In search of the best correlates for local organismal biodiversity in cultivated areas

Based on a transect consisting of 19 identical trap stations in cultivated areas and seminatural habitats, the correlation of species numbers of higher taxonomic groups with total species numbers of flowering plants and arthropods per trap site was calculated. A total of 191214 invertebrate specimens and 2221 species of plants and animals were analysed. Considering the value of the correlation coefficient R2 as well as the effort for sorting and identification, a top twenty list of indicator groups favours Heteroptera, flowering plants, Symphyta and aculeate Hymenoptera as the best choice for biodiversity evaluation. In general, flight traps rated better than pitfall traps. In most taxonomic groups, diversity indices such as the Shannon and the Simpson index were only weakly correlated with local species diversity.     

How wide to cast the net? Cross‐taxon congruence of species richness,community similarity and indicator taxa in ponds

1. Broad‐scale assessments of biodiversity often rely on the use of surrogate taxa, whose reliability has rarely been tested, particularly in freshwater systems. Here we use data from 46 ponds in two regions of the U.K. to explore the performance of macroinvertebrate taxa as surrogates for the rapid assessment of pond biodiversity. For the four dominant taxonomic groups in these ponds (Chironomidae, Coleoptera, Gastropoda and Trichoptera) we explore cross‐taxon species richness relationships in each of the two regions, and also determine the degree of concordance between the different taxa in accurately representing the similarity relationships between pond assemblages. 2. Patterns of cross‐taxon congruence in species richness were highly variable among taxa and study sites, making the use of a single taxon as a predictor of overall macroinvertebrate species richness problematic. In contrast, all four taxa show >70% congruence with the pattern of community similarity between sites resulting from the entire macroinvertebrate dataset, this result being consistent within and between regions. Canonical correspondence analysis demonstrated that all taxa were related in a similar manner to measured environmental parameters, meaning that limited additional ecological information is gained by including a wider range of pond taxa in rapid site assessment. 3. Single taxonomic groups can, therefore, perform consistently as indicators of community similarity between ponds, and no one taxon dramatically outperforms any other in this respect. The relative merits of the four focal taxa as surrogates for pond invertebrate assemblage composition are discussed with reference to ease of survey, ease of identification and ecological range occupied. 4. It is suggested that Coleoptera have a number of advantages as a surrogate taxon, being diverse, easily sampled, readily identified, taxonomically stable, ecologically well understood and occurring across a wide spectrum of pond types. They are therefore recommended for use as a focal group in rapid pond biodiversity assessments, employing an approach such as ours, which examines patterns of assemblage similarity, rather than species richness alone.     

Assessing fern diversity: relative species richness and its environmental correlates in Uganda

Techniques for the rapid quantification of tropical biodiversity are of critical importance in deciding where to invest scarce conservation resources. Here we describe a simple survey method for assessing species-level richness of a poorly known plant group, the pteridophytes. We then illustrate the use of a powerful, rarefaction- based technique of controlling for inevitable differences in sampling effort to calculate the relative species richness of our study sites. Lastly, we explore how closely observed patterns of relative species richness of Ugandan forests are correlated with a suite of simple environmental variables. We find that fully 75% of the variance in our estimate of fern diversity can be predicted from just two measures: soil fertility (scored as C/N ratio, itself related to rainfall); and distance from the nearest putative Pleistocene refugium.     

Surrogates in marine benthic investigations ‐ which taxonomic unit to target?

Although the identification of organisms to the levelof species is the ideal in studies of marinemacrobenthos, there are situations where such a finelevel of taxonomic discrimination may be eitherimpossible or unwarranted, for example when much thefauna is undescribed, or if the task for which samplesare collected does not require them to be identifiedto the species level. The idea that abundances ofhigher taxa, or particular groups of organisms, may beused as surrogates for the total fauna in such studiesis explored in this paper using data from theNorwegian sector of the North Sea. The generalconclusion is that, in surveys of soft sedimentmacrofauna in disturbed areas of the North Sea wherepollution imposes simple spatial gradients on thebenthic communities, little information aboutinter-sample relationships is lost using data based onfamily, polychaete species, or polychaete familyabundances, rather than species abundances. In morepristine areas where spatial patterns are determinedby a number of processes, correlations betweencalculated diversity indices and similarity in faunalpatterns between species and family abundances arestill very high, but less so for polychaete species orpolychaete family abundances. This suggests thatidentification to the level of family may besatisfactory in many routine monitoring surveys,andidentification of only the polychaetes, either to thelevel of species or family, may also be a possiblealternative if there are clear disturbance gradientsin the survey area. Polychaetes are of importance indisturbed areas because the group contains tolerantand intolerant species, and in undisturbed areasbecause within the taxon species have a greater rangeof trophic and reproductive strategies than withinother taxa. Ultimately it is the distribution ofspecies, their identities, and their interactions witheach other and with the environment, that are ofinterest. The use of surrogates is likely to be mostadvantageous if it is only the extent of pollutioneffects from a discrete source that matters, andspecies level baseline studies have already beencompleted.     

Shortcuts in biodiversity research: What determines the performance of higher taxa as surrogates for species?

Biodiversity research is often impeded by the time and resources required to identify species. One possible solution is to use higher taxa to predict species richness and community composition. However, previous studies have shown that the performance of higher taxa as surrogates for species is highly variable, making it difficult to predict whether the method will be reliable for a particular objective. Using 8 independent datasets, I tested whether higher taxa accurately characterize the responses of beetle and ant communities to environmental drivers. For each dataset, ordinations were carried out using species and higher taxa, and the two compared using the Procrustes m² statistic (a scale‐independent variant of Procrustes sum of squares). I then modelled the relationship between five hypothesised explanatory variables and 1) Procrustes m², and 2) the coefficient of determination (R²) for the correlation between richness of species and higher taxa. The species to higher taxon ratio, community structure, beta diversity, completeness of sampling, and taxon (beetles or ants) were all significant predictors of m², together explaining 88% of the variance. The only significant predictor of R² was the species to higher taxon ratio, which explained 45% of the variance. When using higher taxa to predict community composition, better performance is expected when the ratio of species to higher taxa is low, in communities with high evenness and high species turnover, and when there is niche conservation within higher taxa. When using higher taxa to predict species richness, effective surrogacy can be expected when the species to higher taxon ratio is very low. When it is not, surrogacy performance may be strongly influenced by stochastic factors, making predictions of performance difficult.     

Prehistoric human impact on rainforest biodiversity in highland New Guinea

In the highlands of New Guinea, the development of agriculture as an indigenous innovation during the Early Holocene is considered to have resulted in rapid loss of forest cover, a decrease in forest biodiversity and increased land degradation over thousands of years. But how important is human activity in shaping the diversity of vegetation communities over millennial time-scales? An evaluation of the change in biodiversity of forest habitats through the Late Glacial transition to the present in five palaeoecological sites from highland valleys, where intensive agriculture is practised today, is presented. A detailed analysis of the longest and most continuous record from Papua New Guinea is also presented using available biodiversity indices (palynological richness and biodiversity indicator taxa) as a means of identifying changes in diversity. The analysis shows that the collapse of key forest habitats in the highland valleys is evident during the Mid–Late Holocene. These changes are best explained by the adoption of new land management practices and altered disturbance regimes associated with agricultural activity, though climate change may also play a role. The implications of these findings for ecosystem conservation and sustainability of agriculture in New Guinea are discussed.     

An assessment of animal species diversity in continental waters

There is a need for monitoring the status and trends of freshwater biodiversity in order to quantify the impacts of human actions on freshwater systems and to improve freshwater biodiversity conservation. Current projects carrying assessment of freshwater biodiversity focus mainly on leading-better-known groups such as fish, or identify keystone species and/or endemic freshwater systems for conservation purposes. Our purpose is to complete these existing projects by providing quantitative estimates of species number for all freshwater groups on each continent and/or major eco-regions. This article present the results of the first implementation phase carried out from September 2002 to June 2003 and which addressed only freshwater animal species. The project consisted of: (1) compiling existing data from literature, web sites and museum collections; (2) contacting scientific experts of each group to provide a ‘to the best of their knowledge, estimates of species numbers. In this study, we consider as true freshwater species, those that complete part or all of their life cycle in freshwater, and water-dependant species those that need freshwater for food or that permanently use freshwater habitats. The current order of magnitude for known freshwater animal species world wide is 100 000, of which half are insects. Among other groups, there are some 20 000 vertebrate species; 10 000 crustacean species and 5000 mollusc species that are either true freshwater or water-dependant species. The study highlighted gaps in the basic knowledge of species richness at continental and global scales: (1) Some groups such as Protozoa, nematodes or annelids have been less studied and data on their diversity and distribution is scarce. Because current richness estimates for these groups are greatly biased by knowledge availability, we can expect that real species numbers might be much higher. (2) Continents are not equal in the face of scientific studies: South America and Asia are especially lacking global estimates of species richness for many groups, even for some usually well-known ones such as molluscs or insects. The second phase of the project will address freshwater plants and algae. The present status should be considered as a first sketch of the global picture of freshwater biodiversity. We hope that this project will initiate interactive exchange of data to complete and update this first assessment.     

Gastropod diversity,distribution and abundance in habitats with and without anthropogenic disturbances in Lake Victoria,Kenya

We investigated freshwater gastropod diversity, abundance and distribution in habitats with and without anthropogenic disturbance in two localities, Ndere in the Winam Gulf and Mbita Point, Lake Victoria, Kenya, from May 2002 to January 2004. A total of 133 984 gastropod specimens belonging to 15 species were recorded, 14 from Mbita and 12 from Ndere. Two species, Ferrissia kavirondica and Cleopatra cridlandi, which were recorded only from undisturbed habitats, could be indicators of least disturbed habitats. Water chemistry did differ between fish landing sites and undisturbed habitats at some sampling times, indicating that differences due to human impact do exist, but these are dependent on periods of calm weather. The study shows that anthropogenic disturbances cause ecological changes that can be exploited by some snail species, especially Biomphalaria choanomphala and Melanoides tuberculata, while other species may not tolerate these changes. In order to protect gastropod diversity and avoid dominance of intermediate hosts, such as B. choanomphala, a management plan for the use of these fish landing sites should be developed. This could include rules on how to dispose of fish remnants and other wastes so as to reduce local eutrophication, thereby reducing risks associated with transmission of potential snail-borne diseases.     

一种基于公众科学数据的区域性鸟类多样性评价方法

鸟类是理想的生物多样性指示类群。中国观鸟记录中心(以下简称“记录中心”)是目前中国最大的鸟类监测公众科学数据平台, 其记录覆盖94%的全国鸟种和94.3%的县级行政区。本研究基于公众科学数据, 参考《区域生物多样性评价标准》(HJ 623-2011)中的受胁物种丰富度指数, 构建了鸟类丰富度指数(R_{B_A})和珍稀濒危鸟类丰富度指数(R_{TB_A}), 继而提出一种对区域鸟类多样性进行评价的新方法。本研究计算了自2014年起, 各省级、地级、县级行政区(不含市辖区)每年在记录中心的累积记录鸟种数对官方发布鸟种数的覆盖率和省级行政区记录的累积珍稀濒危鸟种数对官方发布数据的覆盖率, 并计算了自2018年起各级行政区每年的R_{B_A}和R_{TB_A}, 以了解各地鸟类丰富度指数的逐年变化情况, 并分析记录中心数据集的发展趋势和两个指数的敏感性。分析结果表明, 记录中心数据对全国各级行政区的鸟种覆盖率自2014年起逐年增加, 在2023年分别有94.1%的省级、59.0%的地级和49.0%的县级行政区(不含市辖区)的鸟种覆盖率超过90%; 记录中心的累积珍稀濒危鸟种数据在省级行政区的覆盖率亦呈上升趋势, 但略低于所有鸟种覆盖率。自2020年起, 全国每年观测到的鸟种数量呈逐年增加趋势, 但其中部分省份每年观测到的鸟种总数在2022年出现下降。自2020年起, 各省级行政区的R_{B_A}和R_{TB_A}整体呈现上升趋势。R_{B_A}范围为0.50-0.96, R_{TB_A}范围为0.45-0.98, 显示R_{TB_A}更为敏感。本研究结果表明, R_{B_A}和R_{TB_A}在本地用户提交记录数量充足的地区有较大的应用价值, 可作为生物多样性评价指标应用。R_{TB_A}对于鸟类多样性的变化更为敏感, 更能体现在地鸟类保护状况。随着记录中心等公众科学平台的发展, 以R_{B_A}和R_{TB_A}为代表的基于公众科学的评价指数在物种多样性评估和物种监测方面有巨大的应用潜力。     

生物多样性与生态系统功能:进展与争论

生物多样性与生态系统功能的关系已成为当前人类社会面临的一个重大科学问题,生物多样性的空前丧失,促使人们开展了大量研究工作来描述物种多样性-生态系统功能关系,并试图揭示多样性与系统功能关系的内在机制,本文将多样性对生态系统功能作用机制的有关假说分为统计学与生物学两大类：前者是从统计学角度来解释观察到的多样性-系统功能模式,包括抽样效应,统计均衡效应等;而后者是基于多样性的生物学效应给出的,包括生态位互补,种间正相互作用,保险效应等,本文较为详细地介绍了该领域内有代表性的实验工作,包括“生态箱”实验,Cedar Creek草地多样性实验,微宇宙实验,欧洲草地实验,以及在这些实验结果解释上的激烈争论。     

Regional patterns of diversity and estimates of global insect species richness

The total number of insect species in the world is an important if elusive figure. We use a fresh approach to estimate global insect species richness, based on biogeographic patterns of diversity of well or better documented taxa. Estimates generated by various calculations, all variations on a theme, largely serve to substantiate suggestions that insect species are likely to number around 10 million or less.