Landscape structure and management regime as indicators of calcareous grassland habitat condition and species diversity

This study investigates the importance of spatial landscape characteristics and habitat management on the condition of calcareous grassland in the North Down Natural Area, Kent UK. We used a digitised map of the study area containing shapefiles of all the habitats including 82 patches of calcareous grassland together with management information for each patch and data on the presence and abundance of a range of calcareous grassland indicator plant species. We defined habitat condition by presence of indicator species and used classification trees to generate models with rules for predicting habitat condition from the landscape spatial characteristics and management information. We also applied the same method to investigate the factors affecting presence or diversity of three ecological groups of positive indicator species and dominance of a negative indicator species. All the models except one showed good classification accuracy and high kappa statistic. Favourable habitat condition was predicted by presence of different types of grazing management, presence of woodland around patches of calcareous grassland and shape complexity. These results indicate that calcareous grassland in favourable condition is management-dependent but also located in less intensively managed landscapes. Unfavourable habitat condition was predicted by threat factors such as lack of management and high incidence of arable or improved grassland around patches of calcareous grassland, indicating nutrient enrichment and habitat degradation. Some of these factors also predicted high diversity of the different ecological species groups. The value of this method for predicting habitat condition and species diversity from baseline ecological data for conservation monitoring at the landscape level is emphasised.     

Genetic diversity of Lotus corniculatus in relation to habitat type,species composition and species diversity

The genetic variability of Lotus corniculatus, a common and important fodder legume, was studied in relation to habitat type and to species diversity at a local level. The study was conducted in Cholomontas mountain, northern Greece, at altitudes of 760–870 m. Genetic material was selected from four forested, at the edge of forest, and four open grassland sites, and was studied with the aid of ISSR molecular markers. The plant cover at each study site was measured and the floristic composition was estimated. The percentage of graminoides increased in grassland sites with high grazing intensity, while the abundance of legumes, including L. corniculatus, forbs and woody species, increased in forested sites with low grazing intensity. Gene diversity H_E within the studied populations of L. corniculatus ranged from 0.167 to 0.213 and Shannon index (I) from 0.269 to 0.340. Genetic differentiation was detected between habitats as well as among the populations in each habitat, although it was low, 3% and 7% respectively. However, genetic differentiation was significant within the populations (90%). Genetic diversity of L. corniculatus was not correlated with species diversity (richness and evenness) either within or between populations, while was negatively correlated with L. corniculatus abundance.     

Late Miocene lagomorphs from the Republic of Moldova

The aim of this paper is to enlarge knowledge about still poorly documented and understood record of Lagomorpha (Mammalia) from the Late Miocene of Moldova. The lagomorph material from two new Late Miocene localities, Razeni (MN11/12), Gradishte (MN12), and re-sampling locality Chimislyia (MN12), of Southern Moldova, is described in detail here. The localities yielded small vertebrate fauna including five lagomorph taxa: Prolagus cf. oeningensis, “Proochotona” cf. eximia, Alilepus laskarewi, “Proochotona” sp., and Alilepus sp. P. cf. oeningensis is described for the first time in the studied area. A short review of the lagomorph record from the Republic of Moldova is provided. This contribution outlines the importance of the lagomorphs for biostratigraphic purposes, and highlighs the gaps in our knowledge related to the faunal succession in this area.     

Integrating habitat diversity into species conservation in the Mediterranean mosaic landscape

Biodiversity conservation requires strategies that encompass a variety of land uses and habitat diversity. In this study, we used sites of high ecological interest identified on the basis of the distribution of priority plant and vertebrate species to assess the implications of habitat diversity for conservation management in the Mediterranean mosaic landscape. 40% of the priority species occur in open habitats that depend on continued human presence and low-intensity land-use activities. Furthermore, 70% of the sites have more than one species habitat and 15% of sites contain more than four different species habitats. By explicitly integrating localized habitat variation, conservation planning can address the multiple conservation issues at stake in regions of high landscape diversity to provide clear and effective management objectives.     

粤东桥溪村风水林群落特征初探

在粤东梅州市桥溪村风水林设立样方,对其乔木层、灌木层和草本层植物进行调查,分析该风水林的群落特征及植物多样性。结果表明:该风水林3 000 m2的样方内,共有维管植物67种,隶属于37个科54个属,其中蕨类植物4科4属4种,裸子植物3科3属3种,被子植物30科47属60种。群落分布型以热带性分布占优势,热带属所占比例为74.08%。群落主要优势科为樟科、壳斗科、金缕梅科,优势种为细柄阿丁枫、刺毛杜鹃、鼠刺、阿丁枫。群落为常绿阔叶林,生活型以高位芽为主,占73.13%,其中又以中高位芽类型最多,约占43%。乔木层可分为三层,但以株高6~9.9 m的个体数为最多;藤本的比例高达17.91%。马尾松、杉木、细柄阿丁枫以及阿丁枫都缺少幼苗贮备,其种群属于衰退状态;而刺毛杜鹃、越南山龙眼幼苗贮备较充足,且刺毛杜鹃种群是典型的增长型种群。该风水林群落比周边其他群落有较高的物种丰富度、植物多样性,且物种分布较为均匀,种间相遇率较大。在群落不同层中,物种丰富度、Margalef指数、Shannon-Winer指数、Simpson指数、种间相遇机率乔木层均为最高,均匀度指数以灌木层较高,草本层的优势度指数最高。桥溪村风水林与粤东和华南地区的其他常绿阔叶林有很大的相似性。该风水林在粤东地区是一种典型的地带性森林,其树种组成是经过长时间对当地环境适应而形成的,具有稳定性和多功能性,对其研究可为华南地区的植物资源保护、生态公益林的保护和营造提供科学依据。     

The effect of horse, cattle and sheep grazing on the diversity and abundance of land snails in nutrient-poor calcareous grasslands

Livestock grazing is a common management practise in semi-natural grasslands in Central Europe. Different types of livestock (horses, cattle, sheep) and grazing intensity are known to affect the richness and composition of plant species. However, knowledge of grazing-dependent effects on invertebrates is limited. We examined the influence of horse, cattle and sheep grazing on the richness, abundance and composition of land snail species in 21 calcareous nutrient-poor grassland areas in the northwestern Jura Mountains, Switzerland. Grazing by different livestock species did not affect the species richness, abundance and species composition of land snails. Furthermore, the number of open-land species and the ratio of large- to small-sized snail species or individuals did not differ among the three pasture types. However, independent of livestock species, grazing intensity negatively influenced the snail fauna. Snail species richness, abundance and number of Red list species decreased with increasing grazing intensity. Grazing intensity also affected the occurrence of individual snail species (Truncatellina cylindrica, Cecilioides acicula, Candidula unifasciata and Trichia plebeia). To preserve the snail fauna in nutrient-poor grasslands, pastures can be stocked with horses, cattle or sheep. However, both maximum stocking rate (number of livestock units per hectare) and grazing duration (number of grazing days per year) must be carefully defined for the proper management of the pastures.     

Effects of species diversity on disease risk

The transmission of infectious diseases is an inherently ecological process involving interactions among at least two, and often many, species. Not surprisingly, then, the species diversity of ecological communities can potentially affect the prevalence of infectious diseases. Although a number of studies have now identified effects of diversity on disease prevalence, the mechanisms underlying these effects remain unclear in many cases. Starting with simple epidemiological models, we describe a suite of mechanisms through which diversity could increase or decrease disease risk, and illustrate the potential applicability of these mechanisms for both vector-borne and non-vector-borne diseases, and for both specialist and generalist pathogens. We review examples of how these mechanisms may operate in specific disease systems. Because the effects of diversity on multi-host disease systems have been the subject of much recent research and controversy, we describe several recent efforts to delineate under what general conditions host diversity should increase or decrease disease prevalence, and illustrate these with examples. Both models and literature reviews suggest that high host diversity is more likely to decrease than increase disease risk. Reduced disease risk with increasing host diversity is especially likely when pathogen transmission is frequency-dependent, and when pathogen transmission is greater within species than between species, particularly when the most competent hosts are also relatively abundant and widespread. We conclude by identifying focal areas for future research, including (1) describing patterns of change in disease risk with changing diversity; (2) identifying the mechanisms responsible for observed changes in risk; (3) clarifying additional mechanisms in a wider range of epidemiological models; and (4) experimentally manipulating disease systems to assess the impact of proposed mechanisms.     

Maintenance of forest species diversity and latitudinal gradient

The species diversity of trees maintained in tropical rain forests is much higher than in temperate, boreal, or seasonally dry tropical forests. Many hypotheses have been proposed for higher diversity in tropical rain forests, including: (i) higher specialization of resource use, (ii) different mode of disturbance, (iii) smaller opportunity for competition on oligotrophic soil, (iv) higher productivity, (v) more active specific herbivores and pathogens, (vi) evolutionary/ecological history. In this paper we report mathematical models for tree-by-tree replacement. First the analysis of random drift model shows that the effect of gap size to species diversity is not very strong. Second we study phenological segregation model, which has the following assumptions: Basic mechanism for many species to coexist in the community is assumed given by the storage effect of lottery model, as species differ in seasonality in peak fruit production and in the subsequent period of high regeneration ability. Gaps formed during unfavorable season accumulate and become available for regeneration in the beginning of the growing season. The resulting synchronization of regeneration opportunity jeopardizes the coexistence of many similar species in seasonal environments. Analysis of a mathematical model shows: (1) the existence of unfavorable season can greatly reduce the diversity of coexisting species. (2) Diversity in the equilibrium community can be high when niche width of each species is broad and resource use is strongly overlapped. (3) Equilibrium community may include several distinct groups of species differing in phenology of regeneration. Effect of unequal niche width and frequency dependent regeneration are also examined.     

千岛湖岛屿化对植物多样性的影响初探

选取千岛湖典型破碎化区域,研究了水库形成后引起的岛屿化对植物物种多样性的影响.在18个大中小型岛屿和一处陆地对照中设立了26个样方,调查乔木和灌木的种类和数量.乔木物种丰富度的单因素方差分析显示:F=13.0,P=0.000,说明各类岛屿间乔木物种差异极显著.多重比较发现大岛上乔木物种丰富度显著高于小岛和中岛,与对照陆地差别不大;灌木的分析显示:F=1.31,P=0.29,说明小、中、大岛和对照陆地灌木物种丰富度差异不显著.Spearman相关性分析显示乔木物种与岛屿面积显著相关,随岛屿面积增大而增加,而灌木物种相关性不显著.Shannon多样性指数分析表明,无论乔木还是灌木其多样性都是大岛最大,陆地次之,而小岛上灌木多样性指数大于中岛.Simpson优势度和Pielou均匀度分析显示,乔木样地中大岛的物种分布均匀性最好,优势种的优势度最低,而灌木样地中小岛的均匀度最高,优势种的优势度最不明显.     

Woody species diversity influences productivity and soil nutrient availability in tropical plantations

We investigated the relationship between plant diversity and ecological function (production and nutrient cycling) in tropical tree plantations. Old plantations (65–72 years) of four different species, namely Araucaria cunninghamii, Agathis robusta, Toona ciliata and Flindersia brayleyana, as well as natural secondary forest were examined at Wongabel State Forest, in the wet tropics region of Queensland, Australia. Two young plantations (23 years) of Araucaria cunninghamii and Pinus caribaea were also examined. The close proximity of the older plantations and natural forests meant they had similar edaphic and climatic conditions. All plantations had been established as monocultures, but had been colonised by a range of native woody plants from the nearby rainforest. The extent to which this had occurred varied with the identity of the plantation species (from 2 to 17 species in 0.1 ha blocks). In many cases these additional species had grown up and joined the forest canopy. This study is one of the few to find a negative relationship between overstorey plant diversity and productivity. The conversion of natural forest with highly productive, low-diversity gymnosperm-dominated plantations (young and old Araucaria cunninghamii and Pinus caribaea) was found to be associated with lower soil nutrient availability (approximately five times less phosphorus and 2.5 times less nitrogen) and lower soil pH (mean = 6.28) compared to the other, less productive plantations. The dominant effects of two species, Araucaria cunninghamii and Hodgkinsonia frutescens, indicate that ecosystem functions such as production and nutrient availability are not determined solely by the number of species, but are more likely to be determined by the characteristics of the species present. This suggests that monoculture plantations can be used to successfully restore some functions (e.g. nutrient cycling and production), but that the level to which such functions can be restored will depend upon the species chosen and site conditions. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Molecular genetic characteristics of Duchenne-Becker muscular dystrophy in the Republic of Moldova

Solution to some problems of clinical genealogical and molecular genetic study of Duchenne muscular dystrophy (DMD) in the Republic of Moldova and prenatal diagnosis aimed at preventing the birth of infants with this disease is proposed. An integrated clinical and molecular genetic study of families with a high risk of DMD has allowed its specific characteristics in the Moldovan population to be identified. The spectrum of mutations at the gene level in DMD patients and their role in prenatal and clinical diagnosis has been determined. RFLP analysis and PCR have been used to estimate the informativeness of families with a high DMD risk; prenatal diagnosis has been performed in some of them. Population analysis of the frequencies of polymorphic restriction sites have been carried out for loci pERT87-8/Tag1, pERT87-15/BamH1, and 16intron/Tag1. The results of analysis of deletion frequencies in the dystrophin gene and the frequencies of the pERT87-8, pERT87-15, and 16intron intragenic polymorphic loci have served as a basis for a strategy of molecular diagnosis. The new strategy allows the informativeness to be evaluated and, hence, clinical, preclinical, and prenatal diagnosis to be performed in approximately 94% of cases. A modified PCR method (MPCR) using the system of primers pERT87-8/Tag1 and 16intron/Tag1 has been developed for direct search for deletions. The method makes it possible to avoid diagnostic errors and decrease both the duration and the cost of the analysis.     

Macroecological patterns of species and genetic diversity in vascular plants of the Mediterranean basin

Aim We address the question of whether broad scale biogeographical structure of species diversity (SD) matches that of genetic diversity (GD) of vascular plants. Location The Mediterranean basin. Methods We normalized vascular plant species richness (SD) estimates per country using the Med‐Checklist taxonomic database. We used a linear regression analysis to correlate normalized country estimates with country longitudinal position. We also compiled published and geo‐referenced within‐population GD data for tree species, which had populations in the Mediterranean. We normalized GD estimates for each population across species. Again, we used a linear regression analysis to correlate GD with population longitudinal position. We then compared the populations’ geographical and bioclimatic trends for GD with Last Glacial Maximum (LGM) palaeo‐climate data and the species current ecological requirements. Results The eastern Mediterranean and the coast of former Yugoslavia had higher SD than other regions. There was no overall spatial structure of SD in the Mediterranean, whereas there was an east–west trend of decreasing GD. This trend for GD tended to covary with an east–west warm/wet–cold/dry trend detected during the LGM. Low elevation xerothermic pine species displayed significantly less GD than higher elevation mesothermic or mountain pine species. Main conclusions We suggest that LGM climate may have significantly shaped the current longitudinal and altitudinal patterns of GD we observed in woody taxa across the Mediterranean, although it did not affect comparable SD patterns. In particular, colder LGM summer temperatures in the western Mediterranean may have reduced population sizes significantly more than in the eastern Mediterranean. As plant species richness and GD did not covary, SD and GD may not be used as surrogates of one another in the Mediterranean basin. As they contain comparatively less GD, conservation priorities in the Mediterranean should focus on hot spots of endemism and Western Mediterranean populations and species.     

Invertebrate herbivory along a gradient of plant species diversity in extensively managed grasslands

Increasing plant diversity has long been hypothesized to negatively affect levels of invertebrate herbivory due to a lower number of specialist insect herbivores in more diverse sites, but studies of natural systems have been rare. We used a planned comparison to study herbivory in a set of 19 semi-natural montane grasslands managed as hay meadows. Herbivory was measured in transects through the plant communities, and in individuals of Plantago lanceolata and Trifolium pratense that were transplanted into each meadow. In addition, plant community biomass and arthropod abundances were determined in the grasslands. Before the first mowing in June, mean herbivory levels correlated negatively with plant species richness, as predicted by theory, but they were also significantly affected by plant community biomass and plant community composition. After mowing, herbivory levels were only significantly related to plant community composition. Damage levels in the transplants were lower than herbivory levels in the established plant communities. Most insect herbivores were generalists and not specialists. The number of insect herbivores and spiders were positively correlated and tended to increase with increasing plant species richness. Herbivory levels were correlated negatively with spider abundances. We conclude that while the predicted negative relationship between plant species richness and insect herbivory can be found in grasslands, the underlying mechanism involves generalist rather than specialist herbivores. Our data also suggest a role of natural enemies in generalist herbivore activities.Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at .     

Long-term after effects of fertilization on above-ground phytomass and species diversity in calcareous grassland

Abstract. Long-term after effects on species number and productivity in calcareous grassland were analyzed after cessation of fertilization. Three series of permanent plots were monitored yearly from 1971 to 1993. These series differed in duration of fertilization and in fertilizer composition, notably the amount of nitrogen and phosphorus. Yearly above-ground production decreased in all series after fertilization had been stopped, however at different speeds. The grass/forb ratio also decreased, while species number and Shannon index of diversity (H') increased. In the series where fertilizer treatment was stopped in 1967 (1968-series), productivity and grass/forb ratio decreased equally as in the plots where fertilization with a high nitrogen content was stopped in 1979 (80/Npk-series). However, species number in the plots of the 80/Npk-series increased faster than in the 1968-series. This was probably the result of a higher number of species present in the seed rain from the surrounding vegetation in the period after 1980 than from after 1968. In the plots receiving a high amount of phosphorus (80/nPk series), the productivity decreased more slowly than in the high nitrogen plots (80/Npk-series). At approximately the same total production level, the grass/forb ratio remained higher for another five-year period in the 80/nPk-series. Species number and the Shannon index of diversity increased more slowly in the 80/nPk-series than in the 80/Npk-series. Over a given range of productivity, changes in species number and Shannon index correlated better with the grass/forb ratio than with total above-ground phytomass. Therefore, restoration of species-rich grassland should not only be focused on lowering the yearly production, but also on reducing the grass component of the vegetation.     

神农架南坡植物群落多样性的海拔梯度格局

神农架南坡在我国植被区划中具有十分重要的意义。在神农架南坡沿海拔梯度设置50个样方进行植物物种多样性调查,通过对样方的数量分类和DCA排序,结合物种丰富度、区系分化强度、区系成分和生活型构成等方面的分析,研究神农架南坡植物物种多样性的垂直格局。结果表明：(1)神农架南坡的植被垂直带谱为：海拔900—1000m以下为常绿阔叶林;1000-1700m为常绿落叶阔叶混交林;1600—2100m为落叶阔叶林;海拔2000—2400m为针阔叶混交林;海拔2300m以上为暗针叶林。(2)植被基带群落中,在物种数量、区系成分和重要值方面,常绿和落叶阔叶树种所占的比例都相差无几。(3)植物多样性的垂直格局基本符合“单峰”模式。峰值出现在海拔1400—1500m;但混交林类型的多样性和区系分化强度较高。(4)在植物区系中,温带成分处于主导地位;世界广布属的比例随海拔上升而增加;而中国特有属仅见于海拔2000m以下。亚热带成分和东亚区域性区系成分都随海拔上升而减少,峰值都位于山地常绿落叶阔叶混交林。(5)蕨类植物丰富度随海拔上升而减小;草本植物丰富度与海拔高度之间没有呈现显著的相关关系;木本植物丰富度总体沿海拔梯度减少,但峰椎处于常绿落叶阔叶林带。针阔混交林样方的平均木本物种数也超过落叶阔叶林带。     

Temporal stability of aquatic food webs: partitioning the effects of species diversity, species composition and enrichment

Theory predicts that species diversity can enhance stability of community‐level biomass while simultaneously decreasing population‐level stability. Enrichment can theoretically destabilize communities but effects may become weaker with increasing diversity because of the inclusion of consumer‐resistant prey. Few experiments using direct manipulations of species diversity have tested these predictions. We used laboratory‐based aquatic food webs to examine the effects of species composition, diversity and enrichment on temporal variability of population‐ and community‐level biomass. We found weak effects of enrichment on population‐ and community‐level stability. However, diversity enhanced community‐level stability while species composition had no influence. In contrast, composition effects outweighed diversity effects when stability was measured at the population level. We found no negative effects of diversity on population‐level stability, in opposition to theory. Our results indicate that diversity can enhance stability in multitrophic systems, but effects vary with the scale of biological organization at which stability is measured.     

Response of plant species and life form diversity to variable fire histories and biomass in the jarrah forest of south‐west Australia

Frequent fires reduce the abundance of woody plant species and favour herbaceous species. Plant species richness also tends to increase with decreasing vegetation biomass and cover due to reduced competition for light. We assessed the influence of variable fire histories and site biomass on the following diversity measures: woody and herbaceous species richness, overall species richness and evenness, and life form evenness (i.e. the relative abundance or dominance among six herbaceous and six woody plant life forms), across 16 mixed jarrah (Eucalyptus marginata) and marri (Corymbia calophylla) forest stands in south‐west Australia. Fire frequency was defined as the total number of fires over a 30‐year period. Overall species richness and species evenness did not vary with fire frequency or biomass. However, there were more herbaceous species (particularly rushes, geophytes and herbs) where there were fewer shrubs and low biomass, suggesting that more herbaceous species coexist where dominance by shrubs is low. Frequently burnt plots also had lower number and abundance of shrub species. Life form evenness was also higher at both high fire frequency and low biomass sites. These results suggest that the impact of fire frequency and biomass on vegetation composition is mediated by local interactions among different life forms rather than among individual species. Our results demonstrate that measuring the variation in the relative diversity of different woody and herbaceous life forms is crucial to understanding the compositional response of forests and other structurally complex vegetation communities to changes in disturbance regime such as increased fire frequency.     

Plant species diversity changes in abandoned chestnut (Castanea sativa) groves in southern France

Over the last few decades, marked land use changes have taken place in many Mediterranean ecosystems. For example, many chestnut groves in France are now abandoned and have turned into 'natural' coppice stands while others are now clear-cut every 10 or 15 years for wood. Species composition and life form diversity of the plant communities have changed markedly both in the abandoned groves and in the periodically clear-cut coppice stands. What are the consequences of these changes on biodiversity at local and regional scales, and what are the implications for 'new forestry' management intended to conserve biodiversity at the same time as it optimizes productivity and profitability? To answer these questions we studied plant species diversity in the understorey strata along a successional gradient including cultivated grove; abandoned grove; young (15 years old), medium (40 years), and old (>55 years) coppice stands. The results showed that species richness decreased quickly but not steadily along this gradient, but life-form spectra data highlighted that the high levels of plant species biodiversity in cultivated groves were due primarily to the large number of therophytes (annual plants). At a shorter time scale, we also studied the consequences of experimental clear-cutting on plant species biodiversity. Direct measurements over four years showed that species richness and diversity in the understorey increased in the first two years after clear-cutting, but decreased during the 3rd and 4th years. This decrease corresponded closely with a steady increase in Leaf Area Index of the forest canopy. These results have been used to suggest some possible ways to manage the biodiversity in these ecosystems.     

The power of time: spatiotemporal scaling of species diversity

The species–area relationship (SAR) provides the foundation for much of theoretical ecology and conservation practice. However, by ignoring time the SAR offers an incomplete model for biodiversity dynamics. We used long‐term data from permanent plots in Kansas grasslands, USA, to show that the increase in the number of species found with increasing periods of observation takes the same power‐law form as the SAR. A statistical model including time, area, and their interaction explains 98% of variation in mean species number and demonstrates that while the effect of time depends on area, and vice versa, time has strong effects on species number even at relatively broad spatial scales. Our results suggest equivalence of underlying processes in space and time and raise questions about the diversity estimates currently used by basic researchers and conservation practitioners.