈倒J形分布,即各径级树木中,更新幼苗、幼树在数量上占绝对优势,随着胸径的增大,立木株数逐渐减少,这种径级结构表明,长白山北坡各海拔群落更新良好,群落处于稳定的发展状态。 相似文献
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采用丰富度指数、物种多样性指数和均匀度指数对山西历山自然保护区猪尾沟森林群落多样性进行研究。结果表明 :1 )同一群落内 ,多样性指数存在一定的波动范围 ;不同群落间 ,物种多样性也存在差异 ,但其并不一定具有统计学意义。由此表明 ,群落之间存在差异 ,同时也存在着连续性。 2 )海拔高度是决定本区多样性分布格局的主导因子 ,随着群落分布海拔高度的增加 ,多样性呈一致的上升趋势 ,即多样性与海拔呈正相关关系。 3)群落物种多样性对海拔的敏感性由大到小的次序为草本层 >乔木层 >灌木层 ,其中乔木层的丰富度指数、草本层均匀度指数与海拔有着极显著的正相关关系 ,而乔木层的多样性指数、草本层的丰富度指数与海拔有着极显著的负相关关系 ,灌木层的多样性与海拔没有显著的相关性。 4)群落中不同结构、不同层次对群落总体多样性的贡献是不同的 ,两种测定方法所产生的总体多样性之间呈显著相关关系 ,表明给定加权参数的测定方法没有影响客观生态意义的反映 ,同时也更好地反映出群落结构对于群落多样性的功能差异 相似文献
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幕阜山地处中亚热带-北亚热带过渡地带,物种资源丰富.通过对其典型样地的调查,分别采用Shannon-Wiener指数、Simpson指数和Pielou均匀度指数作为测度指标,研究了幕阜山地区森林群落结构及其物种多样性特征.结果表明,该地区主要有21个森林群落类型.其中常绿阔叶林中,物种丰富度指数与多样性指数在群落梯度上的总体趋势均为灌木层相对高于乔木层,乔木层相对高于草本层;在落叶阔叶林中,其丰富度指数的趋势为灌木层＞草本层和乔木层,而在草本层与乔木层间是波动的,多样性指数的趋势为灌木层＞草本层＞乔木层;在针叶林中,物种丰富度、多样性指数表现的总趋势基本一致,即灌木层的丰富度相对较高,其次为草本层,乔木层的相对较小.在其他群落类型中,多样性指数、均匀度指数在乔木层、灌木层和草本层则表现出多样化的趋势;另外,从总体上看,各种指数在海拔梯度上并未表现出明显的规律性. 相似文献
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对南山区5个主要天然森林群落(铁榄群落、鼠刺 降真香群落、鸭脚木群落、假苹婆群落、水翁 假苹婆群落)的组成结构及物种多样性进行分析,并与相邻的香港地区地带性森林群落(黄桐群落)作比较。结果表明,依照亚热带及南亚热带森林群落演替规律,南山区天然林处于不同的演替发育阶段：铁榄群落处于演替第3阶段;鼠刺 降真香群落处于第4阶段;其它3个群落处于第5阶段,均未达到稳定的顶极群落阶段。随着铁榄群落、鼠刺 降真香群落、鸭脚木群落、假苹婆群落、水翁 假苹婆群落这个演替序列,物种丰富度的变化规律是：先逐渐上升,到达一个峰值,再缓慢下降。Shannon-Wiener指数和Pielous均匀度指数的变化规律与物种丰富度相同,Simpson指数变化曲线与这些指数相反。但这些指数反映的结果是一致的。综合多个指数分析,鸭脚木群落物种多样性最大,即当群落中阳生性树种与中生性树种优势度相差不大时。群落具有最大的物种多样性。多样性比较结果显示,南山森林群落物种多样性大大低于香港黄桐群落。5个群落的Shannon—Wiener指数在2．04～2．953之间,明显低于黄桐群落,其Shannon—Wiener指数为4．74;Simpson指数0．1～0．268,黄桐群落为0．05;Pielous均匀度指数64．2％～74％,黄桐群落为79％。南山森林群落物种多样性水平低下的状况与长期的人类干扰有关,必须尽快采取“封山育林”等相应措施来促进群落的保护和恢复。 相似文献
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浙江仙居俞坑森林群落物种多样性研究 总被引：4，自引：0，他引：4
分别采用物种丰富度、物种多样性指数和群落均匀度指标对浙江省仙居县俞坑森林群落的物种多样性进行测定和分析。结果表明：本木植物的物种多样性以生境优越的常绿阔叶林为高,木本植物的物种丰富度、物种多样性指数明显大于草本植物。在群落垂直结构中,木本植物等2层的物种丰富度、物种多样性指数均显著大于第1层。物种丰富度以木本第3层最大,草本层最小;而物种多样性指数、群落均匀度则以木本第2层最大、草本层最小。木本植物各层次、草本层的物种多样性各项指标在群落各样地间均有一定的差异。 相似文献
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物种多样性格局与所选择的尺度密切相关,用加性分配法分析柴松(Pinus tabulaeformis f.shekannesis)群落乔木、灌木和草本层在样方、坡位和坡面3种尺度的物种多样性分配关系,结果表明:1)以物种丰富度为指标时,坡面尺度对区域多样性贡献最大,说明在区域范围内坡面是物种组成和维持的关键尺度;而以Shannon和Simpson多样性为指标时,最大多样性分配在样方内,这是由于这2个指数不仅考虑了物种数,还考虑了样方内多度以及常见种和稀有种的影响和作用;2)以Shannon多样性为指标时,样方间、坡位间和坡面间尺度的β多样性对区域多样性贡献的百分比都大于以Simpson多样性为指标时的百分比,这主要是由稀有种在各尺度间的分布格局所决定的;3)样方间、坡位间和坡面间尺度的β多样性大小顺序各不相同,这与群落乔木层、灌木层和草本层的物种组成和分布情况以及不同尺度间环境异质性有密切关系。 相似文献
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闽北地区森林群落物种多样性的测定 总被引：2，自引：0，他引：2
采用8个物种多样性指数对闽北地区的8个森林群落类型物种多样性进行测定,并选用4个种一多度关系模型(对数正态分布、Weibull分布、对数级数分布、生态位优先占领模型)分析其物种-多度关系,把多样性指数与对数正态分布、Weibull分布和生态位优先占领模型的有关参数进行线性回归,以分析多度模型参数描述物种多样性的可行性。结果表明：(1)多数物种多样性指数对群落的测度是一致的,(2)对数正态分布、Weibull分布和生态位优先占领模型对8个群落的物种多度拟合效果很好;(3)对数正态分布、Weibull分布和生态位优先占领模型有关模型参数与部分物种多样性指数的线性关系达显著或极显著水平。通过闽北地区8个类型森林群落物种多样性指数测定,使生物多样性较准确地数量化,同时还说明采用改进单纯形法进行非线性分布函数的拟合是简单有效的,可推广应用。 相似文献
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Miquel De Cáceres Pierre Legendre Renato Valencia Min Cao Li‐Wan Chang George Chuyong Richard Condit Zhanqing Hao Chang‐Fu Hsieh Stephen Hubbell David Kenfack Keping Ma Xiangcheng Mi Md. Nur Supardi Noor Abdul Rahman Kassim Haibao Ren Sheng‐Hsin Su I‐Fang Sun Duncan Thomas Wanhui Ye Fangliang He 《Global Ecology and Biogeography》2012,21(12):1191-1202
Aims With the aim of understanding why some of the world's forests exhibit higher tree beta diversity values than others, we asked: (1) what is the contribution of environmentally related variation versus pure spatial and local stochastic variation to tree beta diversity assessed at the forest plot scale; (2) at what resolution are these beta‐diversity components more apparent; and (3) what determines the variation in tree beta diversity observed across regions/continents? Location World‐wide. Methods We compiled an unprecedented data set of 10 large‐scale stem‐mapping forest plots differing in latitude, tree species richness and topographic variability. We assessed the tree beta diversity found within each forest plot separately. The non‐directional variation in tree species composition among cells of the plot was our measure of beta diversity. We compared the beta diversity of each plot with the value expected under a null model. We also apportioned the beta diversity into four components: pure topographic, spatially structured topographic, pure spatial and unexplained. We used linear mixed models to interpret the variation of beta diversity values across the plots. Results Total tree beta diversity within a forest plot decreased with increasing cell size, and increased with tree species richness and the amount of topographic variability of the plot. The topography‐related component of beta diversity was correlated with the amount of topographic variability but was unrelated to its species richness. The unexplained variation was correlated with the beta diversity expected under the null model and with species richness. Main conclusions Because different components of beta diversity have different determinants, comparisons of tree beta diversity across regions should quantify not only overall variation in species composition but also its components. Global‐scale patterns in tree beta diversity are largely coupled with changes in gamma richness due to the relationship between the latter and the variation generated by local stochastic assembly processes. 相似文献
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S. R. Floeter† C. E. L. Ferreira‡ A. Dominici&#;Arosemena§ I. R. Zalmon 《Journal of fish biology》2004,64(6):1680-1699
Trophic strategies and spatial use habits were investigated in reef fish communities. The results supported the hypothesis of differential use of food resources among tropical and higher latitude reef fishes, i.e . the number of species and relative abundance of fishes relying on relatively low‐quality food significantly decreased from tropical to temperate latitudes. The species : genus ratio of low‐quality food consumers increased toward the tropics, and was higher than the overall ratio considering all fishes in the assemblages. This supports the view that higher speciation rates occurred among this guild of fishes in warm waters. It was also demonstrated that density of herbivorous fishes (the dominant group relying on low‐quality food resources) in the western Atlantic decreased from tropical to temperate latitudes. Spatial use and mobility varied with latitude and consequently reef type and complexity. Fishes with small‐size home ranges predominated on tropical coral reefs. 相似文献
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Werner Ulrich Andres Baselga Buntarou Kusumoto Takayuki Shiono Hanna Tuomisto Yasuhiro Kubota 《Global Ecology and Biogeography》2017,26(1):1-5
Understanding the structure of and spatial variability in the species composition of ecological communities is at the heart of biogeography. In particular, there has been recent controversy about possible latitudinal trends in compositional heterogeneity across localities (β‐diversity). A gradient in the size of the regional species pool alone can be expected to impose a parallel gradient on β‐diversity, but whether β‐diversity also varies independently of the size of the species pool remains unclear. A recently suggested methodological approach to correct latitudinal β‐diversity gradients for the species pool effect is based on randomization null models that remove the effects of gradients in α‐ and γ‐diversity on β‐diversity. However, the randomization process imposes constraints on the variability of α‐diversity, which in turn force γ‐ and β‐diversity to become interdependent, such that any change in one is mirrored in the other. We argue that simple null model approaches are inadequate to discern whether correlations between α‐, β‐ and γ‐diversity reflect processes of ecological interest or merely differences in the size of the species pool among localities. We demonstrate that this kind of Narcissus effect may also apply to other metrics of spatial or phylogenetic species distribution. We highlight that Narcissus effects may lead to artificially high rejection rates for the focal pattern (Type II errors) and caution that these errors have not received sufficient attention in the ecological literature. 相似文献
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Insect herbivory is thought to favour carbon allocation to storage in juveniles of shade‐tolerant trees. This argument assumes that insect herbivory in the understorey is sufficiently intense as to select for storage; however, understoreys might be less attractive to insect herbivores than canopy gaps, because of low resource availability and – at temperate latitudes – low temperatures. Although empirical studies show that shade‐tolerant species in tropical forests do allocate more photosynthate to storage than their light‐demanding associates, the same pattern has not been consistently observed in temperate forests. Does this reflect a latitudinal trend in the relative activity of insect herbivory in gap versus understorey environments? To date there has been no global review of the effect of light environment on insect herbivory in forests. We postulated that if temperature is the primary factor limiting insect herbivory, the effect of gaps on rates of insect herbivory should be more evident in temperate than in tropical forests; due to low growing season temperatures in the oceanic temperate forests of the Southern Hemisphere, the effect of gaps on insect herbivory rates should in turn be stronger there than in the more continental temperate climates of the Northern Hemisphere. We examined global patterns of insect herbivory in gaps versus understories through meta‐analysis of 87 conspecific comparisons of leaf damage in contrasting light environments. Overall, insect herbivory in gaps was significantly higher than in the understorey; insect herbivory was 50% higher in gaps than in understoreys of tropical forests but did not differ significantly between gaps and understories in temperate forests of either hemisphere. Results are consistent with the idea that low resource availability – and not temperature – limits insect herbivore activity in forest understoreys, especially in the tropics, and suggest the selective influence of insect herbivory on late‐successional tree species may have been over‐estimated. 相似文献
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Tia L. Harrison;Zoe A. Parshuram;Megan E. Frederickson;John R. Stinchcombe; 《Molecular ecology》2024,33(1):e17191
Mutualism is thought to be more prevalent in the tropics than temperate zones and may therefore play an important role in generating and maintaining high species richness found at lower latitudes. However, results on the impact of mutualism on latitudinal diversity gradients are mixed, and few empirical studies sample both temperate and tropical regions. We investigated whether a latitudinal diversity gradient exists in the symbiotic microbial community associated with the legume Chamaecrista nictitans. We sampled bacteria DNA from nodules and the surrounding soil of plant roots across a latitudinal gradient (38.64–8.68 °N). Using 16S rRNA sequence data, we identified many non-rhizobial species within C. nictitans nodules that cannot form nodules or fix nitrogen. Species richness increased towards lower latitudes in the non-rhizobial portion of the nodule community but not in the rhizobial community. The microbe community in the soil did not effectively predict the non-rhizobia community inside nodules, indicating that host selection is important for structuring non-rhizobia communities in nodules. We next factorially manipulated the presence of three non-rhizobia strains in greenhouse experiments and found that co-inoculations of non-rhizobia strains with rhizobia had a marginal effect on nodule number and no effect on plant growth. Our results suggest that these non-rhizobia bacteria are likely commensals—species that benefit from associating with a host but are neutral for host fitness. Overall, our study suggests that temperate C. nictitans plants are more selective in their associations with the non-rhizobia community, potentially due to differences in soil nitrogen across latitude. 相似文献
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- Understanding the role of environmental filtering and spatial processes along environmental gradients in assembling and maintaining aquatic communities in rare habitats is crucial for land management and biological conservation. We investigated the relative roles of environmental and spatial factors influencing beta (β) diversity of aquatic macroinvertebrate assemblages in 36 interdunal wetlands from five freshwater sand dune areas across two ecoregions spanning the latitudinal gradient of Lake Michigan. We hypothesised that aquatic macroinvertebrate diversity and composition would vary along the coastline because of an underlying environmental gradient. We predicted high species replacement correlated with environmental (local and regional) conditions and increasing species diversity with decreasing latitude.
- We calculated sample completeness, obtained diversity estimates based on Hill numbers and used abundance-based β partitioning and multivariate analysis to examine β diversity, and its replacement and nestedness components in relation to local and regional predictors.
- Despite a short latitudinal gradient, we detected a significant increase in species richness with decreasing latitude, underpinned by a strong temperature and precipitation gradient. Species replacement (balanced variation in abundance) was high at all spatial scales (wetland, dune area, ecoregion and coastline), and correlated with local and regional environmental variables.
- Community dissimilarity showed no marked increase with spatial extent, which suggests a system where local-scale environmental filtering prevents dispersal driven homogenisation. Both local and bioclimatic factors were correlated with aquatic macroinvertebrate dissimilarity, but local factors played a larger role.
- This study simultaneously examined the response of alpha and β diversity to geographical and environmental variables. Our results indicate that macroinvertebrates respond to abiotic factors by tracking suitable environmental conditions among locally variable interdunal wetlands. Thus, high dispersal along the coastline conveys resiliency to a hydrologically dynamic wetland system, which allows aquatic macroinvertebrates to contribute an integral portion of sand dune biodiversity within the Laurentian Great Lakes region. The high species turnover found suggests that conservation strategies should consider coastline connectivity among dune areas to maintain freshwater biodiversity.
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Shallow subtidal macroalgal communities in the North-eastern Atlantic archipelagos (Azores, Madeira, Canaries and Cape Verde) were studied in order to identify their spatial organization patterns and the main drivers of change. Fifteen islands and 145 sites across 15º of latitude and 2850 km were sampled. We found high spatial variability across the scales considered (archipelago, island and site). The structure of macroalgal communities differed among archipelagos, except between Madeira and the Canaries, which were similar. Across a latitudinal gradient, macroalgal communities in the Azores were clearly separated from the other archipelagos; communities in Madeira and the Canaries occupied an intermediate position, while those in Cape Verde appeared at the opposite end of the gradient. In the Azores, species with warm-temperate affinities dominated communities. Cape Verde communities were, in contrast, dominated by tropical taxa, whereas in the subtropical Canaries and Madeira there was a mixture of species with colder and warmer affinities. Apart from crustose coralline algae, the Dictyotales were the group with greatest cover; larger and longer-lived species were progressively replaced by short-lived species along a latitudinal gradient from north to south. The perennial species Zonaria tournefortii dominated the sea-bottom in the Azores, the semi-perennial Lophophora variegata in the Canaries, the filamentous algae in Madeira and the ephemeral Dictyota dichotoma in Cape Verde. We hypothesized that the differences among archipelagos could be explained by synergies between temperature and herbivory, which increased in diversity southwards, especially in Cape Verde. This was supported by the predominance of non-crustose macroalgae in the Azores and of crustose macroalgae in Cape Verde, as would be predicted from the greater herbivore activity. At the scale of islands and sites, the same set of environmental variables drove differences in macroalgal community structure across all the Macaronesian archipelagos. 相似文献