Impact of exotic invasion on the temporal stability of natural annual plant communities

Much work in ecology has focused on understanding how changes in community diversity and composition will affect the temporal stability of communities (the degree of fluctuations in community abundance or biomass over time). While theory suggests diversity and dominant species can enhance temporal stability, empirical work has tended to focus on testing the effect of diversity, often using synthetic communities created with high species evenness. We use a complementary approach by studying the temporal stability of natural plant communities invaded by a dominant exotic, Erodium cicutarium. Invasion was associated with a significant decline in community diversity and change in the identity of the dominant species allowing us to evaluate predictions about how these changes might affect temporal stability. Community temporal stability was not correlated with community richness or diversity prior to invasion. Following invasion, community stability was again not correlated with community richness but was negatively correlated with community diversity. Before and after invasion, community stability was positively correlated with the stability of the most dominant species in the community, even though the identity of the dominant species changed from a native (prior to invasion) to an exotic species. Our results demonstrate that invasion by a dominant exotic species may reduce diversity without negatively affecting the temporal stability of natural communities. These findings add support to the idea that dominant species can strongly affect temporal stability, independent of community diversity.     

绿肥种植配施减量氮肥对柑橘园杂草群落组成及多样性的影响

以湖北当阳柑橘园杂草群落为对象,研究绿肥种植(自然生草和间种光叶苕子)下配施减量氮肥处理(当地推荐施氮肥量的0%、70%、85%、100%)对橘园杂草群落组成和多样性的影响,并运用Pearson相关分析和典范对应分析探究土壤因子对不同处理下杂草多样性和物种组成的影响。结果显示:(1)经样方调查,试验区共记录杂草植物21科29属30种,以禾本科和菊科为主,稗(Echinochloa crusgalli(L.)Beauv.)、酢浆草(Oxalis corniculata L.)、野老鹳草(Geranium carolinianum L.)等是所有处理中的共有种,自然生草下以匙叶鼠麴草(Gnaphalium pensylvanicum Willd.)和稗为优势种,间种光叶苕子(Vicia villosa Roth.var.glabrescens Koch.)下以酢浆草为优势种;(2)不同氮肥施入量下柑橘园草本物种Margalef指数、Patrick指数、Shannon-Wiener多样性指数和Pielou均匀度指数均无显著差异;相同施肥量下,间种光叶苕子能显著降低柑橘园杂草群落的物种多样性指数;(3)速效磷是显著影响柑橘园草本植物多样性指数的土壤因子;(4)不同处理下影响杂草物种分布的主要土壤因子是速效磷、pH值、含水率和温度。本研究认为无论减施氮肥与否,间种光叶苕子比自然生草更能显著降低杂草群落的物种多样性,从而避免恶性杂草与果树争肥。     

The community structure of bird assemblages on urban strangler figs

Figs have been regarded as keystone plant resources that support diverse tropical vertebrate frugivore communities. Planting or conserving large fig trees, such as stranglers, have therefore been proposed for enhancing urban biodiversity. We compared the diversity and community structure of bird assemblages on strangler figs with non‐fig urban trees as well as between the fruiting and non‐fruiting fig trees in an urban setting in Singapore. The total bird abundance across all the fig trees when in fruit was 4.5‐fold higher than on non‐fig trees and 3.5‐fold higher than when the same fig trees were not fruiting, but only attracted two more species. On individual trees, after accounting for the presence of mistletoes, tree height, the area covered by buildings, road lane density, and the distance to natural vegetation, mean diversity was not different between non‐fig trees and fig trees when they were not in fruit. On the other hand, when fruiting, each fig tree on average had 1.4 more species, 3 more counts of non‐native birds, and 1.6 more counts of insectivorous birds than when not fruiting. There was significant compositional turnover between non‐fig trees and non‐fruiting fig trees, while community dispersion was significantly lower among fig trees in fruit. Our results demonstrate that fig trees provide fruit and non‐fruit resources for birds in an urban landscape but do not necessarily support more diverse total bird assemblages than non‐fig trees. Instead, bird communities on fruiting urban figs would be highly homogeneous and dominated by a few species. Abstract in Malay is available with online material.     

黄土丘陵沟壑区不同坡向撂荒草地植物群落种群空间格局

本研究以黄土丘陵沟壑区4种不同坡向的草地植物群落为研究对象,探讨其物种组成和多样性特征,并运用幂乘方法则分析了群落的空间异质性和种群空间格局.结果表明: 铁杆蒿在不同坡向均有分布,为群落优势种;其他物种在不同坡向群落中的地位及对群落空间格局的贡献不同.不同坡向植物群落的空间分布格局均为集群分布,且聚集程度大小为阳坡＞半阳坡＞半阴坡＞阴坡.群落空间异质性指数与Simpson多样性指数呈显著正相关,与Margalef丰富度指数、Shannon多样性指数和Pielou均匀度指数呈显著负相关.优势种铁杆蒿、亚优势种达乌里胡枝子和长芒草,以及少数伴生种如猪毛蒿、臭草的相对空间异质性指数大于群落整体空间异质性指数,使群落趋于集群分布;多数伴生种如芦苇、苦荬菜、白羊草的相对空间异质性指数与群落整体空间异质性指数相近,它们与群落自身分布状态一致;刺儿菜、米口袋、茭蒿等偶见种的相对空间异质性指数小于群落整体空间异质性指数,降低了群落的聚集程度.综上,群落的聚集程度主要由优势种、亚优势种和偶见种共同决定,其中优势种、亚优势种和部分伴生种促使群落呈聚集分布,偶见种则降低了群落的集群分布.     

Patterns of Species Richness at Varying Scales in Western Kenya: Planning for Agroecosystem Diversification

Agroforestry tree domestication research is geared at promoting diversification of on-farm tree species composition. A survey was conducted in western Kenya with the objective of exploring possibilities for diversification for a particular agroecosystem, involving a complete tree census, tree measurement and collection of ethnobotanical information in 201 small-scale farms. Various approaches to landscape diversification were explored, including random distribution of trees to increase alpha richness and species richness at higher scales in the landscape, and random distribution of species composition over villages to increase the average richness of villages. The results showed that random distribution would result in increments of average species richness in the landscape, without requiring increments of total and average abundance. A new, fast and exact method of calculating site-based species accumulation curves was presented. The method yielded results that were extremely close to classical algorithms using 10,000 randomisations. Four use-groups (beverage, fodder, charcoal and soil fertility enhancement) were identified as use-groups with alpha richness smaller than one species, but only beverage and fodder had lowest richness at all scales (fruit and construction wood joined the four use-groups of lowest average species richness at higher scales in the landscape). The novel approaches used in this study could be used in future biodiversity studies on species accumulation patterns, or on spatial distribution patterns of species richness in a landscape.     

山西五鹿山森林群落木本植物功能多样性

通过选取群落中木本植物种子的扩散方式、传粉方式、植株高度和盖度等13个功能性状,计算出群落的6个功能多样性指数:功能性状距离、功能性状平均距离、功能体积、功能均匀度、功能分散指数和Rao二次熵指数,结合群落物种丰富度指数、Shannon-Wiener指数和物种均匀度指数对山西五鹿山森林群落木本植物功能多样性进行研究。结果表明:(1)功能性状距离、功能性状平均距离、功能体积与物种丰富度、Shannon-Wiener指数显著正相关;功能均匀度与Shannon-Wiener指数、物种均匀度指数显著正相关;功能分散指数、Rao二次熵指数与物种均匀度指数、Shannon-Wiener指数显著正相关;(2)功能多样性的差异很大程度上是由于物种差异所引起的;(3)6个功能多样性指数可分为三类:功能性状距离、功能性状平均距离、功能体积为功能丰富度指数;功能均匀度为功能均匀度指数;功能分散指数和Rao二次熵指数为功能离散度指数。该分类结果符合指数的计算方法和生态学意义,以及相互独立的标准。     

热带北缘鹅凰嶂季雨林四种群落特征及成熟度分析

为分析我国热带北缘季雨林的不同演替阶段的群落特征,该研究对广东阳春鹅凰嶂典型季雨林中4种(A、B、C、D)不同植物群落展开调查,对群落的物种组成、多样性和空间结构等进行分析,判断成熟度差异,预测演替方向,并提出优化建议。结果表明:(1)4种群落林层单一,小径级木与下层木占主体地位,具有1～3种明显的优势树种。(2)Shannon-Wiener指数为2.72～3.74,Simpson指数为0.90～0.97,Pielou均匀度指数为0.74～0.89,各群落多样性特征差异显著。(3)4种群落乔木胸径大小比数为0.49～0.51,角尺度为0.56～0.61,混交度为0.54～0.83,林分空间结构指数为60.57～71.44,林分空间结构距离为53.15～68.53。(4)综合群落基本特征、多样性和空间结构特征的分析得出,各群落的成熟度排名为D>A>C>B。综上认为,4种群落都处于演替前期或中期,乔木个体胸径和树高发展空间较大; 群落整体处于中庸生长状态,个体均呈轻微聚集分布,树种表现为中度、强度或极强度混交,空间结构与理想林分存在一定距离。随着成熟度的增加,4种群落都继续以阳性树种作为主要优势树种进行演替,并初步具备该区域地带性顶极群落的典型植被特征; 季雨林群落物种多样性提高,并向混交度增加、空间结构优化、稳定性增强的趋势演替。该研究结果为群落构建机制和森林结构优化等提供科学依据。未来应对该区域加强监管与保护,同时应对该地区的植被生态学和生物多样性保护展开广泛监测与深入研究。     

Uses of trees in paddy fields in Champasak Province, southern Lao PDR

The species and uses of trees located in paddy fields were investigated in three villages in Champasak Province, Lao PDR. The villages were different in their distance from Pakse City, the capital of the province, and age since foundation. A total of 71 species were recorded, and most were used by local people. The most frequent use was for fruit, firewood, and medicine, though most trees also offered shade for cattle and people. Species composition differed among villages. The youngest paddy supported more trees, remnants of the original forest, for timber. Older paddies supported fewer trees for timber but more for fruit and firewood. The introduced species increased according to the age of the paddy. Products other than timber obtained from the trees were common among villages. The significance of trees in rice cultivation in Laos was compared with that in the Satoyama landscape of Japan.     

红池坝炼山后生态恢复过程中群落特征研究

This paper studied the species composition and the structure and species diversity of communities in Hongchiba area of Wuxi County after controlled burning and aerial-sowing afforestation. The results showed that after buming and afforestation, pure Pinus armandii forest was not developed, but various mixed needle board-leaved forests which comprised P. armandii and native board-leaved trees grew. Various native species contributed to the communities with great species diversity. Shannon-Wiener index was 2.305～3.145, ecological dominance was 0.063～0.151, and evenness was 0.600～0.749. The natural regeneration of P. armandii population was very poor, and there was a trend that P. armandii would be gradually replaced by other native board-leaved trees. It was demonstrated that P. armandii should not be taken as a unique afforesr tree, and controlled burning was not a favorite ecological measure in subtropical area. Native trees should play more important roles in the process of ecological restoration.     

黑龙江大沾河湿地自然保护区鸟类群落结构调查及其多样性分析

采用样线法与网捕法对黑龙江大沾河自然保护区的鸟类资源进行调查,并计算其物种多样性、均匀性及不同生境群落间的相似性.结果表明:大沾河自然保护区共有鸟类16目39科203种,其中雀形目鸟类16科92种,非雀形目鸟类111种,种类较多的科有鹟科、雀科、鸭科、鹬科等.保护区分布的鸟类中,古北种占绝对优势(65.52%),广布种次之(30.54%),东洋界物种极少(3.94%).4种群落类型中,多样性指数排序:湿地>林地>农田>居民点;均匀性指数排序:湿地>林地>农田>居民点;相似性排序:居民点-农田(S=0.25),湿地-林地(S=0.23),农田-湿地(S=0.14)和居民点-林地(S=0.07).     

Experimental Manipulation of Grassland Plant Diversity Induces Complex Shifts in Aboveground Arthropod Diversity

Changes in producer diversity cause multiple changes in consumer communities through various mechanisms. However, past analyses investigating the relationship between plant diversity and arthropod consumers focused only on few aspects of arthropod diversity, e.g. species richness and abundance. Yet, shifts in understudied facets of arthropod diversity like relative abundances or species dominance may have strong effects on arthropod-mediated ecosystem functions. Here we analyze the relationship between plant species richness and arthropod diversity using four complementary diversity indices, namely: abundance, species richness, evenness (equitability of the abundance distribution) and dominance (relative abundance of the dominant species). Along an experimental gradient of plant species richness (1, 2, 4, 8, 16 and 60 plant species), we sampled herbivorous and carnivorous arthropods using pitfall traps and suction sampling during a whole vegetation period. We tested whether plant species richness affects consumer diversity directly (i), or indirectly through increased productivity (ii). Further, we tested the impact of plant community composition on arthropod diversity by testing for the effects of plant functional groups (iii). Abundance and species richness of both herbivores and carnivores increased with increasing plant species richness, but the underlying mechanisms differed between the two trophic groups. While higher species richness in herbivores was caused by an increase in resource diversity, carnivore richness was driven by plant productivity. Evenness of herbivore communities did not change along the gradient in plant species richness, whereas evenness of carnivores declined. The abundance of dominant herbivore species showed no response to changes in plant species richness, but the dominant carnivores were more abundant in species-rich plant communities. The functional composition of plant communities had small impacts on herbivore communities, whereas carnivore communities were affected by forbs of small stature, grasses and legumes. Contrasting patterns in the abundance of dominant species imply different levels of resource specialization for dominant herbivores (narrow food spectrum) and carnivores (broad food spectrum). That in turn could heavily affect ecosystem functions mediated by herbivorous and carnivorous arthropods, such as herbivory or biological pest control.     

Effects of plant species richness and evenness on soil microbial community diversity and function

Understanding the links between plant diversity and soil communities is critical to disentangling the mechanisms by which plant communities modulate ecosystem function. Experimental plant communities varying in species richness, evenness, and density were established using a response surface design and soil community properties including bacterial and archaeal abundance, richness, and evenness were measured. The potential to perform a representative soil ecosystem function, oxidation of ammonium to nitrite, was measured via archaeal and bacterial amoA genes. Structural equation modeling was used to explore the direct and indirect effects of the plant community on soil diversity and potential function. Plant communities influenced archaea and bacteria via different pathways. Species richness and evenness had significant direct effects on soil microbial community structure, but the mechanisms driving these effects did not include either root biomass or the pools of carbon and nitrogen available to the soil microbial community. Species richness had direct positive effects on archaeal amoA prevalence, but only indirect impacts on bacterial communities through modulation of plant evenness. Increased plant evenness increased bacterial abundance which in turn increased bacterial amoA abundance. These results suggest that plant community evenness may have a strong impact on some aspects of soil ecosystem function. We show that a more even plant community increased bacterial abundance, which then increased the potential for bacterial nitrification. A more even plant community also increased total dissolved nitrogen in the soil, which decreased the potential for archaeal nitrification. The role of plant evenness in structuring the soil community suggests mechanisms including complementarity in root exudate profiles or root foraging patterns.     

Species evenness and productivity in experimental plant communities

In nature, plant biomass is not evenly distributed across species, and naturally uncommon species may differ from common species in the probability of loss from the community. Understanding relationships between evenness and productivity is therefore critical to understanding changes in ecosystem functioning as species are lost from communities. We examined data from a large multi-site grassland experiment (BIODEPTH) for relationships between evenness of species composition (proportional abundance of biomass) and total biomass of communities. For plots which started with the same and even species composition, but which diverged in evenness over time, those with lower evenness had a significantly greater biomass. The relationship between evenness and biomass across all plots was also negative. However, for communities where the most common species represented one of the three largest species in monoculture at that site (inclusion of a large dominant species), the relationship was neutral. Path analyses indicated that three paths contributed to this negative relationship. First, higher species richness decreased evenness, but increased biomass (primarily through an increase in maximum plant size). Contrary to predictions, maximum plant size had either no effect on evenness, or a positive effect (in year 3 plots with a large dominant species), thereby reducing this relationship. In year 2, large variation among species in plant size (as measured in monoculture) both decreased evenness and increased biomass, thus increasing the strength of the negative relationship between evenness and biomass. However, the former effect was only found in plots with a large dominant species, the latter only in plots without a large dominant species. When species richness, maximum plant size, and variation in size were accounted for, in year 2 evenness positively affected biomass in plots that included a large dominant species. Our results are consistent with the view that naturally uncommon species may be unaffected by (or even benefit from) the presence of a large naturally common species, and that uncommon plants may have little ability to increase productivity in the absence of such a species. We conclude that the observed negative relationship between evenness and biomass resulted from multiple direct and indirect effects, the relative strength of which depended in part on the presence of large dominant species.     

粤北南方红豆杉植物群落的物种多样性和种群格局

在用样方法取样的基础上 ,分析粤北南方红豆杉生长地植物群落的物种多样性和种群分布格局 ,结果表明 :在调查地南方红豆杉出现于 5种类型的群落中 ;从物种多样性指数的平均值来看 ,灌木层的物种多样性大于乔木层 ,但乔木层和灌木层之间的 Shannon指数和群落均匀度无明显的差异 ;从乔木层和灌木层的变异系数看 ,丰富度、Shannon指数和群落均匀度均表现为乔木层 >灌木层。所调查的南方红豆杉生长地的植物群落的多样性指数和均匀度高于其他类群的南亚热带常绿阔叶林 ,但低于海南岛的热带雨林类群。南方红豆杉生长地植物群落中各优势种群均呈集群分布 ,且集群强度也都较高。南方红豆杉种群在大多数样地中亦呈集群分布     

深圳市大南山地区铁榄群落研究

对深圳市大南山地区的主要植被进行调查研究。结果表明,铁榄(Sinosideroxylon wightianum)常生长在瘠薄坡地、陡峭沟谷中,是该地区最重要的天然林群落,常组成单优势群落,呈斑块状分布,也是该地区存留的少数次生常绿阔叶林群落之一;大南山地区的铁榄群落有10个主要类型,铁榄是常绿阔叶林植被的主要特征种;大南山地区铁榄群落结构简单,物种分布不均匀,物种多样性指数差异较大;铁榄以Ⅱ级小树为主,兼有Ⅰ级苗木和Ⅲ级壮树,表明铁榄在群落中的优势度仍将保持较长一段时间;铁榄与漆树等物种间的种间联结关系薄弱,表明群落处于群落演替的早期发育阶段。     

Epiphytic (including hemiepiphytes) diversity in three timber species in the southwestern Amazon, Brazil

Forestry managers have been searching for ways to reduce the impacts of logging on Amazonian biodiversity, but some basic factors are still not considered in native forestry operations, among them the diversity of epiphytes associated with the logged trees. Our goals in this study were to determine the floristic composition, quantify the species richness, and characterize the species diversity of the vascular epiphytic community present in three timber tree species in Acre State, Brazil. We collected and identified all epiphytes in 30 randomly selected trees ≥35 cm DBH of each of three important timber species, Tabebuia serratifolia, Manilkara inundata and Couratari macrosperma. We also documented the epiphyte diversity in 120 randomly selected trees ≥35 cm DBH of 56 other species to determine whether the three timber species have different epiphyte diversity than the tree community at large. The epiphyte samples in the three timber species showed 77 species, 13 of which were new records for the flora of Acre state. The epiphyte community in the randomly selected trees presented a total of 56 species. The timber species phorophytes hosted on average three times more epiphyte species per tree than the other 120 randomly selected trees. These results show that a substantial portion of local floristic richness can be lost during logging activity due if not properly managed by rescuing epiphytes after felling the trees. Although these epiphytes could contribute positively to forestry sustainability due to their ornamental value, increasing the economic yield per hectare, there are no local initiatives for economic use of epiphytes.     

入闽台湾芒果树冠层节肢动物群落组成结构和多样性

【背景】台湾芒果是我国南方种植的最重要的热带水果之一,其分布广、产量高,极具经济价值。福建地处台湾海峡西岸,与台湾隔海相望,气候条件与台湾相仿,所以台湾芒果很容易在福建定植。然而,台湾芒果在福建的大面积种植,带来了新的虫害问题。因此,掌握台湾芒果园害虫发生的动态及规律对其防治具有重要意义。【方法】2006年8月～2007年8月对福建省惠安县台湾芒果树冠层节肢动物群落进行系统调查。【结果】共采集到28247头节肢动物,隶属于2纲15目79科145种。其中,害虫76种（占总群落物种数的52.41%）、天敌42种（占28.97%）、中性昆虫27种（占18.62%）。芒果园节肢动物的物种丰富度、个体数、群落多样性、均匀性和优势集中性等都呈明显的季节消长规律。多样性指数表现为总群落〉天敌亚群落〉中性昆虫亚群落〉害虫亚群落;均匀度表现为天敌亚群落〉中性昆虫亚群落〉总群落〉害虫亚群落;优势集中性指数表现为害虫亚群落〉中性昆虫亚群落〉总群落〉天敌亚群落。生态优势度测定显示：芒果小爪螨和茶黄蓟马是害虫中的优势种;主要天敌有腹管食螨瓢虫和园蛛科等,优势种是腹管食螨瓢虫;中性昆虫主要以双翅目的花翅摇蚊、啮虫目的凹翅单啮及膜翅目的中国小黑家蚁和红蚂蚁为主。【结论与意义】本研究为芒果园生物资源及天敌的保护与利用、芒果害虫的预测预报和持续控制提供了理论依据。     

Species richness and evenness respond in a different manner to propagule density in developing prairie microcosm communities

Diversity has two basic components: richness, or number of species in a given area, and evenness, or how relative abundance or biomass is distributed among species. Previously, we found that richness and evenness can be negatively related across plant communities and that evenness can account for more variation in Shannon’s diversity index (H′) than richness, which suggests that relationships among diversity components can be complex. Non-positive relationships between evenness and richness could arise due to the effects of migration rate or local species interactions, and relationships could vary depending on how these two processes structure local communities. Here we test whether diversity components are equally or differentially affected over time by changes in seed density (and associated effects on established plant density and competition) in greenhouse communities during the very early stages of community establishment. In our greenhouse experiment, we seeded prairie microcosms filled with bare field soil at three densities with draws from a mix of 22 grass and forb species to test if increased competition intensity or seedling density would affect the relationships among diversity components during early community establishment. Increased seed density treatments caused diversity components to respond in a different manner and to have different relationships with time. Richness increased linearly with seed density early in the experiment when seedling emergence was high, but was unrelated to density later in the experiment. Evenness decreased log-linearly with seed densities on all sampling dates due to a greater dominance by Rudbeckia hirta with higher densities. Early in the experiment, diversity indices weakly reflected differences in richness, but later, after the competitive effects of Rudbeckia hirta became more intense, diversity indices more strongly reflected differences in evenness. This suggests that species evenness and diversity indices do not always positively covary with richness. Based on these results, we suggest that evenness and richness can be influenced by different processes, with richness being more influenced by the number of emerging seedlings and evenness more by species interactions like competition. These results suggest that both diversity components should be measured in plant diversity studies whenever it is possible.     

Consistent Effects of Biodiversity on Ecosystem Functioning Under Varying Density and Evenness

Biodiversity experiments typically vary only species richness and composition, yet the generality of their results relies on consistent effects of these factors even under varying starting conditions of density and evenness. We tested this assumption in a factorial species richness x density x evenness experiment using a pool of 60 common grassland species divided into four functional groups (grasses, legumes, tall herbs and short herbs). Richness varied from 1, 2, 4, 8 to 16 species, total planting density was 1,000 or 2,000 seeds/m², and species were sown in even or uneven proportions, where one functional group was made dominant. Aboveground plant biomass increased linearly with the logarithm of species richness in all density and evenness treatments during all three years of the experiment. This was due to a convergence of realized density and evenness within species richness levels, although functional groups which were initially made dominant retained their dominance. Between species richness levels, realized density increased, and realized evenness decreased with species richness. Thus, more individuals could coexist if they belonged to different species. Within species richness levels, higher biomass values were correlated with lower density, suggesting an underlying thinning process. However, communities with low realized evenness also had low biomass values; thus high biomass did not result from species dominance. So-called complementarity and selection effects were similar across density and evenness treatments, indicating that the mechanisms underpinning the biodiversity effects were not altered. Species richness was the dominant driver of aboveground biomass, irrespective of variations in total densities and species abundance distributions at the start of the experiment; rejecting the hypothesis that initial differences in species abundance distributions might lead to different “stable states” in community structure or biomass. Thus, results from previous biodiversity experiments that only manipulated species richness and composition should be quite robust and broadly generalizable.     

新疆农田系统瓢虫资源调查与多样性研究

为全面了解新疆农田系统瓢虫资源组成以及多样性结构差异,本研究采用网捕法于2018年、2019年连续两年对新疆11个地州50个县/市/区15种农作物生境的406个采集点开展了瓢虫资源系统调查.结果表明:共获7001号瓢虫标本,隶属3亚科13属26种,其中多异瓢虫Hippodamia variegata为绝对优势种类,其个...