Increase In Number Of Species Research Articles

Anti-seasonal flooding drives substantial alterations in riparian plant diversity and niche characteristics in a unique hydro-fluctuation zone.

Human-induced disturbances such as dam construction and regulation have led to widespread alterations in hydrological processes and thus substantially influence plant characteristics in the hydro-fluctuation zones (HFZs). To reveal utilization of limited resources and mechanisms of inter-specific competition and species co-existence of plant communities based on niche breadth and overlap under the different HFZs of the Three Gorges Reservoir (TGR) in China, we conducted a field investigation with 368 quadrats on the effects of hydrological alterations on plant diversity and niche characteristics. The results showed anti-seasonal flooding precipitated the gradual disappearance of the original diverse niches, resulting in the reduction of plant species richness and functional diversity and more obvious competition among plant species with similar resource requirements. Annuals, perennials and shrubs accounted for 71.23%, 27.39% and 1.37%, respectively, suggesting that annuals and flood-tolerant riparian herbs were favored under such novel flooding conditions. A consistent increase in species number, Shannon-Wiener diversity index and Simpson dominance index with altitude was inconsistent with hump-shaped diversity-disturbance relationship of the intermediate disturbance hypothesis, while the opposite trend was observed for the Pielou evenness index. This species distribution pattern might be caused by several synergetic attributes (e.g., the submergence depth, plant tolerant capacity to flooding, life form, dispersal mode and inter-specific competition). Vegetation types shifted from xerophytes to mesophytes and eventually to hygrophytes with the increasing flooding time in the HFZs. Hydrological alterations proved to be the paramount driver of vegetation distribution in the different HFZs. The niche analysis provided the first insights on the mechanisms of resource utilization and inter-specific competition, of which annuals could germinate quickly after soil drainage to achieve the greatest competitive advantages and occupy a larger niche space than other plants. Vegetation was still in the early stage of primary succession in the novel riparian forests. Therefore, vegetation restoration strategies should be biased towards herbaceous plants, due to annuals with better environmental adaptability, supplemented by shrubs and small trees. To establish a complete reference system for vegetation restoration, natural vegetation monitory plots in the different succession stages should be established in the different HFZs of the TGR, and their environmental conditions, community structures and inter-specific relationships further analyzed.

Establishing grassland mixtures on mine wastes – a two-year mesocosm study

Plant growth on mine wastes is restricted by the lack of water, nutrients, phytotoxic responses and the absence of a seedbank. In a mesocosm study, we addressed the establishment of vegetation on metalliferous mine wastes from two seed mixtures. Besides the composition of the vegetation and the increase in plant cover and biomass over time, we studied concentrations of heavy metals in the shoot and analyzed the quantity of throughflow, its pH and EC to follow pollutant discharge. We hypothesized that the types of mine wastes and sown grasslands will affect species composition and the formation of a protective plant cover. Our platform was well-suited to study build-up and succession of a vegetation layer and its potential to stabilize mine wastes. However, the establishing community was less diverse than expected. The dilution of wastes increased species number and biomass, and we found a reduction of material discharge with increasing vegetation cover. Over time, drainage was reduced, while pH of the throughflow did not change. However, it was higher under the addition of greywater. Interestingly, the use of greywater led to a higher biomass in one mixture and slight changes in the chemistry of the throughflow and the plant matter.

A theoretical study of the signal enhancement mechanism of coaxial DP-LIBS

In the field of dual-pulse laser-induced breakdown spectroscopy (DP-LIBS) research, the pursuit of methods for determining pulse intervals and other parameters quickly and conveniently in order to achieve optimal spectral signal enhancement is paramount. To aid researchers in identification of optimal signal enhancement conditions and more accurate interpretation of the underlying signal enhancement mechanisms, theoretical simulations of the spatiotemporal processes of coaxial DP-LIBS-induced plasma have been established in this work. Using a model based on laser ablation and two-dimensional axisymmetric fluid dynamics, plasma evolutions during aluminum–magnesium alloy laser ablation under single-pulse and coaxial dual-pulse excitations have been simulated. The influences of factors, such as delay time, laser fluence, plasma temperature, and particle number density, on the DP-LIBS spectral signals are investigated. Under pulse intervals ranging from 50 to 1500 ns, the time evolutions of spectral line intensity, dual-pulse emission enhancement relative to the single-pulse results, laser irradiance, spatial distribution of plasma temperature and species number density, as well as laser irradiance shielded by plasma have been obtained. The study indicates that the main reason behind the radiation signal enhancement in coaxial DP-LIBS-induced plasma is attributed to the increased species number density and plasma temperature caused by the second laser, and it is inferred that the shielding effect of the plasma mainly occurs in the boundary layer of the stagnation point flow over the target surface. This research provides a theoretical basis for experimental research, parameter optimization, and signal enhancement tracing in DP-LIBS.

Chondrichthyes in the north-western Ionian Sea (central Mediterranean): Species diversity, abundance and spatio-temporal changes

This study provides an updated list of fish in the Class Chondrichthyes sampled during all research projects conducted in the north-western Ionian Sea from 1985 to 2020. A total of 36 Chondrichthyes species belonging to 8 orders and 19 families were detected, most of them distributed over a wide depth range, between shelf and slope. For species assessed by the International Union for Conservation of Nature (IUCN), 8 species are listed as Critically Endangered, 3 as Endangered, 6 Vulnerable and 5 as Near Threatened species. The distribution of cartilaginous fish was examined exploring the historical series of MEDITS data (1995–2020. Changes in the species diversity and in their abundance with time and space were detected and some environmental and anthropogenic drivers that could have caused these changes were analysed. An increase in the presence, number of species and biomass of Chondrichthyes was detected from 1995 to 2020. The GAM analyses seem to indicate that the observed increase in species number and biomass is due to the decrease in fishing capacity and increase in salinity and temperature on the bottom. Furthermore, for the most abundant species, Galeus melastomus, an increase of biomass, size and a deeper distribution over the last 26 years were detected. Significant changes in biomass were also observed for other abundant species in the study area (Scyliorhinus canicula and Raja miraletus). The increase in biomass over time, different from several Mediterranean observations, is discussed in relation to the presence of refuge areas in the north-western Ionian Sea.

High species diversity of Phintella and Phintella-like spiders (Araneae: Salticidae) in Vietnam revealed by DNA-based species delimitation analyses.

Salticidae (jumping spiders) usually exhibit pronounced sexual dimorphism in adult morphology, particularly body coloration and size and shape of the first legs. Consequently, the male and female from the same species might be erroneously assigned to different species or even different genera, which could generate synonymies in classification if only morphological data were used. Phintella is a species-rich genus of Salticidae, which currently exhibits 76 named species. However, the male-female counterpart is unknown for nearly half of the species. In this study, we used a molecular approach to delineate the species boundaries for Phintella and Phintella-like specimens collected in Vietnam, using morphological information as supporting data. We used three gene fragments (mitochondrial COI, 16S-ND1, and nuclear 28S) and biogeographical considerations for species delimitation. A total of 22 putative species were recognized: 18 species of the genus Phintella, one species of the genus Lechia (L. squamata), and three species of the genus Phinteloides. Eleven undescribed species were discovered, of which seven have a male-female combination, two species have only males, and two species have only females. The crown age of Phintella was estimated at the Serravallian stage of the Miocene after the increase of species number around 16 MYA. The crown ages of most putative species recognized in this study were estimated in the Pleistocene, and the divergence among sister species likely occurred from the mid-Miocene to the Pliocene. Our ancestral range reconstruction results showed that the diversification of our ingroup was governed by progressive dispersal events, i.e., Phintella and their related species in Vietnam diversified while expanding their range on the continent. Our results provide fundamental biodiversity data for a high-diversity genus in Vietnamese Phintella spiders.

Species richness estimation of the Afrotropical Darwin wasps (Hymenoptera, Ichneumonidae).

Species richness is one of the fundamental metrics of biodiversity. Estimating species richness helps spotlight taxonomic groups that are particularly under-studied, such as the highly diverse Darwin wasps. The only available estimate of the number of Darwin wasps in the Afrotropics proposed almost 11,000 species, compared to the 2,322 recorded species. However, it relied exclusively on the ratio of morphospecies to described species in Henry Townes' personal collection. We provide an updated estimate of the Afrotropical Darwin wasp species, using empirical data from multiple sources, including the increase in species numbers following generic revisions, morphospecies sorting in natural history collections, and diversity patterns of better-studied insects (butterflies) for extrapolation. Our analyses suggest that our knowledge of Darwin wasps is highly incomplete, with only 13-22% of species known in the five most extensively studied countries in the Afrotropics. We estimate 9,206-15,577 species of Darwin wasps within the entire Afrotropics, with the highest concentration expected in the Equatorial Afrotropics and Madagascar. Due to data constraints, our approach tends to underestimate diversity at each step, rendering the upper estimate (15,577 species) more realistic. We highlight reasons contributing to the gap between recorded and estimated species richness, including logistical and financial factors, as well as post-colonial influences.

Aquatic hyphomycete assemblages of Abies sachalinensis leaf litter immersed in a stream in Hokkaido, Japan

ABSTRACT Aquatic hyphomycetes are key decomposers of plant-litter in freshwater environments. Previous studies have shown that conifer needles are colonized less frequently by aquatic hyphomycetes than broad-leaf species. Sakhalin fir (Abies sachalinensis) is the most common coniferous tree species planted for timber production in Hokkaido, Japan. Herein, we investigated aquatic hyphomycete assemblages involving Sakhalin fir needle litter and compared them with those of broad-leaf tree species, including Japanese oak (Quercus crispula) and Japanese linden (Tilia japonica), during immersion in a stream. Seventy percent of the total fungal species observed in fir needles were also observed in broad-leaf litter. However, the structure of the aquatic hyphomycete assemblages differed between the fir and two broad-leaf species, especially in the middle to late stages of the immersion period. The increase in species number and conidia number in fir needles was slower than that in oak leaves in the early stages of the immersion period. However, they continued to increase rapidly relative to the broad-leaf tree litter during the middle stages of the immersion period. These results suggest that fir needle litter was not difficult for aquatic hyphomycetes to colonize in the middle to late stages of the immersion period.

Environmental Factors Affecting Distribution and Diversity of Phytoplankton in the Irkutsk Reservoir Ecosystem in June 2023

Studying correlations between phytoplankton communities and environmental factors is critical for understanding how aquatic ecosystems function. The high sensitivity of phytoplankton to changes in these factors makes it possible to control the state of the ecosystem of water bodies. Artificial lakes often demonstrate increased trophic status, inducing changes in phytoplankton structure. In this paper, we studied phytoplankton in June 2023 (hydrological spring) in two ecosystems, South Baikal and the Irkutsk Reservoir, that are connected by a water course but have different environmental parameters. The gradient of environmental parameters from the lake towards the reservoir revealed peculiarities in the distribution of some microalgae species. Microscopy and statistical analysis showed that water temperature was the most important factor affecting the structure of the communities. The warmer water of the reservoir, in contrast to the lake, demonstrated a twofold increase in species number, abundance, and biomass. Downstream from the reservoir, we observed a succession in the dominating Baikal species complex, its supplementation, and replacement with other species typical of the summer period and Baikal bays. The trophic status of the reservoir during the study may be described as oligotrophic, with local traits of mesotrophicity; its water refers to Class I and Class II and may be qualified as clean.

Establishment and analysis of biodecomposition model based on cellular automata

In order to explore the relationship between the number and type of species in a plant community and the adaptability of the community to drought environment, we built an optimized cellular automata model to simulate the iteration of individuals in the community. We simplified the model and added random parameters to focus on the correlation between these two quantities, which is also the methodological philosophy of our global model architecture. After many simulations, we found that: the adaptability of community to drought with the increase of species number, effects of species type on community adaptability 3. In the face of current pollution and habitat loss, our model has some implications for strategies to increase long-term community survival.

The latitudinal gradient of functional diversity of Miocene marine mollusks from Chile

Understanding latitudinal variations in biodiversity is central for biogeography. Along the coasts of the Southeast Pacific, several taxa show inverse latitudinal patterns of biodiversity, i.e. increasing species numbers from lower to higher latitudes. A plausible explanation for these patterns is that fjords, formed during the Pleistocene glaciations, increased the diversity of available biotopes that allowed for higher diversity in high latitudes. Assessing this hypothesis requires us to analyze latitudinal patterns of functional diversity (which is intimately related to niche use) in the absence of fjords, i.e. earlier than their formation. Here we test if the fossil record before the generation of fjords shows higher functional diversity at lower than at higher latitudes (a ‘regular' functional diversity gradient).We analyzed four components of functional diversity (functional richness, functional divergence, functional dispersion and functional evenness) for a fossil marine mollusk fauna from the lower Miocene (~18 million years ago) across four regions spanning more than 10 latitudinal degrees of the Chilean coast (between ~34°S and 45°S).The functional richness of gastropods and bivalves decreased non‐linearly from low to high latitudes. Contrarily, the functional evenness of gastropods remained relatively constant across the region and that of bivalves peaked at 45°S. The functional divergence and functional dispersion of taxonomic groups did not exhibit clear patterns of latitudinal variation. The multivariate analysis uncovered non‐linear latitudinal patterns in the abundance of functional groups (gastropods and bivalves), with the largest abundance towards lower latitudes.These results suggest that the niche breadth of mollusk assemblages might have decreased with latitude in the lower Miocene. This work can shed light on the mechanisms underlying the latitudinal variation of diversity observed today, offering a better understanding of how these patterns changed over time.

How the living world evolved and where it's headed now.

The growth of life on Earth over more than 4 billion years has experienced five major extinction events, each followed by a period of rapid increase in species number. When organisms first invaded the land about 480 million years ago, another explosive proliferation of species followed. Our species, Homo sapiens, appeared some 300 000 years ago, developed agriculture about 11 000 years ago and grew rapidly to some 7.8 billion people, who are currently consuming about 175% of the sustainable productivity available worldwide. By mid-century (2050), we will have grown to about 9.9 billion. Wealth is very unequally distributed. Meanwhile, the Earth's mean temperature has increased by 1.1°C above pre-industrial levels, and we are on track for a total increase of 2.6 to 3.9°C. We are driving species to extinction at a rate unprecedented for the past 66 million years. These changes promise to be disastrous for the maintenance of civilization. Indeed, our only hope for a sustainable future will be for us to find a way to overcome our unremitting greed at all levels and to love one another while building social justice. This article is part of the theme issue 'Ecological complexity and the biosphere: the next 30 years'.

Niche conservatism limits the distribution ofMedicagoin the tropics

The increase in species number from poles to the equator is one of the most fundamental patterns in ecology. Although several hypotheses have been proposed, there is a lack of consensus on the mechanisms underlying this pattern. While most hypotheses provide plausible explanation for high tropical diversity of tropical clades, it is unclear if similar mechanisms drive the diversity of extra‐tropical clades. Here, we investigated the environmental drivers influencing the diversity pattern of a Mediterranean plant genusMedicagoand dissect their effects across continents and biomes. We compiled a comprehensive dataset on the distribution of allMedicagospecies and mapped their distribution at the spatial resolution of 100 × 100 km2. We used generalized linear models to quantify the relative effects of environmental factors on the richness patterns ofMedicagoand its two life forms. Next, using geographically weighted regression, we explored the variation in richness–environment relationship across latitude. We found that Quaternary climate change and environmental energy were important explanatory variables, and their effects were consistent at global, continental and biome scales. However, we found contrasting effect of environmental energy in temperate and tropical regions, with species richness increasing with energy in the temperate and decreasing in the tropics. We also found strong affinity ofMedicagospecies to its ancestral Mediterranean climatic niche. Our results suggest that the spatial variation inMedicagorichness patterns may be strongly influenced by heat tolerance as opposed to the tropical clades that depend upon cold tolerance. This dependency on heat tolerance can be attributed to strong niche conservatism exhibited byMedicagospecies. Our findings provide new insights into the richness‐energy hypothesis and suggest that high environmental energy may not necessarily yield high species diversity but may also lower species diversity, especially of extra‐tropical clades towards the tropics.

Predator interference and complexity\u2013stability in food webs

It is predicted that ecological communities will become unstable with increasing species numbers and subsequent interspecific interactions; however, this is contrary to how natural ecosystems with diverse species respond to changes in species numbers. This contradiction has steered ecologists toward exploring what underlying processes allow complex communities to stabilize even through varying pressures. In this study, a food web model is used to show an overlooked role of interference among multiple predator species in solving this complexity–stability problem. Predator interference in large communities weakens species interactions due to a reduction in consumption rates by prey-sharing species in the presence of predators in response to territorial and aggressive behavior, thereby playing a key stabilizing role in communities. Especially when interspecific interference is strong and a community has diverse species and dense species interactions, stabilization is likely to work and creates a positive complexity–stability relationship within a community. The clear positive effect of complexity on community stability is not reflected by/intraspecific interference, emphasizing the key role of interspecific interference among multiple predator species in maintaining larger systems.

2013-2018年武夷山亚热带常绿阔叶林乔木层动态

PDF HTML阅读 XML下载 导出引用 引用提醒 2013-2018年武夷山亚热带常绿阔叶林乔木层动态 DOI: 10.5846/stxb202007051746 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中央级公益性科研院所基本科研业务专项（GYZX200203）；生态环境部生物多样性保护重大工程（ZDGC2019-007-04）；中央级科学事业单位修缮购置专项（2060503） Dynamics of arbor layer in the Subtropical Evergreen Broad-leaved Forest in the Wuyi Mountains, Fujian Province, southeastern China in 2013-2018 Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:从植物群落组成和结构的角度研究森林群落的演替规律，是探究森林群落的退化与恢复过程及相关机制的重要途径，对于指导天然林保护和恢复具有重要理论价值和实践意义。2018年，对面积为9.6 hm2的武夷山亚热带常绿阔叶林样地进行了第2轮调查，并从重要值、物种多度、物种丰富度、Shannon-Wiener多样性指数、Simpson指数、Margalef丰富度指数、Pielou均匀度指数、死亡率、补员率、种群大小变化率、相对适合度、胸径变异系数等角度分析了乔木层群落动态。结果表明：2018年的乔木个体为48科88属174种，较2013年增加了1种。Margalef丰富度指数上升，Shannon-Wiener多样性指数、Simpson指数、Pielou均匀度指数均略有下降。DBH≥1 cm的乔木个体从68336个减少到63897个，共死亡7430个个体，补员2991个个体。群落的年死亡率为2.30%，年补员率为0.96%，种群大小变化率为-1.34%，相对适合度为0.42。群落的平均胸径从5.02（±0.02） cm上升为5.49（±0.03） cm。28个重要值之和由71.92%下降为71.81%，年死亡率为2.46%，年补员率为0.79%，种群大小变化率和相对适合度分别为-1.67%和0.46。物种数增加和群落总个体数下降对Margalef丰富度指数的上升产生直接影响。常见种减少，稀有种增加，预示着一般性扰动会给常见种的种群带来更大的影响。建落种或优势种的缺乏且许多物种优势程度接近，可能使处于同一林冠层的树种对光照等资源的激烈竞争产生导致的高死亡率和低补员率。赤杨叶（Alniphyllum fortunei）、木荷（Schima superba）等阳生树种的种群更新困难可能意味着群落发生了有利于中生和阴生树种的变化。 Abstract:Studying the forest community succession by understanding the characteristics of plant community composition and structure is an important way to explore the degradation and restoration processes, as well as the related mechanisms of forest communities. The study also has important theoretical and practical significance for guiding the conservation and restoration of natural forests. In 2018, relevant data was gathered by the second investigation in the Subtropical Evergreen Broad-leaved Forest plot with an area of 9.6 hm2 in the Wuyi Mountains, Fujian Province, southeastern China. Community dynamics of arbor layer was analyzed based on the perspectives of importance value, species abundance, species richness, Shannon-Wiener Index, Simpson Index, Margalef Index, Pielou Index, mortality rate, recruitment rate, rate of population size change, fitness, and coefficient of diameter at breast height (DBH) variation. The results showed that the community of trees was 48 families, 88 genera, 174 species in 2018, which increased by 1 species compared with 2013. Margalef Index rose, while Shannon-Wiener Index, Simpson Index and Pielou Index declined in the past 5 years. The tree individuals with DBH ≥ 1 cm was reduced from 68336 to 63897, with 7430 dead, and 2991 recruited individuals. Annual mortality rate, annual recruitment rate, rate of population size change, and fitness of the community were 2.30%, 0.96%, -1.34%, and 0.42, respectively. The average DBH of all trees in this community increased from 5.02 (±0.02) cm to 5.49 (±0.03) cm. The total of importance value for the 28 common tree species with higher importance value (>1%) decreased from 71.92% in 2013 to 71.81% in 2018. Annual mortality rate, annual recruitment rate, rate of population size change, and fitness for these common species were 2.46%, 0.79%, -1.67% and 0.46, respectively. The increase of species number and decrease of total tree individuals of community caused a direct impact on the increase of Margalef Richness Index. The decrease of common species and the increase of rare species indicated that the general disturbance would have a greater impact on the population of common species. The lack of constructive species or dominant species and the close dominance of many species may lead to high mortality rate and low recruitment rate of tree species in the same canopy layer for some resources such as light. The difficulty of population regeneration of sun plants such as Alniphyllum fortune, Schima superba may mean that the community has changed in favor of medium and shade plants. 参考文献 相似文献 引证文献

Influence of Biodiesel on Base Oil Oxidation as Measured by FTICR Mass Spectrometry

Internal combustion engine lubricants are subject to thermo-oxidative degradation during use and must be designed to withstand oxidation in order to extend their useful life. Understanding the complex chemical process of thermo-oxidative degradation is essential to designing higher performing engine lubricants. In this study base oil samples composed of a Group II base oil, doped with three different levels of biodiesel (B0, B15, and B100), were subjected to benchtop oxidation testing of up to 168 h, which mimics the conditions experienced in an internal combustion engine. The resulting samples were analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) for ultrahigh-resolution characterization to monitor oxidation as a function of time and biofuel content. Both negative-ion nanoelectrospray ionization and positive-ion atmospheric pressure photoionization were utilized. Most of the oxidation products were found to be polyoxygenated species containing 1–8 oxygen atoms, with the number of detected species increasing with oxidation time. Assessment of the maximum carbon number of protonated classes indicated the involvement of oligomerization reactions; additionally, modeling of mean double bond equivalents (DBE) for each protonated class suggests increasing carbonyl content for each particular class with increasing oxidation time. The oxidations of B15 and B100 doped samples were compared to that of B0. B15 samples were found to correspond closely to B0 samples, with a similar number of species detected. B100 samples showed a significant increase in number of species generated at 24–72 h relative to B0 and B15; however, a similar number of species were observed at 168 h for all samples, indicating a similar level of base oil oxidation at the final oxidation point. FTICR MS is shown to afford new insights into base oil oxidation as a function of time and biofuel content.

Thermodynamic analysis of an ecologically restored plant community:Number of species

Conducting a thermodynamic analysis of a plant community can be an approach to macro-ecology that emphasizes not only the diversity and abundances of plant species but also the exchange of matter and energy among species within the community and that with its physical and biological environment. The experimental data used for the test were obtained from an ecological restoration project implemented at a manganese tailing site. The relations derived from the maximal discrete entropy theorem show that the maximum entropy will increase with increase in the total number of species N, suggesting that N has an upper limit Nm at a habitat subject to its heterogeneity in physical conditions and species resource in its surrounding areas. As an important macroscopic property of an ecosystem, N is the number of species that are present at a habitat while its upper limit Nm is the potential number of species that have been or can be adapted to the physical conditions of the habitat, and can thus possibly be present at the habitat. As a function of the maximum entropy, ln(N) is applied as a biodiversity index. As an upper limit of ln(N), ln(Nm) can be regarded as a biodiversity potential index as it takes into account the available number of species distributed in the surrounding areas of the habitat, showing the potential limit for further increase in its biodiversity. Following the thermodynamic laws, given that there is no further change in system enthalpy H, ∆H = 0, the equilibrium number of species Neq can be found at the point ∆N = 0 and Nm can be determined by Nm = Neq2. The restoration of the investigated plant community was shown to be an irreversible process characterized by spontaneous increases in its total biomass and total number of plant species associated with increases in its enthalpy, Gibbs free energy and entropy. The analytical results gave support to the argument that the internal energy factors of a plant community are functions of its productivity and biodiversity and the difference between ln(N) and ln(Nm) determines its internal energy distribution.

Short-Rotation Coppice Managed According to Ecological Guidelines—What Are the Benefits for Phytodiversity?

In recent years, the impact of short-rotation coppice (SRC) on biodiversity has been a regular subject of research and ecological guidelines have been developed to make biomass cultivation on SRC more compatible with biodiversity concerns. However, since these guidelines are only implemented voluntarily by farmers, there are barely any SRC that are managed according to ecological guidelines. Consequently, knowledge about their importance for farmland biodiversity and about the impact of different measures for increasing biodiversity remains scarce. Therefore, three experimental SRC, which are managed according to ecological guidelines and thus include stands of different tree species (varieties of poplar (Populus) and willow (Salix), rowan (Sorbus aucuparia), silver birch (Betula pendula)) and different growth-stages within the same site, were investigated with regard to their importance as habitat for vascular plants. Species numbers and species composition were compared with the following habitat types: afforestations (AFO), young (HE-Y) and old hedges (HE-O), field margins (FM) and arable land (AL). Furthermore, different stand types (i.e., stands with different tree species and growth-stages, headlands, clearings) within these SRC were surveyed and compared. Species numbers of SRC were similar to HE-Y, AFO and FM and significantly higher than in AL and HE-O. The composition of plant communities in SRC differed considerably from the other farmland habitats, especially from AL, HE-O and FM. Within the SRC, most stand types had similar species numbers. Only the non-harvested poplar stands were particularly species-poor. Harvesting led to increased species numbers. This increase was significant for the poplar stands but only moderate for the willow stands. With regard to their species composition, the different stand types differed considerably in many cases. We conclude that SRC, which are managed according to ecological guidelines, can be an additional measure to promote phytodiversity in agricultural landscapes as they contain relatively high species numbers (of mainly common and adaptable species) and support distinct plant communities that differ from other farmland habitats. Therefore, measures such as the cultivation of different tree species or sectional harvesting could be offered as agri-environmental schemes to further increase the ecological sustainability of biomass production on SRC.

Annelid Diversity: Historical Overview and Future Perspectives

Annelida is a ubiquitous, common and diverse group of organisms, found in terrestrial, fresh waters and marine environments. Despite the large efforts put into resolving the evolutionary relationships of these and other Lophotrochozoa, and the delineation of the basal nodes within the group, these are still unanswered. Annelida holds an enormous diversity of forms and biological strategies alongside a large number of species, following Arthropoda, Mollusca, Vertebrata and perhaps Platyhelminthes, among the species most rich in phyla within Metazoa. The number of currently accepted annelid species changes rapidly when taxonomic groups are revised due to synonymies and descriptions of a new species. The group is also experiencing a recent increase in species numbers as a consequence of the use of molecular taxonomy methods, which allows the delineation of the entities within species complexes. This review aims at succinctly reviewing the state-of-the-art of annelid diversity and summarizing the main systematic revisions carried out in the group. Moreover, it should be considered as the introduction to the papers that form this Special Issue on Systematics and Biodiversity of Annelids.

Changes in plant diversity in a water-limited and isolated high-mountain range (Sierra Nevada, Spain)

Climate change impacts are of a particular concern in small mountain ranges, where cold-adapted plant species have their optimum zone in the upper bioclimatic belts. This is commonly the case in Mediterranean mountains, which often harbour high numbers of endemic species, enhancing the risk of biodiversity losses. This study deals with shifts in vascular plant diversity in the upper zones of the Sierra Nevada, Spain, in relation with climatic parameters during the past two decades. We used vegetation data from permanent plots of three surveys of two GLORIA study regions, spanning a period of 18 years (2001–2019); ERA5 temperature and precipitation data; and snow cover durations, derived from on-site soil temperature data. Relationships between diversity patterns and climate factors were analysed using GLMMs. Species richness showed a decline between 2001 and 2008, and increased thereafter. Species cover increased slightly but significantly, although not for endemic species. While endemics underwent cover losses proportional to non-endemics, more widespread shrub species increased. Precipitation tended to increase during the last decade, after a downward trend since 1960. Precipitation was positively related to species richness, colonisation events, and cover, and negatively to disappearance events. Longer snow cover duration and rising temperatures were also related to increasing species numbers, but not to cover changes. The rapid biotic responses of Mediterranean alpine plants indicate a tight synchronisation with climate fluctuations, especially with water availability. Thus, it rather confirms concerns about biodiversity losses, if projections of increasing temperature in combination with decreasing precipitation hold true.

Impact of El Niño-Southern Oscillation on plankton ciliates from a saline lowland river in South America

We analyzed the structure and dynamics of plankton ciliates from the Salado River, Buenos Aires (Argentina), during El Niño-Southern Oscillation events, to evaluate their response to alterations of certain environmental variables during these climatic phenomena. The basin exhibits intense land use at the headwaters and fluctuating salinity along the main channel, canals and tributaries. During El Niño (1997-1998), heavy rainfall caused high discharge, and low mean conductivity values were recorded along with low mean abundances in the entire basin. During neutral (2004-2005) and La Niña (2007-2009) events, the discharge was reduced, and mean conductivity was double the values recorded during El Niño, with maxima of mean abundances and diversity at the headwaters and the lower basin. The most abundant ciliates were tintinnids, heterotrichs and peritrichs. Species replacement was detected along the river system, mainly during the neutral event. At the headwaters and canals, abundance peaks of certain species were attributed to the strong human impact (nutrients and sewage inputs) and increased salinity, allowing the establishment of euryhaline ciliates. In the middle basin, freshwater species predominated, although less abundantly due to higher water flow. The mouth sector showed abundance peaks of an estuarine tintinnid. Temperature, conductivity and suspended solids were the most important variables driving ciliate structure. High discharge as a result of heavy rainfall during El Niño negatively influenced ciliate assemblages. In contrast, low water conditions during the other events allowed the development of diverse assemblages, increasing species number and abundance of particular species.