香港嘉道理农场次生林区碰撞诱捕网和黑光灯捕虫器采集所得鞘翅目甲虫多样性比较

本文根据1990-1995年在香港嘉道理农场次生林区采集的昆虫标本,首次分析了鞘翅目及其优势科的种类、数量和季节性变化,以及由碰撞诱捕网和黑光灯捕虫器采集所得甲虫在种类、数量和季节性上的差异。在13260号标本中,已鉴定到科的有13253号,分属45科,231种。其中,朽木甲科(Alleculidae)、毛蕈甲科(Biphyllidae)、丸甲科(Byrrhidae)、坚甲科(Colydiidae)、拟球甲科(Corylophidae)、隐食甲科(Cryptophagidae)、水缨甲科(Hydroscaphidae)、伪叶甲科(Lagliidae)、薪甲科(Lathridiidae)、泽甲科(Limnichidae)、黑蕈甲科(Zopheridae)等11个科为香港地区的首次报道,约占本次调查科总数的25％。分析表明：(1)该次生林区的鞘翅目甲虫以蛀木性为主。天牛科(Cerambycidae)、瓢虫科(Coccinellidae)、象甲科(Curculionidae)、花蚤科(Mordellidae)、金龟甲科(Scarabaeidae)、小蠹科(Scolytidae)等6科均为多样性较高(种类≥15或者个体数量≥200)的优势科。(2)鞘翅目个体数量季节性明显,每年自2月开始数量逐渐增加,6—7月为甲虫发生的高峰期,8月显著减少。各优势科甲虫的季节性也存在一定的差异,庞大的小蠹标本数量(85％)说明在此调查期间该科正处于大发生时期。(3)黑光灯捕虫器所捕的甲虫科类和种类较之碰撞诱捕网所捕不尽相同,黑光灯捕虫器所捕的甲虫数量发生高峰期比碰撞诱捕网所捕的甲虫提前一个月。(4)各项多样性指数对不同捕虫器采集所得鞘翅目的测度差异明显,黑光灯捕虫器所捕甲虫的多样度和均匀度指数高于碰撞诱捕网。     

不同稻作方式对稻田杂草群落的影响

运用半试验与调查相结合的方法,以贵州省从江县传统农业区的糯稻和杂交稻为例,研究了在水稻单作（R）、稻-鱼（R-F）和稻-鱼-鸭（R-F-D）3种不同稻作方式下稻田杂草群落的特征.结果表明：糯稻在3种稻作方式下的抑制杂草能力均优于杂交稻;R-F-D显著降低了田间杂草的发生密度,对鸭舌草、节节菜等的抑制效果达到100%,总体抑制杂草效果显著优于其他稻作方式,杂草的物种丰富度及Shannon多样性指数显著降低,Pielou均匀度指数提高,表明群落物种组成发生了很大的改变,降低了原来优势杂草的发生, 是一种较好的可达到抑制杂草效果的稻作方式.     

Of beta diversity,variance, evenness,and dissimilarity

The amount of variation in species composition among sampling units or beta diversity has become a primary tool for connecting the spatial structure of species assemblages to ecological processes. Many different measures of beta diversity have been developed. Among them, the total variance in the community composition matrix has been proposed as a single‐number estimate of beta diversity. In this study, I first show that this measure summarizes the compositional variation among sampling units after nonlinear transformation of species abundances. Therefore, it is not always adequate for estimating beta diversity. Next, I propose an alternative approach for calculating beta diversity in which variance is substituted by a weighted measure of concentration (i.e., an inverse measure of evenness). The relationship between this new measure of beta diversity and so‐called multiple‐site dissimilarity measures is also discussed.     

Darkling beetle communities in two geologically contrasting biotopes: testing biodiversity patterns by microsite comparisons

Studies at a microsite scale, where most of the environmental variation can be reduced to a few factors, may help to identify the actual contribution of a particular environmental factor to community organization. Climate is known to be an important factor for regulating animal diversity. However, for soil‐dwelling animals, the role of soil characteristics can hardly be extracted out because of the inter‐relationships between climate and soil. The community structure of soil‐dwelling darkling beetles inhabiting the two geologically highly contrasting west‐ and east‐facing slopes (WFS and EFS, respectively) of the Mediterranean island of Santorini (Greece) was investigated in a case study aiming to assess the separate influence of soil characteristics and climate. Eroded pumice soils of EFS allowed a higher abundance of darkling beetle individuals and biomass, hosting more productive vegetation and being more penetrable to fossorial larvae. Moreover, the two slopes differed significantly with respect to the abundance of certain species that are characterized by a peculiar morphological adaptation to different soil characteristics. Thus, local geological sharp divergence led to darkling beetle interslope community differences as a result of local selection towards certain species. However, the two communities are similar in terms of darkling beetle diversity, evenness, and species niche‐breadth. This demonstrates that sites sharing the same climatic conditions tend to have similarly structured darkling beetle communities, even if there are marked differences in soil characteristics that promote differences in species composition, thus suggesting that climate is the major factor for regulating species diversity. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98 , 787–793.     

福安三种不同茶园节肢动物群落的消长动态调查

根据对福建福安的3种不同茶园（天香有机茶园、北门高山茶园和溪柄平地茶园）的节肢动物群落消长动态调查。并经多样性分析,结果获知：福安3种茶园节肢动物群落的物种丰富度（s）和多样性指数（H）的大小顺序依次为：天香（S=19．64,H=2．537）〉北门（S=18．01,H=2．502）〉溪柄（S=17．59,H=2．297）;而均匀度指数的大小顺序是：北门（J=0．621）〉天香（J=0．595）〉溪柄（J=0．559）。表明植被比较丰富、人为干扰较少的茶园,节肢动物群落的物种丰富度、多样性指数和均匀度指数较高,害、益虫群落易于保持较好的平衡状态,有利于减少（或不使用）化学农药、发展绿色无公害茶叶生产。     

Community stability under different correlation structures of species’ environmental responses

The outcome of species interactions in a variable environment is expected to depend on how similarly different species react to variation in environmental conditions. We study community stability (evenness and species diversity) in competitive communities that are either closed or subjected to random migration, under different regimes of environmental forcing. Community members respond to environmental variation: (i) independently (IR), (ii) in a positively correlated way (CR), or (iii) hierarchically, according to niche differences (HR). Increasing the amplitude of environmental variation and environmental reddening both reduce species evenness in closed communities through a reduction in species richness and increased skew in species abundances, under all three environmental response scenarios, although autocorrelation only has a minor effect with HR. Open communities show important qualitative differences, according to changes in the correlation structure of species’ environmental responses. There is an intermediate minimum in evenness for HR communities with increasing environmental amplitude, explained by the interaction of changes in species richness and changes in the variance of within-species environmental responses across the community. Changes in autocorrelation also lead to qualitative differences between IR, CR and HR communities. Our results highlight the importance of considering mechanistically derived, hierarchical environmental correlations between species when addressing the influence of environmental variation on ecological communities, not only uniform environmental correlation across all species within a community.     

群落均匀度分形分析

修正了Frontier和Ricotta等关于有效物种丰富度指数A与物种丰富度指数S之间幂律关系的定义．探讨了A与S之间分形关系的生态学意义．认为分形维数D是群落均匀度测度值在物种数S不断增加的过程中．向其逼近的一个理论值;提出了利用双对数坐标上建立的A与S拟合直线的方程．对群落均匀度的4种变化趋势进行描述的方法。以广东黑石顶自然保护区森林演替系列为例．研究了针阔叶混交林和常绿阔叶林样带上．随着样带观察长度的逐渐增加群落均匀度的变化情况。结果表明．230m长的混交林样带只存在一个线性无标度区间．群落均匀度随样带长度的不断增加而逐渐降低．向分形维数D=0．810趋近。170m长的常绿阔叶林样带存在两个线性无标度区问．在0～25m的尺度域内．随着样带长度的逐渐增加均匀度不断降低．向分形维数D=0．525逼近;在30～170m的尺度域内．随着样带观察长度的增加．群落均匀度也逐渐增加．向分形维数D=0．920趋近。     

Invaded grassland communities have altered stability‐maintenance mechanisms but equal stability compared to native communities

Theory predicts that stability should increase with diversity via several mechanisms. We tested predictions in a 5‐year experiment that compared low‐diversity exotic to high‐diversity native plant mixtures under two irrigation treatments. The study included both wet and dry years. Variation in biomass across years (CV) was 50% lower in mixtures than monocultures of both native and exotic species. Growth among species was more asynchronous and overyielding values were greater during and after a drought in native than exotic mixtures. Mean‐variance slopes indicated strong portfolio effects in both community types, but the intercept was higher for exotics than for natives, suggesting that exotics were inherently more variable than native species. However, this failed to result in higher CV's in exotic communities because species that heavily dominated plots tended to have lower than expected variance. Results indicate that diversity‐stability mechanisms are altered in invaded systems compared to native ones they replaced.     

Evenness and diversity in Upper Cambrian – Lower Ordovician trilobite communities from the Central Andean Basin (Cordillera Oriental,Argentina)

Community evenness has recently received much attention, either because it is related to ecosystem functioning or because it may affect estimation of diversity. Temporal and environmental trends in diversity and evenness of trilobite communities during the Late Cambrian – Early Ordovician of the Cordillera Oriental (north‐western Argentina) are here analysed. Richness and evenness increase through time in both deep subtidal (between fair‐weather and storm wave base) and offshore (below storm wave base) communities. Two significant patterns are superimposed on this general trend: (1) the magnitude of the increase in evenness is much more pronounced in deep than in shallower settings, and (2) richness and evenness trajectories are decoupled (while a significant rise in evenness is recorded in the middle Tremadocian (Tr2), an increase in richness is delayed until the late Tremadocian (Tr3)). In contrast to expectations, a single family (Olenidae) is dominant in samples associated with this earlier rise in evenness relative to richness. Hence, this trend is explained neither by the number of families present in the communities nor by the familial identity of the most abundant taxon. Large‐scale comparisons of the timing and geographical components of these trends are restricted to the patterns recognized in Laurentian North American studies. Results from the Cordillera Oriental mirror those of Laurentia regarding the rise in both metrics in deep marine settings. Nevertheless, the timing of this increase in richness and evenness is delayed in the Cordillera Oriental, supporting the idea that palaeogeographical regions differed in the nature and timing of ecological changes. Finally, the rise in trilobite alpha‐diversity through the Late Cambrian – Early Ordovician of the Cordillera Oriental supports the idea that trilobite alpha‐diversity did not decline worldwide, suggesting that the relative decline in trilobite alpha‐diversity is most probably caused by the dilution effect.