戴云山物种多样性与系统发育多样性海拔梯度分布格局及驱动因子

生物多样性的海拔分布格局是生态学研究的热点。海拔作为综合性因子驱动着植物群落的物种、系统发育与功能多样性的空间分布。以戴云山南坡900-1600 m森林植物群落为研究对象,探讨物种多样性、系统发育指数与环境驱动因子的相互关系以及环境因子在群落构建与多样性维持中的重要意义。结果表明：（1）森林植物群落的系统发育多样性与物种多样性沿海拔均呈现中间高度膨胀格局。（2）物种多样性Margalef指数、Shannon-Wiener指数与系统发育多样性指数呈显著正相关,表明物种多样性越高,系统发育多样性也越高。Shannon-Wiener指数与物种多样性指数（Margalef、Pielou、Simpson指数）、系统发育多样性及系统发育结构都存在显著相关性,一定程度上Shannon-Wiener指数可以代替其他指数。Pielou指数、Simpson指数、Shannon-Wiener指数与系统发育结构NRI （Net relatedness index）指数、NTI （Net nearest taxa index）指数存在显著正相关,表明群落优势度、均匀度与系统发育结构相关性较强。（3）土壤全磷含量是影响系统发育多样性和物种多样性的主要驱动因子,土壤含水量是影响Shannon-Wiener、Pielou、Simpson指数的最显著因子,海拔是影响群落系统发育结构的主要因素。海拔是影响系统发育结构变化的主要环境因子,而土壤因子是影响物种多样性与系统发育多样性的主要因素,进一步验证了物种多样性与系统发育多样性的高度相关,结果旨在揭示物种群落空间分布规律。     

A parametric diversity measure combining the relative abundances and taxonomic distinctiveness of species

Most ecological diversity indices summarize the information about the relative abundances of species without reflecting taxonomic differences between species. Nevertheless, in environmental conservation practice, data on species abundances are mostly irrelevant and generally unknown. In such cases, to summarize the conservation value of a given site, so‐called ‘taxonomic diversity’ measures can be used. Such measures are based on taxonomic relations among species and ignore species relative abundances. In this paper, bridging the gap between traditional biodiversity measures and taxonomic diversity measures, I introduce a parametric diversity index that combines species relative abundances with their taxonomic distinctiveness. Due to the parametric nature of the proposed index, the contribution of rare and abundant species to each diversity measure is explicit.     

弃管杉木林杉木数量与群落物种多样性间的关系

森林群落物种多样性格局和动态一直是生态学的研究热点,人工林弃管后演替进程中物种多样性变化也很值得研究。杉木(Cunninghamia lanceolata)作为我国南方林区人工栽培最广、经济价值最高的用材树种之一,其人工林分布面积很大,通常群落结构简单、物种多样性低,然而群落中杉木数量如何影响植物物种多样性,迄今缺乏研究。在浙江省自然保护区内,选择不同疏伐强度和弃管时间的杉木人工林,建立了6个1 hm~2长期动态监测样地,在10 m×10 m、20 m×20 m、50 m×50 m和100 m×100 m尺度下,探究群落物种多样性(物种丰富度、Simpson指数、Shannon-Wiener指数和Pielou均匀度指数)的变化规律,分析杉木数量(多度和相对多度)对物种多样性的影响。结果显示：弃管前对杉木林的疏伐强度越高,演替恢复后的群落物种多样性越高。相同疏伐程度下,物种多样性随演替时间的延长有先升高后降低的趋势。取样尺度小于100 m×100 m时,杉木数量与物种多样性呈极显著负相关;100 m×100 m尺度下仅杉木相对多度与3种多样性指数呈显著负相关,杉木多度与各物种多样性均无显...     

Responses of taxonomic distinctness and species diversity indices to anthropogenic impacts and natural environmental gradients in stream macroinvertebrates

1. Many studies have shown traditional species diversity indices to perform poorly in discriminating anthropogenic influences on biodiversity. By contrast, in marine systems, taxonomic distinctness indices that take into account the taxonomic relatedness of species have been shown to discriminate anthropogenic effects. However, few studies have examined the performance of taxonomic distinctness indices in freshwater systems. 2. We studied the performance of four species diversity indices and four taxonomic distinctness indices for detecting anthropogenic effects on stream macroinvertebrate assemblages. Further, we examined the effects of catchment type and area, as well as two variables (pH and total phosphorus) potentially describing anthropogenic perturbation on biodiversity. 3. We found no indications of degraded biodiversity at the putatively disturbed sites. However, species density, rarefied species richness, Shannon's diversity and taxonomic diversity showed higher index values in streams draining mineral as opposed to peatland catchments. 4. Of the major environmental gradients analysed, biodiversity indices showed the strongest relationships with catchment area, lending further support to the importance of stream size for macroinvertebrate biodiversity. Some of the indices also showed weak linear and quadratic relationships to pH and total phosphorus, and residuals from the biodiversity index‐catchment area regressions (i.e. area effect standardized) were more weakly related to pH and total phosphorus than the original index values. 5. There are a number of reasons why the biodiversity indices did not respond to anthropogenic perturbation. First, some natural environmental gradients may mask the effects of perturbation on biodiversity. Secondly, perturbations of riverine ecosystems in our study area may not be strong enough to cause drastic changes in biodiversity. Thirdly, multiple anthropogenic stressors may either increase or decrease biodiversity, and thus the coarse division of sites into reference and altered streams may be an oversimplification. 6. Although neither species diversity nor taxonomic distinctness indices revealed anthropogenic degradation of macroinvertebrate assemblages in this study, the traditional species diversity and taxonomic distinctness indices were very weakly correlated. Therefore, we urge that biodiversity assessment and conservation planning should utilize a number of different indices, as they may provide complementary information about biotic assemblages.     

A conceptual guide to measuring species diversity

Three metrics of species diversity – species richness, the Shannon index and the Simpson index – are still widely used in ecology, despite decades of valid critiques leveled against them. Developing a robust diversity metric has been challenging because, unlike many variables ecologists measure, the diversity of a community often cannot be estimated in an unbiased way based on a random sample from that community. Over the past decade, ecologists have begun to incorporate two important tools for estimating diversity: coverage and Hill diversity. Coverage is a method for equalizing samples that is, on theoretical grounds, preferable to other commonly used methods such as equal-effort sampling, or rarefying datasets to equal sample size. Hill diversity comprises a spectrum of diversity metrics and is based on three key insights. First, species richness and variants of the Shannon and Simpson indices are all special cases of one general equation. Second, richness, Shannon and Simpson can be expressed on the same scale and in units of species. Third, there is no way to eliminate the effect of relative abundance from estimates of any of these diversity metrics, including species richness. Rather, a researcher must choose the relative sensitivity of the metric towards rare and common species, a concept which we describe as ‘leverage.' In this paper we explain coverage and Hill diversity, provide guidelines for how to use them together to measure species diversity, and demonstrate their use with examples from our own data. We show why researchers will obtain more robust results when they estimate the Hill diversity of equal-coverage samples, rather than using other methods such as equal-effort sampling or traditional sample rarefaction.     

天童国家森林公园树种多样性的加性分配

根据物种丰富度、Shannon指数和Simpson指数建立的物种多样性分配方法,提出分异度系数,对天童森林公园内不同森林类型的树种多样性进行了分析.结果表明,基于物种丰富度指数,总体的多样性只有小部分归功于样方内多样性,而多样性大多分配在样方间、亚群丛间或群丛间,例如在木荷-栲树群丛中,样方内只贡献了20.3%的物种丰富度.而在Shannon指数和Simpson指数中,多样性大多分配在样方内.这种差异主要是由于后两种指数不仅考虑了物种的存在与否,也考虑了其在样方内的多度.同时比较分析了加性分配与传统方法的结果.     

亚高山针叶林人工恢复过程中物种多样性变化

通过样方调查,以空间代替时间的方法,对亚高山人工针叶林恢复过程中,乔木、灌木和草本层物种多样性的变化进行了研究,探讨了不同恢复阶段各层物种的相关系数．结果表明,亚高山人工针叶林恢复过程中物种的丰富度、多样性和均匀性都在波动中逐渐增加,云杉人工林恢复过程中总体上是朝着有利于物种多样性恢复的方向发展．在人工林恢复序列中群落乔木物种的平均相关系数为41．88％。灌木为50．61％,草本为37．22％,说明在70年的人工林恢复过程中,灌木种类具有较高的连续性和稳定性;草本植物则随着人工林环境条件的改变而出现较大的消亡和更新,显示出较大的波动性．乔木层物种的稳定性和连续性介于灌木和草本植物之间．     

A comparison of species diversity estimators

Although having been much criticized, diversity indices are still widely used in animal and plant ecology to evaluate, survey, and conserve ecosystems. It is possible to quantify biodiversity by using estimators for which statistical characteristics and performance are, as yet, poorly defined. In the present study, four of the most frequently used diversity indices were compared: the Shannon index, the Simpson index, the Camargo eveness index, and the Pielou regularity index. Comparisons were performed by simulating the Zipf–Mandelbrot parametric model and estimating three statistics of these indices, i.e., the relative bias, the coefficient of variation, and the relative root-mean-squared error. Analysis of variance was used to determine which of the factors contributed most to the observed variation in the four diversity estimators: abundance distribution model or sample size. The results have revealed that the Camargo eveness index tends to demonstrate a high bias and a large relative root-mean-squared error whereas the Simpson index is least biased and the Shannon index shows a smaller relative root-mean-squared error, regardless of the abundance distribution model used and even when sample size is small. Shannon and Pielou estimators are sensitive to changes in species abundance pattern and present a nonnegligible bias for small sample sizes (<1000 individuals). Received: May 8, 1998 / Accepted: May 6, 1999     

山西七里峪茶条槭群落特征及物种多样性研究

运用TWINSPAN对山西七里峪茶条槭群落类型进行划分,并采用Patrick指数、Simpson指数、Shannon-Wiener指数、Alatalo指数研究群落的物种多样性。结果表明:TWINSPAN将茶条槭群落的73个样方划分为10个群丛;各群丛的物种丰富度指数、多样性指数和均匀度指数之间存在差异,群丛Ⅲ和Ⅶ的丰富度指数和多样性指数较高,群丛Ⅰ的多样性指数较低;各群丛乔木层、灌木层和草本层之间的物种多样性也存在差异,多样性指数大致表现为草本层高于灌木层高于乔木层。土壤中的有机质、速效钾、含水量是影响茶条槭群落物种多样性的主要因素。     

Quantifying the effects of nutrient addition on the taxonomic distinctness of serpentine vegetation

Traditional diversity indices summarize the information about the relative abundances of species within a community without regard to differences between species. However, intuitively, a community composed of dissimilar taxa is more diverse than a community composed of more similar taxa. Therefore, useful indices of diversity should account for taxonomic relations among species. In this paper, a new parametric diversity index that combines species relative abundances and their taxonomic distinctiveness is used to quantify the way in which soil fertilization affects the diversity of a garigue community on ultramafic soils of Tuscany (central Italy). Results show that, while ultramafic soils generally host plant communities of limited taxonomic diversity with respect to similar communities on other substrates, fertilization significantly enhances the biomass production of species that are not exclusive to ultramafic soils. As a consequence, if diversity is measured combining species relative abundances with their taxonomic distinctiveness, nutrient addition tends to increase the diversity of ultramafic communities.     

高寒草地植物物种多样性与功能多样性的关系

物种多样性与功能多样性的关系是生态学当前研究的热点问题之一,不同区域典型生态系统物种多样性和功能多样性的关系研究有利于生物多样性保护理论的全面发展。以青藏高原地区的主要草地生态系统—高寒草甸和高寒草原为研究对象,采用4个物种多样性指数(Patrick丰富度指数、Shannon-Weiner多样性指数、Pielou均匀度指数和Simpson优势度指数)和9个功能多样性指数(FAD功能性状距离指数、MFAD功能性状平均距离指数、基于样地的FDp和基于群落的FDc功能树状图指数、FRic功能体积指数、FEve功能均匀度指数、Rao功能离散度常二次熵指数、FDiv功能离散指数、FDis功能分散指数),分析了高寒草地植物物种多样性、功能多样性关系及其与初级生产力的关系,以期阐明3个科学问题:不同草地类型的高寒草地生态系统植物物种多样性和功能多样性有何差异?高寒草地生态系统的植物物种多样性和功能多样性有何关系?高寒草地生态系统物种多样性、功能多样性对生态系统功能的影响有何异同?研究结果表明:(1)与高寒草原相比,高寒草甸具有更高的物种多样性、功能丰富度和功能离散度;(2)高寒草甸中,Patrick丰富度与功能丰富度指数(FAD、MFAD、FDp、FDc)和功能离散度指数(FDiv)的具有较强的相关性,最优拟合方程分别为幂函数和二次多项式函数;(3)高寒草原中,Patrick丰富度与功能丰富度指数(FAD、MFAD、FDp、FDc、FRic)、Shannon指数和Simpson指数与FEve指数的相关性较强,最优拟合方程为二次多项式函数,Pielou指数与FEve指数的相关性较强,最优拟合方程为指数函数;(4)高寒草甸的初级生产力分别与物种丰富度指数Patrick、功能离散指数FDiv具有较强的相关性;而高寒草原的初级生产力与4个物种多样性指数间均具有较强的相关性,与功能离散指数FDiv具有较强的相关性,最佳拟合方程均为二次多项式函数。研究的总体结论为:物种多样性、功能多样性、二者之间的关系以及二者与生态系统服务功能(以初级生产力为例)之间的关系在高寒草甸和高寒草原群落中表现迥异,因此在研究青藏高原高寒草地的生态功能时,不能仅仅测度传统的物种多样性,还应测度与物种多样性、生态功能密切相关的功能多样性。     

Simultaneous confidence intervals for comparing biodiversity indices estimated from overdispersed count data

Diversity indices might be used to assess the impact of treatments on the relative abundance patterns in species communities. When several treatments are to be compared, simultaneous confidence intervals for the differences of diversity indices between treatments may be used. The simultaneous confidence interval methods described until now are either constructed or validated under the assumption of the multinomial distribution for the abundance counts. Motivated by four example data sets with background in agricultural and marine ecology, we focus on the situation when available replications show that the count data exhibit extra‐multinomial variability. Based on simulated overdispersed count data, we compare previously proposed methods assuming multinomial distribution, a method assuming normal distribution for the replicated observations of the diversity indices and three different bootstrap methods to construct simultaneous confidence intervals for multiple differences of Simpson and Shannon diversity indices. The focus of the simulation study is on comparisons to a control group. The severe failure of asymptotic multinomial methods in overdispersed settings is illustrated. Among the bootstrap methods, the widely known Westfall–Young method performs best for the Simpson index, while for the Shannon index, two methods based on stratified bootstrap and summed count data are preferable. The methods application is illustrated for an example.     

DER: An algorithm for comparing species diversity between assemblages

There is no single diversity index that adequately summarises species diversity, since this is a multidimensional concept and hence should be quantified using a compound statistical measure. Here, we present the DER algorithm, available as an R package on CRAN and as an RWizard application on http://www.ipez.es/RWizard. This algorithm provides tools for differentiating assemblages on the basis of five compounds of diversity: rarity, heterogeneity, evenness, taxonomic/phylogenetic diversity and functional diversity. For all the samples, the algorithm calculates a total of 39 of the indices most often used. All indices of all samples are transformed to a scale range of between 0 and 1, and the algorithm calculates the polar coordinates of all samples with all possible combinations for all five groups of indices. Thus, for each combination, an index of rarity, heterogeneity (species richness is included in this group), evenness, taxonomic/phylogenetic diversity and functional diversity is used for each group to calculate the polar coordinates of all samples. When the polar coordinates of the samples are obtained for each combination, the convex hull and the mean Euclidean distance between samples are calculated. The algorithm selects the combination of indices with the highest value of the mean between convex hull and mean Euclidean distance between samples; priority is therefore given to maximising dispersion between the samples. The polar coordinates of the selected combination are depicted using a diagram from which it is possible to determine the differences in terms of rarity, heterogeneity, evenness, taxonomic/phylogenetic diversity and functional diversity between assemblages.     

Using the relationship between taxonomic and functional diversity to assess functional redundancy in streams of an altered tropical watershed

The relationship between taxonomic and functional diversity indices has been used to better describe and understand the structure of biological communities. Functional diversity is expected to have an asymptotic relationship with species richness because at some point, the addition of new species will increase some of the already established functional groups (functional redundancy). However, the asymptotic relationship may not be reached in intermediately disturbed systems once many intolerant species that would have played a redundant role or even represented some functional groups have been lost. This study aimed to address such a relationship (taxonomic and functional indices) and to evaluate the functional redundancy in intermediately disturbed streams in the Atlantic Rainforest domain. We expected a positive linear relationship between taxonomic and functional diversity; however, we did not expect to find an asymptotic relationship between richness and functional diversity because of the loss of many intolerant species caused by anthropogenic uses. The taxonomic diversity indices were Species Richness (SR) and Simpson’s Diversity (SD), while the functional diversity indices were the Functional Richness (FRic) and Functional Dispersion (FDisp). The two taxonomic and two functional diversity indices showed a significant positive relationship that never reached an asymptote, suggesting low functional redundancy in the fish communities. Our results indicate that care is needed in the management of the studied streams because assemblies with low functional redundancy are more susceptible to loss of functions in the case of species loss.     

坡向和坡位对四川夹金山灌丛群落结构与物种多样性特征的影响

研究不同坡向、坡位夹金山灌丛群落结构和物种多样性特征。结果表明: 在 24 个样地中,共有维管植物 186 种,隶属于 50 科 127 属。其中,灌木层有 32 种,隶属于 14 科 22 属,阴坡下坡位物种数最多;草本层有 154 种,隶属于 43 科 109 属,阴坡物种数最少。灌木层的平均高度表现为阳坡>半阳坡>阴坡,平均密度则相反;草本层平均高度表现为阴坡>半阳坡>阳坡,平均密度无显著变化。坡位仅对阳坡草本层平均高度有显著影响,灌木层物种多样性在阴坡较高,草本层物种多样性在阳坡下坡位和阴坡中坡位较高。坡向对灌木层和草本层 Shannon多样性指数、Simpson优势度指数、物种丰富度指数、Pielou均匀度指数影响显著(除草本层 Simpson 指数),坡位对灌木层和草本层物种多样性指数均无显著影响,坡向和坡位的交互作用对草本层物种多样性的影响大于灌木层。冗余分析(RDA)表明,物种多样性不仅与坡向正弦值、坡向余弦值相关,也与群落结构特征相关性较大。     

吕梁山森林群落草本层植物物种多样性的空间格局及其对模拟增温的响应

为研究气候变暖背景下森林群落草本层植物物种多样性对温度升高的响应及其随海拔、纬度的空间分布格局,按照纬度梯度选择吕梁山系北段的管涔山和南段的五鹿山为研究区,并在每个山地的不同海拔梯度(高、中、低)分别设置对照(CK)、低度增温(OTC1)和高度增温(OTC2) 3种试验样地。于2017年植被生长季对植物多度、频度、盖度、高度进行调查,计算物种多样性指数(Simpson指数、Shannon指数、Pielou指数、Patrick指数)。结果表明:(1)吕梁山森林群落草本层植物物种多样性随海拔呈"v型"变化格局,即在中间海拔梯度处最低,且海拔梯度对各多样性指数的影响均达到极显著水平(P0.01)。(2)物种多样性随纬度升高呈递增趋势(P0.05),即较高纬度山地具有较高的物种多样性。(3)物种多样性随温度升高整体呈递减趋势(P0.05),即温度升高可抑制林下草本层植物物种多样性。(4)在增温处理下,五鹿山草本植物的Simpson指数、Shannon指数和Patrick指数呈递减趋势,Pielou指数先降低后升高;管涔山草本植物的Simpson指数、Shannon指数和Pielou指数先增加后减小,Patrick指数呈递增趋势。整体来说,在吕梁山较低海拔,持续增温会使物种多样性降低;在中等海拔,物种多样性随温度升高呈现先下降后上升的变化趋势;在较高海拔,适度增温可提高物种多样性,持续增温则抑制多样性。因此,增温对吕梁山森林群落草本植物物种多样性的影响随海拔升高整体呈下降趋势。     

间伐强度对阿尔泰山天然林下植被的影响

以阿尔泰山天然林为研究对象,探究不同间伐强度（19%、33%、55%、62%）对林下植被的影响,为该区天然林的经营管理提供理论依据。运用样地调查法,对间伐30 a后的林木进行每木检尺,调查林下植被结构、物种多样性,对测定数据进行单因素方差分析和LSD多重比较检验。结果表明：（1）草本层物种丰富度随间伐强度的增大而增大,62%间伐强度显著大于其他处理;灌木层物种丰富度随间伐强度的增大呈先增后减的趋势,55%间伐强度最大（P>0.05）;不同间伐强度处理之间,林下植被的Simpson指数、Shannon-Wiener指数和Pielou均匀度指数均无显著差异（P>0.05）,草本植物优势种各间伐强度之间大致相同;（2）适当增加间伐强度可以明显提高灌木层和草本层密度,以55%间伐强度为优（P<0.05）,林下植被的盖度随着间伐强度的增大先增后减,间伐显著影响灌木植物盖度,而对草本层盖度则影响不显著（P>0.05）。以上研究表明从恢复林地多样性的角度考虑,间伐强度选取55%更合理。     

A unified index to measure ecological diversity and species rarity

Several indices have been created to measure diversity, and the most frequently used are the Shannon-Wiener (H) and Simpson (D) indices along with the number of species (S) and evenness (E). Controversies about which index should be used are common in literature. However, a generalized entropy (Tsallis entropy) has the potential to solve part of these problems. Here we explore a family of diversity indices (S_q; where q is the Tsallis index) and evenness (E_q), based on Tsallis entropy that incorporates the most used indices. It approaches S when q=0, H when q→1 and gives D when q=2. In general, varying the value of the Tsallis index (q), S_q varies from emphasis on species richness (q<1) to emphasis on dominance (q>1). Similarly, E_q also works as a tool to investigate diversity. In particular, for a given community, its minimum value represents the maximum deviation from homogeneity (E_q=1) for a particular q (herein named q*). It is remarkable that our analysis indicates that q* and its corresponding evenness, E_q*, are negatively affected by S when using simulated data. They may represent an index related to species rarity. Furthermore, S_q* (i.e. the value of S_q for a specific q*) is positively affected by richness that is an important property of any diversity index. In general, our findings indicate that the indices H, D, S, S_q*, E and E_q* are only part of a whole set of possibilities. In addition, the ecological properties of E_q* and S_q*, proposed here for the first time, show promise in ecology.     

芦芽山荷叶坪亚高山草甸生物多样性

以芦芽山荷叶坪亚高山草甸为研究对象,共设置150个5 m×5 m草本样方,进行群落生物学调查,对研究区36种草本植物重要值、α多样性指数、谱系多样性指数及其相关性进行研究.结果表明: 荷叶坪亚高山草甸物种多样性总体分布较均匀,边缘地区物种更丰富,呈现“边缘效应”;4个样地的群落谱系结构呈聚集模式,12个样地的群落谱系结构呈分散模式;谱系多样性指数(PD)与Petrick指数、Simpson指数和Shannon指数呈正相关,净亲缘关系指数(NRI)和最近种间亲缘关系指数(NTI)与α物种多样性指数无明显相关性.     

中国典型森林生态系统乔木层群落物种多样性的空间分布格局及其影响因素

物种多样性地理分布格局及其成因是生物地理学和宏观生态学研究的核心问题之一,基于中国13个典型森林生态系统乔木层群落植物的调查数据,分析物种多样性随经纬度的变化规律,探讨物种多样性空间分布格局的影响因素。结果表明:(1) 13个典型森林生态系统的4个物种多样性指数均随经纬度上升而下降,其中物种丰富度变化更为显著,而Shannon-Wiener指数、Simpson指数和Pielou指数随经度上升变化不显著;(2)相关性分析结果显示,物种多样性指数与植物特性、能量和水分因子的单因素相关关系并不一致。其中,物种丰富度、Shannon-Wiener指数和Simpson指数与年均温、最冷月均温、温度年较差和潜在蒸散量的相关性最显著(P0.01),Pielou指数与年均温、最冷月均温、实际蒸散量、潜在蒸散量和郁闭度有显著相关关系(P0.05);(3)方差分解结果表明,能量和水分的共同作用对物种多样性指数空间分布格局的解释率最高,达到15%—42%;植物特性、能量和水分因子三者共同作用对物种多样性指数空间分布格局解释率次之,为14%—27%;植物特性与能量因子或水分因子两者之间的共同作用以及植物特性和水分因子独立作用对物种多样性指数空间分布格局的解释率较小,其中能量因子对物种多样性指数空间分布格局的单独解释率高于植物特性或水分因子。研究表明能量和水分共同作用是影响大尺度森林乔木层物种多样性空间分布格局形成的主要因素,但植物特性的差异对物种多样性空间分布格局影响也不可忽视。