天目山物种多样性尺度依赖及其与空间格局关系的多重分形

以浙江省天目山国家级自然保护区为例,采用多尺度分析思想,利用多重分形分析方法,研究了不同尺度下物种多样性的变化、空间分布格局以及多样性与空间格局之间的关系。研究主要得到3方面的结论：（1）物种多样性具有尺度依赖性,随着空间尺度的增大,Shannon-Wiener多样性指数Ⅳ增大,Margalef多样性指数足和均匀度指数E减小;（2）多重分形参数αmin。多重分形谱的变化范围SR等能够定量反映物种的空间分布特征,空间大尺度越大,物种越聚集,空间分布越不均匀;（3）物种多样性与空间格局存在线性或幂函数关系。研究表明多重分形分析定量描述物种空间格局是有效性的,多重分形参数与生物多样性之间的定量关系为研究物种空间格局、生态属性与尺度之间的关系奠定了基础。因此,分形结合传统方法,在生物多样性方面的研究将有很大的潜在价值。     

Diversity and Occurrence of Plant-parasitic Nematodes Associated with Golf Course Turfgrasses in North and South Carolina,USA

One hundred and eleven golf courses from 39 counties in the Carolinas were surveyed for plant-parasitic nematodes. Species diversity within habitats was analyzed with five diversity indices including Diversity index (H’), Evenness (J’), Richness (SR), Dominance (λ) and Diversity (H₂). The results revealed a remarkably high diversity of 24 nematode species belonging to 19 genera and 11 families. Of those, 23 species were found in SC, 19 species in NC, and 18 species were detected in both states. Helicotylenchus dihystera, Mesocriconema xenoplax, Hoplolaimus galeatus, Tylenchorhynchus claytoni, Belonolaimus longicaudatus, Meloidogyne graminis and Paratrichodorus minor were the most prevalent and abundant species in golf course turfgrasses in both states. Twelve species were new records of plant parasitic nematodes in turfgrasses in both NC and SC. The results also revealed effects of different habitats on diversity of nematode species in turfgrass ecosystem. H’ and SR values were higher in SC than in NC. H’, J’ and H₂ values were significantly higher in sandy than in clay soil in NC, but no significant differences between sand and clay soil were detected in SC or in pooled data from both states. There were no significant differences for all indices among the management zones (putting green, fairway and tee) in NC. However, in SC and pooled data, H’, SR and H₂ were significantly higher in putting greens than in fairways and tees. Significant differences from different grass species (bermudagrass, creeping bentgrass and zoysiagrass) were detected only in H’, which was significantly higher in zoysiagrass than in bentgrass or bermudagrass in NC. In pooled data, H’ was significantly higher in zoysiagrass samples than in creeping bentgrass samples but was not significantly different from bermudagrass samples.     

Interpreting Ecological Diversity Indices Applied to Terminal Restriction Fragment Length Polymorphism Data: Insights from Simulated Microbial Communities

Ecological diversity indices are frequently applied to molecular profiling methods, such as terminal restriction fragment length polymorphism (T-RFLP), in order to compare diversity among microbial communities. We performed simulations to determine whether diversity indices calculated from T-RFLP profiles could reflect the true diversity of the underlying communities despite potential analytical artifacts. These include multiple taxa generating the same terminal restriction fragment (TRF) and rare TRFs being excluded by a relative abundance (fluorescence) threshold. True community diversity was simulated using the lognormal species abundance distribution. Simulated T-RFLP profiles were generated by assigning each species a TRF size based on an empirical or modeled TRF size distribution. With a typical threshold (1%), the only consistently useful relationship was between Smith and Wilson evenness applied to T-RFLP data (TRF-E_var) and true Shannon diversity (H′), with correlations between 0.71 and 0.81. TRF-H′ and true H′ were well correlated in the simulations using the lowest number of species, but this correlation declined substantially in simulations using greater numbers of species, to the point where TRF-H′ cannot be considered a useful statistic. The relationships between TRF diversity indices and true indices were sensitive to the relative abundance threshold, with greatly improved correlations observed using a 0.1% threshold, which was investigated for comparative purposes but is not possible to consistently achieve with current technology. In general, the use of diversity indices on T-RFLP data provides inaccurate estimates of true diversity in microbial communities (with the possible exception of TRF-E_var). We suggest that, where significant differences in T-RFLP diversity indices were found in previous work, these should be reinterpreted as a reflection of differences in community composition rather than a true difference in community diversity.     

中条山中段木本植物群落植物种多样性分析

采用样方法取样,依据重要值指标运用双向指示种分析(TWINSPAN)法,将山西中条山中段植被群系分成16个群丛。应用丰富度指数（R₁、R₂）、Simpson指数（λ）,Shannon-Weiner指数(H′)和均匀度指数(E₁、E₅)研究了16个群丛的植物种多样性。结果表明：群系植物种多样性指数的大小受立地生境和人为活动的综合影响;森林群落的植物种多样性指数明显高于灌丛群落;群落植物种多样性在空间上的差异不仅决定于物种丰富度指数,更与各物种间的均匀度指数密切相关;进而影响不同层次的物种多样性对群落总体物种多样性的贡献。     

Evaluation of reflectance spectroscopy indices for estimation of chlorophyll content in leaves of a tropical tree species

The effectiveness of eight spectral reflectance indices for estimating chlorophyll (Chl) content in leaves of Eugenia uniflora L., a tropical tree species widely distributed throughout the world and a key species for ecosystem restoration projects, was evaluated. Spectral reflectance indices were tested using sun and shade leaves with a broad variation in leaf mass per area (LMA). Shortly after plants were exposed to chilling temperatures, there was a dramatic visible change in some sun leaves from green to red. Prior to testing Chl-related reflectance indices, the green and red leaves were separated according to the anthocyanin reflectance index (ARI). Slightly green to dark green leaves corresponded to an ARI value less than 0.11 (n = 107), whereas slightly red to red leaves corresponded to an ARI value greater than 0.11 (n = 35). To estimate leaf Chl, two simple reflectance indices (SR₆₈₀ and SR₇₀₅), two normalized difference indices (ND₆₈₀ and ND₇₀₅), two modified reflectance indices (mSR₇₀₅ and mND705), a modified Chl absorption ratio index (mCARI₇₀₅) and an index insensitive to the presence of anthocyanins (CI_re) were evaluated. Good estimates of leaf Chl content were obtained using the reflectance indices tested regardless of the presence of anthocyanins and changes in LMA. Based on the coefficients of determination (r ²) and the root mean square errors (RMS?_c) the best results were obtained with reflectance indices measured at wavelengths of 750 and 705 nm. Considering the performance of the models the best reflectance indices to estimate Chl contents in E. uniflora leaves with a broad variation in LMA and anthocyanin contents was SR₇₀₅ and mCARI₇₀₅.     

Tree diversity in 30-year chronosequences of cool-humid forests

Tree data collected in four inventories of twelve permanent sampling plots during 30 years were analyzed to determine to what extent the abundance of the ubiquitous balsam fir (Abies balsamea) drives tree diversity in mixed stands of Eastern Cape Breton Island, Canada. Dominant deciduous species comprised yellow birch (Betula allegheniensis), sugar maple (Acer saccharum), and American beech (Fagus grandifolia). Tree species richness ranged from 2 to 6. The Shannon–Wiener diversity index indicated that high fir proportion decreased tree species diversity (H’) and structural evenness (J’). The basal area ratio for year 30 over year 1 provided an index of resilience (R) for forest stands subject to natural self-thinning and epidemic insect infestations. There was no significant effect of fir admixture on R since basal area losses due to fir decline were offset within the 30-year period largely by hardwood increases. Stand dynamics were however, structurally stratified due to low R-values for low-diameter trees. The indices H’, J’, and R are recommended for assessing the naturalness and apparent resilience function of tree diversity and large trees in mixed forests of low species richness.     

Species diversity of butterflies in Changbai Mountain in China

Using a modified belt transect method, we investigated the butterfly communities in five different vertical vegetation belts of Changbai Mountain in China from 1992 to 2009; these belts were broadleaf deciduous forest, coniferous–deciduous mixed forest, coniferous forest, erman’s birch forest and alp tundra. We determined the number of species and abundance of butterflies in each belt and in the coniferous–deciduous mixed forest belt, we also compared these parameters among different months. Preston’s lognormal distribution was used to model the species abundance distributions and five indicators (Shannon–Wiener diversity index (H′), Pielou uniformity index (J), Simpson predominance centralization index (C), Margalef abundance index (E) and Jaccard similarity coefficients) were used to analyze the butterfly community diversity. We found four main results. (1) Across all five vertical vegetation belts, 9641 butterflies were collected, belonging to 7 families, 98 genera and 196 species. As altitude increased, the number of butterfly genera and species gradually reduced. There was a relationship between the distribution of dominant species and the total species between each belt and the distribution of vascular plants. (2) The species abundance distribution was successfully modeled as a Preston’s lognormal distribution; the best fit was obtained when α = 0.326, the determinant coefficient of the equation was 0.74798. The species abundance distribution indicates that Changbai Mountain provides a suitable environment for butterflies; there was high species richness and an even distribution of butterfly species. There were few very common and very rare species, with most species having an intermediate abundance. (3) As altitude increased, H′ and E gradually became smaller, while C showed the opposite pattern, and J did not significantly change. The similarity coefficients analysis demonstrated a clear difference among belts; the farther apart any two belts, the smaller the similarity coefficient, indicating less similarity in the butterfly communities. The similarity coefficient between the deciduous forest and the coniferous–deciduous mixed forest belt was the largest (0.651) while that between the deciduous forest and the alp tundra was the smallest (0.141). (4) Comparison of the butterfly species communities among different months in the coniferous–deciduous mixed forest found that H′ and E showed similar directional changes, while the opposite pattern was found with C; the changes in J did not necessarily reflect the actual change in diversity.     

Multifractal analysis of K+ channel activity

The Multifractal version of the Detrended Fluctuation Analysis was used for the study of non-stationary dwell time series of Ca²⁺-activated K⁺ channels (K_Ca channels) in cultured kidney Vero cells and of voltage-dependent K⁺ channels (K_v channels) in mollusc (Lymnaea stagnalis) neurons. The data obtained can briefly be summarized as follows: (i) The generalized fluctuation function F _q (l) strongly depends on the index (order) q; for monofractal time series, such dependence is nonexistent; (ii) The relationship between the scaling exponent τ commonly employed in standard multifractal analysis and q is characterized by two slopes and a transitory region, whereas monofractal processes are characterized by the linear dependence; (iii) The relationship between the singularity spectrum f(h) and the Hurst exponent h is bell-shaped, while in the case of monofractal processes it is represented by a single point f(h) = 1. Random mixing of the time series resulted in the narrowing of the spectrum f(h) and a shift of f(h) towards the value more characteristic of stochastic (monofractal) processes (h ～ 0.5). It is concluded that the activities of both K_Ca channels in kidney Vero cells and of K_V channels in mollusc (Lymnaea stagnalis) neurons can be characterized as multifractal processes.     

Use of 16S rRNA Gene Terminal Restriction Fragment Analysis To Assess the Impact of Solids Retention Time on the Bacterial Diversity of Activated Sludge

Terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes was used to investigate the reproducibility and stability in the bacterial community structure of laboratory-scale sequencing batch bioreactors (SBR) and to assess the impact of solids retention time (SRT) on bacterial diversity. Two experiments were performed. In each experiment two sets of replicate SBRs were operated for a periods of three times the SRT. One set was operated at an SRT of 2 days and another set was operated at an SRT of 8 days. Samples for T-RFLP analysis were collected from the two sets of replicate reactors. HhaI, MspI, and RsaI T-RFLP profiles were analyzed using cluster analysis and diversity statistics. Cluster analysis with Ward's method using Jaccard distance and Hellinger distance showed that the bacterial community structure in both sets of reactors from both experimental runs was dynamic and that replicate reactors were clustered together and evolved similarly from startup. Richness (S), evenness (E), the Shannon-Weaver index (H), and the reciprocal of Simpson's index (1/D) were calculated, and the values were compared between the two sets of reactors. Evenness values were higher for reactors operated at an SRT of 2 days. Statistically significant differences in diversity (H and D) between the two sets of reactors were tested using a randomization procedure, and the results showed that reactors from both experimental runs that were operated at an SRT of 2 days had higher diversity (H and D) at the 5% level. T-RFLP analysis with diversity indices proved to be a powerful tool to analyze changes in the bacterial community diversity in response to changes in the operational parameters of activated-sludge systems.     

Analysis of population genetic structure of ten district populations of the Rostov oblast by means of an extended isonymic method of Barrai and colleagues

Parameters suggested by Barrai et al. (1992), including the random isonymy (I _r), surname diversity (α), migration index (v), and entropy (H) and redundancy (R) of surname distribution have been estimated in ten district populations of the Rostov oblast. Their weighted mean values are the following: I _r = 0.000813, v = 0.048, α = 1334.9, H = 11.30, R = 22.52.     

青海湖湿地鸭科鸟类群落结构

2007 ～2010年每年4～10月,采用直接计数法对青海湖周边6种典型生境包括河口湿地、湖泊、淡水沼泽、淡水泉、岩石湖岸、沙滩中的鸭科鸟类群落进行了调查.共记录到鸭科鸟类9属21种,采用频率指数法确定的优势种有斑头雁( Anser indicus)、赤麻鸭(Tadorna ferruginea)、针尾鸭(Anas a...     

海南三亚滨海雨林、半落叶季雨林到落叶季雨林的植物群落多样性及种间联结研究

为探索三亚沿海地区(自东向西)从滨海雨林过渡到半落叶季雨林、落叶季雨林的物种多样性及种间关系的变化趋势。该文采用植物群落学调查方法对三种植被类型进行群落调查,进一步使用物种丰富度指数(d GL)、Shannon-Wiener指数(H)、Simpson指数(P)和Pielou均匀度指数(E)来表征各植被类型的物种多样性水平,并使用联结系数(AC)、共同出现百分率(PC)及Spearman秩相关系数检验三种方法来表征各植被类型的种间关系。结果表明:(1)从滨海雨林过渡到半落叶季雨林再到落叶季雨林的生态序列变化过程中,森林优势物种组成逐渐由喜湿树种过渡为耐旱性较强的树种。(2)生物多样性的变化与降雨量呈正相关,均呈现自东向西逐渐递减。(3)三种植被类型共有物种的种间关系分析显示,三种植被类型种间关系松散,滨海雨林的种间联结强度相对较高,半落叶季雨林与落叶季雨林相似。综上结果认为,从滨海雨林到落叶季雨林物种间的协同共存关系在减弱,排斥竞争关系在增强;无论是物种组成、物种多样性水平还是种间关系,半落叶季雨林与落叶季雨林更相似。     

Isozyme analysis of genetic variability and population structure of Lactuca L. germplasm

Isozymes were used to investigate the genetic variability, population structure, and relationships of Lactuca germplasm. The isozyme systems revealed 16 putative loci of a total of 31 alleles. Out of these 16 loci, 11 were polymorphic. The average values of expected heterozygosity (H_e), observed heterozygosity (H_o), mean number of alleles per locus (A) and effective number of alleles per locus (A_e) were 0.2227, 0.266, 1.3005 and 1.369, respectively. The average fixation indices were lower than zero for most of the accessions studied, indicating an excess of heterozygotes. Genetic differentiation among accessions (F_ST) exhibited that 51.3% of the isozyme variation was recorded among accessions, and 48.7% of the genetic variation resided within accessions. The average values of total heterozygosity (H_T) and intra-accessional genetic diversity (H_S) were 0.352 and 0.171, respectively. Moreover, the inter-accessional genetic diversity (D_ST) ranged from 0 to 0.424 with an average of 0.18. Cluster analysis revealed that L. sativa cultivars were distributed throughout different Lactuca species. Thereby, isozymes results confirms the hypothesis of the polyphyletic origin of L. sativa. This high level of genetic variation proved that isozymes are efficient for polymorphism analysis of Lactuca germplasm.     

Earthworm communities a bioindicator of arable land management practices: A case study in semiarid region of India

The abundances and activities of earthworms in arable lands depend strongly on management practices and; therefore earthworm can act as a potential bioindicator of land use practices. In this study earthworm diversity and abundances was measured in three differently managed agro-ecosystems i.e. conventional, integrated and organic, in some sites of northern semiarid region of India. The maximal numbers of earthworm occurrence were in integrated farming system (100%, all studied sites showed the presence) followed by organically managed (70%) and conventional (18.9%) agro-ecosystems. A total of six species belonging to four different families were identified during this survey and all recorded earthworm species were present in organically managed agro-ecosystems, while integrated and conventional arable lands exhibited only three earthworm species. The abundance of earthworms in arable system was also directly related to the management practices. The values of ecological indices e.g. Shannon diversity (H′), species dominance (C), the species richness (S) and evenness (E) indicated the anthropogenic pressure on earthworm communities in arable lands of northern India.     

Using food network unfolding to evaluate food–web complexity in terms of biodiversity: theory and applications

Food–web complexity often hinders disentangling functionally relevant aspects of food–web structure and its relationships to biodiversity. Here, we present a theoretical framework to evaluate food–web complexity in terms of biodiversity. Food network unfolding is a theoretical method to transform a complex food web into a linear food chain based on ecosystem processes. Based on this method, we can define three biodiversity indices, horizontal diversity (D_H), vertical diversity (D_V) and range diversity (D_R), which are associated with the species diversity within each trophic level, diversity of trophic levels, and diversity in resource use, respectively. These indices are related to Shannon's diversity index (H′), where H′ = D_H + D_V ? D_R. Application of the framework to three riverine macroinvertebrate communities revealed that D indices, calculated from biomass and stable isotope features, captured well the anthropogenic, seasonal, or other within‐site changes in food–web structures that could not be captured with H′ alone.     

Involvement of β3-adrenergic receptors in in vivo cardiovascular regulation in rainbow trout (Oncorhynchus mykiss)

Currently, we have little information concerning the involvement of β₃-adrenergic receptors (AR) in cardiovascular regulation in fishes. The goal of this study was to investigate the effect of β₃-AR ligands on in vivo cardiovascular function in larval and adult rainbow trout (Oncorhynchus mykiss). In adult fish, injection of BRL₃₇₃₄₄ (β₃-AR agonist) resulted in an increase in heart rate (f_H) (~ 31%) while stroke volume (Sv) was reduced (? 25.9%). Injection of SR_59230A (β₃-AR antagonist) and propranolol (β₁/β₂-AR antagonist) resulted in increases in dorsal aorta blood pressure (P_DA) with differing effect on cardiac variables (f_H and Sv). To confirm specificity of the results, BRL₃₇₃₄₄ was injected following sequential injections of phentolamine (α₁-AR antagonist), atropine (muscarinic antagonist), propranolol and SR_59230A. While phentolamine had no effect on BRL₃₇₃₄₄, atropine completely abolished the influence of BRL₃₇₃₄₄ on f_H, Sv and cardiac output (Q). In larval trout, BRL₃₇₃₄₄ (10 and 100 μM) induced a significant concentration-dependent increase in f_H while SR_59230A (1 and 10 μM) and propranolol (1 and 10 μM) separately caused a significant concentration-dependent decrease. These data suggest that β₃-ARs have an important role in regulation of cardiovascular function, and provide evidence for a potential interaction between muscarinic and adrenergic receptors in rainbow trout.     

太湖湿地昆虫群落结构及多样性

为了探讨太湖湿地昆虫群落的结构和变化规律,对太湖湿地各生境样点昆虫群落进行了调查研究.调查共获得昆虫标本24968号,隶属于13目88科301属318种;半翅目、鳞翅目、鞘翅目和直翅目等为优势类群.各样点昆虫群落多样性指数和均匀度指数特征值为湿地恢复示范区＞渔阳山＞三山岛＞三洋村＞灵湖村,优势集中性指数的特征值比较为:湿地恢复示范区＜渔阳山＜三洋村＜三山岛＜灵湖村.各样点昆虫群落的多样性指数与均匀度指数和丰富度指数表现一致.在时间序列上渔阳山样点昆虫群落的多样性指数波动最小.昆虫群落的极点排序表明渔阳山和湿地恢复示范区样点昆虫群落是最相近的.主分量分析的结果显示太湖湿地昆虫群落主要受捕食性和植食性昆虫群落的影响.湿地恢复示范区样点昆虫群落内天敌昆虫比例偏低,降低了昆虫群落对外界扰动的缓冲能力.综合昆虫群落的各项分析结果发现渔阳山样点昆虫群落稳定性最高,三洋村样点昆虫群落稳定性最低.     

Analyzing the (mis)behavior of Shannon index in eutrophication studies using field and simulated phytoplankton assemblages

The Shannon index of diversity H′ is a commonly used metric in ecology. The tendency of this index to show a unimodal relationship with productivity has been the subject of several studies. In the present work, the behavior of H′ and three related ecological indices (Simpson, Hill, and Evenness) was investigated using phytoplankton assemblages along a eutrophication gradient. We used both natural and simulated assemblages, whereby the comparison enabled us to assess the role of environmental ‘noise’ on index behavior. We developed simulated assemblages based on phytoplankton distributions predicted by two model types: the log series statistical model and the random fraction niche-based model. Using field data, H′ and the related Simpson index showed expected unimodal relationships with eutrophication. The same unimodal relationships were reproduced with simulated assemblages. Comparing the simulations with natural assemblages along a eutrophication gradient showed that there was much unexplained variance in the real-world data, suggesting that these diversity indices are sensitive to stochastic processes. An analysis of the simulated assemblages using relative abundance distributions suggested that increasing H′ and Simpson index values in the low range of the eutrophication gradient were due to increasing species richness, and that decreasing index values in the high range of the eutrophication gradient were due to decreasing evenness. In addition, this analysis revealed how assemblages of identical H′ values arose from contrasting community structures found in the low- and high-range of eutrophication. The high variability and non-linearity of the Shannon and Simpson indices along a eutrophication gradient suggests that these measures of diversity are inappropriate for use as water quality monitoring assessment tools. Indeed, when calculating ecological quality ratios that are employed by the European Water Framework Directive, unreliable (non-monotonic) predictions of water quality resulted.     

Natural succession of grassland on the Loess Plateau of China affects multifractal characteristics of soil particle-size distribution and soil nutrients

Knowledge of the changes of soil properties and soil particle-size distribution (PSD) is important for quantifying soil quality and dynamics during natural succession. We applied multifractal theory to characterize the PSDs in five soil layers of nine croplands abandoned for less than 1 year, 2, 5, 7, 10, 15, 20, 30 and 35 years and evaluated the changes of soil organic carbon (SOC), total nitrogen (total N), total phosphorus (total P), soil texture and multifractal parameters [capacity dimension (D ₀), entropy dimension (D ₁), correlation dimension (D ₂) and Hölder exponent of order zero (α ₀)] during natural succession on the Loess Plateau of China. Rényi spectra (D _q ) and singularity spectra f(α) characterized the PSDs well and sensitively reflected the changes of heterogeneity of the surface soil (0–20 cm) during natural succession. SOC, total N and clay contents and the multifractal parameters increased significantly by the late stage of succession, mostly in the topsoil (0–10 cm). Natural succession thus effectively improved the soil physicochemical properties on the Loess Plateau of China, even though it was time-consuming. SOC and total N contents decreased with depth throughout the natural succession, but the multifractal parameters were higher in the topsoil only in the late stage. D ₁ and D ₂ were strongly and positively correlated with SOC and total N contents in the surface layers and with fine particles in all layers, suggesting that D ₁ and D ₂ may be sensitive and practical indices for quantifying changes in soil properties and erosion.     

Additive partitioning of aquatic invertebrate species diversity across multiple spatial scales

1. Additive partitioning of three measures of diversity (species richness, Shannon's diversity index H and Simpson's diversity D) was used to study the relationship between local and regional diversity of benthic macroinvertebrate communities of boreal lakes (littoral habitats) and streams (riffle habitats) across three spatial scales (sampling sites, ecoregions and biogeographic regions). 2. Alpha (α) and beta (β) diversity are defined as within‐habitat and between‐habitat diversity, respectively. According to the concept of additive partitioning, diversity can be partitioned across multiple spatial scales such that the total (γ) diversity on one spatial scale becomes within‐habitat (α) diversity at the next higher scale. Hence, the total diversity at one scale is determined by the α diversity and the between‐habitat diversity (β) at the next lower scale. Consequently, one of the advantages of additive partitioning is that it is possible to study simultaneously β diversity and the regional‐local species relationship and the scale dependence of α and β components. 3. For both lakes and streams α diversity was low for sites and ecoregions, whereas β diversity was high, indicating that among‐site factors are important in describing the variability among the lakes and streams studied here. 4. Weak, albeit significant, evidence was found for regional and local species saturation patterns. Multiple stepwise regression indicated that local processes might be more important in structuring lake‐littoral and stream‐riffle species assemblages than regional processes. From these results we conclude that environmental heterogeneity may act as an important factor contributing to species coexistence, resulting in the observed saturation patterns. 5. Our study supports the use of additive partitioning for identifying specific patterns of macroinvertebrate diversity on multiple spatial scales and the underlying processes generating these patterns. This information is needed to improve understanding of the relation between patterns and processes affecting (decreasing) trends in aquatic biodiversity.