Higher Plant Species Research Articles

A Review on Antidiarrhoeal, Anti-inflammatory and Antibacterial activity of Adenanthera pavonina leaves

Plants have been used for health care and medical purposes for years. The number of higher plant species on earth is about 250000. It is estimated that 35000 to 70000 species have, at one time or another, been used in some cultures for medicinal purposes. One of these is Adenanthera pavonina which is traditionally used . It also exhibit activity like antidiabetic, antibacterial, cytotoxicity, antifungal, antioxidant, anthelmintic, analgesic, anticonvulsant, depressant, and anti-inflammatory activity. The ethanolic extract of leaves show anti-inflammatory activity and pavonin a five membered lactone ring was isolated from leaves. The purpose of my review is to carry out future work for higher studies

Root morphology and biomechanical characteristics of high altitude alpine plant species and their potential application in soil stabilization

Glacial forefields host young, poorly developed soils with highly unstable environmental conditions. Root system contribution to soil stabilization is a well-known phenomenon. Identifying the functional traits and root morphology of pioneer vegetation that establish on forefields can provide information useful in the practical application of plants in land restoration of high altitude mountain sites.This study aims to gather information on the root morphology and biomechanical characteristics of the 10 most dominant pioneer plant species of the forefield of Lys Glacier (NW Italian Alps).X-ray Computed Tomography (X-ray CT) was used to visualize and quantify non-destructively the root architecture of the studied species. Samples were cored directly from the forefield. Data on root traits such as total root length, rooting depth, root diameter, root length density and number of roots in relation to diameter classes as well as plant height were determined and compared between species. Roots were also tested for their tensile strength resistance.X-ray CT technology allowed us to visualize the 3D root architecture of species intact in their natural soil system. X-ray CT technology provided a visual representation of root–soil interface and information on the exact position, orientation and elongation of the root system in the soil core. Root architecture showed high variability among the studied species. For all species the majority of roots consisted of roots smaller than 0.5mm in diameter. There were also considerable differences found in root diameter and total root length although these were not statistically significant. However, significant differences were found in rooting depth, root length density, plant height and root tensile strength between species and life forms (dwarf shrub, forb, graminoid). In all cases, root tensile strength decreased with increasing root diameter. The highest tensile strength was recorded for graminoids such as Luzula spicata (L.) DC. and Poa laxa Haenke and the lowest for Epilobium fleischeri Hochst.The differences in root properties among the studied species highlight the diverse adaptive and survival strategies plants employ to establish on and thrive in the harsh and unstable soil conditions of a glacier forefield. The data determined in this study could provide a significant contribution to a database that allow those who are working in land restoration and preservation of high altitude mountain sites to employ native species in a more efficient, effective and informed manner.

Plant species richness sustains higher trophic levels of soil nematode communities after consecutive environmental perturbations.

The magnitude and frequency of extreme weather events are predicted to increase in the future due to ongoing climate change. In particular, floods and droughts resulting from climate change are thought to alter the ecosystem functions and stability. However, knowledge of the effects of these weather events on soil fauna is scarce, although they are key towards functioning of terrestrial ecosystems. Plant species richness has been shown to affect the stability of ecosystem functions and food webs. Here, we used the occurrence of a natural flood in a biodiversity grassland experiment that was followed by a simulated summer drought experiment, to investigate the interactive effects of plant species richness, a natural flood, and a subsequent summer drought on nematode communities. Three and five months after the natural flooding, effects of flooding severity were still detectable in the belowground system. We found that flooding severity decreased soil nematode food-web structure (loss of K-strategists) and the abundance of plant feeding nematodes. However, high plant species richness maintained higher diversity and abundance of higher trophic levels compared to monocultures throughout the flood. The subsequent summer drought seemed to be of lower importance but reversed negative flooding effects in some cases. This probably occurred because the studied grassland system is well adapted to drought, or because drought conditions alleviated the negative impact of long-term soil waterlogging. Using soil nematodes as indicator taxa, this study suggests that high plant species richness can maintain soil food web complexity after consecutive environmental perturbations.

Restoring lepidopteran diversity in a tropical dry forest: relative importance of restoration treatment, tree identity and predator pressure.

Tropical dry forests (TDFs) have been widely transformed by human activities worldwide and the ecosystem services they provide are diminishing. There has been an urgent call for conservation and restoration of the degraded lands previously occupied by TDFs. Restoration experiences aim to recover species diversity and ecological functions. Different restoration strategies have been used to maximize plant performance including weeding, planting or using artificial mulching. In this investigation, we evaluated whether different restoration practices influence animal arrival and the reestablishment of biotic interactions. We particularly evaluated lepidopteran larvae diversity and caterpillar predation on plants established under different restoration treatments (mulching, weeding and control) in the Pacific West Coast of México. This study corroborated the importance of plant host identity for lepidopteran presence in a particular area. Lepidopteran diversity and herbivory rates were not affected by the restoration treatment but they were related to tree species. In contrast, caterpillar predation marks were affected by restoration treatment, with a greater number of predation marks in control plots, while caterpillar predation marks among plant species were not significantly different. This study highlights the importance of considering the introduction of high plant species diversity when planning TDF restoration to maximize lepidopteran diversity and ecosystem functioning.

Soils and rainfall drive landscape‐scale changes in the diversity and functional composition of tree communities in premontane tropical forest

AbstractQuestionsPremontane tropical forests harbour exceptionally high plant species diversity; understanding which factors influence their species composition is critical to conserving them, and to predicting how global environmental change will affect them. We asked: (1) how do α‐ and β‐diversity vary at the landscape scale; (2) how important is environmental filtering in structuring these communities; and (3) which soil and climate variables account for the most compositional variation?LocationOld‐growth premontane forest, Fortuna Forest Reserve, western Panama.MethodsAll trees ≥5‐cm DBH were censused in 12 1‐ha plots up to 13 km apart. For each plot, we measured soil properties (0–10 cm depth) at 13 locations, and estimated or measured monthly rainfall. To evaluate how the environmental and spatial variables are associated with community composition, we used ordination and Mantel tests.ResultsDiversity varied nearly three‐fold among plots (68–184 species·ha−1). β‐Diversity was also high, with only one of 364 species present in all plots. Turnover reflected distinct forest community types that have developed on different parent materials: forests on rhyolite had an abundance of either ectomycorrhizal‐associated trees or canopy palms, while forests on the other rock types (andesite, dacite and basalt) were dominated by trees that form arbuscular mycorrhizal associations. While NMDS ordination showed that species turnover was significantly correlated with rainfall seasonality, and also co‐varied with geographic distance. Nonetheless, large compositional differences were apparent among sites <2 km apart with similar rainfall but differing soils. Partial Mantel tests controlling for geographic distance highlighted the relationship between total phosphorus and species composition.ConclusionsSoil nutrient availability and rainfall seasonality in premontane forests at Fortuna are associated with striking variation in the taxonomic and functional composition of nearby tree communities, and with plot differences in species richness comparable in magnitude to those reported over >1000 m a.s.l. in previous studies. Accounting for how local edaphic conditions structure premontane and montane tropical forests will be critical to predicting how tree communities will respond to climate change.

Xanthophyll Cycle Activity in Two Prominent Arctic Shrub Species

ABSTRACTWhen the capacity for photosynthesis is constrained by unfavorable growing conditions, excess absorbed light is safely lost from leaves via thermal energy dissipation—a photoprotective mechanism ubiquitous among higher plants. The relatively low irradiance conditions yet stressful growing environment of the arctic tundra suggest contrasting hypotheses regarding the necessity for plant investment in photoprotection. To examine these hypotheses, the photoprotective pigments of the xanthophyll cycle were investigated in conjunction with non-photochemical quenching (NPQ) of chlorophyll fluorescence emission in two dominant arctic shrub species, Salix pulchra and Betula nana. The xanthophyll cycle pool sizes of S. pulchra leaves were substantially higher than those reported in most other higher plant species, whereas B. nana leaves maintain modestly high xanthophyll cycle pool sizes. In addition, high retention of de-epoxidized xanthophyll cycle pigments in both species and saturation of xanthophyll cycle conversion at low-light intensities were observed and associated with high levels of NPQ. The xanthophyll cycle leaf pigment pools reported are among the first published for arctic plants and support the hypothesis that foliar xanthophyll cycle activity is greater in environments prone to harsher growing conditions.

Arthropod Diversity and Functional Importance in Old-Growth Forests of North America

Old-growth forests have become rare in North America but provide habitat for unique assemblages of species that often are rare in younger forests. Insects and related arthropods reach their highest diversity in old-growth forests because of their stable moderate temperature and relative humidity and the rich variety of resources represented by high plant species richness and structural complexity. Old-growth arthropod assemblages typically are distinct from those in younger, managed forests. Major subcommunities include the arboreal community that is composed of a rich assemblage of herbivores, fungivores, and their associated predators and parasitoids that function to regulate primary production and nutrient fluxes, the stem zone community that includes bark- and wood-boring species and their associated predators and parasitoids that initiate the decomposition of coarse woody debris, and the forest floor community composed of a variety of detritivores, fungivores, burrowers, and their associated predators and parasitoids that are instrumental in litter decomposition. Insect outbreaks are relatively rare in old-growth forests, where the diversity of resources and predators limit population growth. In turn, insects contribute to plant diversity and limit primary production of host plant species, thereby promoting development of old-growth forest characteristics. Arthropods also provide important functions in decomposition and nutrient cycling that may be lost in younger, managed forests with limited provision of coarse woody debris and accumulated litter. Protection of remnant old-growth forests within the forest matrix may be particularly valuable for maintaining the diversity of plant and arthropod predators that can minimize outbreaks, thereby contributing to resilience to changing environmental conditions.

Complete chloroplast genomes from apomictic Taraxacum (Asteraceae): Identity and variation between three microspecies.

Chloroplast DNA sequences show substantial variation between higher plant species, and less variation within species, so are typically excellent markers to investigate evolutionary, population and genetic relationships and phylogenies. We sequenced the plastomes of Taraxacum obtusifrons Markl. (O978); T. stridulum Trávniček ined. (S3); and T. amplum Markl. (A978), three apomictic triploid (2n = 3x = 24) dandelions from the T. officinale agg. We aimed to characterize the variation in plastomes, define relationships and correlations with the apomictic microspecies status, and refine placement of the microspecies in the evolutionary or phylogenetic context of the Asteraceae. The chloroplast genomes of accessions O978 and S3 were identical and 151,322 bp long (where the nuclear genes are known to show variation), while A978 was 151,349 bp long. All three genomes contained 135 unique genes, with an additional copy of the trnF-GGA gene in the LSC region and 20 duplicated genes in the IR region, along with short repeats, the typical major Inverted Repeats (IR1 and IR2, 24,431bp long), and Large and Small Single Copy regions (LSC 83,889bp and SSC 18,571bp in O978). Between the two Taraxacum plastomes types, we identified 28 SNPs. The distribution of polymorphisms suggests some parts of the Taraxacum plastome are evolving at a slower rate. There was a hemi-nested inversion in the LSC region that is common to Asteraceae, and an SSC inversion from ndhF to rps15 found only in some Asteraceae lineages. A comparative repeat analysis showed variation between Taraxacum and the phylogenetically close genus Lactuca, with many more direct repeats of 40bp or more in Lactuca (1% larger plastome than Taraxacum). When individual genes and non-coding regions were for Asteraceae phylogeny reconstruction, not all showed the same evolutionary scenario suggesting care is needed for interpretation of relationships if a limited number of markers are used. Studying genotypic diversity in plastomes is important to characterize the nature of evolutionary processes in nuclear and cytoplasmic genomes with the different selection pressures, population structures and breeding systems.

Are High Carbon Stocks in Agroforests and Forest Associated with High Plant Species Diversity?

Conserving plant diversity and retaining terrestrial carbon stocks are targets for environmental policy and appear to be generally compatible. However, detailed information on the way both respond to agroforestry management is lacking. Rubber and fruit tree agroforestry systems combine planted trees and trees that are tolerated or actively managed that derived from natural vegetation. The research aimed to evaluate plant species diversity, vegetation structure, and C stock in rubber agroforestry system (AF) and secondary forest grown in silty clay and sandy soils in Pulang Pisau Regency, Central Kalimantan province. A number of multistrata agroforestry systems was compared to the secondary (natural) forests (SNF) of the area; these included Fruit-Based Rubber Agroforestry (AFB) of about 100 years of age, Old Rubber Agroforestry (ARO) and Young Rubber Agroforestry (ARY). The highest C stock was found in AFB (415 Mg ha -1 ), while the average C stocks of other AF and SNF were 217 Mg ha -1 . A plant diversity index (H’) was only weakly correlated to aboveground C stocks. Including the farmer-managed agroforests in schemes to reduce emissions from deforestation and forest degradation is relevant, as their carbon stocks match or exceed those of remaining forests in the area.

Flora characteristics of Chenier Wetland in Bohai Bay and biogeographic relations with adjacent wetlands

A key step towards the restoration of heavily disturbed fragile coastal wetland ecosystems is determining the composition and characteristics of the plant communities involved. This study determined and characterized the community of higher plants in the Chenier wetland of Bohai Bay using a combination of field surveys, quadrat approaches, and multivariate statistical analyses. This community was then compared to other adjacent wetlands (Tianjin, Qinhuangdao, Laizhouwan, Jiaozhouwan, and Yellow River Delta wetland) located near the Huanghai and Bohai Seas using principal coordinate analysis (PCoA). Results showed a total of 56 higher plant species belonging to 52 genera from 20 families in Chenier wetland, the majority of which were dicotyledons. Single-species families were predominant, while larger families, including Gramineae, Compositae, Leguminosae, and Chenopodiaceae contained a higher number of species (each⩾6 species). Cosmopolitan species were also dominant with apparent intrazonality. Abundance (number of species) of temperate species was twice that of tropical taxa. Species number of perennial herbs, such as Gramineae and Compositae, was generally higher. Plant diversity in the Chenier wetland, based on the Shannon-Wiener index, was observed to be between the Qinhuangdao and Laizhouwan indices, while no significant difference was found in other wetlands using the Simpson index. Despite these slight differences in diversity, PCoA based on species abundance and composition of the wetland flora suggest that the Bohai Chenier community was highly similar to the coastal wetlands in Tianjin and Laizhouwan, further suggesting that these two wetlands could be important breeding grounds and resources for the restoration of the plant ecosystem in the Chenier wetland.

Evolutionarily conserved untranslated regions facilitate the cloning of complete coding sequences of chondriogenes encoding NADH dehydrogenase subunits in higher plants

In plants, the mitochondrial NADH dehydrogenase(complex I) is a large protein complex transferring electrons to ubiquinone.For the nine chondriogenes encoding complex I subunits (nad1,nad2, nad3, nad4, nad4L, nad5, nad6, nad7, and nad9), an efficientstrategy for the cloning of complete coding sequences (CDSs) is important.Specific orthologous portions of untranslated regions (UTRs)were found based on multiple sequence alignments of chondriogeneorthologues encoding complex I subunits in plant species. Based onthe conservation of partial UTRs, a one-step PCR strategy was conceivedfor the cloning of CDSs of the nine chondriogene orthologues.Using this strategy, the five complete mitochondrial open readingframes (ORFs) , which encode mitochondrial NADH dehydrogenasesubunits, nad1, nad2, nad6, nad7 and nad9 respectively, were cloned inthree angiosperm species: kenaf (Hibiscus cannabinus), camphor tree(Cinnamomum camphora), and ramie (Boehmeria nivea). The fifteencloned PCR products also included 5' and 3'-UTR partial sequences.Moreover, a potential C-U RNA editing site was identified in the startcodon of kenaf nad9. In conclusion, the simple and efficient strategyavoids the use of time-consuming rapid amplification of cDNA ends(RACE) process, and facilitates the cloning mitochondrial completeORFs whose 5' and 3' flanking UTR contain an orthologous regionwith some degeneracy in higher plant species.

中国亚热带地区阔叶林植物的谱系地理历史

PDF HTML阅读 XML下载 导出引用 引用提醒 中国亚热带地区阔叶林植物的谱系地理历史 DOI: 10.5846/stxb201606031072 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金青年科学基金项目（31600301）；上海科技馆引进人才项目 Phylogeographic history of broad-leaved forest plants in subtropical China 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:中国亚热带地区因丰富的植物物种多样性备受生物地理学研究关注，丰富的多样性与中新世以来的地质气候变化密切相关。谱系地理学已成为探讨植物分布模式和遗传格局受地质气候变化影响的主要手段。总结了该地区阔叶林植物对中新世以来地质气候变化的响应模式和种群分化的历史成因。在中新世和上新世时，由于全球变冷、青藏高原抬升和亚洲内陆干旱，阔叶林植物被迫向南退缩，形成不同的谱系。同时，亚洲季风的增强为遗传多样性的增加提供了良好的环境。在更新世冰期和间冰期时，大部分落叶阔叶林和常绿阔叶林植物在多个避难所间存在长期隔离，不同的避难所种群各自经历局部地区的收缩和扩张。长期的隔离使不同谱系间进一步分化，形成高水平的遗传多样性和遗传分化。少部分植物在冰期时向南退缩，并在间冰期时明显向北扩张。最后，就分化时间的准确估计和探究遗传格局背后的机制两方面展望了未来的研究趋势。 Abstract:Subtropical China has drawn considerable attention for biogeography studies because of its high plant species diversity, which has been closely related to geo-climate changes since the Miocene. Phylogeography has become the main method for studying the influence of geo-climate changes on the distribution and genetic structure of plants. In this paper, we review the response patterns to geo-climatic changes since the Miocene and the historical causes of population-level genetic differentiation of broad-leaved forest plants in this region. During the Miocene and Pliocene, broad-leaved forest plants were forced to contract southward and form different lineages because of global cooling, the Qinghai-Tibet Plateau uplift, and Asian interior aridity. Meanwhile, the escalation of Asian monsoons provided suitable environment for diversification. During the glacial and interglacial ages in the Pleistocene, both deciduous and evergreen broad-leaved forests plants mainly underwent long-term isolation in multiple separated refugia. Different refugia populations respectively experienced localized contractions and expansions. Long-term isolation caused further divergence of different lineages, resulting in high genetic diversity and high differentiation. Few plants experienced southward contraction in glacial ages and obvious northward expansion in the interglacial ages. Finally, we speculate on the directions of future research based on accurate divergence time estimations and on mechanisms underlying the genetic structure. 参考文献 相似文献 引证文献

Toxicity testing of chemicals without use of animals

A series of publications on the studies of phytotoxicity of chemicals (pollutants, ecotoxicants), carried out by the author and his research group, have been reviewed. Tests (bioassays) based on experiments with many higher plant species, both terrestrial and aquatic ones (macrophytes), were used in these studies. Among the chemicals tested there were various organic (synthetic detergents, surfactants, and pesticides) and some inorganic (e.g., metal oxide nanoparticles) compounds. New methods for bioassay using plant species never used before have been developed by the author. New facts of phytotoxicity of a synthetic detergent have been discovered and reported. Specifically, an aqueous solution of liquid detergent Frosch (Werner & Mertz, FRG) at a concentration of 0.25 mL/L (and higher concentrations) inhibited the elongation rate of seedlings of Lens culinaris higher plant species. Also, phytotoxicity of synthetic cationic surfactant dodecyltrimethylammonium bromide has been reported for the first time. This surfactant at a concentration of 4 mg/L inhibited the elongation of Lens culinaris plant seedlings. The phytotesting methods contribute to the development of alternative approaches to studying the toxicity of chemicals through non-animal testing.

Habitat selection by breeding WhinchatsSaxicola rubetraat territory and landscape scales

We determined breeding season habitat preferences for a declining migrant grassland bird, the WhinchatSaxicola rubetra,using intensive, territory‐scale habitat and invertebrate data, and independently gathered landscape‐scale field survey and remotely sensed habitat data to determine whether the same habitat relationships were evident at both spatial scales. At the territory scale, low‐elevation and a heterogeneous vegetation structure with a high density of perches and tussocks were the dominant features of occupied habitats. The landscape‐scale model successfully predicted areas where breeding Whinchats were more likely to occur, and similar and consistent relationships with habitat features occurred at both spatial scales. However, plant species richness and topographic slope elicited different responses at different spatial scales, with steeper slopes and high plant species richness favoured at the landscape scale, whereas at the territory scale, low plant species richness was preferred and slope did not determine settlement. These differences reflect differences in the way the data were measured and extrapolated. This study identifies important attributes of lowland grassland habitats and landscapes for a stable population of breeding Whinchats, and the analysis shows the good predictive ability of remotely sensed data to model this species' distribution at larger spatial extents. Our findings provide methods for assessing habitat availability for this declining species and for managing habitats and landscapes to provide these essential elements.

Isolation and Characterization of an Aluminum-resistant Mutant in Rice.

BackgroundAluminum (Al) toxicity represents a major constraint for crop production on acid soils. Rice is a high Al-resistant plant species among small-grain cereals, but its molecular mechanisms of Al resistance are not fully understood. We adopted a forward genetic screen strategy to uncover the Al-resistance mechanisms in rice. In this study, we screened an ethylmethylsulfone (EMS)-mutagenized library to isolate and characterize mutants with altered sensitivity to Al in rice.ResultsTreatment of an Al-intolerant indica variety Kasalath with 20 μM Al induced root swelling. This phenotype could be suppressed by the addition of aminoethoxyvinylglycine (AVG, an ethylene synthesis inhibitor), suggesting that increased production of ethylene is responsible for the root swelling under Al stress. By utilizing the root swelling as an indicator, we developed a highly effective method to screen Al-sensitive or -resistant mutants in rice. Through screening of ~5000 M2 lines, we identified 10 Al-sensitive mutants and one Al-resistant mutant ral1 (resistance to aluminum 1). ral1 mutant showed short root phenotype under normal growth condition, which was attributed to reduced cell elongation in the mutant. A dose-response experiment revealed that ral1 mutant was more resistant to Al than wild-type (WT) at all Al concentrations tested. The mutant was also more resistant to Al when grown in an acid soil. The mutant accumulated much lower Al in the root tips (0–1 cm) than WT. The mutant contained less Al in the cell wall of root tips than WT, whereas Al concentration in the cell sap was similar between WT and the mutant. In addition to Al, the mutant was also more resistant to Cd than WT. Quantitative RT-PCR analysis showed that the expression levels of known Al-resistance genes were not increased in the mutant compared to WT. Genetic analysis indicated that the Al-resistance phenotype in ral1 mutant was controlled by a single recessive gene mapped on the long arm of chromosome 6.ConclusionsWe have developed a highly efficient method for the screening of rice mutants with altered Al sensitivity. We identified a novel mutant ral1 resistant to Al by this screening. The increased resistance of ral1 to Al toxicity is caused by the reduced Al binding to the cell wall of root tips and the responsible gene is mapped on the long arm of chromosome 6.

Genome-wide identification, cloning and characterization of SNARE genes in bread wheat (Triticum aestivum L.) and their response to leaf rust

SNAREs (soluble N-ethylmaleimide sensitive factor adaptor protein receptors) are small polypeptides characterized by a particular domain called the SNARE motif. Compared with the genome of other eukaryotes, monocotyledonous and dicotyledonous plants have more SNAREs indicating their important roles in higher plant species. Higher plants have the capability to form SNARE complexes that are important in determining the precise process of vesicle fusion for intracellular trafficking pathways. SNAREs have been reported to be engaged in the delivery of cell wall precursors to the newly formed cell plate during cytokinesis. The role of SNARE genes in response to plant-pathogen interaction is still not well understood. We found 35 SNARE genes in the wheat genome using a Hidden Markov Model. In this study with combined usage of in silico and molecular cloning technologies, we identified and characterized three SNARE genes (SNARE3, SNARE5 and SNARE6). The deduced amino acid sequences of these SNARE genes contained two characteristic conserved domains – a SNARE motif and a transmembrane domain, and they showed a high degree of homology with other eukaryotic SNARE genes. Phylogenetic analysis and three dimensional structures built with the help of Modeller software confirmed the presence of SNARE motifs in the proteins. The spatio-temporal expression profiling studies exemplify the positive role of SNARE transcripts have in resistant and susceptible wheat plants during incompatible and compatible interaction respectively, in response to Puccinia triticina induced leaf-rust infection. Taken together, our study suggests a role for SNARE genes in vesicle mediated resistance to leaf rust in wheat.

Retention of Atmospheric Particulate by Three Woody Ornamental Species in Santiago, Chile

It is traditionally accepted that urban vegetation contributes to improve air quality by intercepting and retaining the particulate matter. Although the mitigating role of plants has been recognized by several studies, the role of individual species is still poorly understood. This is particularly important in cities like Santiago (Chile), which has high levels of atmospheric particulate and also has high plant species diversity. In this study, we evaluated the retention of atmospheric particles by three widely distributed ornamental species (Nerium oleander, Pittosporum tobira, and Ligustrum lucidum) in Santiago. For this proposal, we took leaf samples in different sampling points across the city which vary in their concentration of atmospheric particulate. Samples were taken 12 and 16 days after a rainfall episode that washed the leaves of plants in the sampling sites. In the laboratory, leaves were washed to recover the surface retained particles that were collected to determine its mass gravimetrically. With this information, we estimated the foliar retention (mass of particulate matter retained in the foliar surface) and daily retention efficiency (mass of particulate matter retained in the foliar surface per day). We found that foliar retention and daily retention efficiency varied significantly between the studied species. The leaves of N. oleander retained 8.2 g m−2 of particulate matter on average, those of P. tobira 6.1 g m−2, and those of L. lucidum 3.9 g m−2; meanwhile, the daily retention efficiencies of particulate matter were 0.6, 0.4, and 0.3 g m−2 day−1 for N. oleander, P. tobira, and L. lucidum, respectively. These results suggest that the studied species retain atmospheric particulate matter differentially in Santiago. These results can be attributed to differences on leaf surface characteristics. The recognition of the most efficient species in the retention of the atmospheric particulate matter can help to decide which species can be used to improve the air quality in the city.

Burrowing and foraging activity of marsh crabs under different inundation regimes

New England salt marshes are susceptible to degradation and habitat loss as a result of increased periods of inundation as sea levels rise. Increased inundation may exacerbate marsh degradation that can result from crab burrowing and foraging. Most studies to date have focused on how crab burrowing and foraging can impact the dominant low marsh plant species, Spartina alterniflora. Here we used a mesocosm experiment to examine the relationship of foraging and burrowing activity in two dominant New England crab species, Sesarma reticulatum and Uca pugilator, and the combined effect of inundation, on the dominant high marsh plant species Spartina patens using a 3×2 factorial design with three crab treatments (Sesarma, Uca, control) at two levels of inundation (low, high). Plants were labeled with a nitrogen (N) stable isotope tracer to estimate plant consumption by the two crab species. At both levels of inundation, we found that S. reticulatum had a significant negative impact on both above- and below-ground biomass by physically clipping and uprooting the plants, whereas U. pugilator had no significant impact. Low inundation treatments for both crab species had significantly greater aboveground biomass than high inundation. Stable N isotope tracer levels were roughly the same for both S. reticulatum and U. pugilator tissue, suggesting that the impact of S. reticulatum on S. patens was not through consumption of the plants. Overall, our results suggest the potential for S. reticulatum to negatively impact marsh stability, and that effects of crab foraging behavior may be heightened by increased inundation.

Effects of grazing management on biodiversity across trophic levels–The importance of livestock species and stocking density in salt marshes

European coastal salt marshes are important for the conservation of numerous species of specialist plants, invertebrates, breeding and migratory birds. When these marshes are managed for nature conservation purposes, livestock grazing is often used to counter the dominance of the tall grass Elytrigia atherica, and the subsequent decline in plant species richness. However, it remains unclear what is the optimal choice of livestock species and stocking density to benefit biodiversity of various trophic levels.To fill this knowledge gap, we set up a triplicate, full factorial grazing experiment with cattle and horse grazing at low and high stocking densities (0.5 or 1 animal ha−1) at the mainland coast of the Dutch Wadden Sea. Here, we present the results after 4 years and integrate these with previously published results from the same experiment to assess effects of livestock grazing on various trophic groups.Stocking density affected almost all measured variables: high stocking densities favoured plant species richness and suppression of E. atherica, whereas low stocking densities favoured abundances of voles, pollinators and flowers. Densities of different functional groups of birds showed no significant response to the regimes, but tended to be somewhat higher under 0.5 horse and 1 cattle ha−1.Choice of livestock species had fewer and smaller effects than stocking density. Horse grazing was detrimental to vole density, and showed an interactive effect with stocking density for Asteraceae flower abundance. Multidiversity, a synthetic whole-ecosystem biodiversity measure, did not differ among regimes. These results are discussed in the light of other results from the same experiment.Because of these contrasting effects on different trophic groups, we advise concurrent application of different grazing regimes within a spatial mosaic, with the inclusion of long-term abandonment. High density horse grazing, however, is detrimental to biodiversity.

Livestock grazing has minimal effect on the species richness and diversity of semi-arid shrubland in the Western Little Karoo, South Africa

The Succulent Karoo, one of two arid biodiversity hotspots in the world, is known for its high plant species richness, but little is known about the influence of topography and how it mediates the potentially deleterious effects of grazing. Changes in vegetation species composition, cover and species diversity were examined along piosphere gradients on northerly slopes, bottomlands and low-lying plains on 45 farms. Landscapes differed in the plant speciesand life-form composition, species richness and cover, with the more species-rich, heterogeneous grassy northerly slopes distinct from the plains and bottomlands, which were dominated by Pteronia pallens, Psilocaulon junceum and Drosanthenum spp. with more annual and ephemeral species. Overall, species richness declined linearly with decreasing rangeland condition. A weak grazing effect was detected only on the north-facing slopes, where shrubs and grass decreased with intense grazing. Years of overgrazing have resulted in the widespread dominance of P. pallens, especially on the plains and bottomlands, rendering them insensitive to grazing. The current condition of the northern slopes should be maintained and managed such that palatable species can spread to more degraded areas of the landscape.