Variation In Species Diversity Research Articles

Density-dependent speciation alters the structure and dynamics of neutral communities.

The neutral theory of biodiversity (NTB) provides an individual-based modeling framework to study eco-evolutionary dynamics. Previous NTB models usually assumed the same per capita rate of speciation across lineages. However, population dynamics may induce macroevolutionary feedbacks that can result in variable per capita speciation rates across lineages. In this paper, with analytical and simulation approaches, we explore how different scenarios of density-dependent speciation may impact the diversity and phylogenetic patterns of neutral communities, and compare the results to predictions of the original NTB model with an invariant speciation rate. Our results show that positive per capita speciation rate-abundance relationships could result in higher species richness and evenness, enhanced stability (evidenced by higher post-disturbance recovery rates and lower temporal variability in species diversity), and higher imbalance in phylogenetic trees. The opposite patterns are predicted when per capita speciation rates decrease with abundance. Particularly, strong negative speciation rate-abundance relationships can generate a positive correlation between phylogenetic age and abundance, which has been observed in Panamanian tree species. Our findings demonstrate the importance of eco-evolutionary feedbacks for understanding long-term diversity and phylogenetic patterns in ecological communities.

Additive partitioning of testate amoeba species diversity across habitat hierarchy within the pristine southern taiga landscape (Pechora-Ilych Biosphere Reserve, Russia)

In order to better understand the distribution patterns of terrestrial eukaryotic microbes and the factors governing them, we studied the diversity partitioning of soil testate amoebae across levels of spatially nested habitat hierarchy in the largest European old-growth dark coniferous forest (Pechora-Ilych Biosphere Reserve; Komi Republic, Russia). The variation in testate amoeba species richness and assemblage structure was analysed in 87 samples from six biotopes in six vegetation types using an additive partitioning procedure and principal component analyses. The 80 taxa recorded represent the highest value of species richness for soil testate amoebae reported for taiga soils so far. Our results indicate that testate amoeba assemblages were highly aggregated at all levels and were mostly controlled by environmental factors rather than dispersal processes. The variation in species diversity of testate amoebae increased from the lowest to the highest hierarchical level. We conclude that, similarly to macroscopic organisms, testate amoeba species richness and community structure are primarily controlled by environmental conditions within the landscape and suggest that metacommunity dynamics of free-living microorganisms are driven by species sorting and/or mass effect processes.

Distinct double flower varieties in Camellia japonica exhibit both expansion and contraction of C-class gene expression.

BackgroundDouble flower domestication is of great value in ornamental plants and presents an excellent system to study the mechanism of morphological alterations by human selection. The classic ABC model provides a genetic framework underlying the control of floral organ identity and organogenesis from which key regulators have been identified and evaluated in many plant species. Recent molecular studies have underscored the importance of C-class homeotic genes, whose functional attenuation contributed to the floral diversity in various species. Cultivated Camellia japonica L. possesses several types of double flowers, however the molecular mechanism underlying their floral morphological diversification remains unclear.ResultsIn this study, we cloned the C-class orthologous gene CjAG in C. japonica. We analyzed the expression patterns of CjAG in wild C. japonica, and performed ectopic expression in Arabidopsis. These results revealed that CjAG shared conserved C-class function that controls stamen and carpel development. Further we analyzed the expression pattern of CjAG in two different C. japonica double-flower varieties, ‘Shibaxueshi’ and ‘Jinpanlizhi’, and showed that expression of CjAG was highly contracted in ‘Shibaxueshi’ but expanded in inner petals of ‘Jinpanlizhi’. Moreover, detailed expression analyses of B- and C-class genes have uncovered differential patterns of B-class genes in the inner organs of ‘Jinpanlizhi’.ConclusionsThese results demonstrated that the contraction and expansion of CjAG expression were associated with the formation of different types of double flowers. Our studies have manifested two different trajectories of double flower domestication regarding the C-class gene expression in C. japonica.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0288-1) contains supplementary material, which is available to authorized users.

Taxonomic and functional diversity of woody plant communities on opposing slopes of inselbergs in southern Brazil

Background: Inselbergs are known to influence vegetation patterns worldwide. In extra-tropical areas, opposing slopes of inselbergs have different exposures to solar radiation; for example, in southern South America, north-facing slopes are more exposed to solar radiation than south-facing slopes, both in terms of angle and period of incidence.Aims: We aim to verify whether species diversity and composition and trait convergence and divergence in woody plant communities are associated with differences in the relative solar radiation intercepted by opposing slopes of inselbergs.Methods: We estimated the relative solar radiation intercepted by opposing slopes of seven inselbergs in southern Brazilian Pampa, applying hill shading estimation (HSE) to a digital elevation model. We recorded woody individuals with a diameter at breast height ≥5 cm in 13 plots placed on north- and south-facing slopes. We tested for the association of species diversity and composition and trait convergence and divergence with HSE.Results: Variation in species diversity and composition was associated with HSE. Less exposed slopes were taxonomically more diverse than more exposed slopes. Convergence and divergence of leaf traits were associated with slope exposure.Conclusions: The low-diversity communities on more exposed slopes likely resulted from filtering by environmental variables associated with slope exposure. The higher diversity of tree communities on less exposed slopes might be attributed to diversification of strategies for resource capture and capacity of supporting more niches due to potentially higher water availability. These findings advanced our understanding of the role of slope exposure for plant community assembly in the extra-tropical South America.

Diversity of hoverfly (Diptera: Syrphidae) communities in different months in eastern part of Zanjan province, Iran

The diversity of hoverfly communities was studied during the growing season (April–September) of 2009 in the eastern part of Zanjan province. Adult specimens were collected and identified. A total of 28 species with 1019 hoverfly individuals were collected, among which Eristalis tenax (Linnaeus), Sphaerophoria scripta (Linnaeus), and Eupeodes corollae (Fabricius) were found to be the most abundant. Monthly variations in species diversity, richness, and evenness of hoverflies were compared. The highest and lowest degrees of species diversity, richness, and evenness were recorded in June and April, respectively. Adult hoverflies first appeared in April reaching a peak in July. However, later in summer their abundance started declining with a decrease recorded in September.

Human interactions with forest landscape in the Khumbu valley, Nepal

Abstract High altitude Himalayan regions are geo-dynamically active and sensitive to natural disturbances. Nonetheless, even in this remote region, human pressure is often most important in influencing forest and landscape structure. In the last decades, fuelwood demand has risen due to increasing numbers of tourists and mountaineers. To understand human interactions with forest resources, stand structure and composition were examined at the landscape scale in the Sagarmatha National Park and its Buffer Zone in the Khumbu valley (Nepal). Using biological and historical data sources, a multi-scale approach revealed the influence of human activities on the distribution of tree species and forest structure. We sampled stand structure and environmental characteristics from 173 plots, and derived anthropogenic variables from thematic maps and satellite images for multivariate statistical analyses. Results suggest relationships among forest structure, anthropogenic influences, and topography. Low-density stands (100–150 tph) with sparse trees and rare big trees were in close proximity (0–36 m) to tracks and lodges. The wide variability in species diversity (0.67 at SNP and 0.58 at BZ) was strongly related to environmental factors, such as elevation, and human pressure. The frequent removal of green branches has adverse effects on tree growth, forest resistance, resilience, and regeneration capacity. We conclude that natural resources can adequately supply the local population needs, but current practices are not sustainable.

English

Forest succession has been reported in forest plantations in tropical forests, but little is known about their successional dynamics because most studies have focused on succession in secondary forests. We assessed changes in species composition and stand structure in secondary and plantation forests in Kakamega rainforest in western Kenya. We used a nested experiment to collect data on tree species types, tree height and stem diameter at breast height from secondary forest stands, mixed indigenous plantations and indigenous and exotic monoculture plantations in three forest blocks. Data were analyzed for variation in species diversity, species similarity to the primary forest, stem density and basal area using analysis of variance in Genstat. The results indicated that species diversity and similarity to the primary forest were not different between secondary and plantation forests. However, successional species occupied all the canopy strata in secondary forests, but they occupied only the shrub and understorey layers of monoculture plantations, and the shrub, understorey and sub-canopy strata of mixed indigenous plantations. Mixed indigenous plantations had become nearly indistinguishable from secondary forests, but monoculture plantations maintained a plantation outlook. Old secondary forest had a significantly lower stem density than plantation forests, but their basal area was not significantly different. Middle-aged and young secondary forests had comparable stem density to plantation forests, but their basal area was significantly lower. The results confirmed that plantation forests are experiencing forest succession in tropical forests, their species composition and stand structure are comparable with secondary forests, but they differ in the emergence pattern of successional species and their distribution in forest canopy strata. Key words: Secondary succession, plantation forests, tropical rainforest, species composition, stand structure.&nbsp

Effects of grazing vs mowing on the functional diversity of sub‐Mediterranean productive grasslands

AbstractQuestionsIn order to preserve the ecosystem functioning of semi‐natural sub‐Mediterranean calcareous grasslands of the Central Apennines, it is vital to understand how functional diversity (FD) changes in relation to different types of disturbance. To compare the effects of sheep grazing and those of late‐summer mowing, we asked: do different types of disturbance (grazing and mowing) affect FD; are FD and species diversity positively correlated in both grazed and mown grasslands; do FD and species diversity take different paths in the two disturbance regimes; and are different FD values related to changes in the composition of traits linked to competitive ability, resource acquisition and resistance strategies?LocationGrazed and mown sites in the Central Apennines (Italy).MethodsWe performed redundancy analysis and indicator species analysis to characterize the trait composition of the two disturbance regimes. We calculated FD for each selected trait and a compound FD for multiple traits, using Rao's quadratic entropy index. Differences in FD between disturbance regimes were tested with a nested ANOVA. We performed a regression analysis between FD and species diversity indices under the two disturbance types.ResultsSpecies and functional diversity were positively correlated in both disturbance types. FD was generally less correlated with species diversity variations in mown grasslands than in grazed ones, suggesting that late mowing leads to higher levels of functional redundancy (i.e. to a wider overlap of species functional composition). Late mowing promoted higher species and functional diversities and a wider variety of functional traits in the plant community. Grazing, besides negatively affecting the species diversity of grasslands, reduced their FD by favouring the dominance of traits related to avoidance and tolerance strategies.ConclusionThe continuation of late mowing is recommended to preserve the richness and variability of functional groups and the ecosystem functioning of sub‐Mediterranean grasslands.

Seasonal and spatial variation in species diversity, abundance, and element accumulation capacities of macroalgae in mangrove forests of Zhanjiang, China

The objective of this study was to investigate whether there was distinctive seasonal and zonal variation in the species diversity, biomass, and element accumulation capacities of macroalgae in two major intertidal mangrove stand types (Avicennia marina assemblage and Sonneratia apetala assemblage) in the Zhanjiang region of southern China. Over a year, 31 species in 15 genera were identified in both mangrove assemblages, of which the dominant species were Cladophoropsis zollingeri and Enteromorpha clathrat. Macroalgal species were significantly most abundant in spring (p<0.05), followed by summer, winter, and autumn. Variation in the zonal distribution of macroalgal species was conspicuous in both intertidal mangrove assemblages, with the greatest abundance in the middle zone, and the least in the front zone. Patterns in the seasonal and zonal variation in macroalgal biomass in the S. apetala assemblage were similar to those of macroalgal species diversity in both mangrove assemblages. The seasonal patterns in tissue concentrations of 15 analyzed elements were not uniform among the macroalgae C. zollingeri, E. clathrata, and Gracilaria salicornia in the A. marina assemblage. All three species exhibited variation in their responses to ambient concentrations of different elements, implying their differential ability to absorb and selectively accumulate certain elements.

Environmental determinants of geographic butterfly richness pattern in eastern China

A long-standing task for ecologists and biogeographers is to reveal the underlying mechanisms accounting for the geographic pattern of species diversity. The number of hypotheses to explain geographic variation in species diversity has increased dramatically during the past half century. The oldest and the most popular one is environmental determination. However, seasonality, the intra-annual variability in climate variables has been rarely related to species richness. In this study, we assessed the relative importance of three environmental hypotheses: energy, seasonality and heterogeneity in explaining species richness pattern of butterflies in Eastern China. In addition, we also examined how environmental variables affect the relationship between species richness of butterflies and seed plants at geographic scale. All the environmental factors significantly affected butterfly richness, except sampling area and coefficient of variation of mean monthly precipitation. Energy and seasonality hypotheses explained comparable variation in butterfly richness (42.3 vs. 39.3 %), higher than that of heterogeneity hypothesis (25.9 %). Variation partitioning indicated that the independent effect of seasonality was much lower (0.0 %) than that of energy (5.5 %) and heterogeneity (6.3 %). However, seasonality performed better in explaining butterfly richness in topographically complex areas, reducing spatial autocorrelation in butterfly richness, and more strongly affect the association between butterflies and seed plants. The positive relationship between seed plant richness and butterfly richness was most likely the result of environmental variables (especially seasonality) influencing them in parallel. Insufficient sampling may partly explain the low explanatory power of environmental model (52.1 %) for geographic butterfly richness pattern. Our results have important implications for predicting the response of butterfly diversity to climate change.

Estrutura das comunidades de macroalgas da bacia de drenagem do rio Cascavel, Estado do Paraná, Brasil

A bacia de drenagem do rio Cascavel encontra-se quase que inteiramente dentro do perímetro urbano do município de Guarapuava, Estado do Paraná, Brasil. Foram amostrados sete segmentos de riachos em duas estações do ano (verão e inverno). Foram encontrados 12 táxons de macroalgas com dominância de Chlorophyta (sete táxons) seguido de Cyanophyta (três táxons), Heterokontophyta e Rhodophyta (um táxon cada). Riqueza, índice de diversidade e equidade foram mais elevados durante o período de inverno enquanto a abundância e dominância foram mais elevadas no verão. Entre as características microambientais, a velocidade da correnteza foi a única que diferiu significativamente entre os períodos climáticos. A Análise de Regressão revelou que a riqueza do substrato foi responsável pela variação de riqueza, diversidade, equidade e dominância de espécies durante o período de verão. Durante o inverno, a velocidade da correnteza foi responsável pela variação da diversidade de espécies. A análise de agrupamento das comunidades de macroalgas não reuniu pontos do mesmo período temporal. A Análise de Correspondência Canônica (CCA) mostrou que os segmentos aproximaram-se devido à ocorrência de uma ou poucas espécies em comum. Os padrões de distribuição espacial e temporal de macroalgas lóticas parecem fortemente influenciados por características de microhabitat em diferentes escalas, porém apoiadas em variáveis mais regionais.

Importance, but not intensity of plant interactions relates to species diversity under the interplay of stress and disturbance

The lack of clarity on how the intensity and importance of plant interactions change under the co‐occurrence of stress and disturbance strongly impedes assessing the relative importance of plant interactions for species diversity. We addressed this issue in subalpine grasslands of the French Pyrenees. A natural soil moisture gradient further experimentally stretched at both ends was used and a mowing disturbance treatment was applied at each position along the soil moisture gradient. Changes in intensity and importance of plant interactions were assessed by a neighbour removal experiment using four target ecotypes. A structural equation modelling approach was used to assess the relative impact of stress, disturbance, the intensity and importance of plant interactions on diversity at both the neighbourhood and community scales. Without mowing, changes in intensity and importance of plant interactions only diverged in the dry part of the soil moisture gradient. The intensity of plant interactions linearly shifted from competition to facilitation with increasing stress, while the importance followed a hump‐shaped relationship. Species diversity components were tightly related to the importance of plant interactions only, both the neighbourhood and community scales. Mowing disturbance strongly reduced the importance of facilitation along the soil moisture gradient, and suppressed the relationship between the importance of plant interactions and diversity components. Together, our results highlight that 1) the importance is the best predictor of variations in species diversity in this subalpine herbaceous system, and 2) that fine‐scale processes such as plant interactions can affect the entire plant communities. Finally, our results suggest that high level of constraints due to co‐occurring stress and disturbance can inhibit the effects of plant interactions on species diversity, highlighting their potential role in regulating diversity and the maintenance/extinction of plant communities.SynthesisHow plant interactions change along environmental gradients is an unsolved debate, particularly when both stress and disturbance interact. This lack of clarity explains why the relative impact of plant interactions (intensity and importance) on species diversity has been rarely assessed. Using an experimental approach, we found that the importance of plant interactions highly contributed to variation in species diversity, confirming that neighbourhood scale processes such as plant interactions can affect the entire plant communities. The co‐occurrence of stress and disturbance inhibited the effects of plant interactions, highlighting that plant interactions may regulate drops of diversity and the maintenance/extinction of plant communities.

English

This study was carried out in small water bodies (SWBs) within Uasin-Gishu and Siaya Counties of Kenya to investigate the effects of water quality on species diversity and richness of macroinvertebrates in these areas. The water quality of the SWBs was assessed in two dams in Uasin-Gishu County (Kesses and Kerita) and the other two in Siaya County (Mauna and Yenga) within Lake Victoria Basin. Water samples for total phosphorus (TP) and total nitrogen (TN) were collected at each sampling station and analyzed using standard methods and procedures. Physico-chemical parameters such as dissolved oxygen (DO), pH and temperature were taken in situ using electronic meters while biological oxygen demand (BOD) was analyzed using Winkler method after 5-days incubation period. Macroinvertebrate samples were collected using a scoop net (500 &micro;m mesh size) then transferred into a white tray for washing and sorting prior to identification. Preliminary tests of water quality parameters were evaluated by GLM analysis of variance of which very significant differences were observed for both spatial (p = 0.004) and temporal (p= 0.001) variability with the measured water quality parameters. The results showed that there is both negative and positive change of macroinvertebrate composition and abundance between SWBs over time due to spatio-temporal variation of water quality parameters. Principle Component Analysis (PCA) further confirms this. PCA described over 90% of variation at the stations. For both seasons, TN, TP, temperature, pH, DO and BOD were found to have a significant influence of the species diversity, dominance and richness of macroinvertebrates. Principle component analysis of TN, TP, DO, pH and BOD for the SWBs described 96% of their variation when they were compared at temporal and spatial scales. This trend leads to the variation in species diversity; dominance and richness of macroinvertebrates in these SWBs. Water quality and littoral invertebrate mean relative abundance were significantly different among the studied small water bodies during the study period. Overall, water quality seemed to have had effect on species diversity, dominance and richness of the invertebrate benthic community therefore can be used as a bio-monitor to aquatic health. Key words: Water quality, macroinvertebrates, species diversity and richness, small water bodies, Lake Victoria basin.

Flood disturbance and predator–prey effects on regional gradients in species diversity

The effects of both abiotic factors and biotic interactions among guilds (i.e., inter-guild effects) have been suggested to be important for understanding spatial variation in species diversity; however, compared to the abiotic effects, the processes by which the inter-guild effects are mediated have been little described. Hence, we investigated stream invertebrate assemblages on Hokkaido Island, Japan, and assessed how the processes of determining regional patterns in species diversity differed among guilds (collector-filterers, collector-gatherers/shredders, scrapers, and predators) by taking both inter-guild and abiotic effects into consideration using Bayesian networks. Collector-gatherers/shredders, collector-filterers, and predators exhibited significant regional gradients in taxonomic richness. Gradients in the former two guilds can be generated by variation in flood disturbance regardless of interactions with other guilds. The gradient in predator taxonomic richness was indirectly related to the disturbance and was directly generated by bottom-up effects through their prey (collector-gatherers/shredders and collector-filterers). We found that not only environmental factors, but also inter-guild effects may be essential for forming the regional gradient in predators, unlike those for collector-gatherers/shredders and collector-filterers. The processes underlying the regional variation in taxonomic richness of the three guilds are interpreted in terms of the "more individuals" hypothesis, facilitation, and predator-prey relationships.

Distribution and Diversity of Intertidal Macrofauna of Dharmadam Beach, South West Coast of India

This contribution presents the abundance and diversity of macrofauna in the pristine intertidal regions of Dharmadam beach along the Kerala coast (South West coast of India) during August 2009 to January 2011.The width of the beach is 15-30m, which alternates according to the tidal height. Environmental parameters like salinity, nutrients, conductivity and total dissolved salts analyzed exhibited significant correlation with macrofauna that dwells in the habitat. Gastropods (45.54%), polychaetes (10%), tanaids (43.4%) dominated in the present study. The monthly variations in abundance were displayed by dominant faunal species in various stations but did not show any seasonal variations except that of Emerita holthuisi , which was observed only in pre monsoon (Feb-May) and monsoon (Jun-Sep) months. Analysis of community indices showed monthly variations in species diversity. The peak mean species diversity was observed in station 1 in May, 2009 and Station 2 in December, 2009 and January, 2010.The spatial distribution of some organisms were not even in the study area. The sparse distribution, low richness and higher dominance of organisms were the characteristic feature of community structure. The dissimilarity trend of organisms like polychaetes, gastropods and total groups were discernible by MDS plotting. It best explained the dominance of polychaetes and gastropods on the beach. Assessing the correlation of water quality parameters to the fauna residing in study area BEST (Bio-Env + Stepwise) analysis was done and salinity showed more significance towards fauna. Draftsman plot were also done to observe the interactions of organisms. The highest correlation has been showed by barnacles and gastropods (0.825).The present study discussed the interaction of organisms in the selected habitat with environmental factors prevailing there along with the diversity and abundance.

Birds in Subsistence and Culture at Viking Age Sites in Denmark

ABSTRACTThis paper reviews the evidence for consumption and use of birds at Danish Viking Age sites. The presence and diversity of wild and domestic bird species were studied on the basis of the avian material retrieved from sites representing a wide range of different habitats covering a period from the Late Germanic Iron Age to early medieval times (ca 5th–12th centuries ad). A large diversity of at least 20 avian families with more than 60 taxa in addition to domestic fowl was documented. Although variation in species diversity and abundance in the assemblages were influenced by recovery methods, some genuine differences emerged regarding site type as well as topographical and geographic variation. Marked differences among avian species within certain bird families were revealed; herons (Ardeidae), birds of prey (Accipitridae), cranes (Gruidae), tetraonids (Tetraonidae) and waders (Scolopacidae) occurred more commonly at certain categories of sites such as high‐status manorial and early urban sites. The usage of eagle feathers was evidenced by cut marks on eagle wing bones and falconry was documented at a few high‐status sites. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Diversity pattern of adult ladybird (Coleoptera: Coccinellidae) communities on pistachio trees in southern parts of Iran in different months

The diversity of ladybird communities was monitored in planted and wild pistachio plantations during the growing season (April–October) of 2010 in the southern part of Iran. On planted pistachio trees, 20 ladybird species were identified, among which Hippodamia variegata (Goeze), Coccinella septempunctata Linnaeus and Scymnus (Pullus) scyriacus (Marseul) were found to be the most abundant. On wild pistachio trees, where 15 species were collected, the most abundant ladybird species was C. septempunctata, followed by S. scyriacus and Adalia bipunctata (Linnaeus). Monthly variations in species diversity, richness and evenness of these beetles were compared between planted and wild pistachio plantations. June and May showed the highest values of the Shannon–Wiener Index in planted and wild pistachio growing areas, respectively. Although there was some variation recorded in species composition, no significant difference was found between species diversity on planted and wild pistachio trees in different months...

Shifts in diversification rates and clade ages explain species richness in higher‐level sedge taxa (Cyperaceae)

Understanding heterogeneity in species richness across the tree of life is a challenge in evolutionary biology. The sedge family, Cyperaceae, is classified into tribes that exhibit a roughly 200-fold range in species richness. The Cyperaceae present an excellent case study in the determinants of species richness within higher-level taxa. We used secondary calibration based on prior studies and fossils from a rush (Juncaceae) and five sedges to calibrate two previously published Cyperaceae phylogenies, then compared our results to previous molecular clock analyses. We used an information-theoretic approach to identify shifts in lineage diversification rates and phylogenetic generalized least squares to fit alternative models of clade species richness. Our results suggest a late Cretaceous origin for Cyperaceae (76-89 mya). The inferred 0.06 speciation events Ma(-1) is comparable to overall diversification rates in the order Poales but faster than angiosperm background rates. A threefold increase in diversification rate at the base of the species-rich SDC+FAEC clade is correlated with climatic changes during the Paleocene-Eocene boundary (ca. 55 mya). The greater driver of among-clade variance in species richness, however, is clade age (simple R(2) = 0.334, P = 0.0006). Although shifts in diversification rates play a role in the generation of heterogeneous patterns of species richness, our study demonstrates that variance in clade age alone explains ca. 33% of among-clade variation in species diversity, which stands in contrast to the general pattern for angiosperms.

Field observed relationships between biodiversity and ecosystem functioning during secondary succession in a tropical lowland rainforest

The relationship between biodiversity and ecosystem functioning (BEF) is one of the most concerned topics in ecology. However, most of the studies have been conducted in controlled experiments in grasslands, few observational field studies have been carried out in forests. In this paper, we report variations of species diversity, functional diversity and aboveground biomass (AGB) for woody plants (trees and shrubs) along a chronosequence of four successional stages (18-year-old fallow, 30-year-old fallow, 60-year-old fallow, and old-growth forest) in a tropical lowland rainforest recovered after shifting cultivation on Hainan Island, China. Fifty randomly selected sample plots of 20 m × 20 m were investigated in each of the four successional stages. Four functional traits (specific leaf area, wood density, maximum species height and leaf dry matter content) were measured for each woody plants species and the relationships between species/functional diversity and AGB during secondary succession were explored. The results showed that both plant diversity and AGB recovered gradually with the secondary succession. AGB was positively correlated with both species and functional diversity in each stage of succession. Consistent with many controlled experimental results in grasslands, our observational field study confirms that ecosystem functioning is closely related to biodiversity during secondary succession in species rich tropical forests.

Diversity and sex ratio of thrips (Thysanoptera species) in winter wheat in Lithuania

A study on the variation of species diversity and sex ratio of thrips in winter wheat (Triticum aestivum L.) was conducted at the Lithuanian Institute of Agriculture (currently – Lithuanian Research Centre for Agriculture and Forestry). Assessments of thrips abundance were carried out from the beginning of tillering (growth stage (GS) 21) until complete maturity (Gs 89). Thirteen thrips species belonging to the three families were identified: 10 thrips species belonged to Thripidae, 2 to Phlaeothripidae and 1 to Aeolothripidae families. In terms of the feeding group, one species (Aeolothrips intermedius) belonged to zoophagous, the rest of the species were phytophagous. Frankliniella intonsa, F. tenuicornis, Haplothrips aculeatus and Limothrips denticornis were the earliest thrips species identified on winter wheat in spring. The dominating species were L. denticornis (41.3%), H. aculeatus (25.8%) and F. tenuicornis (20.5%). An average sex ratio of L. denticornis was 84.7%, and of H. aculeatus – 68.2%, and of F. tenuicornis – 71.1% and of F. intonsa – 60.9%.