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Sample records for affect plant species

  1. Fuel breaks affect nonnative species abundance in Californian plant communities

    USGS Publications Warehouse

    Merriam, K.E.; Keeley, J.E.; Beyers, J.L.

    2006-01-01

    We evaluated the abundance of nonnative plants on fuel breaks and in adjacent untreated areas to determine if fuel treatments promote the invasion of nonnative plant species. Understanding the relationship between fuel treatments and nonnative plants is becoming increasingly important as federal and state agencies are currently implementing large fuel treatment programs throughout the United States to reduce the threat of wildland fire. Our study included 24 fuel breaks located across the State of California. We found that nonnative plant abundance was over 200% higher on fuel breaks than in adjacent wildland areas. Relative nonnative cover was greater on fuel breaks constructed by bulldozers (28%) than on fuel breaks constructed by other methods (7%). Canopy cover, litter cover, and duff depth also were significantly lower on fuel breaks constructed by bulldozers, and these fuel breaks had significantly more exposed bare ground than other types of fuel breaks. There was a significant decline in relative nonnative cover with increasing distance from the fuel break, particularly in areas that had experienced more numerous fires during the past 50 years, and in areas that had been grazed. These data suggest that fuel breaks could provide establishment sites for nonnative plants, and that nonnatives may invade surrounding areas, especially after disturbances such as fire or grazing. Fuel break construction and maintenance methods that leave some overstory canopy and minimize exposure of bare ground may be less likely to promote nonnative plants. ?? 2006 by the Ecological Society of America.

  2. Quantification of Heavy Metals in Mining Affected Soil and Their Bioaccumulation in Native Plant Species.

    PubMed

    Nawab, Javed; Khan, Sardar; Shah, Mohammad Tahir; Khan, Kifayatullah; Huang, Qing; Ali, Roshan

    2015-01-01

    Several anthropogenic and natural sources are considered as the primary sources of toxic metals in the environment. The current study investigates the level of heavy metals contamination in the flora associated with serpentine soil along the Mafic and Ultramafic rocks northern-Pakistan. Soil and wild native plant species were collected from chromites mining affected areas and analyzed for heavy metals (Cr, Ni, Fe, Mn, Co, Cu and Zn) using atomic absorption spectrometer (AAS-PEA-700). The heavy metal concentrations were significantly (p < 0.01) higher in mine affected soil as compared to reference soil, however Cr and Ni exceeded maximum allowable limit (250 and 60 mg kg(-1), respectively) set by SEPA for soil. Inter-metal correlations between soil, roots and shoots showed that the sources of contamination of heavy metals were mainly associated with chromites mining. All the plant species accumulated significantly higher concentrations of heavy metals as compared to reference plant. The open dumping of mine wastes can create serious problems (food crops and drinking water contamination with heavy metals) for local community of the study area. The native wild plant species (Nepeta cataria, Impatiens bicolor royle, Tegetis minuta) growing on mining affected sites may be used for soil reclamation contaminated with heavy metals. PMID:26079739

  3. Population variation affects interactions between two California salt marsh plant species more than precipitation.

    PubMed

    Noto, Akana E; Shurin, Jonathan B

    2016-02-01

    Species that occur along broad environmental gradients often vary in phenotypic traits that make them better adapted to local conditions. Variation in species interactions across gradients could therefore be due to either phenotypic differences among populations or environmental conditions that shift the balance between competition and facilitation. To understand how the environment (precipitation) and variation among populations affect species interactions, we conducted a common garden experiment using two common salt marsh plant species, Salicornia pacifica and Jaumea carnosa, from six salt marshes along the California coast encompassing a large precipitation gradient. Plants were grown alone or with an individual of the opposite species from the same site and exposed to one of three precipitation regimes. J. carnosa was negatively affected in the presence of S. pacifica, while S. pacifica was facilitated by J. carnosa. The strength of these interactions varied by site of origin but not by precipitation treatment. These results suggest that phenotypic variation among populations can affect interaction strength more than environment, despite a threefold difference in precipitation. Geographic intraspecific variation may therefore play an important role in determining the strength of interactions in communities. PMID:26481794

  4. Plant species richness and functional traits affect community stability after a flood event.

    PubMed

    Fischer, Felícia M; Wright, Alexandra J; Eisenhauer, Nico; Ebeling, Anne; Roscher, Christiane; Wagg, Cameron; Weigelt, Alexandra; Weisser, Wolfgang W; Pillar, Valério D

    2016-05-19

    Climate change is expected to increase the frequency and magnitude of extreme weather events. It is therefore of major importance to identify the community attributes that confer stability in ecological communities during such events. In June 2013, a flood event affected a plant diversity experiment in Central Europe (Jena, Germany). We assessed the effects of plant species richness, functional diversity, flooding intensity and community means of functional traits on different measures of stability (resistance, resilience and raw biomass changes from pre-flood conditions). Surprisingly, plant species richness reduced community resistance in response to the flood. This was mostly because more diverse communities grew more immediately following the flood. Raw biomass increased over the previous year; this resulted in decreased absolute value measures of resistance. There was no clear response pattern for resilience. We found that functional traits drove these changes in raw biomass: communities with a high proportion of late-season, short-statured plants with dense, shallow roots and small leaves grew more following the flood. Late-growing species probably avoided the flood, whereas greater root length density might have allowed species to better access soil resources brought from the flood, thus growing more in the aftermath. We conclude that resource inputs following mild floods may favour the importance of traits related to resource acquisition and be less associated with flooding tolerance. PMID:27114578

  5. Cotyledon damage affects seed number through final plant size in the annual grassland species Medicago lupulina

    PubMed Central

    Zhang, Shiting; Zhao, Chuan; Lamb, Eric G.

    2011-01-01

    Background and Aims The effects of cotyledon damage on seedling growth and survival are relatively well established, but little is known about the effects on aspects of plant fitness such as seed number and size. Here the direct and indirect mechanisms linking cotyledon damage and plant fitness in the annual species Medicago lupulina are examined. Methods Growth and reproductive traits, including mature plant size, time to first flowering, flower number, seed number and individual seed mass were monitored in M. lupulina plants when zero, one or two cotyledons were removed at 7 d old. Structural equation modelling (SEM) was used to examine the mechanisms linking cotyledon damage to seed number and seed mass. Key Results Cotyledon damage reduced seed number but not individual seed mass. The primary mechanism was a reduction in plant biomass with cotyledon damage that in turn reduced seed number primarily through a reduction in flower numbers. Although cotyledon damage delayed flower initiation, it had little effect on seed number. Individual seed mass was not affected by cotyledon removal, but there was a trade-off between seed number and seed mass. Conclusions It is shown how a network of indirect mechanisms link damage to cotyledons and fitness in M. lupulina. Cotyledon damage had strong direct effects on both plant size and flowering phenology, but an analysis of the causal relationships among plant traits and fitness components showed that a reduction in plant size associated with cotyledon damage was an important mechanism influencing fitness. PMID:21196450

  6. Species-abundance--seed-size patterns within a plant community affected by grazing disturbance.

    PubMed

    Wu, Gao-lin; Shang, Zhan-huan; Zhu, Yuan-jun; Ding, Lu-ming; Wang, Dong

    2015-04-01

    Seed size has been advanced as a key factor that influences the dynamics of plant communities, but there are few empirical or theoretical predictions of how community dynamics progress based on seed size patterns. Information on the abundance of adults, seedlings, soil seed banks, seed rains, and the seed mass of 96 species was collected in alpine meadows of the Qinghai-Tibetan Plateau (China), which had different levels of grazing disturbance. The relationships between seed-mass-abundance patterns for adults, seedlings, the soil seed bank, and seed rain in the plant community were evaluated using regression models. Results showed that grazing levels affected the relationship between seed size and abundance properties of adult species, seedlings, and the soil seed bank, suggesting that there is a shift in seed-size--species-abundance relationships as a response to the grazing gradient. Grazing had no effect on the pattern of seed-size-seed-rain-abundance at four grazing levels. Grazing also had little effect on the pattern of seed-size--species-abundance and pattern of seed-size--soil-seed-bank-abundance in meadows with no grazing, light grazing, and moderate grazing), but there was a significant negative effect in meadows with heavy grazing. Grazing had little effect on the pattern of seed-size--seedling-abundance with no grazing, but had significant negative effects with light, moderate, and heavy grazing, and the |r| values increased with grazing levels. This indicated that increasing grazing pressure enhanced the advantage of smaller-seeded species in terms of the abundances of adult species, seedlings, and soil seed banks, whereas only the light grazing level promoted the seed rain abundance of larger-seeded species in the plant communities. This study suggests that grazing disturbances are favorable for increasing the species abundance for smaller-seeded species but not for the larger-seeded species in an alpine meadow community. Hence, there is a clear

  7. Are herbage yield and yield stability affected by plant species diversity in sown pasture mixtures?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A tenet of plant biodiversity theory in grasslands is that increased diversity contributes to the stability of ecosystems. In managed grasslands, such as pastures, greater stability of herbage production as a result of increased plant species diversity would be beneficial. In this study, I combined ...

  8. Habitat Heterogeneity Affects Plant and Arthropod Species Diversity and Turnover in Traditional Cornfields.

    PubMed

    Martínez, Eliana; Rös, Matthias; Bonilla, María Argenis; Dirzo, Rodolfo

    2015-01-01

    The expansion of the agricultural frontier by the clearing of remnant forests has led to human-dominated landscape mosaics. Previous studies have evaluated the effect of these landscape mosaics on arthropod diversity at local spatial scales in temperate and tropical regions, but little is known about fragmentation effects in crop systems, such as the complex tropical traditional crop systems that maintain a high diversity of weeds and arthropods in low-Andean regions. To understand the factors that influence patterns of diversity in human-dominated landscapes, we investigate the effect of land use types on plant and arthropod diversity in traditionally managed cornfields, via surveys of plants and arthropods in twelve traditional cornfields in the Colombian Andes. We estimated alpha and beta diversity to analyze changes in diversity related to land uses within a radius of 100 m to 1 km around each cornfield. We observed that forests influenced alpha diversity of plants, but not of arthropods. Agricultural lands had a positive relationship with plants and herbivores, but a negative relationship with predators. Pastures positively influenced the diversity of plants and arthropods. In addition, forest cover seemed to influence changes in plant species composition and species turnover of herbivore communities among cornfields. The dominant plant species varied among fields, resulting in high differentiation of plant communities. Predator communities also exhibited high turnover among cornfields, but differences in composition arose mainly among rare species. The crop system evaluated in this study represents a widespread situation in the tropics, therefore, our results can be of broad significance. Our findings suggest that traditional agriculture may not homogenize biological communities, but instead could maintain the regional pool of species through high beta diversity. PMID:26197473

  9. Habitat Heterogeneity Affects Plant and Arthropod Species Diversity and Turnover in Traditional Cornfields

    PubMed Central

    Martínez, Eliana; Rös, Matthias; Bonilla, María Argenis; Dirzo, Rodolfo

    2015-01-01

    The expansion of the agricultural frontier by the clearing of remnant forests has led to human-dominated landscape mosaics. Previous studies have evaluated the effect of these landscape mosaics on arthropod diversity at local spatial scales in temperate and tropical regions, but little is known about fragmentation effects in crop systems, such as the complex tropical traditional crop systems that maintain a high diversity of weeds and arthropods in low-Andean regions. To understand the factors that influence patterns of diversity in human-dominated landscapes, we investigate the effect of land use types on plant and arthropod diversity in traditionally managed cornfields, via surveys of plants and arthropods in twelve traditional cornfields in the Colombian Andes. We estimated alpha and beta diversity to analyze changes in diversity related to land uses within a radius of 100 m to 1 km around each cornfield. We observed that forests influenced alpha diversity of plants, but not of arthropods. Agricultural lands had a positive relationship with plants and herbivores, but a negative relationship with predators. Pastures positively influenced the diversity of plants and arthropods. In addition, forest cover seemed to influence changes in plant species composition and species turnover of herbivore communities among cornfields. The dominant plant species varied among fields, resulting in high differentiation of plant communities. Predator communities also exhibited high turnover among cornfields, but differences in composition arose mainly among rare species. The crop system evaluated in this study represents a widespread situation in the tropics, therefore, our results can be of broad significance. Our findings suggest that traditional agriculture may not homogenize biological communities, but instead could maintain the regional pool of species through high beta diversity. PMID:26197473

  10. Plant Trait Assembly Affects Superiority of Grazer's Foraging Strategies in Species-Rich Grasslands

    PubMed Central

    Mládek, Jan; Mládková, Pavla; Hejcmanová, Pavla; Dvorský, Miroslav; Pavlu, Vilém; De Bello, Francesco; Duchoslav, Martin; Hejcman, Michal; Pakeman, Robin J.

    2013-01-01

    Background Current plant – herbivore interaction models and experiments with mammalian herbivores grazing plant monocultures show the superiority of a maximizing forage quality strategy (MFQ) over a maximizing intake strategy (MI). However, there is a lack of evidence whether grazers comply with the model predictions under field conditions. Methodology/Findings We assessed diet selection of sheep (Ovis aries) using plant functional traits in productive mesic vs. low-productivity dry species-rich grasslands dominated by resource-exploitative vs. resource-conservative species respectively. Each grassland type was studied in two replicates for two years. We investigated the first grazing cycle in a set of 288 plots with a diameter of 30 cm, i.e. the size of sheep feeding station. In mesic grasslands, high plot defoliation was associated with community weighted means of leaf traits referring to high forage quality, i.e. low leaf dry matter content (LDMC) and high specific leaf area (SLA), with a high proportion of legumes and the most with high community weighted mean of forage indicator value. In contrast in dry grasslands, high community weighted mean of canopy height, an estimate of forage quantity, was the best predictor of plot defoliation. Similar differences in selection on forage quality vs. quantity were detected within plots. Sheep selected plants with higher forage indicator values than the plot specific community weighted mean of forage indicator value in mesic grasslands whereas taller plants were selected in dry grasslands. However, at this scale sheep avoided legumes and plants with higher SLA, preferred plants with higher LDMC while grazing plants with higher forage indicator values in mesic grasslands. Conclusions Our findings indicate that MFQ appears superior over MI only in habitats with a predominance of resource-exploitative species. Furthermore, plant functional traits (LDMC, SLA, nitrogen fixer) seem to be helpful correlates of forage quality

  11. Plant species diversity affects soil-atmosphere fluxes of methane and nitrous oxide.

    PubMed

    Niklaus, Pascal A; Le Roux, Xavier; Poly, Franck; Buchmann, Nina; Scherer-Lorenzen, Michael; Weigelt, Alexandra; Barnard, Romain L

    2016-07-01

    Plant diversity effects on ecosystem functioning can potentially interact with global climate by altering fluxes of the radiatively active trace gases nitrous oxide (N2O) and methane (CH4). We studied the effects of grassland species richness (1-16) in combination with application of fertilizer (nitrogen:phosphorus:potassium = 100:43.6:83 kg ha(-1) a(-1)) on N2O and CH4 fluxes in a long-term field experiment. Soil N2O emissions, measured over 2 years using static chambers, decreased with species richness unless fertilizer was added. N2O emissions increased with fertilization and the fraction of legumes in plant communities. Soil CH4 uptake, a process driven by methanotrophic bacteria, decreased with plant species numbers, irrespective of fertilization. Using structural equation models, we related trace gas fluxes to soil moisture, soil inorganic N concentrations, nitrifying and denitrifying enzyme activity, and the abundance of ammonia oxidizers, nitrite oxidizers, and denitrifiers (quantified by real-time PCR of gene fragments amplified from microbial DNA in soil). These analyses indicated that plant species richness increased soil moisture, which in turn increased N cycling-related activities. Enhanced N cycling increased N2O emission and soil CH4 uptake, with the latter possibly caused by removal of inhibitory ammonium by nitrification. The moisture-related indirect effects were surpassed by direct, moisture-independent effects opposite in direction. Microbial gene abundances responded positively to fertilizer but not to plant species richness. The response patterns we found were statistically robust and highlight the potential of plant biodiversity to interact with climatic change through mechanisms unrelated to carbon storage and associated carbon dioxide removal. PMID:27038993

  12. Do non-native plant species affect the shape of productivity-diversity relationships?

    USGS Publications Warehouse

    Drake, J.M.; Cleland, E.E.; Horner-Devine, M. C.; Fleishman, E.; Bowles, C.; Smith, M.D.; Carney, K.; Emery, S.; Gramling, J.; Vandermast, D.B.; Grace, J.B.

    2008-01-01

    The relationship between ecosystem processes and species richness is an active area of research and speculation. Both theoretical and experimental studies have been conducted in numerous ecosystems. One finding of these studies is that the shape of the relationship between productivity and species richness varies considerably among ecosystems and at different spatial scales, though little is known about the relative importance of physical and biological mechanisms causing this variation. Moreover, despite widespread concern about changes in species' global distributions, it remains unclear if and how such large-scale changes may affect this relationship. We present a new conceptual model of how invasive species might modulate relationships between primary production and species richness. We tested this model using long-term data on relationships between aboveground net primary production and species richness in six North American terrestrial ecosystems. We show that primary production and abundance of non-native species are both significant predictors of species richness, though we fail to detect effects of invasion extent on the shapes of the relationship between species richness and primary production.

  13. Plant invasions differentially affected by diversity and dominant species in native- and exotic-dominated grasslands.

    PubMed

    Xu, Xia; Polley, H Wayne; Hofmockel, Kirsten; Daneshgar, Pedram P; Wilsey, Brian J

    2015-12-01

    Plant invasions are an increasingly serious global concern, especially as the climate changes. Here, we explored how plant invasions differed between native- and novel exotic-dominated grasslands with experimental addition of summer precipitation in Texas in 2009. Exotic species greened up earlier than natives by an average of 18 days. This was associated with a lower invasion rate early in the growing season compared to native communities. However, invasion rate did not differ significantly between native and exotic communities across all sampling times. The predictors of invasion rate differed between native and exotic communities, with invasion being negatively influenced by species richness in natives and by dominant species in exotics. Interestingly, plant invasions matched the bimodal pattern of precipitation in Temple, Texas, and did not respond to the pulse of precipitation during the summer. Our results suggest that we will need to take different approaches in understanding of invasion between native and exotic grasslands. Moreover, with anticipated increasing variability in precipitation under global climate change, plant invasions may be constrained in their response if the precipitation pulses fall outside the normal growing period of invaders. PMID:27069615

  14. Plant compartment and biogeography affect microbiome composition in cultivated and native Agave species.

    PubMed

    Coleman-Derr, Devin; Desgarennes, Damaris; Fonseca-Garcia, Citlali; Gross, Stephen; Clingenpeel, Scott; Woyke, Tanja; North, Gretchen; Visel, Axel; Partida-Martinez, Laila P; Tringe, Susannah G

    2016-01-01

    Desert plants are hypothesized to survive the environmental stress inherent to these regions in part thanks to symbioses with microorganisms, and yet these microbial species, the communities they form, and the forces that influence them are poorly understood. Here we report the first comprehensive investigation of the microbial communities associated with species of Agave, which are native to semiarid and arid regions of Central and North America and are emerging as biofuel feedstocks. We examined prokaryotic and fungal communities in the rhizosphere, phyllosphere, leaf and root endosphere, as well as proximal and distal soil samples from cultivated and native agaves, through Illumina amplicon sequencing. Phylogenetic profiling revealed that the composition of prokaryotic communities was primarily determined by the plant compartment, whereas the composition of fungal communities was mainly influenced by the biogeography of the host species. Cultivated A. tequilana exhibited lower levels of prokaryotic diversity compared with native agaves, although no differences in microbial diversity were found in the endosphere. Agaves shared core prokaryotic and fungal taxa known to promote plant growth and confer tolerance to abiotic stress, which suggests common principles underpinning Agave-microbe interactions. PMID:26467257

  15. Plant Species and Functional Group Combinations Affect Green Roof Ecosystem Functions

    PubMed Central

    Lundholm, Jeremy; MacIvor, J. Scott; MacDougall, Zachary; Ranalli, Melissa

    2010-01-01

    Background Green roofs perform ecosystem services such as summer roof temperature reduction and stormwater capture that directly contribute to lower building energy use and potential economic savings. These services are in turn related to ecosystem functions performed by the vegetation layer such as radiation reflection and transpiration, but little work has examined the role of plant species composition and diversity in improving these functions. Methodology/Principal Findings We used a replicated modular extensive (shallow growing- medium) green roof system planted with monocultures or mixtures containing one, three or five life-forms, to quantify two ecosystem services: summer roof cooling and water capture. We also measured the related ecosystem properties/processes of albedo, evapotranspiration, and the mean and temporal variability of aboveground biomass over four months. Mixtures containing three or five life-form groups, simultaneously optimized several green roof ecosystem functions, outperforming monocultures and single life-form groups, but there was much variation in performance depending on which life-forms were present in the three life-form mixtures. Some mixtures outperformed the best monocultures for water capture, evapotranspiration, and an index combining both water capture and temperature reductions. Combinations of tall forbs, grasses and succulents simultaneously optimized a range of ecosystem performance measures, thus the main benefit of including all three groups was not to maximize any single process but to perform a variety of functions well. Conclusions/Significance Ecosystem services from green roofs can be improved by planting certain life-form groups in combination, directly contributing to climate change mitigation and adaptation strategies. The strong performance by certain mixtures of life-forms, especially tall forbs, grasses and succulents, warrants further investigation into niche complementarity or facilitation as mechanisms

  16. Elevated atmospheric carbon dioxide concentration affects interactions between Spodoptera exigua (Lepidoptera: Noctuidae) larvae and two host plant species outdoors

    SciTech Connect

    Caulfield, F.; Bunce, J.A. )

    1994-08-01

    Beet armyworm, Spodoptera exigua (Huebner), larvae were placed on sugarbeet (Beta vulgaris L.) and pigweed (Amaranthus hybridus L.) plants in outdoor chambers in which the plants were growing at either the ambient ([approximately] 350 [mu]l liter[sup [minus]1]) or ambient plus 350 [mu]l liter[sup [minus]1] ([approximately] 700 [mu]l liter[sup [minus]1]) carbon dioxide concentration. A series of experiments was performed to determine if larvae reduced plant growth differently at the two carbon dioxide concentrations in either species and if the insect growth or survival differed with carbon dioxide concentration. Leaf nitrogen, water, starch, and soluble carbohydrate contents were measured to assess carbon dioxide concentration effects on leaf quality. Insect feeding significantly reduced plant growth in sugarbeet plants at 350 [mu]l liter[sup [minus]1] but not at 700 [mu]l liter[sup [minus]1] nor in pigweed at either carbon dioxide concentration. Larval survival was greater on sugarbeet plants at the elevated carbon dioxide concentration. Increased survival occurred only if the insects were at the elevated carbon dioxide concentration and consumed leaf material grown at the elevated concentration. Leaf quality was only marginally affected by growth at elevated carbon dioxide concentration in these experiments. The results indicate that in designing experiments to predict effects of elevated atmospheric carbon dioxide concentrations on plant-insect interactions, both plants and insects should be exposed to the experimental carbon dioxide concentrations, as well as to as realistic environmental conditions as possible.

  17. Plant compartment and biogeography affect microbiome composition in cultivated and native Agave species.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The primary goal of this research was to investigate the prokaryotic and fungal communities associated with the bulk soil, the rhizosphere, the phyllosphere, and the root and leaf endospheres, for three Agave species: the cultivated Agave tequilana and the native species, A. salmiana and A. deserti ...

  18. Individual species affect plant traits structure in their surroundings: evidence of functional mechanisms of assembly.

    PubMed

    Chacón-Labella, Julia; de la Cruz, Marcelino; Pescador, David S; Escudero, Adrián

    2016-04-01

    Evaluating community assembly through the use of functional traits is a promising tool for testing predictions arising from Niche and Coexistence theories. Although interactions among neighboring species and their inter-specific differences are known drivers of coexistence with a strong spatial signal, assessing the role of individual species on the functional structure of the community at different spatial scales remains a challenge. Here, we ask whether individual species exert a measurable effect on the spatial organization of different functional traits in local assemblages. We first propose and compute two functions that describe different aspects of functional trait organization around individual species at multiple scales: individual weighted mean area relationship and individual functional diversity area relationship. Secondly, we develop a conceptual model on the relationship and simultaneous variation of these two metrics, providing five alternative scenarios in response to the ability of some target species to modify its neighbor environment and the possible assembly mechanisms involved. Our results show that some species influence the spatial structure of specific functional traits, but their effects were always restricted to the finest spatial scales. In the basis of our conceptual model, the observed patterns point to two main mechanisms driving the functional structure of the community at the fine scale, "biotic" filtering meditated by individual species and resource partitioning driven by indirect facilitation rather than by competitive mechanisms. PMID:26820565

  19. Genetically Altered Plant Species

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Researchers in Robert Ferl's lab at the University of Florida in Gainesville, genetically altered this Arabdopsis Thaliana (a brassica species) plant to learn how extreme environments, such as the low atmospheric pressure on Mars, affect plant genes. They inserted green fluorescent protein (GFP) near the on/off switches for anoxia and drought genes. When those genes were turned on after exposure to reduced atmospheric pressure, GFP was turned on as well, causing cells expressing those genes to glow green under a blue light. The natural fluorescence of chlorophyll accounts for the red glow.

  20. Plant Host Species and Geographic Distance Affect the Structure of Aboveground Fungal Symbiont Communities, and Environmental Filtering Affects Belowground Communities in a Coastal Dune Ecosystem.

    PubMed

    David, Aaron S; Seabloom, Eric W; May, Georgiana

    2016-05-01

    Microbial symbionts inhabit tissues of all plants and animals. Their community composition depends largely on two ecological processes: (1) filtering by abiotic conditions and host species determining the environments that symbionts are able to colonize and (2) dispersal-limitation determining the pool of symbionts available to colonize a given host and community spatial structure. In plants, the above- and belowground tissues represent such distinct habitats for symbionts that we expect different effects of filtering and spatial structuring on their symbiont communities. In this study, we characterized above- and belowground communities of fungal endophytes--fungi living asymptomatically within plants--to understand the contributions of filtering and spatial structure to endophyte community composition. We used a culture-based approach to characterize endophytes growing in leaves and roots of three species of coastal beachgrasses in dunes of the USA Pacific Northwest. For leaves, endophyte isolation frequency and OTU richness depended primarily on plant host species. In comparison, for roots, both isolation frequency and OTU richness increased from the nutrient-poor front of the dune to the higher-nutrient backdune. Endophyte community composition in leaves exhibited a distance-decay relationship across the region. In a laboratory assay, faster growth rates and lower spore production were more often associated with leaf- than root-inhabiting endophytes. Overall, our results reveal a greater importance of biotic filtering by host species and dispersal-limitation over regional geographic distances for aboveground leaf endophyte communities and stronger effects of abiotic environmental filtering and locally patchy distributions for belowground root endophyte communities. PMID:26626912

  1. WHEAT LEAF RUST SEVERITY AS AFFECTED BY PLANT DENSITY AND SPECIES PROPORTION IN SIMPLE COMMUNITIES OF WHEAT AND WILD OATS

    EPA Science Inventory

    While it is generally accepted that dense stands of plants exacerbate epidermics caused by foliar pathogens, there is little experimental evidence to support this view. We grew model plant communities consisting of wheat and wild oats at different densities and proportions and ex...

  2. WHEAT LEAF RUST SEVERITY AS AFFECTED BY PLANT DENSITY AND SPECIES PROPORTION IN SIMPLE COMMUNITIES OF WHEAT AND WILD OATS

    EPA Science Inventory

    While it is generally accepted that dense stands of plants exacerbate epidemics caused by foliar pathogens, there is little experimental evidence to support this view. We grew model plant communities consisting of wheat and wild oats at different densities and proportions and exp...

  3. Conservation of tropical plant species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This book is designed to provide a review of the methods and current status of conservation of many tropical plant species. Future perspectives of conservation of tropical species will also be discussed. The section on methods covers the range of conservation techniques, in situ, seed banking, in vi...

  4. Species interactions and plant polyploidy.

    PubMed

    Segraves, Kari A; Anneberg, Thomas J

    2016-07-01

    Polyploidy is a common mode of speciation that can have far-reaching consequences for plant ecology and evolution. Because polyploidy can induce an array of phenotypic changes, there can be cascading effects on interactions with other species. These interactions, in turn, can have reciprocal effects on polyploid plants, potentially impacting their establishment and persistence. Although there is a wealth of information on the genetic and phenotypic effects of polyploidy, the study of species interactions in polyploid plants remains a comparatively young field. Here we reviewed the available evidence for how polyploidy may impact many types of species interactions that range from mutualism to antagonism. Specifically, we focused on three main questions: (1) Does polyploidy directly cause the formation of novel interactions not experienced by diploids, or does it create an opportunity for natural selection to then form novel interactions? (2) Does polyploidy cause consistent, predictable changes in species interactions vs. the evolution of idiosyncratic differences? (3) Does polyploidy lead to greater evolvability in species interactions? From the scarce evidence available, we found that novel interactions are rare but that polyploidy can induce changes in pollinator, herbivore, and pathogen interactions. Although further tests are needed, it is likely that selection following whole-genome duplication is important in all types of species interaction and that there are circumstances in which polyploidy can enhance the evolvability of interactions with other species. PMID:27370313

  5. Extinction risks of Amazonian plant species.

    PubMed

    Feeley, Kenneth J; Silman, Miles R

    2009-07-28

    Estimates of the number, and preferably the identity, of species that will be threatened by land-use change and habitat loss are an invaluable tool for setting conservation priorities. Here, we use collections data and ecoregion maps to generate spatially explicit distributions for more than 40,000 vascular plant species from the Amazon basin (representing more than 80% of the estimated Amazonian plant diversity). Using the distribution maps, we then estimate the rates of habitat loss and associated extinction probabilities due to land-use changes as modeled under 2 disturbance scenarios. We predict that by 2050, human land-use practices will have reduced the habitat available to Amazonian plant species by approximately 12-24%, resulting in 5-9% of species becoming "committed to extinction," significantly fewer than other recent estimates. Contrary to previous studies, we find that the primary determinant of habitat loss and extinction risk is not the size of a species' range, but rather its location. The resulting extinction risk estimates are a valuable conservation tool because they indicate not only the total percentage of Amazonian plant species threatened with extinction but also the degree to which individual species and habitats will be affected by current and future land-use changes. PMID:19617552

  6. How variation between individuals affects species coexistence.

    PubMed

    Hart, Simon P; Schreiber, Sebastian J; Levine, Jonathan M

    2016-08-01

    Although the effects of variation between individuals within species are traditionally ignored in studies of species coexistence, the magnitude of intraspecific variation in nature is forcing ecologists to reconsider. Compelling intuitive arguments suggest that individual variation may provide a previously unrecognised route to diversity maintenance by blurring species-level competitive differences or substituting for species-level niche differences. These arguments, which are motivating a large body of empirical work, have rarely been evaluated with quantitative theory. Here we incorporate intraspecific variation into a common model of competition and identify three pathways by which this variation affects coexistence: (1) changes in competitive dynamics because of nonlinear averaging, (2) changes in species' mean interaction strengths because of variation in underlying traits (also via nonlinear averaging) and (3) effects on stochastic demography. As a consequence of the first two mechanisms, we find that intraspecific variation in competitive ability increases the dominance of superior competitors, and intraspecific niche variation reduces species-level niche differentiation, both of which make coexistence more difficult. In addition, individual variation can exacerbate the effects of demographic stochasticity, and this further destabilises coexistence. Our work provides a theoretical foundation for emerging empirical interests in the effects of intraspecific variation on species diversity. PMID:27250037

  7. Clonal growth and plant species abundance

    PubMed Central

    Herben, Tomáš; Nováková, Zuzana; Klimešová, Jitka

    2014-01-01

    Background and Aims Both regional and local plant abundances are driven by species' dispersal capacities and their abilities to exploit new habitats and persist there. These processes are affected by clonal growth, which is difficult to evaluate and compare across large numbers of species. This study assessed the influence of clonal reproduction on local and regional abundances of a large set of species and compared the predictive power of morphologically defined traits of clonal growth with data on actual clonal growth from a botanical garden. The role of clonal growth was compared with the effects of seed reproduction, habitat requirements and growth, proxied both by LHS (leaf–height–seed) traits and by actual performance in the botanical garden. Methods Morphological parameters of clonal growth, actual clonal reproduction in the garden and LHS traits (leaf-specific area – height – seed mass) were used as predictors of species abundance, both regional (number of species records in the Czech Republic) and local (mean species cover in vegetation records) for 836 perennial herbaceous species. Species differences in habitat requirements were accounted for by classifying the dataset by habitat type and also by using Ellenberg indicator values as covariates. Key Results After habitat differences were accounted for, clonal growth parameters explained an important part of variation in species abundance, both at regional and at local levels. At both levels, both greater vegetative growth in cultivation and greater lateral expansion trait values were correlated with higher abundance. Seed reproduction had weaker effects, being positive at the regional level and negative at the local level. Conclusions Morphologically defined traits are predictive of species abundance, and it is concluded that simultaneous investigation of several such traits can help develop hypotheses on specific processes (e.g. avoidance of self-competition, support of offspring) potentially

  8. Characteristics of initial deposition and behavior of radiocesium in forest ecosystems of different locations and species affected by the Fukushima Daiichi Nuclear Power Plant accident.

    PubMed

    Komatsu, Masabumi; Kaneko, Shinji; Ohashi, Shinta; Kuroda, Katsushi; Sano, Tetsuya; Ikeda, Shigeto; Saito, Satoshi; Kiyono, Yoshiyuki; Tonosaki, Mario; Miura, Satoru; Akama, Akio; Kajimoto, Takuya; Takahashi, Masamichi

    2016-09-01

    After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, information about stand-level spatial patterns of radiocesium initially deposited in the surrounding forests was essential for predicting the future dynamics of radiocesium and suggesting a management plan for contaminated forests. In the first summer (approximately 6 months after the accident), we separately estimated the amounts of radiocesium ((134)Cs and (137)Cs; Bq m(-2)) in the major components (trees, organic layers, and soils) in forests of three sites with different contamination levels. For a Japanese cedar (Cryptomeria japonica) forest studied at each of the three sites, the radiocesium concentration greatly differed among the components, with the needle and organic layer having the highest concentrations. For these cedar forests, the proportion of the (137)Cs stock in the aboveground tree biomass varied from 22% to 44% of the total (137)Cs stock; it was 44% in highly contaminated sites (7.0 × 10(5) Bq m(-2)) but reduced to 22% in less contaminated sites (1.1 × 10(4) Bq m(-2)). In the intermediate contaminated site (5.0-5.8 × 10(4) Bq m(-2)), 34% of radiocesium was observed in the aboveground tree biomass of the Japanese cedar stand. However, this proportion was considerably smaller (18-19%) in the nearby mixed forests of the Japanese red pine (Pinus densiflora) and deciduous broad-leaved trees. Non-negligible amounts of (134)Cs and (137)Cs were detected in both the sapwood and heartwood of all the studied tree species. This finding suggested that the uptake or translocation of radiocesium had already started within 6 months after the accident. The belowground compartments were mostly present in the organic layer and the uppermost (0-5 cm deep) mineral soil layer at all the study sites. We discussed the initial transfer process of radiocesium deposited in the forest and inferred that the type of initial deposition (i.e., dry versus wet radiocesium deposition), the amount of

  9. Soil organisms shape the competition between grassland plant species.

    PubMed

    Sabais, Alexander C W; Eisenhauer, Nico; König, Stephan; Renker, Carsten; Buscot, François; Scheu, Stefan

    2012-12-01

    Decomposers and arbuscular mycorrhizal fungi (AMF) both determine plant nutrition; however, little is known about their interactive effects on plant communities. We set up a greenhouse experiment to study effects of plant competition (one- and two-species treatments), Collembola (Heteromurus nitidus and Protaphorura armata), and AMF (Glomus intraradices) on the performance (above- and belowground productivity and nutrient uptake) of three grassland plant species (Lolium perenne, Trifolium pratense, and Plantago lanceolata) belonging to three dominant plant functional groups (grasses, legumes, and herbs). Generally, L. perenne benefited from being released from intraspecific competition in the presence of T. pratense and P. lanceolata. However, the presence of AMF increased the competitive strength of P. lanceolata and T. pratense against L. perenne and also modified the effects of Collembola on plant productivity. The colonization of roots by AMF was reduced in treatments with two plant species suggesting that plant infection by AMF was modified by interspecific plant interactions. Collembola did not affect total colonization of roots by AMF, but increased the number of mycorrhizal vesicles in P. lanceolata. AMF and Collembola both enhanced the amount of N and P in plant shoot tissue, but impacts of Collembola were less pronounced in the presence of AMF. Overall, the results suggest that, by differentially affecting the nutrient acquisition and performance of plant species, AMF and Collembola interactively modify plant competition and shape the composition of grassland plant communities. The results suggest that mechanisms shaping plant community composition can only be understood when complex belowground interactions are considered. PMID:22678109

  10. Phytophthora Species, New Threats to the Plant Health in Korea

    PubMed Central

    Hyun, Ik-Hwa; Choi, Woobong

    2014-01-01

    Given the lack of a resistant genetic pool in host plants, the introduction of exotic invasive pathogens can result in epidemics that affect a specific ecosystem and economy. Plant quarantine, which is designed to protect endemic plant resources, is a highly invaluable safeguard that should keep biosecurity with increasing international trade and global transportation. A total of 34 species of plant pathogens including Phytophthora infestans were documented as introduced from other countries into Korea from 1900 to 2010. The genus Phytophthora, classified in oomycetes, includes more than 120 species that are mostly recognized worldwide as highly invasive plant pathogens. After 2000, over 50 new species of Phytophthora were identified internationally as plant pathogens occurring in crops and forest trees. In Korea, Phytophthora is also one of the most serious plant pathogens. To date, 22 species (about one-fifth of known species) of the genus have been identified and reported as plant pathogens in the country. The likelihood of new exotic Phytophthora species being introduced into Korea continues to increase, thus necessitating intensive plant quarantine inspections. As new potential threats to plant health in Korea, six Phytophthora species, namely, P. alni, P. inundata, P. kernoviae, P. pinifolia, P. quercina, and P. ramorum, are discussed in this review with focus on history, disease, biology, management, and plant quarantine issues. PMID:25506298

  11. SELECTING PLANT SPECIES FOR PESTICIDE REGISTRATION TESTS

    EPA Science Inventory

    Current test protocols used by the US EPA for the registration of pesticides examines plant responses of 10 crop species but may not examine regionally important native plants or crops. In order to test the efficiency of current test protocols we selected six native plant species...

  12. A parasitic plant increases native and exotic plant species richness in vernal pools

    PubMed Central

    Graffis, Andrea M.; Kneitel, Jamie M.

    2015-01-01

    Species interactions are well known to affect species diversity in communities, but the effects of parasites have been less studied. Previous studies on parasitic plants have found both positive and negative effects on plant community diversity. Cuscuta howelliana is an abundant endemic parasitic plant that inhabits California vernal pools. We tested the hypothesis that C. howelliana acts as a keystone species to increase plant species richness in vernal pools through a C. howelliana removal experiment at Beale Air Force Base in north-central California. Vernal pool endemic plants were parasitized more frequently, and Eryngium castrense and Navarretia leucocephala were the most frequently parasitized host plant species of C. howelliana. Cuscuta howelliana caused higher plant species richness, both natives and exotics, compared with removal plots. However, there was no single plant species that significantly increased with C. howelliana removal. Decreases in Eryngium castrense percent cover plots with C. howelliana is a plausible explanation for differences in species richness. In conclusion, C. howelliana led to changes in species composition and increases in plant species richness, consistent with what is expected from the effects of a keystone species. This research provides support for a shift in management strategies that focus on species-specific targets to strategies that target maintenance of complex species interactions and therefore maximize biodiversity and resilience of ecosystems. PMID:26307042

  13. Endangered Species (Plants). LC Science Tracer Bullet.

    ERIC Educational Resources Information Center

    Niskern, Diana, Comp.

    This guide is intended for those who wish to study the literature dealing with various aspects of endangered plant species. This document includes the following sections, some of which are bibliographies: (1) "Introductions to the Topic"; (2) "Subject Headings" (for endangered species of plants used by the Library of Congress); (3) "General…

  14. The Invasive Plant Species Education Guide

    ERIC Educational Resources Information Center

    Mason, Kevin; James, Krista; Carlson, Kitrina; D'Angelo, Jean

    2010-01-01

    To help high school students gain a solid understanding of invasive plant species, university faculty and students from the University of Wisconsin-Stout (UW-Stout) and a local high school teacher worked together to develop the Invasive Plant Species (IPS) Education Guide. The IPS Education Guide includes nine lessons that give students an…

  15. Exotic plant species invade hot spots of native plant diversity

    USGS Publications Warehouse

    Stohlgren, T.J.; Binkley, D.; Chong, G.W.; Kalkhan, M.A.; Schell, L.D.; Bull, K.A.; Otsuki, Y.; Newman, G.; Bashkin, M.; Yowhan, S.

    1999-01-01

    Some theories and experimental studies suggest that areas of low plant species richness may be invaded more easily than areas of high plant species richness. We gathered nested-scale vegetation data on plant species richness, foliar cover, and frequency from 200 1-m2 subplots (20 1000-m2 modified-Whittaker plots) in the Colorado Rockies (USA), and 160 1-m2 subplots (16 1000-m2 plots) in the Central Grasslands in Colorado, Wyoming, South Dakota, and Minnesota (USA) to test the generality of this paradigm. At the 1-m2 scale, the paradigm was supported in four prairie types in the Central Grasslands, where exotic species richness declined with increasing plant species richness and cover. At the 1-m2 scale, five forest and meadow vegetation types in the Colorado Rockies contradicted the paradigm; exotic species richness increased with native-plant species richness and foliar cover. At the 1000-m2 plot scale (among vegetation types), 83% of the variance in exotic species richness in the Central Grasslands was explained by the total percentage of nitrogen in the soil and the cover of native plant species. In the Colorado Rockies, 69% of the variance in exotic species richness in 1000-m2 plots was explained by the number of native plant species and the total percentage of soil carbon. At landscape and biome scales, exotic species primarily invaded areas of high species richness in the four Central Grasslands sites and in the five Colorado Rockies vegetation types. For the nine vegetation types in both biomes, exotic species cover was positively correlated with mean foliar cover, mean soil percentage N, and the total number of exotic species. These patterns of invasibility depend on spatial scale, biome and vegetation type, spatial autocorrelation effects, availability of resources, and species-specific responses to grazing and other disturbances. We conclude that: (1) sites high in herbaceous foliar cover and soil fertility, and hot spots of plant diversity (and

  16. Increasing enemy biodiversity strengthens herbivore suppression on two plant species.

    PubMed

    Straub, Cory S; Snyder, William E

    2008-06-01

    Concern over biodiversity loss, especially at higher trophic levels, has led to a surge in studies investigating how changes in natural enemy diversity affect community and ecosystem functioning. These studies have found that increasing enemy diversity can strengthen, weaken, and not affect prey suppression, demonstrating that multi-enemy effects on prey are context-dependent. Here we ask how one factor, plant species identity, influences multi-enemy effects on prey. We focused on two plant species of agricultural importance, potato (Solanum tuberosum), and collards (Brassica oleracea L.). These species share a common herbivorous pest, the green peach aphid (Myzus persicae), but vary in structural and chemical traits that affect aphid reproductive rates and which may also influence inter-enemy interactions. In a large-scale field experiment, overall prey exploitation varied dramatically among the plant species, with enemies reducing aphid populations by approximately 94% on potatoes and approximately 62% on collards. Increasing enemy diversity similarly strengthened aphid suppression on both plants, however, and there was no evidence that plant species identity significantly altered the relationship between enemy diversity and prey suppression. Microcosm experiments suggested that, on both collards and potatoes, intraspecific competition among natural enemies exceeded interspecific competition. Enemy species showed consistent and significant differences in where they foraged on the plants, and enemies in the low-diversity treatment tended to spend less time foraging than enemies in the high-diversity treatment. These data suggest that increasing enemy diversity may strengthen aphid suppression because interspecific differences in where enemies forage on the plant allow for greater resource partitioning. Further, these functional benefits of diversity appear to be robust to changes in plant species identity. PMID:18589525

  17. Herbivory of an invasive slug is affected by earthworms and the composition of plant communities

    PubMed Central

    2013-01-01

    Background Biodiversity loss and species invasions are among the most important human-induced global changes. Moreover, these two processes are interlinked as ecosystem invasibility is considered to increase with decreasing biodiversity. In temperate grasslands, earthworms serve as important ecosystem engineers making up the majority of soil faunal biomass. Herbivore behaviour has been shown to be affected by earthworms, however it is unclear whether these effects differ with the composition of plant communities. To test this we conducted a mesocosm experiment where we added earthworms (Annelida: Lumbricidae) to planted grassland communities with different plant species composition (3 vs. 12 plant spp.). Plant communities had equal plant densities and ratios of the functional groups grasses, non-leguminous forbs and legumes. Later, Arion vulgaris slugs (formerly known as A. lusitanicus; Gastropoda: Arionidae) were added and allowed to freely choose among the available plant species. This slug species is listed among the 100 worst alien species in Europe. We hypothesized that (i) the food choice of slugs would be altered by earthworms’ specific effects on the growth and nutrient content of plant species, (ii) slug herbivory will be less affected by earthworms in plant communities containing more plant species than in those with fewer plant species because of a more readily utilization of plant resources making the impacts of earthworms less pronounced. Results Slug herbivory was significantly affected by both earthworms and plant species composition. Slugs damaged 60% less leaves when earthworms were present, regardless of the species composition of the plant communities. Percent leaf area consumed by slugs was 40% lower in communities containing 12 plant species; in communities containing only three species earthworms increased slug leaf area consumption. Grasses were generally avoided by slugs. Leaf length and number of tillers was increased in mesocosms

  18. Intraspecific genetic variation and species coexistence in plant communities.

    PubMed

    Ehlers, Bodil K; Damgaard, Christian F; Laroche, Fabien

    2016-01-01

    Many studies report that intraspecific genetic variation in plants can affect community composition and coexistence. However, less is known about which traits are responsible and the mechanisms by which variation in these traits affect the associated community. Focusing on plant-plant interactions, we review empirical studies exemplifying how intraspecific genetic variation in functional traits impacts plant coexistence. Intraspecific variation in chemical and architectural traits promotes species coexistence, by both increasing habitat heterogeneity and altering competitive hierarchies. Decomposing species interactions into interactions between genotypes shows that genotype × genotype interactions are often intransitive. The outcome of plant-plant interactions varies with local adaptation to the environment and with dominant neighbour genotypes, and some plants can recognize the genetic identity of neighbour plants if they have a common history of coexistence. Taken together, this reveals a very dynamic nature of coexistence. We outline how more traits mediating plant-plant interactions may be identified, and how future studies could use population genetic surveys of genotype distribution in nature and methods from trait-based ecology to better quantify the impact of intraspecific genetic variation on plant coexistence. PMID:26790707

  19. Spatial heterogeneity of plant-soil feedback affects root interactions and interspecific competition.

    PubMed

    Hendriks, Marloes; Ravenek, Janneke M; Smit-Tiekstra, Annemiek E; van der Paauw, Jan Willem; de Caluwe, Hannie; van der Putten, Wim H; de Kroon, Hans; Mommer, Liesje

    2015-08-01

    Plant-soil feedback is receiving increasing interest as a factor influencing plant competition and species coexistence in grasslands. However, we do not know how spatial distribution of plant-soil feedback affects plant below-ground interactions. We investigated the way in which spatial heterogeneity of soil biota affects competitive interactions in grassland plant species. We performed a pairwise competition experiment combined with heterogeneous distribution of soil biota using four grassland plant species and their soil biota. Patches were applied as quadrants of 'own' and 'foreign' soils from all plant species in all pairwise combinations. To evaluate interspecific root responses, species-specific root biomass was quantified using real-time PCR. All plant species suffered negative soil feedback, but strength was species-specific, reflected by a decrease in root growth in own compared with foreign soil. Reduction in root growth in own patches by the superior plant competitor provided opportunities for inferior competitors to increase root biomass in these patches. These patterns did not cascade into above-ground effects during our experiment. We show that root distributions can be determined by spatial heterogeneity of soil biota, affecting plant below-ground competitive interactions. Thus, spatial heterogeneity of soil biota may contribute to plant species coexistence in species-rich grasslands. PMID:25871977

  20. Variability in Phoma species affecting sugar beet

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phoma betae can cause damage to sugar beet (Beta vulgaris) at multiple growth stages. It has historically been an important seedling disease, but this is largely managed by ensuring clean seed for planting. The pathogen also can cause a root rot, a leaf spot, and rotting of beets during storage. In ...

  1. Species interaction mechanisms maintain grassland plant species diversity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Theory has outpaced empirical research in pursuit of identifying mechanisms maintaining species diversity. Here we demonstrate how data from diversity-ecosystem functioning experiments can be used to test maintenance of diversity theory. We predict that grassland plant diversity can be maintained by...

  2. Competition with wind-pollinated plant species alters floral traits of insect-pollinated plant species

    PubMed Central

    Flacher, Floriane; Raynaud, Xavier; Hansart, Amandine; Motard, Eric; Dajoz, Isabelle

    2015-01-01

    Plant traits related to attractiveness to pollinators (e.g. flowers and nectar) can be sensitive to abiotic or biotic conditions. Soil nutrient availability, as well as interactions among insect-pollinated plants species, can induce changes in flower and nectar production. However, further investigations are needed to determine the impact of interactions between insect-pollinated species and abiotically pollinated species on such floral traits, especially floral rewards. We carried out a pot experiment in which three insect-pollinated plant species were grown in binary mixtures with four wind-pollinated plant species, differing in their competitive ability. Along the flowering period, we measured floral traits of the insect-pollinated species involved in attractiveness to pollinators (i.e. floral display size, flower size, daily and total 1) flower production, 2) nectar volume, 3) amount of sucrose allocated to nectar). Final plant biomass was measured to quantify competitive interactions. For two out of three insect-pollinated species, we found that the presence of a wind-pollinated species can negatively impact floral traits involved in attractiveness to pollinators. This effect was stronger with wind-pollinated species that induced stronger competitive interactions. These results stress the importance of studying the whole plant community (and not just the insect-pollinated plant community) when working on plant-pollinator interactions. PMID:26335409

  3. Ensemble habitat mapping of invasive plant species

    USGS Publications Warehouse

    Stohlgren, T.J.; Ma, P.; Kumar, S.; Rocca, M.; Morisette, J.T.; Jarnevich, C.S.; Benson, N.

    2010-01-01

    Ensemble species distribution models combine the strengths of several species environmental matching models, while minimizing the weakness of any one model. Ensemble models may be particularly useful in risk analysis of recently arrived, harmful invasive species because species may not yet have spread to all suitable habitats, leaving species-environment relationships difficult to determine. We tested five individual models (logistic regression, boosted regression trees, random forest, multivariate adaptive regression splines (MARS), and maximum entropy model or Maxent) and ensemble modeling for selected nonnative plant species in Yellowstone and Grand Teton National Parks, Wyoming; Sequoia and Kings Canyon National Parks, California, and areas of interior Alaska. The models are based on field data provided by the park staffs, combined with topographic, climatic, and vegetation predictors derived from satellite data. For the four invasive plant species tested, ensemble models were the only models that ranked in the top three models for both field validation and test data. Ensemble models may be more robust than individual species-environment matching models for risk analysis. ?? 2010 Society for Risk Analysis.

  4. Ensemble habitat mapping of invasive plant species.

    PubMed

    Stohlgren, Thomas J; Ma, Peter; Kumar, Sunil; Rocca, Monique; Morisette, Jeffrey T; Jarnevich, Catherine S; Benson, Nate

    2010-02-01

    Ensemble species distribution models combine the strengths of several species environmental matching models, while minimizing the weakness of any one model. Ensemble models may be particularly useful in risk analysis of recently arrived, harmful invasive species because species may not yet have spread to all suitable habitats, leaving species-environment relationships difficult to determine. We tested five individual models (logistic regression, boosted regression trees, random forest, multivariate adaptive regression splines (MARS), and maximum entropy model or Maxent) and ensemble modeling for selected nonnative plant species in Yellowstone and Grand Teton National Parks, Wyoming; Sequoia and Kings Canyon National Parks, California, and areas of interior Alaska. The models are based on field data provided by the park staffs, combined with topographic, climatic, and vegetation predictors derived from satellite data. For the four invasive plant species tested, ensemble models were the only models that ranked in the top three models for both field validation and test data. Ensemble models may be more robust than individual species-environment matching models for risk analysis. PMID:20136746

  5. Evidence for electrotropism in some plant species

    NASA Astrophysics Data System (ADS)

    Gorgolewski, S.; Rożej, B.

    2001-01-01

    The ever-present global Atmospheric Electrical Field (AEF) is used by many plant species. There are many natural habitats with electrotropic plants and habitats with no AEF. The plants growing there are not electrotropic, like the plants growing under the canopies of the trees or the Arecibo radio telescope. Examples are given of different plants which belong to one or the other class, and the criteria how to distinguish them. In addition to natural habitat observations, laboratory experiments were run in search of the sensitivity of electrotropic effect to different electric field intensities. During a few years, it was established that in very strong fields (of the order of 1 MV/m) all plants respond immediately to the field. This type of reaction is due to the Coulomb forces, but electrotropism depends on electric field interaction with ions. The "reference field" (130 V/m) was always used with stronger fields in the several kV/m range which enhance plant growth rate and size similar to plant growth hormones. Surprising effects were also observed with reversed and horizontal field polarity. In conclusion electrotropic plants deprived of the electrical field do not develop as expected, as can be seen in Biosphere 2. This is an instructive example of what happens when we forget to provide the plants with this vital natural environmental factor. Electrical fields of different intensity, directions and configurations are cheap and easy to generate.

  6. Herbivore effects on plant species density at varying productivity levels

    USGS Publications Warehouse

    Gough, L.; Grace, J.B.

    1998-01-01

    Artificially increasing primary productivity decreases plant species richness in many habitats; herbivory may affect this outcome, but it has rarely been directly addressed in fertilization studies. This experiment was conducted in two Louisiana coastal marshes to examine the effects of nutrient enrichment and sediment addition on herbaceous plant communities with and without vertebrate herbivory. After three growing seasons, fertilization increased community biomass in all plots, but decreased species density (the number of species per unit area) only in plots protected from herbivory. Herbivory alone did not alter species density at either site. At the brackish marsh, herbivory caused a shift in dominance in the fertilized plots from a species that is considered the competitive dominant, but is selectively eaten, to another less palatable species. At the fresh marsh, increased dead biomass in the absence of herbivory and in the fertilized plots probably contributed to the decrease in species density, perhaps by limiting germination of annuals. Our results support those of other fertilization studies in which plant species density decreases with increased biomass, but only in those plots protected from herbivory.

  7. Heterogeneous distribution of metabolites across plant species

    NASA Astrophysics Data System (ADS)

    Takemoto, Kazuhiro; Arita, Masanori

    2009-07-01

    We investigate the distribution of flavonoids, a major category of plant secondary metabolites, across species. Flavonoids are known to show high species specificity, and were once considered as chemical markers for understanding adaptive evolution and characterization of living organisms. We investigate the distribution among species using bipartite networks, and find that two heterogeneous distributions are conserved among several families: the power-law distributions of the number of flavonoids in a species and the number of shared species of a particular flavonoid. In order to explain the possible origin of the heterogeneity, we propose a simple model with, essentially, a single parameter. As a result, we show that two respective power-law statistics emerge from simple evolutionary mechanisms based on a multiplicative process. These findings provide insights into the evolution of metabolite diversity and characterization of living organisms that defy genome sequence analysis for different reasons.

  8. Cryobanking of plant species, promise and status

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Currently, the PAGRP has over 4,000 unique samples of clonally propagated species and about 49,000 seed samples in long-term liquid nitrogen storage. Cryopreservation of plant genetic resources has several advantages over germplasm maintenance in field or in vitro; the main of the advantages are pro...

  9. Plant ecology. Anthropogenic environmental changes affect ecosystem stability via biodiversity.

    PubMed

    Hautier, Yann; Tilman, David; Isbell, Forest; Seabloom, Eric W; Borer, Elizabeth T; Reich, Peter B

    2015-04-17

    Human-driven environmental changes may simultaneously affect the biodiversity, productivity, and stability of Earth's ecosystems, but there is no consensus on the causal relationships linking these variables. Data from 12 multiyear experiments that manipulate important anthropogenic drivers, including plant diversity, nitrogen, carbon dioxide, fire, herbivory, and water, show that each driver influences ecosystem productivity. However, the stability of ecosystem productivity is only changed by those drivers that alter biodiversity, with a given decrease in plant species numbers leading to a quantitatively similar decrease in ecosystem stability regardless of which driver caused the biodiversity loss. These results suggest that changes in biodiversity caused by drivers of environmental change may be a major factor determining how global environmental changes affect ecosystem stability. PMID:25883357

  10. Forty-nine New Host Plant Species for Bemisia tabaci (Hemiptera: Aleyrodidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The sweetpotato whitefly, Bemisia tabaci (Gennadius), is a worldwide pest of numerous agricultural and ornamental crops. In addition to directly feeding on plants, it also acts as a vector of plant viruses of cultivated and uncultivated host plant species. Moreover, host plants can affect the popula...

  11. Plant species evaluated for new crop potential

    SciTech Connect

    Carr, M.E.

    1985-01-01

    Ninety-two plant species from various regions of the USA were screened for their energy-producing potential. Samples were analysed for oil, polyphenol, hydrocarbon and protein. Oil fractions of some species were analysed for classes of lipid constituents and yields of unsaponifiable matter and fatty acids were determined. Hydrocarbon fractions of some species were analysed for rubber, gutta and waxes. Average MW and MW distribution of rubber and gutta were determined. Complete analytical data for 16 species is presented. Large quantities of oil were obtained from Philadelphus coronarius, Cacalia muhlenbergii, Lindera benzoin and Koelreuteria paniculata. High yields of polyphenols came from Acer ginnala, Cornus obliqua and Salix caprea and maximum yields of hydrocarbon and protein were from Elymus virginicus and Lindera benzoin, respectively.

  12. Herbivory affects salt marsh succession dynamics by suppressing the recovery of dominant species.

    PubMed

    Daleo, Pedro; Alberti, Juan; Pascual, Jesús; Canepuccia, Alejandro; Iribarne, Oscar

    2014-05-01

    Disturbance can generate heterogeneous environments and profoundly influence plant diversity by creating patches at different successional stages. Herbivores, in turn, can govern plant succession dynamics by determining the rate of species replacement, ultimately affecting plant community structure. In a south-western Atlantic salt marsh, we experimentally evaluated the role of herbivory in the recovery following disturbance of the plant community and assessed whether herbivory affects the relative importance of sexual and clonal reproduction on these dynamics. Our results show that herbivory strongly affects salt marsh secondary succession by suppressing seedlings and limiting clonal colonization of the dominant marsh grass, allowing subordinate species to dominate disturbed patches. These results demonstrate that herbivores can have an important role in salt marsh community structure and function, and can be a key force during succession dynamics. PMID:24549938

  13. A Fungal Endosymbiont Affects Host Plant Recruitment Through Seed- and Litter-mediated Mechanisms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    1. Many grass species are associated with maternally transmitted fungal endophytes. Increasing evidence shows that endophytes enhance host plant success under varied conditions, yet studies have rarely considered alternative mechanisms whereby these mutualistic symbionts may affect regeneration from...

  14. Species differences in whole plant carbon balance following winter dormancy in Alaskan tundra plants

    SciTech Connect

    Bret-Harte, M.S.; Chapin, F.S. III

    1995-09-01

    We froze ramets of seven vascular plant species and a mixed community of mosses common to upland tussock tundra for several months, then measured whole-plant photosynthesis and respiration in a growth chamber under simulated spring conditions, to examine whole plant carbon metabolism following winter dormancy. In addition, respiration and photosynthesis of aboveground stems and leaves were measured in the field in a spatial gradient away from a melting snowbank, at comparable developmental stages. Species differences in early respiration were not pronounced, but large differences were seen once development of leaves began. Root development in deciduous shrubs delayed their attainment of a positive whole plant carbon balance compared to that seen in aboveground stems and leaves alone, and partially compensated for differences in photosynthetic rates between shrubs and other species. Temporal patterns of carbon metabolism during spring growth may affect competitive balance in tussock tundra and vegetation response to global change.

  15. Litsea Species as Potential Antiviral Plant Sources.

    PubMed

    Guan, Yifu; Wang, Dongying; Tan, Ghee T; Van Hung, Nguyen; Cuong, Nguyen Manh; Pezzuto, John M; Fong, Harry H S; Soejarto, Djaja Doel; Zhang, Hongjie

    2016-04-01

    Litsea verticillata Hance (Lauraceae), a Chinese medicine used to treat swelling caused by injury or by snake bites, was the first plant identified by our National Institutes of Health (NIH)-funded International Cooperative Biodiversity Group (ICBG) project to exhibit anti-HIV activities. From this plant, we discovered a class of 8 novel litseane compounds, prototypic sesquiterpenes, all of which demonstrated anti-HIV activities. In subsequent studies, 26 additional compounds of different structural types were identified. During our continuing investigation of this plant species, we identified two new litseanes, litseaverticillols L and M, and a new sesquiterpene butenolide, litseasesquibutenolide. Litseaverticillols L and M were found to inhibit HIV-1 replication, with an IC[Formula: see text] value of 49.6[Formula: see text][Formula: see text]M. To further determine the antiviral properties of this plant, several relatively abundant isolates, including a litseane compound, two eudesmane sesquiterpenes and three lignans, were evaluated against an additional 21 viral targets. Lignans 8 and 9 were shown to be active against the Epstein-Barr Virus (EBV), with EC[Formula: see text] values of 22.0[Formula: see text][Formula: see text]M ([Formula: see text]) and 16.2[Formula: see text][Formula: see text]M ([Formula: see text]), respectively. Since many antiviral compounds have been discovered in L. verticillata, we further prepared 38 plant extracts made from the different plant parts of 9 additional Litsea species. These extracts were evaluated for their anti-HIV and cytotoxic activities, and four of the extracts, which ranged across three different species, displayed 97-100% inhibitory effects against HIV replication without showing cytotoxicity to a panel of human cell lines at a concentration of 20[Formula: see text][Formula: see text]g/mL. PMID:27080941

  16. Does mechanical disturbance affect the performance and species composition of submerged macrophyte communities?

    NASA Astrophysics Data System (ADS)

    Zhang, Qian; Xu, Ying-Shou; Huang, Lin; Xue, Wei; Sun, Gong-Qi; Zhang, Ming-Xiang; Yu, Fei-Hai

    2014-05-01

    Submerged macrophyte communities are frequently subjected to disturbance of various frequency and strength. However, there is still little experimental evidence on how mechanical disturbance affects the performance and species composition of such plant communities. In a greenhouse experiment, we constructed wetland communities consisting of five co-occurring clonal submerged macrophyte species (Hydrilla verticillata, Elodea canadensis, Ceratophyllum demersum, Chara fragilis, and Myriophyllum spicatum) and subjected these communities to three mechanical disturbance regimes (no, moderate and strong disturbance). Strong mechanical disturbance greatly decreased overall biomass, number of shoot nodes and total shoot length, and increased species diversity (evenness) of the total community. It also substantially decreased the growth of the most abundant species (H. verticillata), but did not affect growth of the other four species. Our data reveal that strong disturbance can have different effects on different submerged macrophyte species and thus alters the performance and species composition of submerged macrophyte communities.

  17. Does mechanical disturbance affect the performance and species composition of submerged macrophyte communities?

    PubMed

    Zhang, Qian; Xu, Ying-Shou; Huang, Lin; Xue, Wei; Sun, Gong-Qi; Zhang, Ming-Xiang; Yu, Fei-Hai

    2014-01-01

    Submerged macrophyte communities are frequently subjected to disturbance of various frequency and strength. However, there is still little experimental evidence on how mechanical disturbance affects the performance and species composition of such plant communities. In a greenhouse experiment, we constructed wetland communities consisting of five co-occurring clonal submerged macrophyte species (Hydrilla verticillata, Elodea canadensis, Ceratophyllum demersum, Chara fragilis, and Myriophyllum spicatum) and subjected these communities to three mechanical disturbance regimes (no, moderate and strong disturbance). Strong mechanical disturbance greatly decreased overall biomass, number of shoot nodes and total shoot length, and increased species diversity (evenness) of the total community. It also substantially decreased the growth of the most abundant species (H. verticillata), but did not affect growth of the other four species. Our data reveal that strong disturbance can have different effects on different submerged macrophyte species and thus alters the performance and species composition of submerged macrophyte communities. PMID:24811826

  18. Plant Size as Determinant of Species Richness of Herbivores, Natural Enemies and Pollinators across 21 Brassicaceae Species

    PubMed Central

    Schlinkert, Hella; Westphal, Catrin; Clough, Yann; László, Zoltán; Ludwig, Martin; Tscharntke, Teja

    2015-01-01

    Large plants are often more conspicuous and more attractive for associated animals than small plants, e.g. due to their wider range of resources. Therefore, plant size can positively affect species richness of associated animals, as shown for single groups of herbivores, but studies usually consider intraspecific size differences of plants in unstandardised environments. As comprehensive tests of interspecific plant size differences under standardised conditions are missing so far, we investigated effects of plant size on species richness of all associated arthropods using a common garden experiment with 21 Brassicaceae species covering a broad interspecific plant size gradient from 10 to 130 cm height. We recorded plant associated ecto- and endophagous herbivores, their natural enemies and pollinators on and in each aboveground plant organ, i.e. flowers, fruits, leaves and stems. Plant size (measured as height from the ground), the number of different plant organ entities and their biomass were assessed. Increasing plant size led to increased species richness of associated herbivores, natural enemies and pollinating insects. This pattern was found for ectophagous and endophagous herbivores, their natural enemies, as well as for herbivores associated with leaves and fruits and their natural enemies, independently of the additional positive effects of resource availability (i.e. organ biomass or number of entities and, regarding natural enemies, herbivore species richness). We found a lower R2 for pollinators compared to herbivores and natural enemies, probably caused by the high importance of flower characteristics for pollinator species richness besides plant size. Overall, the increase in plant height from 10 to 130 cm led to a 2.7-fold increase in predicted total arthropod species richness. In conclusion, plant size is a comprehensive driver of species richness of the plant associated arthropods, including pollinators, herbivores and their natural enemies

  19. RESPONSE OF WETLAND PLANT SPECIES TO HYDROLOGIC CONDITIONS

    EPA Science Inventory

    Understanding hydrologic requirements of native and introduced species is critical to sustaining native plant communities in wetlands of disturbed landscapes. We examined plant assemblages and 31 species from emergent wetlands in an urbanizing area of the Pacific Northwest, USA,...

  20. RESPONSE OF WETLAND PLANT SPECIES TO HYDROLOGIC CONDITIONS

    EPA Science Inventory

    Understanding hydrologic requirements of native and introduced species is critical to sustaining native plant communities in wetlands of disturbed landscapes. We examined plant assemblages and 31 species from emergent wetlands in an urbanizing area of the Pacific Northwest, USA, ...

  1. Genomic Basis of Plant Pathogen Suppression by Biocontrol Pseudomonas Species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Various plant commensal bacterial species, which naturally colonize the plant rhizosphere, are able to suppress fungal, bacterial, viral and even insect plant pathogens. These biocontrol activities are elicited primarily through the production of secreted exoenzymes and secondary metabolites that ma...

  2. Between-Population Outbreeding Affects Plant Defence

    PubMed Central

    Leimu, Roosa; Fischer, Markus

    2010-01-01

    Between-population crosses may replenish genetic variation of populations, but may also result in outbreeding depression. Apart from direct effects on plant fitness, these outbreeding effects can also alter plant-herbivore interactions by influencing plant tolerance and resistance to herbivory. We investigated effects of experimental within- and between-population outbreeding on herbivore resistance, tolerance and plant fitness using plants from 13 to 19 Lychnis flos-cuculi populations. We found no evidence for outbreeding depression in resistance reflected by the amount of leaf area consumed. However, herbivore performance was greater when fed on plants from between-population compared to within-population crosses. This can reflect outbreeding depression in resistance and/or outbreeding effects on plant quality for the herbivores. The effects of type of cross on the relationship between herbivore damage and plant fitness varied among populations. This demonstrates how between-population outbreeding effects on tolerance range from outbreeding depression to outbreeding benefits among plant populations. Finally, herbivore damage strengthened the observed outbreeding effects on plant fitness in several populations. These results raise novel considerations on the impact of outbreeding on the joint evolution of resistance and tolerance, and on the evolution of multiple defence strategies. PMID:20838662

  3. Arbuscular mycorrhizae of dominant plant species in Yungas forests, Argentina.

    PubMed

    Becerra, Alejandra G; Cabello, Marta; Zak, Marcelo R; Bartoloni, Norberto

    2009-01-01

    In Argentina the Yungas forests are among the ecosystems most affected by human activity, with loss of biodiversity. To assess the arbuscular mycorrhizal (AM) colonization and the arbuscular mycorrhizal fungi (AMF) spore numbers in these ecosystems, the roots of the most dominant native plants (one tree, Alnus acuminata; three herbaceous, Duchesnea indica, Oxalis conorrhiza, Trifolium aff. repens; and one shrub, Sambucus peruviana) were studied throughout the year from two sites of Yungas forests. Assessments of mycorrhizal colonization (percent root length, intraradical structures) were made by washing and staining the roots. Soil samples of each plant species were pooled and subsamples were obtained to determine AM spore numbers. The herbaceous species formed both Arum- and Paris-type morphologies, whereas the tree and the shrub species formed respectively single structural types of Arum- and Paris-type. AM colonization, intraradical fungi structures and AMF spore numbers displayed variation in species, seasons and sites. D. indica showed the highest AM colonization, whereas the highest spore numbers was observed in the rhizosphere of A. acuminata. No correlation was observed between spore numbers and root length percentage colonized by AM fungi. Results of this study showed that Alnus acuminata is facultatively AM. The AM colonization, intraradical fungi structures and AMF spore numbers varied in species depending on phenological, climatic and edaphic conditions. PMID:19750940

  4. Tree species richness affecting fine root biomass in European forests

    NASA Astrophysics Data System (ADS)

    Finér, Leena; Domisch, Timo; Vesterdal, Lars; Dawud, Seid M.; Raulund-Rasmussen, Karsten

    2016-04-01

    Fine roots are an important factor in the forest carbon cycle, contributing significantly to below-ground biomass and soil carbon storage. Therefore it is essential to understand the role of the forest structure, indicated by tree species diversity in controlling below-ground biomass and managing the carbon pools of forest soils. We studied how tree species richness would affect fine root biomass and its distribution in the soil profile and biomass above- and below-ground allocation patterns of different tree species. Our main hypothesis was that increasing tree species richness would lead to below-ground niche differentiation and more efficient soil exploitation by the roots, resulting in a higher fine root biomass in the soil. We sampled fine roots of trees and understorey vegetation in six European forest types in Finland, Poland, Germany, Romania, Italy and Spain, representing boreal, temperate and Mediterranean forests, established within the FunDivEUROPE project for studying the effects of tree species diversity on forest functioning. After determining fine root biomasses, we identified the percentages of different tree species in the fine root samples using the near infrared reflectance spectroscopy (NIRS) method. Opposite to our hypothesis we did not find any general positive relationship between tree species richness and fine root biomass. A weak positive response found in Italy and Spain seemed to be related to dry environmental conditions during Mediterranean summers. At the Polish site where we could sample deeper soil layers (down to 40 cm), we found more tree fine roots in the deeper layers under species-rich forests, as compared to the monocultures, indicating the ability of trees to explore more resources and to increase soil carbon stocks. Tree species richness did not affect biomass allocation patterns between above- and below-ground parts of the trees.

  5. Herbicide drift affects plant and arthropod communities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field edges, old fields, and other semi-natural habitats in agricultural landscapes support diverse plant communities that help sustain pollinators, predators, and other beneficial arthropods. These plant and arthropod communities may be at persistent ecotoxicological risk from herbicides applied to...

  6. Plant Hormones: How They Affect Root Formation.

    ERIC Educational Resources Information Center

    Reinhard, Diana Hereda

    This science study aid, produced by the U.S. Department of Agriculture, includes a series of plant rooting activities for secondary science classes. The material in the pamphlet is written for students and includes background information on plant hormones, a vocabulary list, and five learning activities. Objectives, needed materials, and…

  7. Affective responses in tamarins elicited by species-specific music.

    PubMed

    Snowdon, Charles T; Teie, David

    2010-02-23

    Theories of music evolution agree that human music has an affective influence on listeners. Tests of non-humans provided little evidence of preferences for human music. However, prosodic features of speech ('motherese') influence affective behaviour of non-verbal infants as well as domestic animals, suggesting that features of music can influence the behaviour of non-human species. We incorporated acoustical characteristics of tamarin affiliation vocalizations and tamarin threat vocalizations into corresponding pieces of music. We compared music composed for tamarins with that composed for humans. Tamarins were generally indifferent to playbacks of human music, but responded with increased arousal to tamarin threat vocalization based music, and with decreased activity and increased calm behaviour to tamarin affective vocalization based music. Affective components in human music may have evolutionary origins in the structure of calls of non-human animals. In addition, animal signals may have evolved to manage the behaviour of listeners by influencing their affective state. PMID:19726444

  8. Meaningful traits for grouping plant species across arid ecosystems.

    PubMed

    Bär Lamas, Marlene Ivonne; Carrera, A L; Bertiller, M B

    2016-05-01

    Grouping species may provide some degree of simplification to understand the ecological function of plants on key ecosystem processes. We asked whether groups of plant species based on morpho-chemical traits associated with plant persistence and stress/disturbance resistance reflect dominant plant growth forms in arid ecosystems. We selected twelve sites across an aridity gradient in northern Patagonia. At each site, we identified modal size plants of each dominant species and assessed specific leaf area (SLA), plant height, seed mass, N and soluble phenol concentration in green and senesced leaves at each plant. Plant species were grouped according with plant growth forms (perennial grasses, evergreen shrubs and deciduous shrubs) and plant morphological and/or chemical traits using cluster analysis. We calculated mean values of each plant trait for each species group and plant growth form. Plant growth forms significantly differed among them in most of the morpho-chemical traits. Evergreen shrubs were tall plants with the highest seed mass and soluble phenols in leaves, deciduous shrubs were also tall plants with high SLA and the highest N in leaves, and perennial grasses were short plants with high SLA and low concentration of N and soluble phenols in leaves. Grouping species by the combination of morpho-chemical traits yielded 4 groups in which species from one growth form prevailed. These species groups differed in soluble phenol concentration in senesced leaves and plant height. These traits were highly correlated. We concluded that (1) plant height is a relevant synthetic variable, (2) growth forms adequately summarize ecological strategies of species in arid ecosystems, and (3) the inclusion of plant morphological and chemical traits related to defenses against environmental stresses and herbivory enhanced the potential of species grouping, particularly within shrubby growth forms. PMID:26897637

  9. STRESS ETHYLENE EVOLUTION: A MEASURE OF OZONE AFFECTS ON PLANTS

    EPA Science Inventory

    To determine if ethylene evolution by plants is correlated with the ozone stress, a range of plants species and cultivars was exposed to varying ozone concentrations. Following exposure, the plants were encapsulated in plastic bags and incubated for up to 22h. The stress-induced ...

  10. Nutrient enrichment affects the mechanical resistance of aquatic plants.

    PubMed

    Lamberti-Raverot, Barbara; Puijalon, Sara

    2012-10-01

    For many plant species, nutrient availability induces important anatomical responses, particularly the production of low-density tissues to the detriment of supporting tissues. Due to the contrasting biomechanical properties of plant tissues, these anatomical responses may induce important modifications in the biomechanical properties of plant organs. The aim of this study was to determine the effects of nutrient enrichment on the anatomical traits of two freshwater plant species and its consequences on plant biomechanical performance. Two plant species were grown under controlled conditions in low versus high nutrient levels. The anatomical and biomechanical traits of the plant stems were measured. Both species produced tissues with lower densities under nutrient-rich conditions, accompanied by modifications in the structure of the aerenchyma for one species. As expected, nutrient enrichment also led to important modifications in the biomechanical properties of the stem for both species. In particular, mechanical resistance (breaking force and strength) and stiffness of stems were significantly reduced under nutrient rich conditions. The production of weaker stem tissues as a result of nutrient enrichment may increase the risk of plants to mechanical failure, thus challenging plant maintenance in mechanically stressful or disturbed habitats. PMID:23028018

  11. Osmolyte cooperation affects turgor dynamics in plants.

    PubMed

    Argiolas, Alfredo; Puleo, Gian Luigi; Sinibaldi, Edoardo; Mazzolai, Barbara

    2016-01-01

    Scientists have identified turgor-based actuation as a fundamental mechanism in plant movements. Plant cell turgor is generated by water influx due to the osmolyte concentration gradient through the cell wall and the plasma membrane behaving as an osmotic barrier. Previous studies have focused on turgor modulation with respect to potassium chloride (KCl) concentration changes, although KCl is not efficiently retained in the cell, and many other compounds, including L-glutamine (L-Gln) and D-glucose (D-Glc), are present in the cytosol. In fact, the contributions of other osmolytes to turgor dynamics remain to be elucidated. Here, we show the association of osmolytes and their consequent cooperative effects on the time-dependent turgor profile generated in a model cytosol consisting of KCl, D-Glc and L-Gln at experimentally measured plant motor/generic cell concentrations and at modified concentrations. We demonstrate the influence and association of the osmolytes using osmometry and NMR measurements. We also show, using a plant cell-inspired device we previously developed, that osmolyte complexes, rather than single osmolytes, permit to obtain higher turgor required by plant movements. We provide quantitative cues for deeper investigations of osmolyte transport for plant movement, and reveal the possibility of developing osmotic actuators exploiting a dynamically varying concentration of osmolytes. PMID:27445173

  12. Osmolyte cooperation affects turgor dynamics in plants

    PubMed Central

    Argiolas, Alfredo; Puleo, Gian Luigi; Sinibaldi, Edoardo; Mazzolai, Barbara

    2016-01-01

    Scientists have identified turgor-based actuation as a fundamental mechanism in plant movements. Plant cell turgor is generated by water influx due to the osmolyte concentration gradient through the cell wall and the plasma membrane behaving as an osmotic barrier. Previous studies have focused on turgor modulation with respect to potassium chloride (KCl) concentration changes, although KCl is not efficiently retained in the cell, and many other compounds, including L-glutamine (L-Gln) and D-glucose (D-Glc), are present in the cytosol. In fact, the contributions of other osmolytes to turgor dynamics remain to be elucidated. Here, we show the association of osmolytes and their consequent cooperative effects on the time-dependent turgor profile generated in a model cytosol consisting of KCl, D-Glc and L-Gln at experimentally measured plant motor/generic cell concentrations and at modified concentrations. We demonstrate the influence and association of the osmolytes using osmometry and NMR measurements. We also show, using a plant cell-inspired device we previously developed, that osmolyte complexes, rather than single osmolytes, permit to obtain higher turgor required by plant movements. We provide quantitative cues for deeper investigations of osmolyte transport for plant movement, and reveal the possibility of developing osmotic actuators exploiting a dynamically varying concentration of osmolytes. PMID:27445173

  13. Osmolyte cooperation affects turgor dynamics in plants

    NASA Astrophysics Data System (ADS)

    Argiolas, Alfredo; Puleo, Gian Luigi; Sinibaldi, Edoardo; Mazzolai, Barbara

    2016-07-01

    Scientists have identified turgor-based actuation as a fundamental mechanism in plant movements. Plant cell turgor is generated by water influx due to the osmolyte concentration gradient through the cell wall and the plasma membrane behaving as an osmotic barrier. Previous studies have focused on turgor modulation with respect to potassium chloride (KCl) concentration changes, although KCl is not efficiently retained in the cell, and many other compounds, including L-glutamine (L-Gln) and D-glucose (D-Glc), are present in the cytosol. In fact, the contributions of other osmolytes to turgor dynamics remain to be elucidated. Here, we show the association of osmolytes and their consequent cooperative effects on the time-dependent turgor profile generated in a model cytosol consisting of KCl, D-Glc and L-Gln at experimentally measured plant motor/generic cell concentrations and at modified concentrations. We demonstrate the influence and association of the osmolytes using osmometry and NMR measurements. We also show, using a plant cell-inspired device we previously developed, that osmolyte complexes, rather than single osmolytes, permit to obtain higher turgor required by plant movements. We provide quantitative cues for deeper investigations of osmolyte transport for plant movement, and reveal the possibility of developing osmotic actuators exploiting a dynamically varying concentration of osmolytes.

  14. Dioecy, more than monoecy, affects plant spatial genetic structure: the case study of Ficus

    PubMed Central

    Nazareno, Alison G; Alzate-Marin, Ana L; Pereira, Rodrigo Augusto S

    2013-01-01

    In this analysis, we attempt to understand how monoecy and dioecy drive spatial genetic structure (SGS) in plant populations. For this purpose, plants of the genus Ficus were used as a comparative model due to their particular characteristics, including high species diversity, variation in life histories, and sexual systems. One of the main issues we assessed is whether dioecious fig tree populations are more spatially genetically structured than monoecious populations. Using the Sp statistic, which allows for quantitative comparisons among different studies, we compared the extent of SGS between monoecious and dioecious Ficus species. To broaden our conclusions we used published data on an additional 27 monoecious and dioecious plant species. Furthermore, genetic diversity analyses were performed for two monoecious Ficus species using 12 microsatellite markers in order to strengthen our conclusions about SGS. Our results show that dioecy, more than monoecy, significantly contributes to SGS in plant populations. On average, the estimate of Sp was six times higher for dioecious Ficus species than monoecious Ficus species and it was two times higher in dioecious than monoecious plant species. Considering these results, we emphasize that the long-distance pollen dispersal mechanism in monoecious Ficus species seems to be the dominant factor in determining weak spatial genetic structure, high levels of genetic diversity, and lack of inbreeding. Although Ficus constitute a model species to study SGS, a more general comparison encompassing a wider range of plants is required in order to better understand how sexual systems affect genetic structure. PMID:24223285

  15. New pasture plants intensify invasive species risk.

    PubMed

    Driscoll, Don A; Catford, Jane A; Barney, Jacob N; Hulme, Philip E; Inderjit; Martin, Tara G; Pauchard, Aníbal; Pyšek, Petr; Richardson, David M; Riley, Sophie; Visser, Vernon

    2014-11-18

    Agricultural intensification is critical to meet global food demand, but intensification threatens native species and degrades ecosystems. Sustainable intensification (SI) is heralded as a new approach for enabling growth in agriculture while minimizing environmental impacts. However, the SI literature has overlooked a major environmental risk. Using data from eight countries on six continents, we show that few governments regulate conventionally bred pasture taxa to limit threats to natural areas, even though most agribusinesses promote taxa with substantial weed risk. New pasture taxa (including species, subspecies, varieties, cultivars, and plant-endophyte combinations) are bred with characteristics typical of invasive species and environmental weeds. By introducing novel genetic and endophyte variation, pasture taxa are imbued with additional capacity for invasion and environmental impact. New strategies to prevent future problems are urgently needed. We highlight opportunities for researchers, agribusiness, and consumers to reduce environmental risks associated with new pasture taxa. We also emphasize four main approaches that governments could consider as they build new policies to limit weed risks, including (i) national lists of taxa that are prohibited based on environmental risk; (ii) a weed risk assessment for all new taxa; (iii) a program to rapidly detect and control new taxa that invade natural areas; and (iv) the polluter-pays principle, so that if a taxon becomes an environmental weed, industry pays for its management. There is mounting pressure to increase livestock production. With foresight and planning, growth in agriculture can be achieved sustainably provided that the scope of SI expands to encompass environmental weed risks. PMID:25368175

  16. New pasture plants intensify invasive species risk

    PubMed Central

    Driscoll, Don A.; Catford, Jane A.; Barney, Jacob N.; Hulme, Philip E.; Inderjit; Martin, Tara G.; Pauchard, Aníbal; Pyšek, Petr; Richardson, David M.; Riley, Sophie; Visser, Vernon

    2014-01-01

    Agricultural intensification is critical to meet global food demand, but intensification threatens native species and degrades ecosystems. Sustainable intensification (SI) is heralded as a new approach for enabling growth in agriculture while minimizing environmental impacts. However, the SI literature has overlooked a major environmental risk. Using data from eight countries on six continents, we show that few governments regulate conventionally bred pasture taxa to limit threats to natural areas, even though most agribusinesses promote taxa with substantial weed risk. New pasture taxa (including species, subspecies, varieties, cultivars, and plant-endophyte combinations) are bred with characteristics typical of invasive species and environmental weeds. By introducing novel genetic and endophyte variation, pasture taxa are imbued with additional capacity for invasion and environmental impact. New strategies to prevent future problems are urgently needed. We highlight opportunities for researchers, agribusiness, and consumers to reduce environmental risks associated with new pasture taxa. We also emphasize four main approaches that governments could consider as they build new policies to limit weed risks, including (i) national lists of taxa that are prohibited based on environmental risk; (ii) a weed risk assessment for all new taxa; (iii) a program to rapidly detect and control new taxa that invade natural areas; and (iv) the polluter-pays principle, so that if a taxon becomes an environmental weed, industry pays for its management. There is mounting pressure to increase livestock production. With foresight and planning, growth in agriculture can be achieved sustainably provided that the scope of SI expands to encompass environmental weed risks. PMID:25368175

  17. Plant diversity and functional groups affect Si and Ca pools in aboveground biomass of grassland systems.

    PubMed

    Schaller, Jörg; Roscher, Christiane; Hillebrand, Helmut; Weigelt, Alexandra; Oelmann, Yvonne; Wilcke, Wolfgang; Ebeling, Anne; Weisser, Wolfgang W

    2016-09-01

    Plant diversity is an important driver of nitrogen and phosphorus stocks in aboveground plant biomass of grassland ecosystems, but plant diversity effects on other elements also important for plant growth are less understood. We tested whether plant species richness, functional group richness or the presence/absence of particular plant functional groups influences the Si and Ca concentrations (mmol g(-1)) and stocks (mmol m(-2)) in aboveground plant biomass in a large grassland biodiversity experiment (Jena Experiment). In the experiment including 60 temperate grassland species, plant diversity was manipulated as sown species richness (1, 2, 4, 8, 16) and richness and identity of plant functional groups (1-4; grasses, small herbs, tall herbs, legumes). We found positive species richness effects on Si as well as Ca stocks that were attributable to increased biomass production. The presence of particular functional groups was the most important factor explaining variation in aboveground Si and Ca stocks (mmol m(-2)). Grass presence increased the Si stocks by 140 % and legume presence increased the Ca stock by 230 %. Both the presence of specific plant functional groups and species diversity altered Si and Ca stocks, whereas Si and Ca concentration were affected mostly by the presence of specific plant functional groups. However, we found a negative effect of species diversity on Si and Ca accumulation, by calculating the deviation between mixtures and mixture biomass proportions, but in monoculture concentrations. These changes may in turn affect ecosystem processes such as plant litter decomposition and nutrient cycling in grasslands. PMID:27164912

  18. Host Plants Affect the Foraging Success of Two Parasitoids that Attack Light Brown Apple Moth Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae).

    PubMed

    Feng, Yi; Wratten, Steve; Sandhu, Harpinder; Keller, Michael

    2015-01-01

    The light brown apple moth, Epiphyas postvittana is a key pest of wine grapes in Australia. Two parasitoids, Dolichogenidea tasmanica and Therophilus unimaculatus, attack the larval stage of this pest. D. tasmanica is dominant in vineyards, whereas T. unimaculatus is mainly active in native vegetation. We sought to understand why they differ in their use of habitats. Plants are a major component of habitats of parasitoids, and herbivore-infested plants influence parasitoid foraging efficiency by their architecture and emission of volatile chemicals. We investigated how different plant species infested by E. postvittana could affect the foraging success of the two parasitoid species in both laboratory and field experiments. Four common host-plant species were selected for this study. In paired-choice experiments to determine the innate foraging preferences for plants, both parasitoid species showed differences in innate search preferences among plant species. The plant preference of D. tasmanica was altered by oviposition experience with hosts that were feeding on other plant species. In a behavioral assay, the two parasitoid species allocated their times engaged in various types of behavior differently when foraging on different plant species. For both parasitoids, parasitism on Hardenbergia violacea was the highest of the four plant species. Significantly more larvae dropped from Myoporum insulare when attacked than from the other three host-plant species, which indicates that parasitism is also affected by interactions between plants and host insects. In vineyards, parasitism by D. tasmanica was significantly lower on M. insulare than on the other three host-plant species, but the parasitism rates were similar among the other three plant species. Our results indicate that plants play a role in the habitat preferences of these two parasitoid species by influencing their foraging behavior, and are likely to contribute to their distributions among habitats. PMID

  19. Host Plants Affect the Foraging Success of Two Parasitoids that Attack Light Brown Apple Moth Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae)

    PubMed Central

    Feng, Yi; Wratten, Steve; Sandhu, Harpinder; Keller, Michael

    2015-01-01

    The light brown apple moth, Epiphyas postvittana is a key pest of wine grapes in Australia. Two parasitoids, Dolichogenidea tasmanica and Therophilus unimaculatus, attack the larval stage of this pest. D. tasmanica is dominant in vineyards, whereas T. unimaculatus is mainly active in native vegetation. We sought to understand why they differ in their use of habitats. Plants are a major component of habitats of parasitoids, and herbivore-infested plants influence parasitoid foraging efficiency by their architecture and emission of volatile chemicals. We investigated how different plant species infested by E. postvittana could affect the foraging success of the two parasitoid species in both laboratory and field experiments. Four common host-plant species were selected for this study. In paired-choice experiments to determine the innate foraging preferences for plants, both parasitoid species showed differences in innate search preferences among plant species. The plant preference of D. tasmanica was altered by oviposition experience with hosts that were feeding on other plant species. In a behavioral assay, the two parasitoid species allocated their times engaged in various types of behavior differently when foraging on different plant species. For both parasitoids, parasitism on Hardenbergia violacea was the highest of the four plant species. Significantly more larvae dropped from Myoporum insulare when attacked than from the other three host-plant species, which indicates that parasitism is also affected by interactions between plants and host insects. In vineyards, parasitism by D. tasmanica was significantly lower on M. insulare than on the other three host-plant species, but the parasitism rates were similar among the other three plant species. Our results indicate that plants play a role in the habitat preferences of these two parasitoid species by influencing their foraging behavior, and are likely to contribute to their distributions among habitats. PMID

  20. Agroforestry planting design affects loblolly pine growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of plantation design on resource utilization has not been adequately investigated in agroforestry plantations. An experiment was conducted near Booneville, AR on a silt loam soil with a fragipan. Loblolly pine trees were planted in 1994 in an east-west row orientation in three designs: ...

  1. Conservation tillage affects species composition but not species diversity: a comparative study in Northern Italy.

    PubMed

    Boscutti, Francesco; Sigura, Maurizia; Gambon, Nadia; Lagazio, Corrado; Krüsi, Bertil O; Bonfanti, Pierluigi

    2015-02-01

    Conservation tillage (CT) is widely considered to be a practice aimed at preserving several ecosystem functions. In the literature, however, there seems to be no clear pattern with regard to its benefits on species diversity and species composition. In Northern Italy, we compared species composition and diversity of both vascular plants and Carabids under two contrasting tillage systems, i.e., CT and conventional tillage, respectively. We hypothesized a significant positive impact of CT on both species diversity and composition. We also considered the potential influence of crop type. The tillage systems were studied under open field conditions with three types of annual crops (i.e., maize, soybean, and winter cereals), using a split-plot design on pairs of adjacent fields. Linear mixed models were applied to test tillage system, crop, and interaction effects on diversity indices. Plant and Carabids communities were analyzed by multivariate methods (CCA). On the whole, 136 plant and 51 carabid taxa were recorded. The two tillage systems studied did not differ in floristic or carabid diversity. Species composition, by contrast, proved to be characteristic for each combination of tillage system and crop type. In particular, CT fields were characterized by nutrient demanding weeds and the associated Carabids. The differences were especially pronounced in fields with winter cereals. The same was true for the flora and Carabids along the field boundaries. For studying the effects of CT practices on the sustainability of agro-ecosystems, therefore, the focus should be on species composition rather than on diversity measures. PMID:25392019

  2. Conservation Tillage Affects Species Composition But Not Species Diversity: A Comparative Study in Northern Italy

    NASA Astrophysics Data System (ADS)

    Boscutti, Francesco; Sigura, Maurizia; Gambon, Nadia; Lagazio, Corrado; Krüsi, Bertil O.; Bonfanti, Pierluigi

    2015-02-01

    Conservation tillage (CT) is widely considered to be a practice aimed at preserving several ecosystem functions. In the literature, however, there seems to be no clear pattern with regard to its benefits on species diversity and species composition. In Northern Italy, we compared species composition and diversity of both vascular plants and Carabids under two contrasting tillage systems, i.e., CT and conventional tillage, respectively. We hypothesized a significant positive impact of CT on both species diversity and composition. We also considered the potential influence of crop type. The tillage systems were studied under open field conditions with three types of annual crops (i.e., maize, soybean, and winter cereals), using a split-plot design on pairs of adjacent fields. Linear mixed models were applied to test tillage system, crop, and interaction effects on diversity indices. Plant and Carabids communities were analyzed by multivariate methods (CCA). On the whole, 136 plant and 51 carabid taxa were recorded. The two tillage systems studied did not differ in floristic or carabid diversity. Species composition, by contrast, proved to be characteristic for each combination of tillage system and crop type. In particular, CT fields were characterized by nutrient demanding weeds and the associated Carabids. The differences were especially pronounced in fields with winter cereals. The same was true for the flora and Carabids along the field boundaries. For studying the effects of CT practices on the sustainability of agro-ecosystems, therefore, the focus should be on species composition rather than on diversity measures.

  3. Root-Zone Glyphosate Exposure Adversely Affects Two Ditch Species

    PubMed Central

    Saunders, Lyndsay E.; Koontz, Melissa B.; Pezeshki, Reza

    2013-01-01

    Glyphosate, one of the most applied herbicides globally, has been extensively studied for its effects on non-target organisms. In the field, following precipitation, glyphosate runs off into agricultural ditches where it infiltrates into the soil and thus may encounter the roots of vegetation. These edge-of-field ditches share many characteristics with wetlands, including the ability to reduce loads of anthropogenic chemicals through uptake, transformation, and retention. Different species within the ditches may have a differential sensitivity to exposure of the root zone to glyphosate, contributing to patterns of abundance of ruderal species. The present laboratory experiment investigated whether two species commonly found in agricultural ditches in southcentral United States were affected by root zone glyphosate in a dose-dependent manner, with the objective of identifying a sublethal concentration threshold. The root zone of individuals of Polygonum hydropiperoides and Panicum hemitomon were exposed to four concentrations of glyphosate. Leaf chlorophyll content was measured, and the ratio of aboveground biomass to belowground biomass and survival were quantified. The findings from this study showed that root zone glyphosate exposure negatively affected both species including dose-dependent reductions in chlorophyll content. P. hydropiperdoides showed the greatest negative response, with decreased belowground biomass allocation and total mortality at the highest concentrations tested. PMID:24833234

  4. Native and Non-Native Supergeneralist Bee Species Have Different Effects on Plant-Bee Networks

    PubMed Central

    Giannini, Tereza C.; Garibaldi, Lucas A.; Acosta, Andre L.; Silva, Juliana S.; Maia, Kate P.; Saraiva, Antonio M.; Guimarães, Paulo R.; Kleinert, Astrid M. P.

    2015-01-01

    Supergeneralists, defined as species that interact with multiple groups of species in ecological networks, can act as important connectors of otherwise disconnected species subsets. In Brazil, there are two supergeneralist bees: the honeybee Apis mellifera, a non-native species, and Trigona spinipes, a native stingless bee. We compared the role of both species and the effect of geographic and local factors on networks by addressing three questions: 1) Do both species have similar abundance and interaction patterns (degree and strength) in plant-bee networks? 2) Are both species equally influential to the network structure (nestedness, connectance, and plant and bee niche overlap)? 3) How are these species affected by geographic (altitude, temperature, precipitation) and local (natural vs. disturbed habitat) factors? We analyzed 21 plant-bee weighted interaction networks, encompassing most of the main biomes in Brazil. We found no significant difference between both species in abundance, in the number of plant species with which each bee species interacts (degree), and in the sum of their dependencies (strength). Structural equation models revealed the effect of A. mellifera and T. spinipes, respectively, on the interaction network pattern (nestedness) and in the similarity in bee’s interactive partners (bee niche overlap). It is most likely that the recent invasion of A. mellifera resulted in its rapid settlement inside the core of species that retain the largest number of interactions, resulting in a strong influence on nestedness. However, the long-term interaction between native T. spinipes and other bees most likely has a more direct effect on their interactive behavior. Moreover, temperature negatively affected A. mellifera bees, whereas disturbed habitats positively affected T. spinipes. Conversely, precipitation showed no effect. Being positively (T. spinipes) or indifferently (A. mellifera) affected by disturbed habitats makes these species prone to

  5. Plant inter-species effects on rhizosphere priming effect and nitrogen acquisition by plants

    NASA Astrophysics Data System (ADS)

    Sun, Yue; Xu, Xingliang; Yang, Baijie; Kuzyakov, Yakov

    2015-04-01

    Rhizosphere interactions play a central role linking roots-soil system and regulate various aspects of nutrient cycling. Rhizodeposition inputs are known to change soil organic matter (SOM) decomposition via rhizosphere priming effects (RPEs) through enhancing soil biological activity and altering microbial community structure. The magnitude of RPEs varies widely among plant-species and root biomass possibly due to different quality and quantity of rhizodeposits. However, it is virtually unknown whether the RPEs are influenced by plant inter-species interactions and how these processes affect N mineralization and available N for plants. Monocultures of maize (M) and soybean (S), and mixed cultures of maize/maize (MM), soybean/soybean (SS), maize/soybean (MS) were grown over a 45-day greenhouse experiment. We labeled them with plant litter that was enriched in13C and 15N. The 15N distributions in plants and microbial biomass were measured at 14, 35, and 45days after labeling. The RPEs were positive under all plants, ranging from 11.7% to 138.3% and gradually decreased with plant growth. The RPE in the SS was significantly higher than these in others treatments at 14 days, while at 45 days it was higher in the MS than these from their monocultures, suggesting that the RPE was enhanced by the inter-species effects of maize and soybean. The litter decomposition ratio and 15N recovery of plants and microorganism increased with the root growth across all plants. The 15N recovery of plants in the MS (14.2%) was higher than these in the MM (12.3%) and SS(9.7%) at 45 days. Similarly, the 15N recovery of microorganism in the corresponding treatments was 6.7%, 2.2%, and 6.8%, respectively. The MS showed higher soil organic N mineralization amount than that from all soybean and maize monocultures at 45 days. We conclude that plant inter-species interactions may have significant effect on rhizosphere priming and modify the plant N uptake from litter resource and SOM.

  6. Plant Species Recovery on a Compacted Skid Road

    PubMed Central

    Demir, Murat; Makineci, Ender; Gungor, Beyza Sat

    2008-01-01

    This study was executed to determine the plant species of herbaceous cover in a skid road subjected to soil compaction due to timber skidding in a beech (Fagus orientalis Lipsky.) stand. Our previous studies have shown that ground based timber skidding destroys the soils extremely, and degradations on ecosystem because of the timber skidding limit recovery and growth of plant cover on skid roads. However, some plant species show healthy habitat, recovery and they can survive after the extreme degradation in study area. We evaluated composition of these plant species and their cover-abundance scales in 100 m x 3 m transect. 15 plant species were determined belongs to 12 plant families and Liliaceae was the highest representative plant family. Smilax aspera L., Epimedium pubigerum (DC.) Moren et Decaisne, Carex distachya Desf. var. distachya Desf., Pteridium aquilinum (L.) Kuhn., Trachystemon orientalis (L.) G. Don, Hedera helix L. have the highest cover-abundance scale overall of determined species on compacted skid road.

  7. How neighbor canopy architecture affects target plant performance

    SciTech Connect

    Tremmel, D.C.; Bazzaz, F.A. )

    1993-10-01

    Plant competition occurs through the negative effects that individual plants have on resource availability to neighboring individuals. Therefore competition experiments need to examine how different species change resource availability to their neighbors, and how different species respond to these changes-allocationally, architecturally, and physiologically-through time. In a greenhouse study we used a model system of annuals to examine how canopies of species having differing morphologies differed in their architectures and light-interception abilities, and how different species performed when grown in these canopies. Abutilon theophrasti, Datura stramonium, and Polygonum pensylvanicum were grown as [open quotes]targets[close quotes]. Plants were grown in pots, with one target plant and four neighbor plants. Detailed measurements of neighbor canopy structure and target plant canopy architecture were made at five harvests. Species with different morphologies showed large differences in canopy structure, particularly when grass and forb species were compared. Setaria, a grass, had a more open canopy than the other species (all forbs), and was a consistently weak competitor. Overall, however, the relative effects of different neighbors on target biomass varied with target species. Target biomass was poorly correlated with neighbor biomass and leaf area, but was highly correlated with a measure of target light-interception ability that took into account both target leaf deployment and neighbor light interception. Despite clear differences among neighbor species in canopy structure and effect on light penetration, the results suggest no broad generalizations about the effects of different species as neighbors. Knowledge of morphological, physiological, and life history characteristics of both the target and neighbor species may be necessary to explain the results of their competition. 53 refs., 4 figs., 4 tabs.

  8. Do transgenic plants affect rhizobacteria populations?

    PubMed Central

    Filion, Martin

    2008-01-01

    Summary Plant genetic manipulation has led to the development of genetically modified plants (GMPs) expressing various traits. Since their first commercial use in 1996, GMPs have been increasingly used, reaching a global cultivating production area of 114.3 million hectares in 2007. The rapid development of agricultural biotechnology and release of GMPs have provided many agronomic and economic benefits, but has also raised concerns over the potential impact these plants might have on the environment. Among these environmental concerns, the unintentional impact that GMPs might have on soil‐associated microbes, especially rhizosphere‐inhabiting bacteria or rhizobacteria, represents one of the least studied and understood areas. As rhizobacteria are responsible for numerous key functions including nutrient cycling and decomposition, they have been defined as good indicator organisms to assess the general impact that GMPs might have on the soil environment. This minireview summarizes the results of various experiments that have been conducted to date on the impact of GMPs on rhizobacteria. Both biological and technical parameters are discussed and an attempt is made to determine if specific rhizobacterial responses exist for the different categories of GMPs developed to date. PMID:21261867

  9. Deviation from niche optima affects the nature of plant-plant interactions along a soil acidity gradient.

    PubMed

    He, Lei; Cheng, Lulu; Hu, Liangliang; Tang, Jianjun; Chen, Xin

    2016-01-01

    There is increasing recognition of the importance of niche optima in the shift of plant-plant interactions along environmental stress gradients. Here, we investigate whether deviation from niche optima would affect the outcome of plant-plant interactions along a soil acidity gradient (pH = 3.1, 4.1, 5.5 and 6.1) in a pot experiment. We used the acid-tolerant species Lespedeza formosa Koehne as the neighbouring plant and the acid-tolerant species Indigofera pseudotinctoria Mats. or acid-sensitive species Medicago sativa L. as the target plants. Biomass was used to determine the optimal pH and to calculate the relative interaction index (RII). We found that the relationships between RII and the deviation of soil pH from the target's optimal pH were linear for both target species. Both targets were increasingly promoted by the neighbour as pH values deviated from their optima; neighbours benefitted target plants by promoting soil symbiotic arbuscular mycorrhizal fungi, increasing soil organic matter or reducing soil exchangeable aluminium. Our results suggest that the shape of the curve describing the relationship between soil pH and facilitation/competition depends on the soil pH optima of the particular species. PMID:26740568

  10. Herbivore and Fungal Pathogen Exclusion Affects the Seed Production of Four Common Grassland Species

    PubMed Central

    Dickson, Timothy L.; Mitchell, Charles E.

    2010-01-01

    Insect herbivores and fungal pathogens can independently affect plant fitness, and may have interactive effects. However, few studies have experimentally quantified the joint effects of insects and fungal pathogens on seed production in non-agricultural populations. We examined the factorial effects of insect herbivore exclusion (via insecticide) and fungal pathogen exclusion (via fungicide) on the population-level seed production of four common graminoid species (Andropogon gerardii, Schizachyrium scoparium, Poa pratensis, and Carex siccata) over two growing seasons in Minnesota, USA. We detected no interactive effects of herbivores and pathogens on seed production. However, the seed production of all four species was affected by either insecticide or fungicide in at least one year of the study. Insecticide consistently doubled the seed production of the historically most common species in the North American tallgrass prairie, A. gerardii (big bluestem). This is the first report of insect removal increasing seed production in this species. Insecticide increased A. gerardii number of seeds per seed head in one year, and mass per seed in both years, suggesting that consumption of flowers and seed embryos contributed to the effect on seed production. One of the primary insect species consuming A. gerardii flowers and seed embryos was likely the Cecidomyiid midge, Contarinia wattsi. Effects on all other plant species varied among years. Herbivores and pathogens likely reduce the dispersal and colonization ability of plants when they reduce seed output. Therefore, impacts on seed production of competitive dominant species may help to explain their relatively poor colonization abilities. Reduced seed output by dominant graminoids may thereby promote coexistence with subdominant species through competition-colonization tradeoffs. PMID:20711408

  11. Arbuscular mycorrhizal fungi reduce the differences in competitiveness between dominant and subordinate plant species.

    PubMed

    Mariotte, Pierre; Meugnier, Claire; Johnson, David; Thébault, Aurélie; Spiegelberger, Thomas; Buttler, Alexandre

    2013-05-01

    In grassland communities, plants can be classified as dominants or subordinates according to their relative abundances, but the factors controlling such distributions remain unclear. Here, we test whether the presence of the arbuscular mycorrhizal (AM) fungus Glomus intraradices affects the competitiveness of two dominant (Taraxacum officinale and Agrostis capillaris) and two subordinate species (Prunella vulgaris and Achillea millefolium). Plants were grown in pots in the presence or absence of the fungus, in monoculture and in mixtures of both species groups with two and four species. In the absence of G. intraradices, dominants were clearly more competitive than subordinates. In inoculated pots, the fungus acted towards the parasitic end of the mutualism-parasitism continuum and had an overall negative effect on the growth of the plant species. However, the negative effects of the AM fungus were more pronounced on dominant species reducing the differences in competitiveness between dominant and subordinate species. The effects of G. intraradices varied with species composition highlighting the importance of plant community to mediate the effects of AM fungi. Dominant species were negatively affected from the AM fungus in mixtures, while subordinates grew identically with and without the fungus. Therefore, our findings predict that the plant dominance hierarchy may flatten out when dominant species are more reduced than subordinate species in an unfavourable AM fungal relationship (parasitism). PMID:23064770

  12. Students' Perception of Plant and Animal Species: A Case Study from Rural Argentina

    ERIC Educational Resources Information Center

    Nates, Juliana; Campos, Claudia; Lindemann-Matthies, Petra

    2010-01-01

    Exotic species seriously affect local biodiversity in Argentina. This article investigates how students in San Juan province perceive native and exotic species. With the help of a written questionnaire, 865 students (9-17 years old) were asked to name the plant and animal they liked most, disliked most, and perceived as most useful, and to name…

  13. Assessing the risk of Glyphosate to native plants and weedy Brassicaceae species of North Dakota

    EPA Science Inventory

    This study was conducted to determine the ecological risk to native plants and weedy Brassicaceae species which may be growing in areas affected by off target movement of glyphosate applied to glyphosate-resistant canola (Brassica napus). Ten native grass and forb species were ...

  14. Divergent composition but similar function of soil food webs of individual plants: plant species and community effects.

    PubMed

    Bezemer, T M; Fountain, M T; Barea, J M; Christensen, S; Dekker, S C; Duyts, H; van Hal, R; Harvey, J A; Hedlund, K; Maraun, M; Mikola, J; Mladenov, A G; Robin, C; de Ruiter, P C; Scheu, S; Setälä, H; Smilauer, P; van der Putten, W H

    2010-10-01

    Soils are extremely rich in biodiversity, and soil organisms play pivotal roles in supporting terrestrial life, but the role that individual plants and plant communities play in influencing the diversity and functioning of soil food webs remains highly debated. Plants, as primary producers and providers of resources to the soil food web, are of vital importance for the composition, structure, and functioning of soil communities. However, whether natural soil food webs that are completely open to immigration and emigration differ underneath individual plants remains unknown. In a biodiversity restoration experiment we first compared the soil nematode communities of 228 individual plants belonging to eight herbaceous species. We included grass, leguminous, and non-leguminous species. Each individual plant grew intermingled with other species, but all plant species had a different nematode community. Moreover, nematode communities were more similar when plant individuals were growing in the same as compared to different plant communities, and these effects were most apparent for the groups of bacterivorous, carnivorous, and omnivorous nematodes. Subsequently, we analyzed the composition, structure, and functioning of the complete soil food webs of 58 individual plants, belonging to two of the plant species, Lotus corniculatus (Fabaceae) and Plantago lanceolata (Plantaginaceae). We isolated and identified more than 150 taxa/groups of soil organisms. The soil community composition and structure of the entire food webs were influenced both by the species identity of the plant individual and the surrounding plant community. Unexpectedly, plant identity had the strongest effects on decomposing soil organisms, widely believed to be generalist feeders. In contrast, quantitative food web modeling showed that the composition of the plant community influenced nitrogen mineralization under individual plants, but that plant species identity did not affect nitrogen or carbon

  15. Short communication: occurrence of Arcobacter species in industrial dairy plants.

    PubMed

    Serraino, A; Giacometti, F

    2014-01-01

    The present study investigated the presence of Arcobacter spp. in industrial dairy plants. Between February and September 2013, pasteurized milk used for cheesemaking, processing and cleaning water, cheese, and environmental samples from different plant sites, including surfaces in contact or not in contact with food, were sampled. A total of 126 samples were analyzed by the cultural method and isolates were identified by multiplex PCR. Arcobacter spp. were isolated from 22 of 75 environmental samples (29.3%): of them, 22.7% were surfaces in contact with food and 38.7% surfaces not in contact with food. A total of 135 Arcobacter spp. isolates were obtained; of these, 129 and 6 were identified as Arcobacter butzleri and Arcobacter cryaerophilus, respectively. All food processing water and pasteurized milk samples were negative for Arcobacter species. We were not able to determine the primary source of contamination, but the isolation of both A. butzleri and A. cryaerophilus in surfaces in contact with food before and during manufacturing suggests that Arcobacter spp. are not or are only partially affected by routine sanitizing procedures in the industrial dairy plants studied. The efficacy of sanitizing procedures should be evaluated and further studies are needed to determine whether certain Arcobacter strains persist for long periods of time in industrial dairy plants and whether they can survive in different types of cheese in cases of postprocessing contamination. PMID:24534515

  16. Mapping National Plant Biodiversity Patterns in South Korea with the MARS Species Distribution Model.

    PubMed

    Choe, Hyeyeong; Thorne, James H; Seo, Changwan

    2016-01-01

    Accurate information on the distribution of existing species is crucial to assess regional biodiversity. However, data inventories are insufficient in many areas. We examine the ability of Multivariate Adaptive Regression Splines (MARS) multi-response species distribution model to overcome species' data limitations and portray plant species distribution patterns for 199 South Korean plant species. The study models species with two or more observations, examines their contribution to national patterns of species richness, provides a sensitivity analysis of different range threshold cutoff approaches for modeling species' ranges, and presents considerations for species modeling at fine spatial resolution. We ran MARS models for each species and tested four threshold methods to transform occurrence probabilities into presence or absence range maps. Modeled occurrence probabilities were extracted at each species' presence points, and the mean, median, and one standard deviation (SD) calculated to define data-driven thresholds. A maximum sum of sensitivity and specificity threshold was also calculated, and the range maps from the four cutoffs were tested using independent plant survey data. The single SD values were the best threshold tested for minimizing omission errors and limiting species ranges to areas where the associated occurrence data were correctly classed. Eight individual species range maps for rare plant species were identified that are potentially affected by resampling predictor variables to fine spatial scales. We portray spatial patterns of high species richness by assessing the combined range maps from three classes of species: all species, endangered and endemic species, and range-size rarity of all species, which could be used in conservation planning for South Korea. The MARS model is promising for addressing the common problem of few species occurrence records. However, projected species ranges are highly dependent on the threshold and scale

  17. Binucleation to breed new plant species adaptable to their environments

    PubMed Central

    Moustafa, Khaled

    2015-01-01

    Classical plant breeding approaches may fall short to breed new plant species of high environmental and ecological interests. Biotechnological and genetic manipulations, on the other hand, may hold more effective capabilities to circumvent the limitations of sexual incompatibility and conventional breeding programs. Given that plant cells encompass multiple copies of organellar genomes (mitochondrial and plastidial genomes), an important question could be raised about whether an artificial attempt to duplicate the nuclear genome might also be conceivable through a binucleation approach (generating plant cells with 2 nuclei from 2 different plant species) for potential production of new polyploidies that would characterize new plant species. Since the complexities of plant genomes are the result of multiple genome duplications, an artificial binucleation approach would thus be of some interest to eventually varying plant genomes and producing new polyploidy from related or distal plant species. Here, I discuss the potentiality of such an approach to engineer binucleated plant cells as a germ of new plant species to fulfill some environmental applications such as increasing the biodiversity and breeding new species adaptable to harsh environmental stresses and increasing green surfaces to reduce atmospheric pollutions in arid lands with poor vegetation. PMID:26322577

  18. Binucleation to breed new plant species adaptable to their environments.

    PubMed

    Moustafa, Khaled

    2015-01-01

    Classical plant breeding approaches may fall short to breed new plant species of high environmental and ecological interests. Biotechnological and genetic manipulations, on the other hand, may hold more effective capabilities to circumvent the limitations of sexual incompatibility and conventional breeding programs. Given that plant cells encompass multiple copies of organellar genomes (mitochondrial and plastidial genomes), an important question could be raised about whether an artificial attempt to duplicate the nuclear genome might also be conceivable through a binucleation approach (generating plant cells with 2 nuclei from 2 different plant species) for potential production of new polyploidies that would characterize new plant species. Since the complexities of plant genomes are the result of multiple genome duplications, an artificial binucleation approach would thus be of some interest to eventually varying plant genomes and producing new polyploidy from related or distal plant species. Here, I discuss the potentiality of such an approach to engineer binucleated plant cells as a germ of new plant species to fulfill some environmental applications such as increasing the biodiversity and breeding new species adaptable to harsh environmental stresses and increasing green surfaces to reduce atmospheric pollutions in arid lands with poor vegetation. PMID:26322577

  19. Origin matters: diversity affects the performance of alien invasive species but not of native species.

    PubMed

    Sun, Yan; Müller-Schärer, Heinz; Maron, John L; Schaffner, Urs

    2015-06-01

    At local scales, it has often been found that invasibility decreases with increasing resident plant diversity. However, whether resident community diversity similarly resists invasion by alien versus native species is seldom studied. We examined this issue by invading constructed native plant assemblages that varied in species and functional richness with invasive alien or native Asteraceae species. Assemblages were also invaded with spotted knapweed, Centaurea stoebe, a native European aster that has been previously used in diversity-invasibility experiments in North America. We also conducted a field survey to explore the generality of the patterns generated from our experimental study. Both experimental and observational work revealed that increasing diversity reduced the performance of alien but not native invaders. Centaurea stoebe invading its native community performed poorly regardless of resident diversity, whereas in a parallel, previously published study conducted in North America, C. stoebe easily invaded low-diversity but not high-diversity assemblages. Our results suggest that diversity is an attribute of resident communities that makes them more or less susceptible to invasion by novel invasive alien but not native plant species. PMID:25996858

  20. Effects of invasive plant species on pollinator service and reproduction in native plants at Acadia National Park

    USGS Publications Warehouse

    Stubbs, C.J.; Drummond, F.; Ginsberg, H.

    2007-01-01

    Invasive plant species can have profound negative effects on natural communities by competively excluding native species. Berberis thunbergii (Japanese barberry), Frangula alnus (glossy or alder buckthorn) and Lythrum salicaria (purple loosestrife) are invasive species known to reduce native plant diversity and are thus of great concern to Acadia National Park. Pollinators visit them for nectar and pollen. The effects of invasive plant species on pollinator behavior were investigated by comparing pollinator visitation to co-flowering native and invasive species with visitation to native species growing alone. The effect of invasives on pollination of native plants was studied by comparing fruit set in patches of the native species growing near invasives with patches far from invasive species in Acadia National Park. The coflowering pairs were as follows: in the spring native Vaccinium angustifolium (lowbush blueberry) was paired with B. thunbergii; in early summer native Viburnum nudum (wild raisin) was paired with F. alnus ; in late summer native Spiraea alba (meadowsweet) was paired with L. salicaria. We investigated whether these invasives competed with native plants for pollinators in Acadia and thus negatively affected native plant reproduction. Our objectives were to determine: 1) the influence, if any, of each invasive on pollinator visitation to a co-flowering native species, 2) factors that might affect visitation, 3) invasive pollen transfer to native plants, and 4) whether invasives influence native plant reproduction (fruit set). Our findings indicate that at times the number of flower visitors to natives was lower or the species composition of visitors different when invasives were present, that invasives sometimes attracted more pollinators, that generally the invasives were more rewarding as far as nectar and pollen availability for pollinators, and that generally native plant fruit set and seed set was not significantly lowered in the presence of

  1. Polyphenoloxidase Silencing Affects Latex Coagulation in Taraxacum Species1[W

    PubMed Central

    Wahler, Daniela; Gronover, Christian Schulze; Richter, Carolin; Foucu, Florence; Twyman, Richard M.; Moerschbacher, Bruno M.; Fischer, Rainer; Muth, Jost; Prüfer, Dirk

    2009-01-01

    Latex is the milky sap that is found in many different plants. It is produced by specialized cells known as laticifers and can comprise a mixture of proteins, carbohydrates, oils, secondary metabolites, and rubber that may help to prevent herbivory and protect wound sites against infection. The wound-induced browning of latex suggests that it contains one or more phenol-oxidizing enzymes. Here, we present a comprehensive analysis of the major latex proteins from two dandelion species, Taraxacum officinale and Taraxacum kok-saghyz, and enzymatic studies showing that polyphenoloxidase (PPO) is responsible for latex browning. Electrophoretic analysis and amino-terminal sequencing of the most abundant proteins in the aqueous latex fraction revealed the presence of three PPO-related proteins generated by the proteolytic cleavage of a single precursor (pre-PPO). The laticifer-specific pre-PPO protein contains a transit peptide that can target reporter proteins into chloroplasts when constitutively expressed in dandelion protoplasts, perhaps indicating the presence of structures similar to plastids in laticifers, which lack genuine chloroplasts. Silencing the PPO gene by constitutive RNA interference in transgenic plants reduced PPO activity compared with wild-type controls, allowing T. kok-saghyz RNA interference lines to expel four to five times more latex than controls. Latex fluidity analysis in silenced plants showed a strong correlation between residual PPO activity and the coagulation rate, indicating that laticifer-specific PPO plays a major role in latex coagulation and wound sealing in dandelions. In contrast, very little PPO activity is found in the latex of the rubber tree Hevea brasiliensis, suggesting functional divergence of latex proteins during plant evolution. PMID:19605551

  2. Offspring size in a resident species affects community assembly.

    PubMed

    Davis, Kurt; Marshall, Dustin J

    2014-03-01

    Offspring size is a trait of fundamental importance that affects the ecology and evolution of a range of organisms. Despite the pervasive impact of offspring size for those offspring, the influence of offspring size on other species in the broader community remains unexplored. Such community-wide effects of offspring size are likely, but they have not been anticipated by theory or explored empirically. For a marine invertebrate community, we manipulated the size and density of offspring of a resident species (Watersipora subtorquata) in the field and examined subsequent community assembly around that resident species. Communities that assembled around larger offspring were denser and less diverse than communities that assembled around smaller offspring. Differences in niche usage by colonies from smaller and larger offspring may be driving these community-level effects. Our results suggest that offspring size is an important but unexplored source of ecological variation and that life-history theory must accommodate the effects of offspring size on community assembly. Life-history theory often assumes that environmental variation drives intraspecific variation in offspring size, and our results show that the converse can also occur. PMID:26046291

  3. Alien Roadside Species More Easily Invade Alpine than Lowland Plant Communities in a Subarctic Mountain Ecosystem

    PubMed Central

    Lembrechts, Jonas J.; Milbau, Ann; Nijs, Ivan

    2014-01-01

    Effects of roads on plant communities are not well known in cold-climate mountain ecosystems, where road building and development are expected to increase in future decades. Knowledge of the sensitivity of mountain plant communities to disturbance by roads is however important for future conservation purposes. We investigate the effects of roads on species richness and composition, including the plant strategies that are most affected, along three elevational gradients in a subarctic mountain ecosystem. We also examine whether mountain roads promote the introduction and invasion of alien plant species from the lowlands to the alpine zone. Observations of plant community composition were made together with abiotic, biotic and anthropogenic factors in 60 T-shaped transects. Alpine plant communities reacted differently to road disturbances than their lowland counterparts. On high elevations, the roadside species composition was more similar to that of the local natural communities. Less competitive and ruderal species were present at high compared with lower elevation roadsides. While the effects of roads thus seem to be mitigated in the alpine environment for plant species in general, mountain plant communities are more invasible than lowland communities. More precisely, relatively more alien species present in the roadside were found to invade into the surrounding natural community at high compared to low elevations. We conclude that effects of roads and introduction of alien species in lowlands cannot simply be extrapolated to the alpine and subarctic environment. PMID:24586947

  4. Plant exposures: a state profile of the most common species.

    PubMed

    Krenzelok, E P; Jacobsen, T D; Aronis, J M

    1996-08-01

    Plant exposures are the fourth most common cause of poisoning and 86% of those exposures involve the pediatric population. The large number of plant-related exposures and the lack of knowledge about plant toxicity has led to plant paranoia and considerable educational efforts to reduce the number of exposures. These efforts are often dictated by misconceptions and folklore. AAPCC TESS data on all plant exposures for the years 1985-1994 were electronically analyzed by plant species and state to establish a frequency distribution in the US. Aggregate national data was also tabulated. A total of 912,534 plant exposures were analyzed to tabulate the top 30 plant exposures for each state. Philodendron species were the most common exposures, followed by Dieffenbachia species, Euphorbia pulcherrima, Capsicum annuum and Ilex species. There were considerable differences between states relating to indoor vs outdoor plants and native vs introduced varieties. Plant exposures are common and poison information centers devote significant clinical service and educational effort to manage them and to enhance public awareness. Recognition of specific plant species and exposure frequency in a poison center region can be a basis for staff education and the development of appropriate poison prevention education brochures. This can direct better utilization of poison center's resources. PMID:8829350

  5. Rapid plant evolution in the presence of an introduced species alters community composition.

    PubMed

    Smith, David Solance; Lau, Matthew K; Jacobs, Ryan; Monroy, Jenna A; Shuster, Stephen M; Whitham, Thomas G

    2015-10-01

    Because introduced species may strongly interact with native species and thus affect their fitness, it is important to examine how these interactions can cascade to have ecological and evolutionary consequences for whole communities. Here, we examine the interactions among introduced Rocky Mountain elk, Cervus canadensis nelsoni, a common native plant, Solidago velutina, and the diverse plant-associated community of arthropods. While introduced species are recognized as one of the biggest threats to native ecosystems, relatively few studies have investigated an evolutionary mechanism by which introduced species alter native communities. Here, we use a common garden design that addresses and supports two hypotheses. First, native S. velutina has rapidly evolved in the presence of introduced elk. We found that plants originating from sites with introduced elk flowered nearly 3 weeks before plants originating from sites without elk. Second, evolution of S. velutina results in a change to the plant-associated arthropod community. We found that plants originating from sites with introduced elk supported an arthropod community that had ~35 % fewer total individuals and a different species composition. Our results show that the impacts of introduced species can have both ecological and evolutionary consequences for strongly interacting species that subsequently cascade to affect a much larger community. Such evolutionary consequences are likely to be long-term and difficult to remediate. PMID:26062439

  6. Plant hybrid zones affect biodiversity: Tools for a genetic-based understanding of community structure

    SciTech Connect

    Whitham, T.G.; Martinsen, G.D.; Keim, P.; Floate, K.D.; Dungey, H.S. |; Potts, B.M.

    1999-03-01

    Plant hybrid zones are dynamic centers of ecological and evolutionary processes for plants and their associated communities. Studies in the wild and in gardens with synthetic crosses showed that hybrid eucalypts supports the greatest species richness and abundances of insect and fungal taxa. In an updated review of 152 case studies of taxa associated with diverse hybridizing systems, there were 43 (28%) cases of hybrids being more susceptible than their parent species, 7 (5%) resistant, 35 (23%) additive, 35 (23%) dominant, and 32 (21%) showed no response to hybridization. Thus, most taxa respond to hybrids in ways that result in equal or greater abundance, and hybrids tend to accumulate the taxa of their parent species. These studies suggest that genetic-based plant traits affect the distribution of many species and that the variation in hybrids can be used as tools to examine the genetic components of community structure and biodiversity.

  7. Species-area relationships in Mediterranean-climate plant communities

    USGS Publications Warehouse

    Keeley, J.E.; Fotheringham, C.J.

    2003-01-01

    Aim: To determine the best-fit model of species-area relationships for Mediterranean-type plant communities and evaluate how community structure affects these species-area models. Location: Data were collected from California shrublands and woodlands and compared with literature reports for other Mediterranean-climate regions. Methods: The number of species was recorded from 1, 100 and 1000 m2 nested plots. Best fit to the power model or exponential model was determined by comparing adjusted r2 values from the least squares regression, pattern of residuals, homoscedasticity across scales, and semi-log slopes at 1-100 m2 and 100-1000 m2. Dominance-diversity curves were tested for fit to the lognormal model, MacArthur's broken stick model, and the geometric and harmonic series. Results: Early successional Western Australia and California shrublands represented the extremes and provide an interesting contrast as the exponential model was the best fit for the former, and the power model for the latter, despite similar total species richness. We hypothesize that structural differences in these communities account for the different species-area curves and are tied to patterns of dominance, equitability and life form distribution. Dominance-diversity relationships for Western Australian heathlands exhibited a close fit to MacArthur's broken stick model, indicating more equitable distribution of species. In contrast, Californian shrublands, both postfire and mature stands, were best fit by the geometric model indicating strong dominance and many minor subordinate species. These regions differ in life form distribution, with annuals being a major component of diversity in early successional Californian shrublands although they are largely lacking in mature stands. Both young and old Australian heathlands are dominated by perennials, and annuals are largely absent. Inherent in all of these ecosystems is cyclical disequilibrium caused by periodic fires. The potential for

  8. Habitats as Complex Odour Environments: How Does Plant Diversity Affect Herbivore and Parasitoid Orientation?

    PubMed Central

    Wäschke, Nicole; Hardge, Kristin; Hancock, Christine; Hilker, Monika; Obermaier, Elisabeth; Meiners, Torsten

    2014-01-01

    Plant diversity is known to affect success of host location by pest insects, but its effect on olfactory orientation of non-pest insect species has hardly been addressed. First, we tested in laboratory experiments the hypothesis that non-host plants, which increase odour complexity in habitats, affect the host location ability of herbivores and parasitoids. Furthermore, we recorded field data of plant diversity in addition to herbivore and parasitoid abundance at 77 grassland sites in three different regions in Germany in order to elucidate whether our laboratory results reflect the field situation. As a model system we used the herb Plantago lanceolata, the herbivorous weevil Mecinus pascuorum, and its larval parasitoid Mesopolobus incultus. The laboratory bioassays revealed that both the herbivorous weevil and its larval parasitoid can locate their host plant and host via olfactory cues even in the presence of non-host odour. In a newly established two-circle olfactometer, the weeviĺs capability to detect host plant odour was not affected by odours from non-host plants. However, addition of non-host plant odours to host plant odour enhanced the weeviĺs foraging activity. The parasitoid was attracted by a combination of host plant and host volatiles in both the absence and presence of non-host plant volatiles in a Y-tube olfactometer. In dual choice tests the parasitoid preferred the blend of host plant and host volatiles over its combination with non-host plant volatiles. In the field, no indication was found that high plant diversity disturbs host (plant) location by the weevil and its parasitoid. In contrast, plant diversity was positively correlated with weevil abundance, whereas parasitoid abundance was independent of plant diversity. Therefore, we conclude that weevils and parasitoids showed the sensory capacity to successfully cope with complex vegetation odours when searching for hosts. PMID:24416354

  9. Regional climate model downscaling may improve the prediction of alien plant species distributions

    NASA Astrophysics Data System (ADS)

    Liu, Shuyan; Liang, Xin-Zhong; Gao, Wei; Stohlgren, Thomas J.

    2014-12-01

    Distributions of invasive species are commonly predicted with species distribution models that build upon the statistical relationships between observed species presence data and climate data. We used field observations, climate station data, and Maximum Entropy species distribution models for 13 invasive plant species in the United States, and then compared the models with inputs from a General Circulation Model (hereafter GCM-based models) and a downscaled Regional Climate Model (hereafter, RCM-based models).We also compared species distributions based on either GCM-based or RCM-based models for the present (1990-1999) to the future (2046-2055). RCM-based species distribution models replicated observed distributions remarkably better than GCM-based models for all invasive species under the current climate. This was shown for the presence locations of the species, and by using four common statistical metrics to compare modeled distributions. For two widespread invasive taxa ( Bromus tectorum or cheatgrass, and Tamarix spp. or tamarisk), GCM-based models failed miserably to reproduce observed species distributions. In contrast, RCM-based species distribution models closely matched observations. Future species distributions may be significantly affected by using GCM-based inputs. Because invasive plants species often show high resilience and low rates of local extinction, RCM-based species distribution models may perform better than GCM-based species distribution models for planning containment programs for invasive species.

  10. Factors Affecting the Distribution Pattern of Wild Plants with Extremely Small Populations in Hainan Island, China

    PubMed Central

    Chen, Yukai; Yang, Xiaobo; Yang, Qi; Li, Donghai; Long, Wenxing; Luo, Wenqi

    2014-01-01

    Understanding which factors affect the distribution pattern of extremely small populations is essential to the protection and propagation of rare and endangered plant species. In this study, we established 108 plots covering the entire Hainan Island, and measured the appearance frequency and species richness of plant species with extremely small populations, as well as the ecological environments and human disturbances during 2012–2013. We explored how the ecological environments and human activities affected the distribution pattern of these extremely small populations. Results showed that the extremely small populations underwent human disturbances and threats, and they were often found in fragmental habitats. The leading factors changing the appearance frequency of extremely small populations differed among plant species, and the direct factors making them susceptible to extinction were human disturbances. The peak richness of extremely small populations always occurred at the medium level across environmental gradients, and their species richness always decreased with increasing human disturbances. However, the appearance frequencies of three orchid species increased with the increasing human disturbances. Our study thus indicate that knowledge on how the external factors, such as the ecological environment, land use type, roads, human activity, etc., affect the distribution of the extremely small populations should be taken for the better protecting them in the future. PMID:24830683

  11. Factors affecting the distribution pattern of wild plants with extremely small populations in Hainan Island, China.

    PubMed

    Chen, Yukai; Yang, Xiaobo; Yang, Qi; Li, Donghai; Long, Wenxing; Luo, Wenqi

    2014-01-01

    Understanding which factors affect the distribution pattern of extremely small populations is essential to the protection and propagation of rare and endangered plant species. In this study, we established 108 plots covering the entire Hainan Island, and measured the appearance frequency and species richness of plant species with extremely small populations, as well as the ecological environments and human disturbances during 2012-2013. We explored how the ecological environments and human activities affected the distribution pattern of these extremely small populations. Results showed that the extremely small populations underwent human disturbances and threats, and they were often found in fragmental habitats. The leading factors changing the appearance frequency of extremely small populations differed among plant species, and the direct factors making them susceptible to extinction were human disturbances. The peak richness of extremely small populations always occurred at the medium level across environmental gradients, and their species richness always decreased with increasing human disturbances. However, the appearance frequencies of three orchid species increased with the increasing human disturbances. Our study thus indicate that knowledge on how the external factors, such as the ecological environment, land use type, roads, human activity, etc., affect the distribution of the extremely small populations should be taken for the better protecting them in the future. PMID:24830683

  12. Factors affecting Archaeal Lipid Compositions of the Sulfolobus Species

    NASA Astrophysics Data System (ADS)

    He, L.; Han, J.; Wei, Y.; Lin, L.; Wei, Y.; Zhang, C.

    2010-12-01

    Temperature is the best known variable affecting the distribution of the archaeal glycerol dibiphytanyl glycerol tetraethers (GDGTs) in marine and freshwater systems. Other variables such as pH, ionic strength, or bicarbonate concentration may also affect archaeal GDGTs in terrestrial systems. Studies of pure cultures can help us pinpoint the specific effects these variables may have on archaeal lipid distribution in natural environments. In this study, three Sulfolobus species (HG4, HB5-2, HB9-6) isolated from Tengchong hot springs (pH 2-3, temperature 73-90°C) in China were used to investigate the effects of temperature, pH, substrate, and type of strain on the composition of GDGTs. Results showed that increase in temperature had negative effects on the relative contents of GDGT-0 (no cyclopentyl rings), GDGT-1 (one cyclopentyl ring), GDGT-2 and GDGT-3 but positive effects on GDGT-4, GDGT-4', GDGT-5 and GDGT-5'. Increase in pH, on the other hand, had negative effects on GDGT-0, GDGT-1, GDGT-4', GDGT-5 and GDGT-5', and positive effects on GDGT-3 and GDGT-4. GDGT-2 remained relatively constant with changing pH. When the HG4 was grown on different substrates, GDGT-5 was five time more abundant in sucrose-grown cultures than in yeast extract- or sulfur- grown cultures, suggesting that carbohydrates may stimulate the production of GDGT-5. For all three species, the ring index (average number of rings) of GDGTs correlated positively with incubation temperature. In HG4, ring index was much lower at optimal pH (3.5) than at other pH values. Ring index of HB5-2 or HB9-6 is higher than that of HG4, suggesting that speciation may affect the degree of cyclization of GDGT of the Sulfolobus. These results indicate that individual archaeal lipids respond differently to changes in environmental variables, which may be also species specific.

  13. Plant species composition and biofuel yields of conservation grasslands.

    PubMed

    Adler, Paul R; Sanderson, Matt A; Weimer, Paul J; Vogel, Kenneth P

    2009-12-01

    Marginal croplands, such as those in the Conservation Reserve Program (CRP), have been suggested as a source of biomass for biofuel production. However, little is known about the composition of plant species on these conservation grasslands or their potential for ethanol production. Our objective was to assess the potential of CRP and other conservation grasslands for biofuel production, describing the relationships of plant species richness and tall native C4 prairie grass abundance with plant chemical composition and the resulting potential ethanol yield. We determined plant species composition and diversity at multiple scales with the modified Whittaker plot technique, aboveground biomass, plant chemical composition, and potential ethanol yield at 34 sites across the major ecological regions of the northeastern USA. Conservation grasslands with higher numbers of plant species had lower biomass yields and a lower ethanol yield per unit biomass compared with sites with fewer species. Thus, biofuel yield per unit land area decreased by 77% as plant species richness increased from 3 to 12.8 species per m2. We found that, as tall native C4 prairie grass abundance increased from 1.7% to 81.6%, the number of plant species decreased and aboveground biomass per unit land area and ethanol yield per unit biomass increased resulting in a 500% increased biofuel yield per unit land area. Plant species richness and composition are key determinants of biomass and ethanol yields from conservation grasslands and have implications for low-input high-diversity systems. Designing systems to include a large proportion of species with undesirable fermentation characteristics could reduce ethanol yields. PMID:20014588

  14. Ecophysiological studies of Mediterranean plant species at the Castelporziano estate

    NASA Astrophysics Data System (ADS)

    Manes, Fausto; Seufert, Günther; Vitale, Marcello

    The aim of this work was to characterize the eco-physiological performance of the main plant species of the Castelporziano site by single leaf investigations. We measured the leaf gas exchange of Quercus ilex L., Pinus pinea L., Pistacia lentiscus L. and Asphodelus microcarpus L. for several days. Additionally, the xylem water potential of Quercus ilex, Pinus pinea and Pistacia lentiscus was recorded in order to obtain more physiological background information for the discussion of the trace gas emissions. This study indicates significantly different physiological responses to the different environmental conditions. In particular, summer conditions (high values of light, air temperature and low xylem water potentials) caused the depression of photosynthesis in Quercus ilex and Pinus pinea but did not affect photosynthesis of Pistacia lentiscus and Asphodelus microcarpus. This should be taken into account when discussing VOC emission rates and fluxes.

  15. Mapping National Plant Biodiversity Patterns in South Korea with the MARS Species Distribution Model

    PubMed Central

    Choe, Hyeyeong; Thorne, James H.; Seo, Changwan

    2016-01-01

    Accurate information on the distribution of existing species is crucial to assess regional biodiversity. However, data inventories are insufficient in many areas. We examine the ability of Multivariate Adaptive Regression Splines (MARS) multi-response species distribution model to overcome species’ data limitations and portray plant species distribution patterns for 199 South Korean plant species. The study models species with two or more observations, examines their contribution to national patterns of species richness, provides a sensitivity analysis of different range threshold cutoff approaches for modeling species’ ranges, and presents considerations for species modeling at fine spatial resolution. We ran MARS models for each species and tested four threshold methods to transform occurrence probabilities into presence or absence range maps. Modeled occurrence probabilities were extracted at each species’ presence points, and the mean, median, and one standard deviation (SD) calculated to define data-driven thresholds. A maximum sum of sensitivity and specificity threshold was also calculated, and the range maps from the four cutoffs were tested using independent plant survey data. The single SD values were the best threshold tested for minimizing omission errors and limiting species ranges to areas where the associated occurrence data were correctly classed. Eight individual species range maps for rare plant species were identified that are potentially affected by resampling predictor variables to fine spatial scales. We portray spatial patterns of high species richness by assessing the combined range maps from three classes of species: all species, endangered and endemic species, and range-size rarity of all species, which could be used in conservation planning for South Korea. The MARS model is promising for addressing the common problem of few species occurrence records. However, projected species ranges are highly dependent on the threshold and scale

  16. The factors controlling species density in herbaceous plant communities: An assessment

    USGS Publications Warehouse

    Grace, J.B.

    1999-01-01

    This paper evaluates both the ideas and empirical evidence pertaining to the control of species density in herbaceous plant communities. While most theoretical discussions of species density have emphasized the importance of habitat productivity and disturbance regimes, many other factors (e.g. species pools, plant litter accumulation, plant morphology) have been proposed to be important. A review of literature presenting observations on the density of species in small plots (in the vicinity of a few square meters or less), as well as experimental studies, suggests several generalizations: (1) Available data are consistent with an underlying unimodal relationship between species density and total community biomass. While variance in species density is often poorly explained by predictor variables, there is strong evidence that high levels of community biomass are antagonistic to high species density. (2) Community biomass is just one of several factors affecting variations in species density. Multivariate analyses typically explain more than twice as much variance in species density as can be explained by community biomass alone. (3) Disturbance has important and sometimes complex effects on species density. In general, the evidence is consistent with the intermediate disturbance hypothesis but exceptions exist and effects can be complex. (4) Gradients in the species pool can have important influences on patterns of species density. Evidence is mounting that a considerable amount of the observed variability in species density within a landscape or region may result from environmental effects on the species pool. (5) Several additional factors deserve greater consideration, including time lags, species composition, plant morphology, plant density and soil microbial effects. Based on the available evidence, a conceptual model of the primary factors controlling species density is presented here. This model suggests that species density is controlled by the effects of

  17. Plant Species Diversity and Pasture Management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Farmers face many challenges in pasture management, such as evolving agri-environmental schemes to protect natural resources, and need new management techniques to remain sustainable. Ecological research indicates that increased plant biodiversity benefits ecosystem functions such as primary product...

  18. Herbivory and dominance shifts among exotic and congeneric native plant species during plant community establishment.

    PubMed

    Engelkes, Tim; Meisner, Annelein; Morriën, Elly; Kostenko, Olga; Van der Putten, Wim H; Macel, Mirka

    2016-02-01

    Invasive exotic plant species often have fewer natural enemies and suffer less damage from herbivores in their new range than genetically or functionally related species that are native to that area. Although we might expect that having fewer enemies would promote the invasiveness of the introduced exotic plant species due to reduced enemy exposure, few studies have actually analyzed the ecological consequences of this situation in the field. Here, we examined how exposure to aboveground herbivores influences shifts in dominance among exotic and phylogenetically related native plant species in a riparian ecosystem during early establishment of invaded communities. We planted ten plant communities each consisting of three individuals of each of six exotic plant species as well as six phylogenetically related natives. Exotic plant species were selected based on a rapid recent increase in regional abundance, the presence of a congeneric native species, and their co-occurrence in the riparian ecosystem. All plant communities were covered by tents with insect mesh. Five tents were open on the leeward side to allow herbivory. The other five tents were completely closed in order to exclude insects and vertebrates. Herbivory reduced aboveground biomass by half and influenced which of the plant species dominated the establishing communities. Exposure to herbivory did not reduce the total biomass of natives more than that of exotics, so aboveground herbivory did not selectively enhance exotics during this early stage of plant community development. Effects of herbivores on plant biomass depended on plant species or genus but not on plant status (i.e., exotic vs native). Thus, aboveground herbivory did not promote the dominance of exotic plant species during early establishment of the phylogenetically balanced plant communities. PMID:26481795

  19. Phytotoxins produced by plant pathogenic Streptomyces species.

    PubMed

    Bignell, D R D; Fyans, J K; Cheng, Z

    2014-02-01

    Streptomyces is a large genus consisting of soil-dwelling, filamentous bacteria that are best known for their capability of producing a vast array of medically and agriculturally useful secondary metabolites. In addition, a small number of Streptomyces spp. are capable of colonizing and infecting the underground portions of living plants and causing economically important crop diseases such as potato common scab (CS). Research into the mechanisms of Streptomyces plant pathogenicity has led to the identification and characterization of several phytotoxic secondary metabolites that are known or suspected of contributing to diseases in various plants. The best characterized are the thaxtomin phytotoxins, which play a critical role in the development of CS, acid scab and soil rot of sweet potato. In addition, the best-characterized CS-causing pathogen, Streptomyces scabies, produces a molecule that is predicted to resemble the Pseudomonas syringae coronatine phytotoxin and which contributes to seedling disease symptom development. Other Streptomyces phytotoxic secondary metabolites that have been identified include concanamycins, FD-891 and borrelidin. Furthermore, there is evidence that additional, unknown metabolites may participate in Streptomyces plant pathogenicity. Such revelations have implications for the rational development of better management procedures for controlling CS and other Streptomyces plant diseases. PMID:24131731

  20. Relative abundance of an invasive alien plant affects insect-flower interaction networks in Ireland

    NASA Astrophysics Data System (ADS)

    Stout, Jane C.; Casey, Leanne M.

    2014-02-01

    Invasive alien flowering plants may affect native plant pollinator interactions and have knock on impacts on populations of native plants and animals. The magnitude of these impacts, however, may be modified by the relative abundance of the invasive plant and the number of flowers it presents.We tested this by examining the structure of insect-flower interaction networks in six sites with increasing levels of invasion by Rhododendron ponticum in Ireland.Neither flower-visiting insect abundance, species richness nor diversity were related to R. ponticum flower abundance, but the composition of insect communities was. The total number of flowers in a site increased with the relative abundance of R. ponticum flowers but the number of co-flowering native plant species in these sites was low (<6), making interaction networks relatively small.As a result, changes in interaction network properties (connectance, interaction evenness and network level specialisation), which correlated with R. ponticum flower abundance, were a result of the small network size rather than due to changes in the resilience of networks.Overall, we conclude that the impacts of invasive alien plants on native plant-pollinator interactions are not only species specific, but site specific, according to the abundance of flowers produced by both the invasive and the native plants.

  1. Are the metabolomic responses to folivory of closely related plant species linked to macroevolutionary and plant-folivore coevolutionary processes?

    PubMed

    Rivas-Ubach, Albert; Hódar, José A; Sardans, Jordi; Kyle, Jennifer E; Kim, Young-Mo; Oravec, Michal; Urban, Otmar; Guenther, Alex; Peñuelas, Josep

    2016-07-01

    The debate whether the coevolution of plants and insects or macroevolutionary processes (phylogeny) is the main driver determining the arsenal of molecular defensive compounds of plants remains unresolved. Attacks by herbivorous insects affect not only the composition of defensive compounds in plants but also the entire metabolome. Metabolomes are the final products of genotypes and are constrained by macroevolutionary processes, so closely related species should have similar metabolomic compositions and may respond in similar ways to attacks by folivores. We analyzed the elemental compositions and metabolomes of needles from three closely related Pinus species with distant coevolutionary histories with the caterpillar of the processionary moth respond similarly to its attack. All pines had different metabolomes and metabolic responses to herbivorous attack. The metabolomic variation among the species and the responses to folivory reflected their macroevolutionary relationships, with P. pinaster having the most divergent metabolome. The concentrations of terpenes were in the attacked trees supporting the hypothesis that herbivores avoid plant individuals with higher concentrations. Our results suggest that macroevolutionary history plays important roles in the metabolomic responses of these pine species to folivory, but plant-insect coevolution probably constrains those responses. Combinations of different evolutionary factors and trade-offs are likely responsible for the different responses of each species to folivory, which is not necessarily exclusively linked to plant-insect coevolution. PMID:27386082

  2. Widespread plant species: natives vs. aliens in our changing world

    USGS Publications Warehouse

    Stohlgren, Thomas J.; Pyšek, Petr; Kartesz, John; Nishino, Misako; Pauchard, Aníbal; Winter, Marten; Pino, Joan; Richardson, David M.; Wilson, John R.U.; Murray, Brad R.; Phillips, Megan L.; Ming-yang, Li; Celesti-Grapow, Laura; Font, Xavier

    2011-01-01

    Estimates of the level of invasion for a region are traditionally based on relative numbers of native and alien species. However, alien species differ dramatically in the size of their invasive ranges. Here we present the first study to quantify the level of invasion for several regions of the world in terms of the most widely distributed plant species (natives vs. aliens). Aliens accounted for 51.3% of the 120 most widely distributed plant species in North America, 43.3% in New South Wales (Australia), 34.2% in Chile, 29.7% in Argentina, and 22.5% in the Republic of South Africa. However, Europe had only 1% of alien species among the most widespread species of the flora. Across regions, alien species relative to native species were either as well-distributed (10 comparisons) or more widely distributed (5 comparisons). These striking patterns highlight the profound contribution that widespread invasive alien plants make to floristic dominance patterns across different regions. Many of the most widespread species are alien plants, and, in particular, Europe and Asia appear as major contributors to the homogenization of the floras in the Americas. We recommend that spatial extent of invasion should be explicitly incorporated in assessments of invasibility, globalization, and risk assessments.

  3. Widespread plant species: Natives versus aliens in our changing world

    USGS Publications Warehouse

    Stohlgren, T.J.; Pysek, P.; Kartesz, J.; Nishino, M.; Pauchard, A.; Winter, M.; Pino, J.; Richardson, D.M.; Wilson, J.R.U.; Murray, B.R.; Phillips, M.L.; Ming-yang, L.; Celesti-Grapow, L.; Font, X.

    2011-01-01

    Estimates of the level of invasion for a region are traditionally based on relative numbers of native and alien species. However, alien species differ dramatically in the size of their invasive ranges. Here we present the first study to quantify the level of invasion for several regions of the world in terms of the most widely distributed plant species (natives vs. aliens). Aliens accounted for 51.3% of the 120 most widely distributed plant species in North America, 43.3% in New South Wales (Australia), 34.2% in Chile, 29.7% in Argentina, and 22.5% in the Republic of South Africa. However, Europe had only 1% of alien species among the most widespread species of the flora. Across regions, alien species relative to native species were either as well-distributed (10 comparisons) or more widely distributed (5 comparisons). These striking patterns highlight the profound contribution that widespread invasive alien plants make to floristic dominance patterns across different regions. Many of the most widespread species are alien plants, and, in particular, Europe and Asia appear as major contributors to the homogenization of the floras in the Americas. We recommend that spatial extent of invasion should be explicitly incorporated in assessments of invasibility, globalization, and risk assessments. ?? 2011 Springer Science+Business Media B.V.

  4. Human population, grasshopper and plant species richness in European countries

    NASA Astrophysics Data System (ADS)

    Steck, Claude E.; Pautasso, Marco

    2008-11-01

    Surprisingly, several studies over large scales have reported a positive spatial correlation of people and biodiversity. This pattern has important implications for conservation and has been documented for well studied taxa such as plants, amphibians, reptiles, birds and mammals. However, it is unknown whether the pattern applies also to invertebrates other than butterflies and more work is needed to establish whether the species-people relationship is explained by both variables correlating with other environmental factors. We studied whether grasshopper species richness (Orthoptera, suborder Caelifera) is related to human population size in European countries. As expected, the number of Caelifera species increases significantly with increasing human population size. But this is not the case when controlling for country area, latitude and number of plant species. Variations in Caelifera species richness are primarily associated with variations in plant species richness. Caelifera species richness also increases with decreasing mean annual precipitation, Gross Domestic Product per capita (used as an indicator for economic development) and net fertility rate of the human population. Our analysis confirms the hypothesis that the broad-scale human population-biodiversity correlations can be explained by concurrent variations in factors other than human population size such as plant species richness, environmental productivity, or habitat heterogeneity. Nonetheless, more populated countries in Europe still have more Caelifera species than less populated countries and this poses a particular challenge for conservation.

  5. Thermal Hyperspectral Remote Sensing for Plant Species and Stress Detection

    NASA Astrophysics Data System (ADS)

    Schlerf, M.; Rock, G.; Ullah, S.; Gerhards, M.; Udelhoven, T.; Skidmore, A. K.

    2014-12-01

    Thermal infrared (TIR) spectroscopy offers a novel opportunity for measuring emissivity spectra of natural surfaces. Emissivity spectra are not directly measured, they first have to be retrieved from the raw measurements. Once retrieved, the spectra can be used, for example, to discriminate plant species or to detect plant stress. Knowledge of plant species distribution is essential for the sustainable management of ecosystems. Remote sensing of plant species has so far mostly been limited to data in the visible and near-infrared where, however, different species often reveal similar reflectance curves. Da Luz and Crowley showed in a recent paper that in the TIR plants indeed have distinct spectral features. Also with a certain species, subtle changes of emissivity in certain wavebands may occur, when biochemical compounds change due to osmotic adjustment induced by water stress. Here we show, that i) emissive imaging spectroscopy allows for reliable and accurate retrieval of plant emissivity spectra, ii) emissivity spectra are well suited to discriminate plant species, iii) a reduction in stomatal conductance (caused by stress) changes the thermal infrared signal. For 13 plant species in the laboratory and for 8 plant species in a field setup emissivity spectra were retrieved. A comparison shows, that for most species the shapes of the emissivity curves agree quite well, but that clear offsets between the two types of spectra exist. Discrimination analysis revealed that based on the lab spectra, 13 species could be distinguished with an average overall classification accuracy of 92% using the 6 best spectral bands. For the field spectra (8 species), a similar high OAA of 89% was achieved. Species discrimination is likely to be possible due to variations in the composition of the superficial epidermal layer of plant leaves and in internal chemical concentrations producing unique emissivity features. However, to date, which spectral feature is responsible for which

  6. [Traightened on Chinese endemic seed plant species of medicine plants used in Tibetan medicine].

    PubMed

    Zhou, Hua-rong; Mu, Ze-jing; Du, Xiao-lang; He, Jun-wei; Cao, Lan; Zhong, Guo-yue

    2015-09-01

    This paper is in order to discussion with the composition and characteristics of Tibetan medicine plant resources, and promote the reasonable protection and utilization of the resources of Tibetan materia medica. Statistical analysis of species, distributions, and others of Chinese endemic seed plant from Tibetan medicine plants and usually used in the clinic of Tibetan medicine. The results showed that there are 523 species (25%) of Chinese endemic seed plant, belonging to 65 families and 162 genera, in about 2 000 varieties of Tibetan medicine plants recorded in relevant literatures. There are 180 Chinese endemic seed plant species (28%) belonging to 42 families and 72 genera from 625 medicine plants usually used in the clinic of Tibetan medicine. Specifically, the most of these Chinese endemic seed plant species are characteristic crude drug used in Tibetan medicine, and mainly or only distributed in Qinghai-Tibet Plateau. And a few species of them were intersected with traditional Chinese medicines (TCM) and other ethnic medicines. In addition, about 10% are listed in China Species Red List. The Qinghai-Tibet Plateau is the most abundant areas of Areal-types of the Chinese endemic seed plant. This is the biological and ecological reason formation the characteristics of Tibetan medicine plant resources. Therefore, strengthen the research of Chinese endemic seed plants used in Tibetan medicine is great significance for the reasonable protection and utilization of Tibetan medicine plant resources. PMID:26978990

  7. Climate warming affects biological invasions by shifting interactions of plants and herbivores.

    PubMed

    Lu, Xinmin; Siemann, Evan; Shao, Xu; Wei, Hui; Ding, Jianqing

    2013-08-01

    Plants and herbivorous insects can each be dramatically affected by temperature. Climate warming may impact plant invasion success directly but also indirectly through changes in their natural enemies. To date, however, there are no tests of how climate warming shifts the interactions among invasive plants and their natural enemies to affect invasion success. Field surveys covering the full latitudinal range of invasive Alternanthera philoxeroides in China showed that a beetle introduced for biocontrol was rare or absent at higher latitudes. In contrast, plant cover and mass increased with latitude. In a 2-year field experiment near the northern limit of beetle distribution, we found the beetle sustained populations across years under elevated temperature, dramatically decreasing A. philoxeroides growth, but it failed to overwinter in ambient temperature. Together, these results suggest that warming will allow the natural enemy to expand its range, potentially benefiting biocontrol in regions that are currently too cold for the natural enemy. However, the invader may also expand its range further north in response to warming. In such cases where plants tolerate cold better than their natural enemies, the geographical gap between plant and herbivorous insect ranges may not disappear but will shift to higher latitudes, leading to a new zone of enemy release. Therefore, warming will not only affect plant invasions directly but also drive either enemy release or increase that will result in contrasting effects on invasive plants. The findings are also critical for future management of invasive species under climate change. PMID:23640751

  8. Global response patterns of terrestrial plant species to nitrogen addition.

    PubMed

    Xia, Jianyang; Wan, Shiqiang

    2008-07-01

    Better understanding of the responses of terrestrial plant species under global nitrogen (N) enrichment is critical for projection of changes in structure, functioning, and service of terrestrial ecosystems. Here, a meta-analysis of data from 304 studies was carried out to reveal the general response patterns of terrestrial plant species to the addition of N. Across 456 terrestrial plant species included in the analysis, biomass and N concentration were increased by 53.6 and 28.5%, respectively, under N enrichment. However, the N responses were dependent upon plant functional types, with significantly greater biomass increases in herbaceous than in woody species. Stimulation of plant biomass by the addition of N was enhanced when other resources were improved. In addition, the N responses of terrestrial plants decreased with increasing latitude and increased with annual precipitation. Dependence of the N responses of terrestrial plants on biological realms, functional types, tissues, other resources, and climatic factors revealed in this study can help to explain changes in species composition, diversity, community structure and ecosystem functioning under global N enrichment. These findings are critical in improving model simulation and projection of terrestrial carbon sequestration and its feedbacks to global climate change, especially when progressive N limitation is taken into consideration. PMID:19086179

  9. Plant volatiles induced by herbivore egg deposition affect insects of different trophic levels.

    PubMed

    Fatouros, Nina E; Lucas-Barbosa, Dani; Weldegergis, Berhane T; Pashalidou, Foteini G; van Loon, Joop J A; Dicke, Marcel; Harvey, Jeffrey A; Gols, Rieta; Huigens, Martinus E

    2012-01-01

    Plants release volatiles induced by herbivore feeding that may affect the diversity and composition of plant-associated arthropod communities. However, the specificity and role of plant volatiles induced during the early phase of attack, i.e. egg deposition by herbivorous insects, and their consequences on insects of different trophic levels remain poorly explored. In olfactometer and wind tunnel set-ups, we investigated behavioural responses of a specialist cabbage butterfly (Pieris brassicae) and two of its parasitic wasps (Trichogramma brassicae and Cotesia glomerata) to volatiles of a wild crucifer (Brassica nigra) induced by oviposition of the specialist butterfly and an additional generalist moth (Mamestra brassicae). Gravid butterflies were repelled by volatiles from plants induced by cabbage white butterfly eggs, probably as a means of avoiding competition, whereas both parasitic wasp species were attracted. In contrast, volatiles from plants induced by eggs of the generalist moth did neither repel nor attract any of the tested community members. Analysis of the plant's volatile metabolomic profile by gas chromatography-mass spectrometry and the structure of the plant-egg interface by scanning electron microscopy confirmed that the plant responds differently to egg deposition by the two lepidopteran species. Our findings imply that prior to actual feeding damage, egg deposition can induce specific plant responses that significantly influence various members of higher trophic levels. PMID:22912893

  10. Effects of earthworm invasion on plant species richness in northern hardwood forests.

    PubMed

    Holdsworth, Andrew R; Frelich, Lee E; Reich, Peter B

    2007-08-01

    The invasion of non-native earthworms (Lumbricus spp.) into a small number of intensively studied stands of northern hardwood forest has been linked to declines in plant diversity and the local extirpation of one threatened species. It is unknown, however, whether these changes have occurred across larger regions of hardwood forests, which plant species are most vulnerable, or with which earthworm species such changes are associated most closely. To address these issues we conducted a regional survey in the Chippewa and Chequamegon national forests in Minnesota and Wisconsin (U.S.A.), respectively. We sampled earthworms, soils, and vegetation, examined deer browse in 20 mature, sugar-maple-dominated forest stands in each national forest, and analyzed the relationship between invasive earthworms and vascular plant species richness and composition. Invasion by Lumbricus was a strong indicator of reduced plant richness in both national forests. The mass of Lumbricus juveniles was significantly and negatively related to plant-species richness in both forests. In addition, Lumbricus was a significant factor affecting plant richness in a full model that included multiple variables. In the Chequamegon National Forest earthworm mass was associated with higher sedge cover and lower cover of sugar maple seedlings and several forb species. The trends were similar but not as pronounced in Chippewa, perhaps due to lower deer densities and different earthworm species composition. Our results provide regional evidence that invasion by Lumbricus species may be an important mechanism in reduced plant-species richness and changes in plant communities in mature forests dominated by sugar maples. PMID:17650250

  11. Nutritive value in relation to plant species diversity of pastures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Planting forage mixtures may benefit pasture herbage production; however, changes in botanical composition could cause unstable nutritive value. Data from two grazing studies and a farm survey were used to examine how plant species diversity influenced herbage nutritive value. In one grazing study,...

  12. When Are Native Species Inappropriate for Conservation Plantings

    EPA Science Inventory

    Conservation agencies and organizations are generally reluctant to encourage the use of invasive plant species in conservation programs. Harsh lessons learned in the past have resulted in tougher screening protocols for non-indigenous species introductions and removal of many no...

  13. Contrasting soil ciliate species richness and abundance between two tropical plant species: a test of the plant effect.

    PubMed

    Acosta-Mercado, D; Lynn, D H

    2006-05-01

    We still have a rudimentary understanding about the mechanism by which plant roots may stimulate soil microbial interactions. A biochemical model involving plant-derived biochemical fractions, such as exudates, has been used to explain this "rhizosphere effect" on bacteria. However, the variable response of other soil microbial groups, such as protozoa, to the rhizosphere suggests that other factors could be involved in shaping their communities. Thus, two experiments were designed to: (1) determine whether stimulatory and/or inhibiting factors associated with particular plant species regulate ciliate diversity and abundance and (2) obtain a better understanding about the mechanism by which these plant factors operate in the rhizosphere. Bacterial and chemical slurries were reciprocally exchanged between two plant species known to differ in terms of ciliate species richness and abundance (i.e., Canella winterana and plantation Tectona grandis). Analysis of variance showed that the bacteria plus nutrients and the nutrients only treatment had no significant effect on overall ciliate species richness and abundance when compared to the control treatment. However, the use of only colpodean species increased the taxonomic resolution of treatment effects revealing that bacterial slurries had a significant effect on colpodean ciliate species richness. Thus, for particular rhizosphere ciliates, biological properties, such as bacterial diversity or abundance, may have a strong influence on their diversity and possibly abundance. These results are consistent with a model of soil bacteria-mediated mutualisms between plants and protozoa. PMID:16645921

  14. Plant species effects on soil nutrients and chemistry in arid ecological zones.

    PubMed

    Johnson, Brittany G; Verburg, Paul S J; Arnone, John A

    2016-09-01

    The presence of vegetation strongly influences ecosystem function by controlling the distribution and transformation of nutrients across the landscape. The magnitude of vegetation effects on soil chemistry is largely dependent on the plant species and the background soil chemical properties of the site, but has not been well quantified along vegetation transects in the Great Basin. We studied the effects of plant canopy cover on soil chemistry within five different ecological zones, subalpine, montane, pinyon-juniper, sage/Mojave transition, and desert shrub, in the Great Basin of Nevada all with similar underlying geology. Although plant species differed in their effects on soil chemistry, the desert shrubs Sarcobatus vermiculatus, Atriplex spp., Coleogyne ramosissima, and Larrea tridentata typically exerted the most influence on soil chemistry, especially amounts of K(+) and total nitrogen, beneath their canopies. However, the extent to which vegetation affected soil nutrient status in any given location was not only highly dependent on the species present, and presumably the nutrient requirements and cycling patterns of the plant species, but also on the background soil characteristics (e.g., parent material, weathering rates, leaching) where plant species occurred. The results of this study indicate that the presence or absence of a plant species, especially desert shrubs, could significantly alter soil chemistry and subsequently ecosystem biogeochemistry and function. PMID:27255124

  15. Distribution and content of ellagitannins in Finnish plant species.

    PubMed

    Moilanen, Johanna; Koskinen, Piia; Salminen, Juha-Pekka

    2015-08-01

    The results of a screening study, in which a total of 82 Finnish plant species were studied for their ellagitannin composition and content, are presented. The total ellagitannin content was determined by HPLC-DAD, the detected ellagitannins were further characterized by HPLC-ESI-QTOF-MS and divided into four structurally different sub-groups. Thirty plant species were found to contain ellagitannins and the ellagitannin content in the crude extracts varied from few mgg(-1) to over a hundred mgg(-1). Plant families that were rich in ellagitannins (>90mgg(-1) of the crude extract) were Onagraceae, Lyhtraceae, Geraniaceae, Elaeagnaceae, Fagaceae and some species from Rosaceae. Plant species that contained moderate amounts of ellagitannins (31-89mgg(-1) of the crude extract) were representatives of the family Rosaceae. Plant species that contained low amounts of ellagitannins (1-30mgg(-1) of the crude extract) were representatives of the families Betulaceae and Myricaceae. The specific ellagitannin composition of the species allowed their chemotaxonomic classification and the comparison between the older Cronquist's classification and the nowadays preferred Angiosperm Phylogeny Group classification. PMID:25819000

  16. How Do Earthworms, Soil Texture and Plant Composition Affect Infiltration along an Experimental Plant Diversity Gradient in Grassland?

    PubMed Central

    Fischer, Christine; Roscher, Christiane; Jensen, Britta; Eisenhauer, Nico; Baade, Jussi; Attinger, Sabine; Scheu, Stefan; Weisser, Wolfgang W.; Schumacher, Jens; Hildebrandt, Anke

    2014-01-01

    Background Infiltration is a key process in determining the water balance, but so far effects of earthworms, soil texture, plant species diversity and their interaction on infiltration capacity have not been studied. Methodology/Principal Findings We measured infiltration capacity in subplots with ambient and reduced earthworm density nested in plots of different plant species (1, 4, and 16 species) and plant functional group richness and composition (1 to 4 groups; legumes, grasses, small herbs, tall herbs). In summer, earthworm presence significantly increased infiltration, whereas in fall effects of grasses and legumes on infiltration were due to plant-mediated changes in earthworm biomass. Effects of grasses and legumes on infiltration even reversed effects of texture. We propose two pathways: (i) direct, probably by modifying the pore spectrum and (ii) indirect, by enhancing or suppressing earthworm biomass, which in turn influenced infiltration capacity due to change in burrowing activity of earthworms. Conclusions/Significance Overall, the results suggest that spatial and temporal variations in soil hydraulic properties can be explained by biotic processes, especially the presence of certain plant functional groups affecting earthworm biomass, while soil texture had no significant effect. Therefore biotic parameters should be taken into account in hydrological applications. PMID:24918943

  17. Predicting species' maximum dispersal distances from simple plant traits.

    PubMed

    Tamme, Riin; Götzenberger, Lars; Zobel, Martin; Bullock, James M; Hooftman, Danny A P; Kaasik, Ants; Pärtel, Meelis

    2014-02-01

    Many studies have shown plant species' dispersal distances to be strongly related to life-history traits, but how well different traits can predict dispersal distances is not yet known. We used cross-validation techniques and a global data set (576 plant species) to measure the predictive power of simple plant traits to estimate species' maximum dispersal distances. Including dispersal syndrome (wind, animal, ant, ballistic, and no special syndrome), growth form (tree, shrub, herb), seed mass, seed release height, and terminal velocity in different combinations as explanatory variables we constructed models to explain variation in measured maximum dispersal distances and evaluated their power to predict maximum dispersal distances. Predictions are more accurate, but also limited to a particular set of species, if data on more specific traits, such as terminal velocity, are available. The best model (R2 = 0.60) included dispersal syndrome, growth form, and terminal velocity as fixed effects. Reasonable predictions of maximum dispersal distance (R2 = 0.53) are also possible when using only the simplest and most commonly measured traits; dispersal syndrome and growth form together with species taxonomy data. We provide a function (dispeRsal) to be run in the software package R. This enables researchers to estimate maximum dispersal distances with confidence intervals for plant species using measured traits as predictors. Easily obtainable trait data, such as dispersal syndrome (inferred from seed morphology) and growth form, enable predictions to be made for a large number of species. PMID:24669743

  18. Corridors affect plants, animals, and their interactions in fragmented landscapes.

    SciTech Connect

    Tewksbury, Joshua, J.; Levey, Douglas, J.; Haddad, Nick, M.; Sargent, Sarah; Orrock, John, L.; Weldon, Aimee; Danielson, Brent, J.; Brinkerhoff, Jory; Damschen, Ellen, I.; Townsend, Patricia

    2002-10-01

    Tewksbury, J.J., D.J. Levey, N.M. Haddad, S. Sargent, J.L. Orrock, A. Weldon, B.J. Danielson, J. Brinkerhoff, E.I. Damschen, and P. Townsend. 2002. Corridors affect plants, animals, and their interactions in fragmented landscapes. PNAS 99(20):12923-12926. Among the most popular strategies for maintaining populations of both plants and animals in fragmented landscapes is to connect isolated patches with thin strips of habitat, called corridors. Corridors are thought to increase the exchange of individuals between habitat patches, promoting genetic exchange and reducing population fluctuations. Empirical studies addressing the effects of corridors have either been small in scale or have ignored confounding effects of increased habitat area created by the presence of a corridor. These methodological difficulties, coupled with a paucity of studies examining the effects of corridors on plants and plant-animal interactions, have sparked debate over the purported value of corridors in conservation planning. We report results of a large-scale experiment that directly address this debate. We demonstrate that corridors not only increase the exchange of animals between patches, but also facilitate two key plant-animal interactions: pollination and seed dispersal. Our results show that the beneficial effects of corridors extend beyond the area they add, and suggest that increased plant and animal movement through corridors will have positive impacts on plant populations and community interactions in fragmented landscapes.

  19. Plant Volatiles Induced by Herbivore Egg Deposition Affect Insects of Different Trophic Levels

    PubMed Central

    Fatouros, Nina E.; Lucas-Barbosa, Dani; Weldegergis, Berhane T.; Pashalidou, Foteini G.; van Loon, Joop J. A.; Dicke, Marcel; Harvey, Jeffrey A.; Gols, Rieta; Huigens, Martinus E.

    2012-01-01

    Plants release volatiles induced by herbivore feeding that may affect the diversity and composition of plant-associated arthropod communities. However, the specificity and role of plant volatiles induced during the early phase of attack, i.e. egg deposition by herbivorous insects, and their consequences on insects of different trophic levels remain poorly explored. In olfactometer and wind tunnel set-ups, we investigated behavioural responses of a specialist cabbage butterfly (Pieris brassicae) and two of its parasitic wasps (Trichogramma brassicae and Cotesia glomerata) to volatiles of a wild crucifer (Brassica nigra) induced by oviposition of the specialist butterfly and an additional generalist moth (Mamestra brassicae). Gravid butterflies were repelled by volatiles from plants induced by cabbage white butterfly eggs, probably as a means of avoiding competition, whereas both parasitic wasp species were attracted. In contrast, volatiles from plants induced by eggs of the generalist moth did neither repel nor attract any of the tested community members. Analysis of the plant’s volatile metabolomic profile by gas chromatography-mass spectrometry and the structure of the plant-egg interface by scanning electron microscopy confirmed that the plant responds differently to egg deposition by the two lepidopteran species. Our findings imply that prior to actual feeding damage, egg deposition can induce specific plant responses that significantly influence various members of higher trophic levels. PMID:22912893

  20. Season and light affect constitutive defenses of understory shrub species against folivorous insects

    NASA Astrophysics Data System (ADS)

    Karolewski, Piotr; Giertych, Marian J.; Żmuda, Michał; Jagodziński, Andrzej M.; Oleksyn, Jacek

    2013-11-01

    Understory shrubs contribute to overall species diversity, providing habitat and forage for animals, influence soil chemistry and forest microclimate. However, very little is known about the chemical defense of various shrub species against folivorous insects. Using six shrub species, we tested how seasonal changes and light conditions affect their constitutive defense to insect damage. We monitored leaf perforation, concentrations of total phenols, condensed tannins, nitrogen (N), and total nonstructural carbohydrates (TNC). Leaf damage caused by insects was low in Sambucus nigra, Cornus sanguinea, and Frangula alnus, intermediate in Corylus avellana and Prunus serotina, and high in Prunus padus. Leaves of all the species, when growing in high light conditions, had high concentrations of defense metabolites. Except for C. avellana, leaves of the other shrub species growing in full sun were less injured than those in shade. This may be due to higher concentrations of defense metabolites and lower concentrations of nitrogen. Similar patterns of the effects of light on metabolites studied and N were observed for leaves with varying location within the crown of individual shrubs (from the top of the south direction to the bottom of the north), as for leaves from shrubs growing in full sun and shrubs in the shade of canopy trees. A probable cause of the greater damage of more sunlit leaves of C. avellana was the fact that they were herbivorized mostly by Altica brevicollis, a specialist insect that prefers plant tissues with a high TNC level and is not very sensitive to a high level of phenolic compounds.

  1. Diversity of Riparian Plants among and within Species Shapes River Communities

    PubMed Central

    Jackrel, Sara L.; Wootton, J. Timothy

    2015-01-01

    Organismal diversity among and within species may affect ecosystem function with effects transmitting across ecosystem boundaries. Whether recipient communities adjust their composition, in turn, to maximize their function in response to changes in donor composition at these two scales of diversity is unknown. We use small stream communities that rely on riparian subsidies as a model system. We used leaf pack experiments to ask how variation in plants growing beside streams in the Olympic Peninsula of Washington State, USA affects stream communities via leaf subsidies. Leaves from red alder (Alnus rubra), vine maple (Acer cinereus), bigleaf maple (Acer macrophyllum) and western hemlock (Tsuga heterophylla) were assembled in leaf packs to contrast low versus high diversity, and deployed in streams to compare local versus non-local leaf sources at the among and within species scales. Leaves from individuals within species decomposed at varying rates; most notably thin leaves decomposed rapidly. Among deciduous species, vine maple decomposed most rapidly, harbored the least algal abundance, and supported the greatest diversity of aquatic invertebrates, while bigleaf maple was at the opposite extreme for these three metrics. Recipient communities decomposed leaves from local species rapidly: leaves from early successional plants decomposed rapidly in stream reaches surrounded by early successional forest and leaves from later successional plants decomposed rapidly adjacent to later successional forest. The species diversity of leaves inconsistently affected decomposition, algal abundance and invertebrate metrics. Intraspecific diversity of leaf packs also did not affect decomposition or invertebrate diversity. However, locally sourced alder leaves decomposed more rapidly and harbored greater levels of algae than leaves sourced from conspecifics growing in other areas on the Olympic Peninsula, but did not harbor greater aquatic invertebrate diversity. In contrast to

  2. Diversity of Riparian Plants among and within Species Shapes River Communities.

    PubMed

    Jackrel, Sara L; Wootton, J Timothy

    2015-01-01

    Organismal diversity among and within species may affect ecosystem function with effects transmitting across ecosystem boundaries. Whether recipient communities adjust their composition, in turn, to maximize their function in response to changes in donor composition at these two scales of diversity is unknown. We use small stream communities that rely on riparian subsidies as a model system. We used leaf pack experiments to ask how variation in plants growing beside streams in the Olympic Peninsula of Washington State, USA affects stream communities via leaf subsidies. Leaves from red alder (Alnus rubra), vine maple (Acer cinereus), bigleaf maple (Acer macrophyllum) and western hemlock (Tsuga heterophylla) were assembled in leaf packs to contrast low versus high diversity, and deployed in streams to compare local versus non-local leaf sources at the among and within species scales. Leaves from individuals within species decomposed at varying rates; most notably thin leaves decomposed rapidly. Among deciduous species, vine maple decomposed most rapidly, harbored the least algal abundance, and supported the greatest diversity of aquatic invertebrates, while bigleaf maple was at the opposite extreme for these three metrics. Recipient communities decomposed leaves from local species rapidly: leaves from early successional plants decomposed rapidly in stream reaches surrounded by early successional forest and leaves from later successional plants decomposed rapidly adjacent to later successional forest. The species diversity of leaves inconsistently affected decomposition, algal abundance and invertebrate metrics. Intraspecific diversity of leaf packs also did not affect decomposition or invertebrate diversity. However, locally sourced alder leaves decomposed more rapidly and harbored greater levels of algae than leaves sourced from conspecifics growing in other areas on the Olympic Peninsula, but did not harbor greater aquatic invertebrate diversity. In contrast to

  3. Apparent competition and native consumers exacerbate the strong competitive effect of an exotic plant species.

    PubMed

    Orrock, John L; Dutra, Humberto P; Marquis, Robert J; Barber, Nicholas

    2015-04-01

    Direct and indirect effects can play a key role in invasions, but experiments evaluating both are rare. We examined the roles of direct competition and apparent competition by exotic Amur honeysuckle (Lonicera maackii) by manipulating (1) L. maackii vegetation, (2) presence of L. maackii fruits, and (3) access to plants by small mammals and deer. Direct competition with L. maackii reduced the abundance and richness of native and exotic species, and native consumers significantly reduced the abundance and richness of native species. Although effects of direct competition and consumption were more pervasive, richness of native plants was also reduced through apparent competition, as small-mammal consumers reduced richness only when L. maackii fruits were present. Our experiment reveals the multiple, interactive pathways that affect the success and impact of an invasive exotic plant: exotic plants may directly benefit from reduced attack by native consumers, may directly exert strong competitive effects on native plants, and may also benefit from apparent competition. PMID:26230025

  4. Plant surface wax affects parasitoid's response to host footprints

    NASA Astrophysics Data System (ADS)

    Rostás, Michael; Ruf, Daniel; Zabka, Vanessa; Hildebrandt, Ulrich

    2008-10-01

    The plant surface is the substrate upon which herbivorous insects and natural enemies meet and thus represents the stage for interactions between the three trophic levels. Plant surfaces are covered by an epicuticular wax layer which is highly variable depending on species, cultivar or plant part. Differences in wax chemistry may modulate ecological interactions. We explored whether caterpillars of Spodoptera frugiperda, when walking over a plant surface, leave a chemical trail (kairomones) that can be detected by the parasitoid Cotesia marginiventris. Chemistry and micromorphology of cuticular waxes of two barley eceriferum wax mutants ( cer-za.126, cer-yp.949) and wild-type cv. Bonus (wt) were assessed. The plants were then used to investigate potential surface effects on the detectability of caterpillar kairomones. Here we provide evidence that C. marginiventris responds to chemical footprints of its host. Parasitoids were able to detect the kairomone on wild-type plants and on both cer mutants but the response to cer-yp.949 (reduced wax, high aldehyde fraction) was less pronounced. Experiments with caterpillar-treated wt and mutant leaves offered simultaneously, confirmed this observation: no difference in wasp response was found when wt was tested against cer-za.126 (reduced wax, wt-like chemical composition) but wt was significantly more attractive than cer-yp.949. This demonstrates for the first time that the wax layer can modulate the detectability of host kairomones.

  5. Which Factors Affect the Success or Failure of Eradication Campaigns against Alien Species?

    PubMed Central

    Pluess, Therese; Jarošík, Vojtěch; Pyšek, Petr; Cannon, Ray; Pergl, Jan; Breukers, Annemarie; Bacher, Sven

    2012-01-01

    Although issues related to the management of invasive alien species are receiving increasing attention, little is known about which factors affect the likelihood of success of management measures. We applied two data mining techniques, classification trees and boosted trees, to identify factors that relate to the success of management campaigns aimed at eradicating invasive alien invertebrates, plants and plant pathogens. We assembled a dataset of 173 different eradication campaigns against 94 species worldwide, about a half of which (50.9%) were successful. Eradications in man-made habitats, greenhouses in particular, were more likely to succeed than those in (semi-)natural habitats. In man-made habitats the probability of success was generally high in Australasia, while in Europe and the Americas it was higher for local infestations that are easier to deal with, and for international campaigns that are likely to profit from cross-border cooperation. In (semi-) natural habitats, eradication campaigns were more likely to succeed for plants introduced as an ornamental and escaped from cultivation prior to invasion. Averaging out all other factors in boosted trees, pathogens, bacteria and viruses were most, and fungi the least likely to be eradicated; for plants and invertebrates the probability was intermediate. Our analysis indicates that initiating the campaign before the extent of infestation reaches the critical threshold, starting to eradicate within the first four years since the problem has been noticed, paying special attention to species introduced by the cultivation pathway, and applying sanitary measures can substantially increase the probability of eradication success. Our investigations also revealed that information on socioeconomic factors, which are often considered to be crucial for eradication success, is rarely available, and thus their relative importance cannot be evaluated. Future campaigns should carefully document socioeconomic factors to

  6. Negative effects of fluoranthene on the ecophysiology of tomato plants (Lycopersicon esculentum Mill) Fluoranthene mists negatively affected tomato plants.

    PubMed

    Oguntimehin, Ilemobayo; Eissa, Fawzy; Sakugawa, Hiroshi

    2010-02-01

    Cherry tomato plants (Lycopersicon esculentum Mill) were sprayed with fluoranthene and mixture of fluoranthene and mannitol solutions for 30d. The exposure was carried out in growth chambers in field conditions, and the air was filtered through charcoal filters to remove atmospheric contaminants. Plants were sprayed with 10microM fluoranthene as mist until they reached the fruiting stage, and the eco-physiological parameters were measured to determine the effects of the treatments. We measured CO(2) uptake and water vapour exchange, chlorophyll fluorescence, leaf pigment contents, visual symptoms and biomass allocation. Fluoranthene which was deposited as mist onto leaves negatively affected both growth and the quality of tomato plants, while other treatments did not. The photosynthetic rate measured at saturated irradiance was approximately 37% lower in fluoranthene-treated plants compared with the control group. Other variables, such as stomata conductance, the photochemical efficiency of PSII in the dark, Chl a, Chl b, and the total chlorophyll contents of the tomato leaves were significantly reduced in the fluoranthene-treated plants. Tomato plants treated with fluoranthene showed severe visible injury symptoms on the foliage during the exposure period. Mannitol (a reactive oxygen scavenger) mitigated effects of fluoranthene; thus, reactive oxygen species generated through fluoranthene may be responsible for the damaged tomato plants. It is possible for fluoranthene to decrease the aesthetic and hence the economic value of this valuable crop plant. PMID:20006894

  7. Floristic summary of plant species in the air pollution literature

    USGS Publications Warehouse

    Bennett, J.P.

    1996-01-01

    A floristic summary and analysis was performed on a list of the plant species that have been studied for the effects of gaseous and chemical air pollutants on vegetation in order to compare the species with the flora of North America north of Mexico. The scientific names of 2081 vascular plant species were extracted from almost 4000 journal articles stored in two large literature databases on the effects of air pollutants on plants. Three quarters of the plant species studied occur in North America, but this was only 7% of the total North American flora. Sixteen percent and 56% of all North American genera and families have been studied. The most studied genus is Pinus with 70% of the North American species studied, and the most studied family is the grass family, with 12% of the species studied. Although Pinus is ranked 86th in the North American flora, the grass family is ranked third, indicating that representation at the family level is better than at the genus level. All of the top ten families in North America are represented in the top 20 families in the air pollution effects literature, but only one genus (Lupinus) in the top ten genera in North America is represented in the top thirteen genera in the air pollution literature.

  8. Insufficient Sampling to Identify Species Affected by Turbine Collisions

    PubMed Central

    Beston, Julie A; Diffendorfer, Jay E; Loss, Scott

    2015-01-01

    We compared the number of avian species detected and the sampling effort during fatality monitoring at 50 North American wind facilities. Facilities with short intervals between sampling events and high effort detected more species, but many facilities appeared undersampled. Species accumulation curves for 2 wind facilities studied for more than 1 year had yet to reach an asymptote. The monitoring effort that is typically invested is likely inadequate to identify all of the species killed by wind turbines. This may understate impacts for rare species of conservation concern that collide infrequently with turbines but suffer disproportionate consequences from those fatalities. Published 2015. This article is a U.S. Government work and is in the public domain in the USA. PMID:25914425

  9. Insufficient sampling to identify species affected by turbine collisions

    USGS Publications Warehouse

    Beston, Julie A.; Diffendorfer, James E.; Loss, Scott

    2015-01-01

    We compared the number of avian species detected and the sampling effort during fatality monitoring at 50 North American wind facilities. Facilities with short intervals between sampling events and high effort detected more species, but many facilities appeared undersampled. Species accumulation curves for 2 wind facilities studied for more than 1 year had yet to reach an asymptote. The monitoring effort that is typically invested is likely inadequate to identify all of the species killed by wind turbines. This may understate impacts for rare species of conservation concern that collide infrequently with turbines but suffer disproportionate consequences from those fatalities. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

  10. Allelopathic effect of a native species on a major plant invader in Europe.

    PubMed

    Christina, Mathias; Rouifed, Soraya; Puijalon, Sara; Vallier, Félix; Meiffren, Guillaume; Bellvert, Floriant; Piola, Florence

    2015-04-01

    Biological invasions have become a major global issue in ecosystem conservation. As formalized in the "novel weapon hypothesis", the allelopathic abilities of species are actively involved in invasion success. Here, we assume that allelopathy can also increase the biotic resistance of native species against invasion. We tested this hypothesis by studying the impact of the native species Sambucus ebulus on the colonization of propagules of the invasive species Fallopiaxbohemica and the subsequent development of plants from these. Achenes and rhizome fragments from two natural populations were grown in a greenhouse experiment for 50 days. We used an experimental design that involved "donor" and "target" pots in order to separate resource competition from allelopathy. An allelopathic treatment effect was observed for plant growth but not for propagule establishment. Treatment affected, in particular, the growth of Fallopia plants originating from achenes, but there was less influence on plants originating from rhizomes. By day 50, shoot height had decreased by 27% for plants originating from rhizomes and by 38% for plants originating from achenes. The number of leaves for plants originating from achenes had only decreased by 20%. Leaf and above- and below-ground dry masses decreased with treatment by 40, 41 and 25% for plants originating from rhizomes and 70, 61 and 55% for plants originating from achenes, respectively. S. ebulus extracts were analysed using high-performance chromatography, and the choice of test molecules was narrowed down. Our results suggest native species use allelopathy as a biotic containment mechanism against the naturalization of invasive species. PMID:25740225

  11. Allelopathic effect of a native species on a major plant invader in Europe

    NASA Astrophysics Data System (ADS)

    Christina, Mathias; Rouifed, Soraya; Puijalon, Sara; Vallier, Félix; Meiffren, Guillaume; Bellvert, Floriant; Piola, Florence

    2015-04-01

    Biological invasions have become a major global issue in ecosystem conservation. As formalized in the "novel weapon hypothesis", the allelopathic abilities of species are actively involved in invasion success. Here, we assume that allelopathy can also increase the biotic resistance of native species against invasion. We tested this hypothesis by studying the impact of the native species Sambucus ebulus on the colonization of propagules of the invasive species Fallopia x bohemica and the subsequent development of plants from these. Achenes and rhizome fragments from two natural populations were grown in a greenhouse experiment for 50 days. We used an experimental design that involved "donor" and "target" pots in order to separate resource competition from allelopathy. An allelopathic treatment effect was observed for plant growth but not for propagule establishment. Treatment affected, in particular, the growth of Fallopia plants originating from achenes, but there was less influence on plants originating from rhizomes. By day 50, shoot height had decreased by 27 % for plants originating from rhizomes and by 38 % for plants originating from achenes. The number of leaves for plants originating from achenes had only decreased by 20 %. Leaf and above- and below-ground dry masses decreased with treatment by 40, 41 and 25 % for plants originating from rhizomes and 70, 61 and 55 % for plants originating from achenes, respectively. S. ebulus extracts were analysed using high-performance chromatography, and the choice of test molecules was narrowed down. Our results suggest native species use allelopathy as a biotic containment mechanism against the naturalization of invasive species.

  12. Impacts of invasive nonnative plant species on the rare forest herb Scutellaria montana

    NASA Astrophysics Data System (ADS)

    Sikkema, Jordan J.; Boyd, Jennifer N.

    2015-11-01

    Invasive plant species and overabundant herbivore populations have the potential to significantly impact rare plant species given their increased risk for local extirpation and extinction. We used interacting invasive species removal and grazer exclusion treatments replicated across two locations in an occurrence of rare Scutellaria montana (large-flowered skullcap) in Chattanooga, Tennessee, USA, to assess: 1) competition by invasive Ligustrum sinense (Chinese privet) and Lonicera japonica (Japanese honeysuckle) and 2) the role of invasive species in mediating Oedocoilus virginianus (white-tailed deer) grazing of S. montana. Contrary to our hypothesis that invasive species presence would suppress S. montana directly via competition, S. montana individuals experienced a seasonal increase in stem height when invasive species were intact but not when invasive species were removed. Marginally significant results indicated that invasive species may afford S. montana protection from grazers, and we suggest that invasive species also could protect S. montana from smaller herbivores and/or positively influence abiotic conditions. In contrast to growth responses, S. montana individuals protected from O. virginianus exhibited a decrease in flowering between seasons relative to unprotected plants, but invasive species did not affect this variable. Although it has been suggested that invasive plant species may negatively influence S. montana growth and fecundity, our findings do not support related concerns. As such, we suggest that invasive species eradication efforts in S. montana habitat could be more detrimental than positive due to associated disturbance. However, the low level of invasion of our study site may not be representative of potential interference in more heavily infested habitat.

  13. Which ornamental plant species effectively remove benzene from indoor air?

    NASA Astrophysics Data System (ADS)

    Liu, Yan-Ju; Mu, Yu-Jing; Zhu, Yong-Guan; Ding, Hui; Crystal Arens, Nan

    Phytoremediation—using plants to remove toxins—is an attractive and cost effective way to improve indoor air quality. This study screened ornamental plants for their ability to remove volatile organic compounds from air by fumigating 73 plant species with 150 ppb benzene, an important indoor air pollutant that poses a risk to human health. The 10 species found to be most effective at removing benzene from air were fumigated for two more days (8 h per day) to quantify their benzene removal capacity. Crassula portulacea, Hydrangea macrophylla, Cymbidium Golden Elf., Ficus microcarpa var. fuyuensis, Dendranthema morifolium, Citrus medica var. sarcodactylis, Dieffenbachia amoena cv. Tropic Snow; Spathiphyllum Supreme; Nephrolepis exaltata cv. Bostoniensis; Dracaena deremensis cv. Variegata emerged as the species with the greatest capacity to remove benzene from indoor air.

  14. Getting the right traits: reproductive and dispersal characteristics predict the invasiveness of herbaceous plant species.

    PubMed

    Moravcová, Lenka; Pyšek, Petr; Jarošík, Vojtěch; Pergl, Jan

    2015-01-01

    To better understand the effect of species traits on plant invasion, we collected comparative data on 20 reproductive and dispersal traits of 93 herbaceous alien species in the Czech Republic, central Europe, introduced after 1500 A. D. We explain plant invasion success, expressed by two measures: invasiveness, i.e. whether the species is naturalized but non-invasive, or invasive; and dominance in plant communities expressed as the mean cover in vegetation plots. We also tested how important reproductive and dispersal traits are in models including other characteristics generally known to predict invasion outcome, such as plant height, life history and residence time. By using regression/classification trees we show that the biological traits affect invasion success at all life stages, from reproduction (seed production) to dispersal (propagule properties), and the ability to compete with resident species (height). By including species traits information not usually available in multispecies analyses, we provide evidence that traits do play important role in determining the outcome of invasion and can be used to distinguish between alien species that reach the final stage of the invasion process and dominate the local communities from those that do not. No effect of taxonomy ascertained in regression and classification trees indicates that the role of traits in invasiveness should be assessed primarily at the species level. PMID:25906399

  15. Getting the Right Traits: Reproductive and Dispersal Characteristics Predict the Invasiveness of Herbaceous Plant Species

    PubMed Central

    Moravcová, Lenka; Pyšek, Petr; Pergl, Jan

    2015-01-01

    To better understand the effect of species traits on plant invasion, we collected comparative data on 20 reproductive and dispersal traits of 93 herbaceous alien species in the Czech Republic, central Europe, introduced after 1500 A. D. We explain plant invasion success, expressed by two measures: invasiveness, i.e. whether the species is naturalized but non-invasive, or invasive; and dominance in plant communities expressed as the mean cover in vegetation plots. We also tested how important reproductive and dispersal traits are in models including other characteristics generally known to predict invasion outcome, such as plant height, life history and residence time. By using regression/classification trees we show that the biological traits affect invasion success at all life stages, from reproduction (seed production) to dispersal (propagule properties), and the ability to compete with resident species (height). By including species traits information not usually available in multispecies analyses, we provide evidence that traits do play important role in determining the outcome of invasion and can be used to distinguish between alien species that reach the final stage of the invasion process and dominate the local communities from those that do not. No effect of taxonomy ascertained in regression and classification trees indicates that the role of traits in invasiveness should be assessed primarily at the species level. PMID:25906399

  16. Carbon storage potential by four macrophytes as affected by planting diversity in a created wetland.

    PubMed

    Means, Mary M; Ahn, Changwoo; Korol, Alicia R; Williams, Lisa D

    2016-01-01

    Wetland creation has become a commonplace method for mitigating the loss of natural wetlands. Often mitigation projects fail to restore ecosystem services of the impacted natural wetlands. One of the key ecosystem services of newly created wetlands is carbon accumulation/sequestration, but little is known about how planting diversity (PD) affects the ability of herbaceous wetland plants to store carbon in newly created wetlands. Most mitigation projects involve a planting regime, but PD, which may be critical in establishing biologically diverse and ecologically functioning wetlands, is seldom required. Using a set of 34 mesocosms (∼1 m(2) each), we investigated the effects of planting diversity on carbon storage potential of four native wetland plant species that are commonly planted in created mitigation wetlands in Virginia - Carex vulpinoidea, Eleocharis obtusa, Juncus effusus, and Mimulus ringens. The plants were grown under the four distinctive PD treatments [i.e., monoculture (PD 1) through four different species mixture (PD 4)]. Plant biomass was harvested after two growing seasons and analyzed for tissue carbon content. Competition values (CV) were calculated to understand how the PD treatment affected the competitive ability of plants relative to their biomass production and thus carbon storage potentials. Aboveground biomass ranged from 988 g/m(2) - 1515 g/m(2), being greatest in monocultures, but only when compared to the most diverse mixture (p = 0.021). However, carbon storage potential estimates per mesocosm ranged between 344 g C/m(2) in the most diverse mesocosms (PD 4) to 610 g C/m(2) in monoculture ones with no significant difference (p = 0.089). CV of E. obtusa and C. vulpinoidea showed a declining trend when grown in the most diverse mixtures but J. effusus and M. ringens displayed no difference across the PD gradient (p = 0.910). In monocultures, both M. ringens, and J. effusus appeared to store carbon as biomass more

  17. Plant-Species Diversity Correlates with Genetic Variation of an Oligophagous Seed Predator

    PubMed Central

    Laukkanen, Liisa; Mutikainen, Pia; Muola, Anne; Leimu, Roosa

    2014-01-01

    Several characteristics of habitats of herbivores and their food-plant communities, such as plant-species composition and plant quality, influence population genetics of both herbivores and their host plants. We investigated how different ecological and geographic factors affect genetic variation in and differentiation of 23 populations of the oligophagous seed predator Lygaeus equestris (Heteroptera) in southwestern Finland and in eastern Sweden. We tested whether genetic differentiation of the L. equestris populations was related to the similarity of vegetation, and whether there was more within-population genetic variation in habitats with a high number of plant species or in those with a large population of the primary food plant, Vincetoxicum hirundinaria. We also tested whether genetic differentiation of the populations was related to the geographic distance, and whether location of the populations on islands or on mainland, island size, or population size affected within-population genetic variation. Pairwise FST ranged from 0 to 0.1 indicating low to moderate genetic differentiation of populations. Differentiation increased with geographic distance between the populations, but was not related to the similarity of vegetation between the habitats. Genetic variation within the L. equestris populations did not increase with the population size of the primary food plant. However, the more diverse the plant community the higher was the level of genetic variation within the L. equestris population. Furthermore, the level of genetic variation did not vary significantly between island and mainland populations. The effect of the population size on within-population genetic variation was related to island size. Usually small populations are susceptible to loss of genetic variation, but small L. equestris populations on large islands seemed to maintain a relatively high level of within-population genetic variation. Our findings suggest that, in addition to geographic

  18. Invasive vascular plant species of limnocrenic karst springs in Poland

    NASA Astrophysics Data System (ADS)

    Spałek, Krzysztof

    2015-04-01

    Natural water reservoirs are very valuable floristic sites in Poland. Among them, the most important for preservation of biodiversity of flora are limnocrenic karst springs. The long-term process of human pressure on habitats of this type caused disturbance of their biological balance. Changes in the water regime, industrial development and chemisation of agriculture, especially in the period of last two hundred years, led to systematic disappearance of localities of many plant species connected with rare habitats and also to appear numerous invasive plant species. They are: Acorus calamus, Echinocystis lobata, Elodea canadensis, Erechtites hieraciifolia, Impatiens glandulifera, Solidago canadensis, S. gigantea and S. graminifolia. Fielworks were conducted in 2010-2014.

  19. Ontogenetic shifts in plant interactions vary with environmental severity and affect population structure.

    PubMed

    le Roux, Peter C; Shaw, Justine D; Chown, Steven L

    2013-10-01

    Environmental conditions and plant size may both alter the outcome of inter-specific plant-plant interactions, with seedlings generally facilitated more strongly than larger individuals in stressful habitats. However, the combined impact of plant size and environmental severity on interactions is poorly understood. Here, we tested explicitly for the first time the hypothesis that ontogenetic shifts in interactions are delayed under increasingly severe conditions by examining the interaction between a grass, Agrostis magellanica, and a cushion plant, Azorella selago, along two severity gradients. The impact of A. selago on A. magellanica abundance, but not reproductive effort, was related to A. magellanica size, with a trend for delayed shifts towards more negative interactions under greater environmental severity. Intermediate-sized individuals were most strongly facilitated, leading to differences in the size-class distribution of A. magellanica on the soil and on A. selago. The A. magellanica size-class distribution was more strongly affected by A. selago than by environmental severity, demonstrating that the plant-plant interaction impacts A. magellanica population structure more strongly than habitat conditions. As ontogenetic shifts in plant-plant interactions cannot be assumed to be constant across severity gradients and may impact species population structure, studies examining the outcome of interactions need to consider the potential for size- or age-related variation in competition and facilitation. PMID:23738758

  20. Fusarium Oxysporum Volatiles Enhance Plant Growth Via Affecting Auxin Transport and Signaling

    PubMed Central

    Bitas, Vasileios; McCartney, Nathaniel; Li, Ningxiao; Demers, Jill; Kim, Jung-Eun; Kim, Hye-Seon; Brown, Kathleen M.; Kang, Seogchan

    2015-01-01

    Volatile organic compounds (VOCs) have well-documented roles in plant-plant communication and directing animal behavior. In this study, we examine the less understood roles of VOCs in plant-fungal relationships. Phylogenetically and ecologically diverse strains of Fusarium oxysporum, a fungal species complex that often resides in the rhizosphere of assorted plants, produce volatile compounds that augment shoot and root growth of Arabidopsis thaliana and tobacco. Growth responses of A. thaliana hormone signaling mutants and expression patterns of a GUS reporter gene under the auxin-responsive DR5 promoter supported the involvement of auxin signaling in F. oxysporum volatile-mediated growth enhancement. In addition, 1-naphthylthalamic acid, an inhibitor of auxin efflux, negated F. oxysporum volatile-mediated growth enhancement in both plants. Comparison of the profiles of volatile compounds produced by F. oxysporum strains that differentially affected plant growth suggests that the relative compositions of both growth inhibitory and stimulatory compounds may determine the degree of plant growth enhancement. Volatile-mediated signaling between fungi and plants may represent a potentially conserved, yet mostly overlooked, mechanism underpinning plant-fungus interactions and fungal niche adaption. PMID:26617587

  1. Acclimation of plant species to elevated CO{sub 2}

    SciTech Connect

    Olavi, K.; Ball, J.T.; Seemann, J.

    1995-06-01

    Plant species differ in assimilated carbon partitioning between starch, sucrose and hexose sugars. Soluble sugars have been implicated to play a role in downregulating rubisco and other photosynthesis enzymes on the level of transcription. In this study we compared high CO{sub 2} response of plants with different physiology. Cucumber, tobacco and sunflower were chosen as relatively good starch accumulators, spinach and sugar-beet as species with high leaf soluble sugar levels. In addition woody species cottonwood and salt cedar and one C{sub 4} species (corn) were studied. Plants were grown from seed at three CO{sub 2} levels: 330 {mu}bar, 660 {mu}bar and 1500 {mu}bar. Two soil nitrogen levels were used: one that allowed normal growth and the other that caused about 5 times growth suppression. All species except corn (C{sub 4}) showed downregulation of leaf rubisco activity. This downregulation was due to decrease of rubisco content, activation state remaining unchanged. Initial slope of AC{sub i} curve and rubisco activity were in good correlation. Low and high nitrogen plants had similar relative changes in photosynthetic activity. Final harvest onground weight correlated with CO{sub 2} uptake at growth conditions. We concluded that soluble sugars per se do not cause downregulation of leaf photosynthetic activity at high CO{sub 2}.

  2. Plant species richness drives the density and diversity of Collembola in temperate grassland

    NASA Astrophysics Data System (ADS)

    Sabais, Alexander C. W.; Scheu, Stefan; Eisenhauer, Nico

    2011-05-01

    Declining biodiversity is one of the most important aspects of anthropogenic global change phenomena, but the implications of plant species loss for soil decomposers are little understood. We used the experimental grassland community of the Jena Experiment to assess the response of density and diversity of Collembola to varying plant species richness, plant functional group richness and plant functional group identity. We sampled the experimental plots in spring and autumn four years after establishment of the experimental plant communities. Collembola density and diversity significantly increased with plant species and plant functional group richness highlighting the importance of the singular hypothesis for soil invertebrates. Generally, grasses and legumes beneficially affected Collembola density and diversity, whereas effects of small herbs usually were detrimental. These impacts were largely consistent in spring and autumn. By contrast, in the presence of small herbs the density of hemiedaphic Collembola and the diversity of Isotomidae increased in spring whereas they decreased in autumn. Beneficial impacts of plant diversity as well as those of grasses and legumes were likely due to increased root and microbial biomass, and elevated quantity and quality of plant residues serving as food resources for Collembola. By contrast, beneficial impacts of small herbs in spring probably reflect differences in microclimatic conditions, and detrimental effects in autumn likely were due to low quantity and quality of resources. The results point to an intimate relationship between plants and the diversity of belowground biota, even at small spatial scales, contrasting the findings of previous studies. The pronounced response of soil animals in the present study was presumably due to the fact that plant communities had established over several years. As decomposer invertebrates significantly impact plant performance, changes in soil biota density and diversity are likely

  3. Comprehensive review on phytotechnology: Heavy metals removal by diverse aquatic plants species from wastewater.

    PubMed

    Rezania, Shahabaldin; Taib, Shazwin Mat; Md Din, Mohd Fadhil; Dahalan, Farrah Aini; Kamyab, Hesam

    2016-11-15

    Environmental pollution specifically water pollution is alarming both in the developed and developing countries. Heavy metal contamination of water resources is a critical issue which adversely affects humans, plants and animals. Phytoremediation is a cost-effective remediation technology which able to treat heavy metal polluted sites. This environmental friendly method has been successfully implemented in constructed wetland (CWs) which is able to restore the aquatic biosystem naturally. Nowadays, many aquatic plant species are being investigated to determine their potential and effectiveness for phytoremediation application, especially high growth rate plants i.e. macrophytes. Based on the findings, phytofiltration (rhizofiltration) is the sole method which defined as heavy metals removal from water by aquatic plants. Due to specific morphology and higher growth rate, free-floating plants were more efficient to uptake heavy metals in comparison with submerged and emergent plants. In this review, the potential of wide range of aquatic plant species with main focus on four well known species (hyper-accumulators): Pistia stratiotes, Eicchornia spp., Lemna spp. and Salvinia spp. was investigated. Moreover, we discussed about the history, methods and future prospects in phytoremediation of heavy metals by aquatic plants comprehensively. PMID:27474848

  4. Effects of Previous Land-Use on Plant Species Composition and Diversity in Mediterranean Forests.

    PubMed

    Kouba, Yacine; Martínez-García, Felipe; de Frutos, Ángel; Alados, Concepción L

    2015-01-01

    At some point in their history, most forests in the Mediterranean Basin have been subjected to intensive management or converted to agriculture land. Knowing how forest plant communities recovered after the abandonment of forest-management or agricultural practices (including livestock grazing) provides a basis for investigating how previous land management have affected plant species diversity and composition in forest ecosystems. Our study investigated the consequences of historical "land management" practices on present-day Mediterranean forests by comparing species assemblages and the diversity of (i) all plant species and (ii) each ecological group defined by species' habitat preferences and successional status (i.e., early-, mid-, and late-successional species). We compared forest stands that differed both in land-use history and in successional stage. In addition, we evaluated the value of those stands for biodiversity conservation. The study revealed significant compositional differentiation among stands that was due to among-stand variations in the diversity (namely, species richness and evenness) of early-, intermediate-, and late-successional species. Historical land management has led to an increase in compositional divergences among forest stands and the loss of late-successional forest species. PMID:26397707

  5. Virulence of oomycete pathogens from Phragmites australis-invaded and noninvaded soils to seedlings of wetland plant species

    PubMed Central

    Crocker, Ellen V; Karp, Mary Ann; Nelson, Eric B

    2015-01-01

    Soil pathogens affect plant community structure and function through negative plant–soil feedbacks that may contribute to the invasiveness of non-native plant species. Our understanding of these pathogen-induced soil feedbacks has relied largely on observations of the collective impact of the soil biota on plant populations, with few observations of accompanying changes in populations of specific soil pathogens and their impacts on invasive and noninvasive species. As a result, the roles of specific soil pathogens in plant invasions remain unknown. In this study, we examine the diversity and virulence of soil oomycete pathogens in freshwater wetland soils invaded by non-native Phragmites australis (European common reed) to better understand the potential for soil pathogen communities to impact a range of native and non-native species and influence invasiveness. We isolated oomycetes from four sites over a 2-year period, collecting nearly 500 isolates belonging to 36 different species. These sites were dominated by species of Pythium, many of which decreased seedling survival of a range of native and invasive plants. Despite any clear host specialization, many of the Pythium species were differentially virulent to the native and non-native plant species tested. Isolates from invaded and noninvaded soils were equally virulent to given individual plant species, and no apparent differences in susceptibility were observed between the collective groups of native and non-native plant species. PMID:26078850

  6. Plant rhizosphere species-specific stoichiometry and regulation of extracellular enzyme and microbial community structure

    NASA Astrophysics Data System (ADS)

    Bell, C. W.; Calderon, F.; Pendall, E.; Wallenstein, M. D.

    2012-12-01

    Plant communities affect the activity and composition of soil microbial communities through alteration of the soil environment during root growth; substrate availability through root exudation; nutrient availability through plant uptake; and moisture regimes through transpiration. As a result, positive feedbacks in soil properties can result from alterations in microbial community composition and function in the rhizosphere zone. At the ecosystem-scale, many properties of soil microbial communities can vary between forest stands dominated by different species, including community composition and stoichiometry. However, the influence of smaller individual plants on grassland soils and microbial communities is less well documented. There is evidence to suggest that some plants can modify their soil environment in a manner that favors their persistence. For example, when Bromus tectorum plants invade, soil microbial communities tend to have higher N mineralization rates (in the rhizosphere zone) relative to native plants. If tight linkages between individual plant species and microbial communities inhabiting the rhizosphere exist, we hypothesized that any differences among plant species specific rhizosphere zones could be observed by shifts in: 1) soil -rhizosphere microbial community structure, 2) enzymatic C:N:P acquisition activities, 3) alterations in the soil C chemistry composition in the rhizosphere, and 4) plant - soil - microbial C:N:P elemental stoichiometry. We selected and grew 4 different C3 grasses species including three species native to the Shortgrass Steppe region (Pascopyrum smithii, Koeleria macrantha, and Vulpia octoflora) and one exotic invasive plant species (B. tectorum) in root-boxes that are designed to allow for easy access to the rhizosphere. The field soil was homogenized using a 4mm sieve and mixed 1:1 with sterile sand and seeded as monocultures (24 replicate root - boxes for each species). Plant and soil samples (along with no - plant

  7. Spatial variability in plant species composition and peatland carbon exchange

    NASA Astrophysics Data System (ADS)

    Goud, E.; Moore, T. R.; Roulet, N. T.

    2015-12-01

    Plant species shifts in response to global change will have significant impacts on ecosystem carbon (C) exchange and storage arising from changes in hydrology. Spatial variation in peatland C fluxes have largely been attributed to the spatial distribution of microhabitats that arise from variation in surface topography and water table depth, but little is known about how plant species composition impacts peatland C cycling or how these impacts will be influenced by changing environmental conditions. We quantified the effect of species composition and environmental variables on carbon dioxide (CO2) and methane (CH4) fluxes over 2 years in a temperate peatland for four plant communities situated along a water table gradient from ombrotrophic bog to beaver pond. We hypothesized that (i) spatial heterogeneity in species composition would drive predictable spatial heterogeneity in C fluxes due to variation in plant traits and ecological tolerances, and (ii) increases in peat temperature would increase C fluxes. Species had different effects on C fluxes primarily due to differences in leaf traits. Differences in ecological tolerances among communities resulted in different rates of CO2 exchange in response to changes in water table depth. There was an overall reduction in ecosystem respiration (ER), gross primary productivity (GPP) and CH4 flux in response to colder peat temperatures in the second year, and the additive effects of a deeper water table in the bog margin and pond sites further reduced flux rates in these areas. These results demonstrate that different plant species can increase or decrease the flux of C into and out of peatlands based on differences in leaf traits and ecological tolerances, and that CO2 and CH4 fluxes are sensitive to changes in soil temperature, especially when coupled with changes in moisture availability.

  8. Species Composition of Bacterial Communities Influences Attraction of Mosquitoes to Experimental Plant Infusions

    PubMed Central

    Ponnusamy, Loganathan; Wesson, Dawn M.; Arellano, Consuelo; Schal, Coby

    2013-01-01

    In the container habitats of immature mosquitoes, catabolism of plant matter and other organic detritus by microbial organisms produces metabolites that mediate the oviposition behavior of Aedes aegypti and Aedes albopictus. Public health agencies commonly use oviposition traps containing plant infusions for monitoring populations of these mosquito species, which are global vectors of dengue viruses. In laboratory experiments, gravid females exhibited significantly diminished responses to experimental infusions made with sterilized white oak leaves, showing that attractive odorants were produced through microbial metabolic activity. We evaluated effects of infusion concentration and fermentation time on attraction of gravid females to infusions made from senescent bamboo or white oak leaves. We used plate counts of heterotrophic bacteria, total counts of 4′,6-diamidino-2-phenylindole-stained bacterial cells, and 16S ribosomal DNA (rDNA) polymerase chain reaction–denaturing gradient gel electrophoresis (DGGE) to show that changes in the relative abundance of bacteria and the species composition of bacterial communities influenced attraction of gravid A. aegypti and A. albopictus mosquitoes to infusions. DGGE profiles showed that bacterial species composition in infusions changed over time. Principal components analysis indicated that oviposition responses to plant infusions were in general most affected by bacterial diversity and abundance. Analysis of bacterial 16S rDNA sequences derived from DGGE bands revealed that Proteo-bacteria (Alpha-, Beta-, Delta-, and Gamma-) were the predominant bacteria detected in both types of plant infusions. Gravid A. aegypti were significantly attracted to a mix of 14 bacterial species cultured from bamboo leaf infusion. The oviposition response of gravid mosquitoes to plant infusions is strongly influenced by abundance and diversity of bacterial species, which in turn is affected by plant species, leaf biomass, and fermentation

  9. Metal species involved in long distance metal transport in plants

    PubMed Central

    Álvarez-Fernández, Ana; Díaz-Benito, Pablo; Abadía, Anunciación; López-Millán, Ana-Flor; Abadía, Javier

    2014-01-01

    The mechanisms plants use to transport metals from roots to shoots are not completely understood. It has long been proposed that organic molecules participate in metal translocation within the plant. However, until recently the identity of the complexes involved in the long-distance transport of metals could only be inferred by using indirect methods, such as analyzing separately the concentrations of metals and putative ligands and then using in silico chemical speciation software to predict metal species. Molecular biology approaches also have provided a breadth of information about putative metal ligands and metal complexes occurring in plant fluids. The new advances in analytical techniques based on mass spectrometry and the increased use of synchrotron X-ray spectroscopy have allowed for the identification of some metal-ligand species in plant fluids such as the xylem and phloem saps. Also, some proteins present in plant fluids can bind metals and a few studies have explored this possibility. This study reviews the analytical challenges researchers have to face to understand long-distance metal transport in plants as well as the recent advances in the identification of the ligand and metal-ligand complexes in plant fluids. PMID:24723928

  10. Molecular diagnosis of Eimeria species affecting naturally infected Gallus gallus.

    PubMed

    Carvalho, F S; Wenceslau, A A; Teixeira, M; Albuquerque, G R

    2011-01-01

    We used PCR to test various protocols and define a technique for DNA extraction directly from chicken-shed stool samples for the identification of Eimeria species that parasitize birds. It was possible to extract and amplify DNA of seven Eimeria species from field stool samples, using both protocols tested; extractions made with phenol/chloroform protocols gave the best results. The primers were specific and sensitive, allowing amplification of samples containing as few as 20 oocysts, both in individual and in a multiplex PCR. Individualized PCR with the phenol/chloroform DNA extraction protocol detected a larger number of Eimeria species. Molecular diagnosis was found to be practical and precise, and can be used for monitoring and epidemiological studies of Eimeria. PMID:21710449

  11. Does a decade of elevated [CO2] affect a desert perennial plant community?

    PubMed

    Newingham, Beth A; Vanier, Cheryl H; Kelly, Lauren J; Charlet, Therese N; Smith, Stanley D

    2014-01-01

    Understanding the effects of elevated [CO2 ] on plant community structure is crucial to predicting ecosystem responses to global change. Early predictions suggested that productivity in deserts would increase via enhanced water-use efficiency under elevated [CO2], but the response of intact arid plant communities to elevated [CO2 ] is largely unknown. We measured changes in perennial plant community characteristics (cover, species richness and diversity) after 10 yr of elevated [CO2] exposure in an intact Mojave Desert community at the Nevada Desert Free-Air CO2 Enrichment (FACE) Facility. Contrary to expectations, total cover, species richness, and diversity were not affected by elevated [CO2]. Over the course of the experiment, elevated [CO2] had no effect on changes in cover of the evergreen C3 shrub, Larrea tridentata; alleviated decreases in cover of the C4 bunchgrass, Pleuraphis rigida; and slightly reduced the cover of C3 drought-deciduous shrubs. Thus, we generally found no effect of elevated [CO2] on plant communities in this arid ecosystem. Extended drought, slow plant growth rates, and highly episodic germination and recruitment of new individuals explain the lack of strong perennial plant community shifts after a decade of elevated [CO2]. PMID:24117700

  12. Does vegetation complexity affect host plant chemistry, and thus multitrophic interactions, in a human-altered landscape?

    PubMed

    Wäschke, Nicole; Hancock, Christine; Hilker, Monika; Obermaier, Elisabeth; Meiners, Torsten

    2015-09-01

    Anthropogenic land use may shape vegetation composition and affect trophic interactions by altering concentrations of host plant metabolites. Here, we investigated the hypotheses that: (1) plant N and defensive secondary metabolite contents of the herb Plantago lanceolata are affected by land use intensity (LUI) and the surrounding vegetation composition (=plant species richness and P. lanceolata density), and that (2) changes in plant chemistry affect abundances of the herbivorous weevils Mecinus pascuorum and Mecinus labilis, as well as their larval parasitoid Mesopolobus incultus, in the field. We determined plant species richness, P. lanceolata density, and abundances of the herbivores and the parasitoid in 77 grassland plots differing in LUI index in three regions across Germany. We also measured the N and secondary metabolite [the iridoid glycosides (IGs) aucubin and catalpol] contents of P. lanceolata leaves. Mixed-model analysis revealed that: (1) concentrations of leaf IGs were positively correlated with plant species richness; leaf N content was positively correlated with the LUI index. Furthermore: (2) herbivore abundance was not related to IG concentrations, but correlated negatively with leaf N content. Parasitoid abundance correlated positively only with host abundance over the three regions. Structural equation models revealed a positive impact of IG concentrations on parasitoid abundance in one region. We conclude that changes in plant chemistry due to land use and/or vegetation composition may affect higher trophic levels and that the manifestation of these effects may depend on local biotic or abiotic features of the landscape. PMID:25986560

  13. Stimulated rhizodegradation of atrazaine by selected plant species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The efficacy of vegetative buffer strips (VBS) in removing herbicides deposited from surface runoff is related to the ability of plant species to promote rapid herbicide degradation. A growth chamber study was conducted to investigate the rhizodegradation of 14C-atrazine and the relationship of degr...

  14. Gloger's rule in plants: The species and ecosystem levels.

    PubMed

    Lev-Yadun, Simcha

    2015-01-01

    Gloger's rule posits that darker birds are found more often in humid environments than in arid ones, especially in the tropics. Accordingly, desert-inhabiting animals tend to be light-colored. This rule is also true for certain mammalian groups, including humans. Gloger's rule is manifested at 2 levels: (1) at the species level (different populations of the same species have different pigmentation at different latitudes), and (2) at the species assembly level (different taxa at a certain geography have different pigmentation than other taxa found at different habitats or latitudes). Concerning plants, Gloger's rule was first proposed to operate in many plant species growing in sand dunes, sandy shores and in deserts, because of being white, whitish, or silver colored, based on white trichomes, because of sand grains and clay particles glued to sticky glandular trichomes, or because of light-colored waxes. Recently, Gloger's rule was shown to also be true at the intraspecific level in relation to protection of anthers from UV irradiation. While Gloger's rule is true in certain plant taxa and ecologies, there are others where "anti-Gloger" coloration patterns exist. In some of these the selective agents are known and in others they are not. I present both Gloger and "anti-Gloger" cases and argue that this largely neglected aspect of plant biology deserves much more research attention. PMID:26786012

  15. Plant species composition and biofuel yields of conservation grasslands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Marginal croplands, such as those in the Conservation Reserve Program (CRP), have been suggested as a source of biomass for biofuel production. However, little is known about the composition of plant species on these conservation grasslands or their potential for ethanol production. Our objective w...

  16. AIRBORNE HYPERSPECTRAL IDENTIFICATION OF INVASIVE AND OPPORTUNISTIC WETLANDS PLANT SPECIES

    EPA Science Inventory

    Coastal wetlands are among the most fragmented and disturbed ecosystems and the Great Lakes are no exception. One possible result is the observed increase in the presence and dominance of invasive and other opportunistic plant species, such as the common reed (Phragmites australi...

  17. ORGANIC PESTICIDE MODIFICATION OF SPECIES INTERACTIONS USING ANNUAL PLANT COMMUNITIES

    EPA Science Inventory

    A method is proposed and tested for assessing multispecies responses to three pesticides (atrazine, 2,4,D and malathion). Pesticides were applied at two concentrations, mon model plant communities grown in raised beds using soil containing a natural weed bank. over by species was...

  18. Mycorrhizal dependency of some endemic and endangered Hawaiian plant species.

    PubMed

    Gemma, J N; Koske, R E; Habte, M

    2002-02-01

    Four endemic species of Hawaiian plants were tested for their response to inoculation with a Hawaiian isolate of Glomus aggregatum (an arbuscular mycorrhizal fungus [AMF]) when grown in a native soil with or without P added to achieve different soil-solution P levels. The endangered species (Sesbania tomentosa [Fabaceae] and Colubrina oppositifolia [Rhamnaceae]) and two nonendangered species (Bidens sandvicensis and B. asymmetrica × sandvicensis [Asteraceae]) were tested. When soil-solution P levels in greenhouse trials were similar to unfertilized field soils (e.g., 0.005-0.020 mg P/L), shoots of inoculated plants were 2.1 to 7.0 times larger than noninoculated plants. Leaf tissue P levels and root biomass in these species showed similar responses to inoculation. Mycorrhizal dependencies ranging from 44 to 88% were measured when plants were grown in low-P soils and were -4-42% in soil with P levels typical of highly productive agricultural soils. A survey of P levels in a variety of native (nonagricultural) Hawaiian soils indicated the widespread occurrence of P-limited sites (mean = 0.010 mg P/L, range = <0.001-0.030 mg P/L; N = 41). The terms "ecological mycorrhizal dependency" (EMD) and "agricultural mycorrhizal dependency" (AMD) are introduced to refine the concept of mycorrhizal dependency. PMID:21669742

  19. Stimulated Rhizodegradation of Atrazine by Selected Plant Species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The efficacy of vegetative buffer strips (VBS) in removing herbicides from surface runoff is related to the ability of plant species to promote rapid herbicide degradation. A growth chamber study was conducted to investigate the rhizodegradation of 14C-atrazine and the relationship of degradation w...

  20. The importance of education in managing invasive plant species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasive plant species can establish in diverse environments and with the increase in human mobility, they are no longer restricted to isolated pockets in remote parts of the world. Cheat grass (Bromus tectorum L.) in rangelands, purple loosestrife (Lythrum salicaria L.) in wet lands and Canada this...

  1. Gloger's rule in plants: The species and ecosystem levels

    PubMed Central

    Lev-Yadun, Simcha

    2015-01-01

    Gloger's rule posits that darker birds are found more often in humid environments than in arid ones, especially in the tropics. Accordingly, desert-inhabiting animals tend to be light-colored. This rule is also true for certain mammalian groups, including humans. Gloger's rule is manifested at 2 levels: (1) at the species level (different populations of the same species have different pigmentation at different latitudes), and (2) at the species assembly level (different taxa at a certain geography have different pigmentation than other taxa found at different habitats or latitudes). Concerning plants, Gloger's rule was first proposed to operate in many plant species growing in sand dunes, sandy shores and in deserts, because of being white, whitish, or silver colored, based on white trichomes, because of sand grains and clay particles glued to sticky glandular trichomes, or because of light-colored waxes. Recently, Gloger's rule was shown to also be true at the intraspecific level in relation to protection of anthers from UV irradiation. While Gloger's rule is true in certain plant taxa and ecologies, there are others where “anti-Gloger” coloration patterns exist. In some of these the selective agents are known and in others they are not. I present both Gloger and “anti-Gloger” cases and argue that this largely neglected aspect of plant biology deserves much more research attention. PMID:26786012

  2. RANGELAND BIOSOLIDS APPLICATIONS AFFECTS ON PLANT PRODUCTIVITY AND SPECIES DIVERSITY.

    EPA Science Inventory

    The study site contains a total of 6 treatment plots replicated 4 times in a randomized complete block design. In spring 2002, biosolids will be reapplied to one-half of each treatment plot at the appropriate rate, except for the 0 Mg ha-1 treatment. The following parameters wi...

  3. Biosynthesis of Jasmonic Acid by Several Plant Species 1

    PubMed Central

    Vick, Brady A.; Zimmerman, Don C.

    1984-01-01

    Six plant species metabolized 18O-labeled 12-oxo-cis,cis-10,15-phytodienoic acid (12-oxo-PDA) to short chain cyclic fatty acids. The plant species were corn (Zea mays L.), eggplant (Solanum melongena L.), flax (Linum usitatissimum L.), oat (Avena sativa L.), sunflower (Helianthus annuus L.), and wheat (Triticum aestivum L.). Among the products was jasmonic acid, a natural plant constituent with growth-regulating properties. The pathway is the same as the one recently reported by us for jasmonic acid synthesis in Vicia faba L. pericarp. First, the ring double bond of 12-oxo-PDA is saturated; then β-oxidation enzymes remove six carbons from the carboxyl side chain of the ring. Substrate specificity studies indicated that neither the stereochemistry of the side chain at carbon 13 of 12-oxo-PDA nor the presence of the double bond at carbon 15 was crucial for either enzyme step. The presence of enzymes which convert 12-oxo-PDA to jasmonic acid in several plant species indicates that this may be a general metabolic pathway in plants. PMID:16663643

  4. Different tree species affect soil respiration spatial distribution in a subtropical forest of southern Taiwan

    NASA Astrophysics Data System (ADS)

    Chiang, Po-Neng; Yu, Jui-Chu; Wang, Ya-nan; Lai, Yen-Jen

    2014-05-01

    Global forests contain 69% of total carbon stored in forest soil and litter. But the carbon storage ability and release rate of warming gases of forest soil also affect global climate change. Soil carbon cycling processes are paid much attention by ecological scientists and policy makers because of the possibility of carbon being stored in soil via land use management. Soil respiration contributed large part of terrestrial carbon flux, but the relationship of soil respiration and climate change was still obscurity. Most of soil respiration researches focus on template and tropical area, little was known that in subtropical area. Afforestation is one of solutions to mitigate CO2 increase and to sequestrate CO2 in tree and soil. Therefore, the objective of this study is to clarify the relationship of tree species and soil respiration distribution in subtropical broad-leaves plantation in southern Taiwan. The research site located on southern Taiwan was sugarcane farm before 2002. The sugarcane was removed and fourteen broadleaved tree species were planted in 2002-2005. Sixteen plots (250m*250m) were set on 1 km2 area, each plot contained 4 subplots (170m2). The forest biomass (i.e. tree height, DBH) understory biomass, litter, and soil C were measured and analyzed at 2011 to 2012. Soil respiration measurement was sampled in each subplot in each month. The soil belongs to Entisol with over 60% of sandstone. The soil pH is 5.5 with low base cations because of high sand percentage. Soil carbon storage showed significantly negative relationship with soil bulk density (p<0.001) in research site. The differences of distribution of live tree C pool among 16 plots were affected by growth characteristic of tree species. Data showed that the accumulation amount of litterfall was highest in December to February and lowest in June. Different tree species planted in 16 plots, resulting in high spatial variation of litterfall amount. It also affected total amount of litterfall

  5. Accumulation of K+ and Cs+ in Tropical Plant Species

    NASA Astrophysics Data System (ADS)

    Velasco, H.; Anjos, R. M.; Zamboni, C. B.; Macario, K. D.; Rizzotto, M.; Cid, A. S.; Medeiros, I. M. A.; Fernández, J.; Rubio, L.; Audicio, P.; Lacerda, T.

    2010-08-01

    Concentrations of K+ and 137Cs+ in tissues of the Citrus aurantifolia were measured both by gamma spectrometry and neutron activation analysis, aiming to understand the behavior of monovalent inorganic cations in plants as well as its capability to store these elements. In contrast to K+, Cs+ ions are not essential elements to plants, what might explain the difference in bioavailability. However, our results have shown that 137Cs+ is positively correlated to 40K+ concentration within tropical plant species, suggesting that these elements might be assimilated in a similar way, and that they pass through the biological cycle together. A simple mathematical model was also proposed to describe the temporal evolution of 40K activity concentration in such tropical woody fruit species. This model exhibited close agreement with the 40K experimental results in the fruit ripening processes of lemon trees.

  6. Plant species richness and ecosystem multifunctionality in global drylands

    USGS Publications Warehouse

    Maestre, Fernando T.; Quero, Jose L.; Gotelli, Nicholas J.; Escudero, Adrian; Ochoa, Victoria; Delgado-Baquerizo, Manuel; Garcia-Gomez, Miguel; Bowker, Matthew A.; Soliveres, Santiago; Escolar, Cristina; Garcia-Palacios, Pablo; Berdugo, Miguel; Valencia, Enrique; Gozalo, Beatriz; Gallardo, Antonio; Aguilera, Lorgio; Arredondo, Tulio; Blones, Julio; Boeken, Bertrand; Bran, Donaldo; Conceicao, Abel A.; Cabrera, Omar; Chaieb, Mohamed; Derak, Mchich; Eldridge, David J.; Espinosa, Carlos I.; Florentino, Adriana; Gaitan, Juan; Gatica, M. Gabriel; Ghiloufi, Wahida; Gomez-Gonzalez, Susana; Gutie, Julio R.; Hernandez, Rosa M.; Huang, Xuewen; Huber-Sannwald, Elisabeth; Jankju, Mohammad; Miriti, Maria; Monerris, Jorge; Mau, Rebecca L.; Morici, Ernesto; Naseri, Kamal; Ospina, Abelardo; Polo, Vicente; Prina, Anibal; Pucheta, Eduardo; Ramirez-Collantes, David A.; Romao, Roberto; Tighe, Matthew; Torres-Diaz, Cristian; Val, James; Veiga, Jose P.; Wang, Deli; Zaady, Eli

    2012-01-01

    Experiments suggest that biodiversity enhances the ability of ecosystems to maintain multiple functions, such as carbon storage, productivity, and the buildup of nutrient pools (multifunctionality). However, the relationship between biodiversity and multifunctionality has never been assessed globally in natural ecosystems. We report here on a global empirical study relating plant species richness and abiotic factors to multifunctionality in drylands, which collectively cover 41% of Earth's land surface and support over 38% of the human population. Multifunctionality was positively and significantly related to species richness. The best-fitting models accounted for over 55% of the variation in multifunctionality and always included species richness as a predictor variable. Our results suggest that the preservation of plant biodiversity is crucial to buffer negative effects of climate change and desertification in drylands.

  7. Plant species richness and ecosystem multifunctionality in global drylands

    PubMed Central

    Maestre, Fernando T.; Quero, José L.; Gotelli, Nicholas J.; Escudero, Adriá; Ochoa, Victoria; Delgado-Baquerizo, Manuel; García-Gómez, Miguel; Bowker, Matthew A.; Soliveres, Santiago; Escolar, Cristina; García-Palacios, Pablo; Berdugo, Miguel; Valencia, Enrique; Gozalo, Beatriz; Gallardo, Antonio; Aguilera, Lorgio; Arredondo, Tulio; Blones, Julio; Boeken, Bertrand; Bran, Donaldo; Conceição, Abel A.; Cabrera, Omar; Chaieb, Mohamed; Derak, Mchich; Eldridge, David J.; Espinosa, Carlos I.; Florentino, Adriana; Gaitán, Juan; Gatica, M. Gabriel; Ghiloufi, Wahida; Gómez-González, Susana; Gutiérrez, Julio R.; Hernández, Rosa M.; Huang, Xuewen; Huber-Sannwald, Elisabeth; Jankju, Mohammad; Miriti, Maria; Monerris, Jorge; Mau, Rebecca L.; Morici, Ernesto; Naseri, Kamal; Ospina, Abelardo; Polo, Vicente; Prina, Aníbal; Pucheta, Eduardo; Ramírez-Collantes, David A.; Romão, Roberto; Tighe, Matthew; Torres-Díaz, Cristian; Val, James; Veiga, José P.; Wang, Deli; Zaady, Eli

    2013-01-01

    Experiments suggest that biodiversity enhances the ability of ecosystems to maintain multiple functions, such as carbon storage, productivity, and buildup of nutrient pools (multifunctionality). However, the relationship between biodiversity and multifunctionality has never been assessed globally in natural ecosystems. We report on the first global empirical study relating plant species richness and abiotic factors to multifunctionality in drylands, which collectively cover 41% of Earth’s land surface and support over 38% of the human population. Multifunctionality was positively and significantly related to species richness. The best-fitting models accounted for over 55% of the variation in multifunctionality, and always included species richness as a predictor variable. Our results suggest that preservation of plant biodiversity is crucial to buffer negative effects of climate change and desertification in drylands. PMID:22246775

  8. Population Genomics for Understanding Adaptation in Wild Plant Species.

    PubMed

    Weigel, Detlef; Nordborg, Magnus

    2015-01-01

    Darwin's theory of evolution by natural selection is the foundation of modern biology. However, it has proven remarkably difficult to demonstrate at the genetic, genomic, and population level exactly how wild species adapt to their natural environments. We discuss how one can use large sets of multiple genome sequences from wild populations to understand adaptation, with an emphasis on the small herbaceous plant Arabidopsis thaliana. We present motivation for such studies; summarize progress in describing whole-genome, species-wide sequence variation; and then discuss what insights have emerged from these resources, either based on sequence information alone or in combination with phenotypic data. We conclude with thoughts on opportunities with other plant species and the impact of expected progress in sequencing technology and genome engineering for studying adaptation in nature. PMID:26436459

  9. Regeneration niche differentiates functional strategies of desert woody plant species

    PubMed Central

    Briggs, John M.

    2010-01-01

    Plant communities vary dramatically in the number and relative abundance of species that exhibit facilitative interactions, which contributes substantially to variation in community structure and dynamics. Predicting species’ responses to neighbors based on readily measurable functional traits would provide important insight into the factors that structure plant communities. We measured a suite of functional traits on seedlings of 20 species and mature plants of 54 species of shrubs from three arid biogeographic regions. We hypothesized that species with different regeneration niches—those that require nurse plants for establishment (beneficiaries) versus those that do not (colonizers)—are functionally different. Indeed, seedlings of beneficiary species had lower relative growth rates, larger seeds and final biomass, allocated biomass toward roots and height at a cost to leaf mass fraction, and constructed costly, dense leaf and root tissues relative to colonizers. Likewise at maturity, beneficiaries had larger overall size and denser leaves coupled with greater water use efficiency than colonizers. In contrast to current hypotheses that suggest beneficiaries are less “stress-tolerant” than colonizers, beneficiaries exhibited conservative functional strategies suited to persistently dry, low light conditions beneath canopies, whereas colonizers exhibited opportunistic strategies that may be advantageous in fluctuating, open microenvironments. In addition, the signature of the regeneration niche at maturity indicates that facilitation expands the range of functional diversity within plant communities at all ontogenetic stages. This study demonstrates the utility of specific functional traits for predicting species’ regeneration niches in hot deserts, and provides a framework for studying facilitation in other severe environments. Electronic supplementary material The online version of this article (doi:10.1007/s00442-010-1741-y) contains supplementary

  10. Effects of Previous Land-Use on Plant Species Composition and Diversity in Mediterranean Forests

    PubMed Central

    Kouba, Yacine; Martínez-García, Felipe; de Frutos, Ángel; Alados, Concepción L.

    2015-01-01

    At some point in their history, most forests in the Mediterranean Basin have been subjected to intensive management or converted to agriculture land. Knowing how forest plant communities recovered after the abandonment of forest-management or agricultural practices (including livestock grazing) provides a basis for investigating how previous land management have affected plant species diversity and composition in forest ecosystems. Our study investigated the consequences of historical “land management” practices on present-day Mediterranean forests by comparing species assemblages and the diversity of (i) all plant species and (ii) each ecological group defined by species’ habitat preferences and successional status (i.e., early-, mid-, and late-successional species). We compared forest stands that differed both in land-use history and in successional stage. In addition, we evaluated the value of those stands for biodiversity conservation. The study revealed significant compositional differentiation among stands that was due to among-stand variations in the diversity (namely, species richness and evenness) of early-, intermediate-, and late-successional species. Historical land management has led to an increase in compositional divergences among forest stands and the loss of late-successional forest species. PMID:26397707

  11. Beetle and plant density as cues initiating dispersal in two species of adult predaceous diving beetles.

    PubMed

    Yee, Donald A; Taylor, Stacy; Vamosi, Steven M

    2009-05-01

    Dispersal can influence population dynamics, species distributions, and community assembly, but few studies have attempted to determine the factors that affect dispersal of insects in natural populations. Consequently, little is known about how proximate factors affect the dispersal behavior of individuals or populations, or how an organism's behavior may change in light of such factors. Adult predaceous diving beetles are active dispersers and are important predators in isolated aquatic habitats. We conducted interrelated studies to determine how several factors affected dispersal in two common pond-inhabiting species in southern Alberta, Canada: Graphoderus occidentalis and Rhantus sericans. Specifically, we (1) experimentally tested the effect of plant and beetle densities on dispersal probabilities in ponds; (2) surveyed ponds and determined the relationships among beetle densities and plant densities and water depth; and (3) conducted laboratory trials to determine how beetle behavior changed in response to variation in plant densities, conspecific densities, food, and water depth. Our field experiment determined that both species exhibited density dependence, with higher beetle densities leading to higher dispersal probabilities. Low plant density also appeared to increase beetle dispersal. Consistent with our experimental results, densities of R. sericans in ponds were significantly related to plant density and varied also with water depth; G. occidentalis densities did not vary with either factor. In the laboratory, behavior varied with plant density only for R. sericans, which swam at low density but were sedentary at high density. Both species responded to depth, with high beetle densities eliciting beetles to spend more time in deeper water. The presence of food caused opposite responses for G. occidentalis between experiments. Behavioral changes in response to patch-level heterogeneity likely influence dispersal in natural populations and are expected

  12. Soil microbes and plant invasions—how soil-borne pathogens regulate plant populations and affect plant invasions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Exotic plant invaders are a major global threat to biodiversity and ecosystem function. Here I present multiple lines of evidence suggesting that soil microbial communities affect the population growth rates of Prunus serotina in its native range and affect its invasiveness abroad. Research often ...

  13. Soil-occupancy effects of invasive and native grassland plant species on composition and diversity of mycorrhizal associations

    USGS Publications Warehouse

    Jordan, Nicholas R.; Aldrich-Wolfe, Laura; Huerd, Sheri C.; Larson, Diane L.; Muehlbauer, Gary

    2012-01-01

    Diversified grasslands that contain native plant species can produce biofuels, support sustainable grazing systems, and produce other ecosystem services. However, ecosystem service production can be disrupted by invasion of exotic perennial plants, and these plants can have soil-microbial “legacies” that may interfere with establishment and maintenance of diversified grasslands even after effective management of the invasive species. The nature of such legacies is not well understood, but may involve suppression of mutualisms between native species and soil microbes. In this study, we tested the hypotheses that legacy effects of invasive species change colonization rates, diversity, and composition of arbuscular-mycorrhizal fungi (AMF) associated with seedlings of co-occurring invasive and native grassland species. In a glasshouse, experimental soils were conditioned by cultivating three invasive grassland perennials, three native grassland perennials, and a native perennial mixture. Each was grown separately through three cycles of growth, after which we used T-RFLP analysis to characterize AMF associations of seedlings of six native perennial and six invasive perennial species grown in these soils. Legacy effects of soil conditioning by invasive species did not affect AMF richness in seedling roots, but did affect AMF colonization rates and the taxonomic composition of mycorrhizal associations in seedling roots. Moreover, native species were more heavily colonized by AMF and roots of native species had greater AMF richness (number of AMF operational taxonomic units per seedling) than did invasive species. The invasive species used to condition soil in this experiment have been shown to have legacy effects on biomass of native seedlings, reducing their growth in this and a previous similar experiment. Therefore, our results suggest that successful plant invaders can have legacies that affect soil-microbial associations of native plants and that these effects

  14. Inoculation of Transgenic Resistant Potato by Phytophthora infestans Affects Host Plant Choice of a Generalist Moth.

    PubMed

    Abreha, Kibrom B; Alexandersson, Erik; Vossen, Jack H; Anderson, Peter; Andreasson, Erik

    2015-01-01

    Pathogen attack and the plant's response to this attack affect herbivore oviposition preference and larval performance. Introduction of major resistance genes against Phytophthora infestans (Rpi-genes), the cause of the devastating late blight disease, from wild Solanum species into potato changes the plant-pathogen interaction dynamics completely, but little is known about the effects on non-target organisms. Thus, we examined the effect of P. infestans itself and introduction of an Rpi-gene into the crop on host plant preference of the generalist insect herbivore, Spodoptera littoralis (Lepidoptera: Noctuidae). In two choice bioassays, S. littoralis preferred to oviposit on P. infestans-inoculated plants of both the susceptible potato (cv. Desiree) and an isogenic resistant clone (A01-22: cv. Desiree transformed with Rpi-blb1), when compared to uninoculated plants of the same genotype. Both cv. Desiree and clone A01-22 were equally preferred for oviposition by S. littoralis when uninoculated plants were used, while cv. Desiree received more eggs compared to the resistant clone when both were inoculated with the pathogen. No significant difference in larval and pupal weight was found between S. littoralis larvae reared on leaves of the susceptible potato plants inoculated or uninoculated with P. infestans. Thus, the herbivore's host plant preference in this system was not directly associated with larval performance. The results indicate that the Rpi-blb1 based resistance in itself does not influence insect behavior, but that herbivore oviposition preference is affected by a change in the plant-microbe interaction. PMID:26053171

  15. Positive indirect interactions between neighboring plant species via a lizard pollinator.

    PubMed

    Hansen, Dennis M; Kiesbüy, Heine C; Jones, Carl G; Müller, Christine B

    2007-04-01

    In natural communities, species are embedded in networks of direct and indirect interactions. Most studies on indirect interactions have focused on how they affect predator-prey or competitive relationships. However, it is equally likely that indirect interactions play an important structuring role in mutualistic relationships in a natural community. We demonstrate experimentally that on a small spatial scale, dense thickets of endemic Pandanus plants have a strong positive trait-mediated indirect effect on the reproduction of the declining endemic Mauritian plant Trochetia blackburniana. This effect is mediated by the endemic gecko Phelsuma cepediana moving between Pandanus thickets, a preferred microhabitat, and nearby T. blackburniana plants, where it feeds on nectar and pollinates the plants. Our findings emphasize the importance of considering plant-animal interactions such as pollination at relatively small spatial scales in both basic ecological studies and applied conservation management. PMID:17262697

  16. Mercury uptake and accumulation by four species of aquatic plants.

    PubMed

    Skinner, Kathleen; Wright, Nicole; Porter-Goff, Emily

    2007-01-01

    The effectiveness of four aquatic plants including water hyacinth (Eichornia crassipes), water lettuce (Pistia stratiotes), zebra rush (Scirpus tabernaemontani) and taro (Colocasia esculenta) were evaluated for their capabilities in removing mercury from water. The plants were exposed to concentrations of 0 mg/L, 0.5 mg/L or 2 mg/L of mercury for 30 days. Assays were conducted using both Microtox (water) and cold vapor Atomic Absorption Spectroscopy (AAS) (roots and water). The Microtox results indicated that the mercury induced acute toxicity had been removed from the water. AAS confirmed an increase of mercury within the plant root tissue and a corresponding decrease of mercury in the water. All species of plants appeared to reduce mercury concentrations in the water via root uptake and accumulation. Water lettuce and water hyacinth appeared to be the most effective, followed by taro and zebra rush, respectively. PMID:16781033

  17. Climate change hampers endangered species through intensified moisture-related plant stresses (Invited)

    NASA Astrophysics Data System (ADS)

    Bartholomeus, R.; Witte, J.; van Bodegom, P.; Dam, J. V.; Aerts, R.

    2010-12-01

    With recent climate change, extremes in meteorological conditions are forecast and observed to increase globally, and to affect vegetation composition. More prolonged dry periods will alternate with more intensive rainfall events, both within and between years, which will change soil moisture dynamics. In temperate climates, soil moisture, in concert with nutrient availability and soil acidity, is the most important environmental filter in determining local plant species composition, as it determines the availability of both oxygen and water to plant roots. These resources are indispensable for meeting the physiological demands of plants. The consequences of climate change for our natural environment are among the most pressing issues of our time. The international research community is beginning to realise that climate extremes may be more powerful drivers of vegetation change and species extinctions than slow-and-steady climatic changes, but the causal mechanisms of such changes are presently unknown. The roles of amplitudes in water availability as drivers of vegetation change have been particularly elusive owing to the lack of integration of the key variables involved. Here we show that the combined effect of increased rainfall variability, temperature and atmospheric CO2-concentration will lead to an increased variability in both wet and dry extremes in stresses faced by plants (oxygen and water stress, respectively). We simulated these plant stresses with a novel, process-based approach, incorporating in detail the interacting processes in the soil-plant-atmosphere interface. In order to quantify oxygen and water stress with causal measures, we focused on interacting meteorological, soil physical, microbial, and plant physiological processes in the soil-plant-atmosphere system. As both the supply and demand of oxygen and water depend strongly on the prevailing meteorological conditions, both oxygen and water stress were calculated dynamically in time to

  18. Plant species richness increases phosphatase activities in an experimental grassland

    NASA Astrophysics Data System (ADS)

    Hacker, Nina; Wilcke, Wolfgang; Oelmann, Yvonne

    2014-05-01

    Plant species richness has been shown to increase aboveground nutrient uptake requiring the mobilization of soil nutrient pools. For phosphorus (P) the underlying mechanisms for increased P release in soil under highly diverse grassland mixtures remain obscure because aboveground P storage and concentrations of inorganic and organic P in soil solution and differently reactive soil P pools are unrelated (Oelmann et al. 2011). The need of plants and soil microorganisms for P can increase the exudation of enzymes hydrolyzing organically bound P (phosphatases) which might represent an important release mechanism of inorganic P in a competitive environment such as highly diverse grassland mixtures. Our objectives were to test the effects of i) plant functional groups (legumes, grasses, non-leguminous tall and small herbs), and of (ii) plant species richness on microbial P (Pmic) and phosphatase activities in soil. In autumn 2013, we measured Pmic and alkaline phosphomonoesterase and phosphodiesterase activities in soil of 80 grassland mixtures comprising different community compositions and species richness (1, 2, 4, 8, 16, 60) in the Jena Experiment. In general, Pmic and enzyme activities were correlated (r = 0.59 and 0.46 for phosphomonoesterase and phosphodiesterase activities, respectively; p

  19. Light dependency of VOC emissions from selected Mediterranean plant species

    NASA Astrophysics Data System (ADS)

    Owen, S. M.; Harley, P.; Guenther, A.; Hewitt, C. N.

    The light, temperature and stomatal conductance dependencies of volatile organic compound (VOC) emissions from ten plant species commonly found in the Mediterranean region were studied using a fully controlled leaf cuvette in the laboratory. At standard conditions of temperature and light (30°C and 1000 μmol m -2 s -1 PAR), low emitting species ( Arbutus unedo, Pinus halepensis, Cistus incanus, Cistus salvifolius, Rosmarinus officinalis and Thymus vulgaris) emitted between 0.1 and 5.0 μg (C) (total VOCs) g -1 dw h -1, a medium emitter ( Pinus pinea) emitted between 5 and 10 μg (C) g -1 dw h -1 and high emitters ( Cistus monspeliensis, Lavendula stoechas and Quercus sp.) emitted more than 10 μg (C) g -1 dw h -1. VOC emissions from all of the plant species investigated showed some degree of light dependency, which was distinguishable from temperature dependency. Emissions of all compounds from Quercus sp. were light dependent. Ocimene was one of several monoterpene compounds emitted by P. pinea and was strongly correlated to light. Only a fraction of monoterpene emissions from C. incanus exhibited apparent weak light dependency but emissions from this plant species were strongly correlated to temperature. Data presented here are consistent with past studies, which show that emissions are independent of stomatal conductance. These results may allow more accurate predictions of monoterpene emission fluxes from the Mediterranean region to be made.

  20. Plant responses to climatic extremes: within-species variation equals among-species variation.

    PubMed

    Malyshev, Andrey V; Arfin Khan, Mohammed A S; Beierkuhnlein, Carl; Steinbauer, Manuel J; Henry, Hugh A L; Jentsch, Anke; Dengler, Jürgen; Willner, Evelin; Kreyling, Juergen

    2016-01-01

    Within-species and among-species differences in growth responses to a changing climate have been well documented, yet the relative magnitude of within-species vs. among-species variation has remained largely unexplored. This missing comparison impedes our ability to make general predictions of biodiversity change and to project future species distributions using models. We present a direct comparison of among- versus within-species variation in response to three of the main stresses anticipated with climate change: drought, warming, and frost. Two earlier experiments had experimentally induced (i) summer drought and (ii) spring frost for four common European grass species and their ecotypes from across Europe. To supplement existing data, a third experiment was carried out, to compare variation among species from different functional groups to within-species variation. Here, we simulated (iii) winter warming plus frost for four grasses, two nonleguminous, and two leguminous forbs, in addition to eleven European ecotypes of the widespread grass Arrhenatherum elatius. For each experiment, we measured: (i) C/N ratio and biomass, (ii) chlorophyll content and biomass, and (iii) plant greenness, root (15) N uptake, and live and dead tissue mass. Using coefficients of variation (CVs) for each experiment and response parameter, a total of 156 within- vs. among-species comparisons were conducted, comparing within-species variation in each of four species with among-species variation for each seed origin (five countries). Of the six significant differences, within-species CVs were higher than among-species CVs in four cases. Partitioning of variance within each treatment in two of the three experiments showed that within-species variability (ecotypes) could explain an additional 9% of response variation after accounting for the among-species variation. Our observation that within-species variation was generally as high as among-species variation emphasizes the importance of

  1. Coal fly ash effluent affects the distributions of Brachionus calyciflorus sibling species.

    PubMed

    Zhang, Gen; Xi, Yi-Long; Xue, Ying-Hao; Xiang, Xian-Ling; Wen, Xin-Li

    2015-02-01

    Fly ash, a coal combustion residue of thermal power plants and a source of multiple pollutants, has been recognized as an environmental hazard all over the world. Although it is known that fly ash effluent affects density, diversity and distribution of rotifers in drainage systems and receiving water bodies, the effect of fly ash effluent on the distributions of highly similar rotifer species remains unknown. In this study, the mtDNA COI genes of 90 individuals in Brachionus calyciflorus complex from Lake Hui (as a fly ash discharge water pond) and other two neighboring lakes (Lake Fengming and Lake Tingtang) were sequenced and analyzed, and the responses in selected life table demographic parameters (life expectancy at hatching, net reproductive rate, intrinsic rate of population increase and proportion of sexual offspring) of different rotifer populations to fly ash effluent were investigated. Overall, 72 mtDNA haplotypes were defined, and were split into two clades by the phylogenetic trees. The divergence of COI gene sequences between the two clades ranged from 11.8% to17.8%, indicating the occurrence of two sibling species (sibling species I and sibling species II). Sibling species I distributed in all the three lakes, showing strong capabilities for dispersal and colonization, which were supported by its higher level of gene flow (2.60-4.04) between the populations from Lake Hui and each of the other two lakes, longer life expectancy at hatching (101.6-148.2 h), and higher net reproductive rate (4.4-16.4 offspring/female) and intrinsic rate of population increase (0.60-0.98/d) when cultured in aerated tap water and fly ash effluent. Sibling species II distributed in both Lake Tingtang and Lake Fengming, showing that its dispersal existed between the two lakes. Considering that the distance between Lake Hui and Lake Fengming is shorter than that between Lake Tingtang and Lake Fengming, sibling species II is able to disperse at least from Lake Fengming to Lake

  2. Interactive effects of elevation, species richness and extreme climatic events on plant-pollinator networks.

    PubMed

    Hoiss, Bernhard; Krauss, Jochen; Steffan-Dewenter, Ingolf

    2015-11-01

    Plant-pollinator interactions are essential for the functioning of terrestrial ecosystems, but are increasingly affected by global change. The risks to such mutualistic interactions from increasing temperature and more frequent extreme climatic events such as drought or advanced snow melt are assumed to depend on network specialization, species richness, local climate and associated parameters such as the amplitude of extreme events. Even though elevational gradients provide valuable model systems for climate change and are accompanied by changes in species richness, responses of plant-pollinator networks to climatic extreme events under different environmental and biotic conditions are currently unknown. Here, we show that elevational climatic gradients, species richness and experimentally simulated extreme events interactively change the structure of mutualistic networks in alpine grasslands. We found that the degree of specialization in plant-pollinator networks (H2') decreased with elevation. Nonetheless, network specialization increased after advanced snow melt at high elevations, whereas changes in network specialization after drought were most pronounced at sites with low species richness. Thus, changes in network specialization after extreme climatic events depended on climatic context and were buffered by high species richness. In our experiment, only generalized plant-pollinator networks changed in their degree of specialization after climatic extreme events. This indicates that contrary to our assumptions, network generalization may not always foster stability of mutualistic interaction networks. PMID:26332102

  3. Effects of Host Plant Factors on the Bacterial Communities Associated with Two Whitefly Sibling Species

    PubMed Central

    Su, Ming-Ming; Guo, Lei; Tao, Yun-Li; Zhang, You-Jun; Wan, Fang-Hao; Chu, Dong

    2016-01-01

    Background Although discrepancy in the specific traits and ecological characteristics of Bemisia tabaci between species are partially attributed to the B. tabaci-associated bacteria, the factors that affect the diversity of B. tabaci-associated bacteria are not well-understood. We used the metagenomic approach to characterize the B. tabaci-associated bacterial community because the approach is an effective tool to identify the bacteria. Methodology and Results To investigate the effects of the host plant and a virus, tomato yellow leaf curl virus (TYLCV), on the bacterial communities of B. tabaci sibling species B and Q, we analyzed the bacterial communities associated with whitefly B and Q collected from healthy cotton, healthy tomato, and TYLCV-infected tomato. The analysis used miseq-based sequencing of a variable region of the bacterial 16S rDNA gene. For the bacteria associated with B. tabaci, we found that the influence of the host plant species was greater than that of the whitefly cryptic species. With further analysis of host plants infected with the TYLCV, the virus had no significant effects on the B. tabaci-associated bacterial community. Conclusions The effects of different plant hosts and TYLCV-infection on the diversity of B. tabaci-associated bacterial communities were successfully analyzed in this study. To explain why B. tabaci sibling species with different host ranges differ in performance, the analysis of the bacterial community may be essential to the explanation. PMID:27008327

  4. Stochastic changes affect Solanum wild species following autopolyploidization

    PubMed Central

    Carputo, Domenico

    2013-01-01

    Polyploidy is very common within angiosperms, and several studies are in progress to ascertain the effects of early polyploidization at the molecular, physiological, and phenotypic level. Extensive studies are available only in synthetic allopolyploids. By contrast, less is known about the consequences of autopolyploidization. The current study aimed to assess the occurrence and extent of genetic, epigenetic, and anatomical changes occurring after oryzaline-induced polyploidization of Solanum commersonii Dunal and Solanum bulbocastanum Dunal, two diploid (2n=2×=24) potato species widely used in breeding programmes. Microsatellite analysis showed no polymorphisms between synthetic tetraploids and diploid progenitors. By contrast, analysis of DNA methylation levels indicated that subtle alterations at CG and CHG sites were present in tetraploids of both species. However, no change occurred concurrently in all tetraploids analysed with respect to their diploid parent, revealing a stochastic trend in the changes observed. The morpho-anatomical consequences of polyploidization were studied in leaf main veins and stomata. With only a few exceptions, analyses showed no clear superiority of tetraploids in terms of leaf thickness and area, vessel number, lumen size and vessel wall thickness, stomata pore length and width, guard cell width, and stomatal density compared with their diploid progenitors. These results are consistent with the hypothesis that there are no traits systematically associated with autopolyploidy. PMID:23307917

  5. Species-specific toxicity of ceria nanoparticles to Lactuca plants.

    PubMed

    Zhang, Peng; Ma, Yuhui; Zhang, Zhiyong; He, Xiao; Li, Yuanyuan; Zhang, Jing; Zheng, Lirong; Zhao, Yuliang

    2015-02-01

    Species-specific differences in the toxicity of manufactured nanoparticles (MNPs) have been reported, but the underlying mechanisms are unknown. We previously found that CeO2 NPs inhibited root elongation of head lettuce, whereas no toxic effect was observed on other plants (such as wheat, cucumber and radish). In this study, interactions between Lactuca plants and three types of CeO2 NPs (lab-synthesized 7 and 25 nm CeO2 NPs, and a commercial CeO2 NPs) were investigated. It was found that CeO2 NPs were toxic to three kinds of Lactuca genus plants and different CeO2 NPs showed different degrees of toxicity. The results of X-ray absorption near edge fine structure indicate that small parts of CeO2 NPs were transformed from Ce(IV) to Ce(III) in roots of the plants that were treated with CeO2 NPs during the seed germination stage. But the high sensitivity of Lactuca plants to the released Ce(3+) ions caused the species-specific phytotoxicity of CeO2 NPs. Differences in sizes and zeta potentials among three types of CeO2 NPs resulted in their different degrees of biotransformation which accounted for the discrepancy in the toxicity to Lactuca plants. This study is among the few, and may indeed the first, that addresses the relation between the physicochemical properties of nanoparticles and its species-specific phytotoxicity. PMID:24256192

  6. Methylated arsenic species in plants originate from soil microorganisms.

    PubMed

    Lomax, Charlotte; Liu, Wen-Ju; Wu, Liyou; Xue, Kai; Xiong, Jinbo; Zhou, Jizhong; McGrath, Steve P; Meharg, Andrew A; Miller, Anthony J; Zhao, Fang-Jie

    2012-02-01

    • Inorganic arsenic (iAs) is a ubiquitous human carcinogen, and rice (Oryza sativa) is the main contributor to iAs in the diet. Methylated pentavalent As species are less toxic and are routinely found in plants; however, it is currently unknown whether plants are able to methylate As. • Rice, tomato (Solanum lycopersicum) and red clover (Trifolium pratense) were exposed to iAs, monomethylarsonic acid (MMA(V)), or dimethylarsinic acid (DMA(V)), under axenic conditions. Rice seedlings were also grown in two soils under nonsterile flooded conditions, and rice plants exposed to arsenite or DMA(V) were grown to maturity in nonsterile hydroponic culture. Arsenic speciation in samples was determined by HPLC-ICP-MS. • Methylated arsenicals were not found in the three plant species exposed to iAs under axenic conditions. Axenically grown rice was able to take up MMA(V) or DMA(V), and reduce MMA(V) to MMA(III) but not convert it to DMA(V). Methylated As was detected in the shoots of soil-grown rice, and in rice grain from nonsterile hydroponic culture. GeoChip analysis of microbial genes in a Bangladeshi paddy soil showed the presence of the microbial As methyltransferase gene arsM. • Our results suggest that plants are unable to methylate iAs, and instead take up methylated As produced by microorganisms. PMID:22098145

  7. Networks of plants: how to measure similarity in vegetable species.

    PubMed

    Vivaldo, Gianna; Masi, Elisa; Pandolfi, Camilla; Mancuso, Stefano; Caldarelli, Guido

    2016-01-01

    Despite the common misconception of nearly static organisms, plants do interact continuously with the environment and with each other. It is fair to assume that during their evolution they developed particular features to overcome similar problems and to exploit possibilities from environment. In this paper we introduce various quantitative measures based on recent advancements in complex network theory that allow to measure the effective similarities of various species. By using this approach on the similarity in fruit-typology ecological traits we obtain a clear plant classification in a way similar to traditional taxonomic classification. This result is not trivial, since a similar analysis done on the basis of diaspore morphological properties do not provide any clear parameter to classify plants species. Complex network theory can then be used in order to determine which feature amongst many can be used to distinguish scope and possibly evolution of plants. Future uses of this approach range from functional classification to quantitative determination of plant communities in nature. PMID:27271207

  8. Networks of plants: how to measure similarity in vegetable species

    PubMed Central

    Vivaldo, Gianna; Masi, Elisa; Pandolfi, Camilla; Mancuso, Stefano; Caldarelli, Guido

    2016-01-01

    Despite the common misconception of nearly static organisms, plants do interact continuously with the environment and with each other. It is fair to assume that during their evolution they developed particular features to overcome similar problems and to exploit possibilities from environment. In this paper we introduce various quantitative measures based on recent advancements in complex network theory that allow to measure the effective similarities of various species. By using this approach on the similarity in fruit-typology ecological traits we obtain a clear plant classification in a way similar to traditional taxonomic classification. This result is not trivial, since a similar analysis done on the basis of diaspore morphological properties do not provide any clear parameter to classify plants species. Complex network theory can then be used in order to determine which feature amongst many can be used to distinguish scope and possibly evolution of plants. Future uses of this approach range from functional classification to quantitative determination of plant communities in nature. PMID:27271207

  9. Plant functional traits and the multidimensional nature of species coexistence

    PubMed Central

    Kraft, Nathan J. B.; Godoy, Oscar; Levine, Jonathan M.

    2015-01-01

    Understanding the processes maintaining species diversity is a central problem in ecology, with implications for the conservation and management of ecosystems. Although biologists often assume that trait differences between competitors promote diversity, empirical evidence connecting functional traits to the niche differences that stabilize species coexistence is rare. Obtaining such evidence is critical because traits also underlie the average fitness differences driving competitive exclusion, and this complicates efforts to infer community dynamics from phenotypic patterns. We coupled field-parameterized mathematical models of competition between 102 pairs of annual plants with detailed sampling of leaf, seed, root, and whole-plant functional traits to relate phenotypic differences to stabilizing niche and average fitness differences. Single functional traits were often well correlated with average fitness differences between species, indicating that competitive dominance was associated with late phenology, deep rooting, and several other traits. In contrast, single functional traits were poorly correlated with the stabilizing niche differences that promote coexistence. Niche differences could only be described by combinations of traits, corresponding to differentiation between species in multiple ecological dimensions. In addition, several traits were associated with both fitness differences and stabilizing niche differences. These complex relationships between phenotypic differences and the dynamics of competing species argue against the simple use of single functional traits to infer community assembly processes but lay the groundwork for a theoretically justified trait-based community ecology. PMID:25561561

  10. Feeding Experience of Bemisia tabaci (Hemiptera: Aleyrodidae) Affects Their Performance on Different Host Plants

    PubMed Central

    Shah, M. Mostafizur Rahman; Liu, Tong-Xian

    2013-01-01

    The sweetpotato whitefly, Bemisia tabaci biotype B is extremely polyphagous with >600 species of host plants. We hypothesized that previous experience of the whitefly on a given host plant affects their host selection and performance on the plants without previous experience. We investigated the host selection for feeding and oviposition of adults and development and survival of immatures of three host-plant-experienced populations of B. tabaci, namely Bemisia-eggplant, Bemisia-tomato and Bemisia-cucumber, on their experienced host plant and each of the three other plant species (eggplant, tomato, cucumber and pepper) without previous experience. We found that the influence of previous experience of the whiteflies varied among the populations. All populations refused pepper for feeding and oviposition, whereas the Bemisia-cucumber and the Bemisia-eggplant strongly preferred cucumber. Bemisia-tomato did not show strong preference to any of the three host palnts. Development time from egg to adult eclosion varied among the populations, being shortest on eggplant, longest on pepper, and intermediate on tomato and cucumber except for the Bemisia-cucumber developed similarly on tomato and pepper. The survivorship from egg to adult eclosion of all populations was highest on eggplant (80-98%), lowest on pepper (0-20%), and intermediate on tomato and cucumber. In conclusion, the effects of previous experience of whiteflies on host selection for feeding and oviposition, development, and survivorship varied depending on host plants, and host plants play a stronger role than previous experience. Preference of feeding and oviposition by adults may not accurately reflect host suitability of immatures. These results provided important information for understanding whitefly population dynamics and dispersal among different crop systems. PMID:24146985

  11. Cupriavidus plantarum sp. nov., a plant-associated species.

    PubMed

    Estrada-de Los Santos, Paulina; Solano-Rodríguez, Roosivelt; Matsumura-Paz, Lucía Tomiko; Vásquez-Murrieta, María Soledad; Martínez-Aguilar, Lourdes

    2014-11-01

    During a survey of plant-associated bacteria in northeast Mexico, a group of 13 bacteria was isolated from agave, maize and sorghum plants rhizosphere. This group of strains was related to Cupriavidus respiraculi (99.4 %), but a polyphasic investigation based on DNA-DNA hybridization analysis, other genotypic studies and phenotypic features showed that this group of strains actually belongs to a new Cupriavidus species. Consequently, taking all the results together, the description of Cupriavidus plantarum sp. nov. is proposed. PMID:25098225

  12. Why Would Plant Species Become Extinct Locally If Growing Conditions Improve?

    PubMed Central

    Kramer, Koen; Bijlsma, Rienk-Jan; Hickler, Thomas; Thuiller, Wilfried

    2012-01-01

    Two assumptions underlie current models of the geographical ranges of perennial plant species: 1. current ranges are in equilibrium with the prevailing climate, and 2. changes are attributable to changes in macroclimatic factors, including tolerance of winter cold, the duration of the growing season, and water stress during the growing season, rather than to biotic interactions. These assumptions allow model parameters to be estimated from current species ranges. Deterioration of growing conditions due to climate change, e.g. more severe drought, will cause local extinction. However, for many plant species, the predicted climate change of higher minimum temperatures and longer growing seasons means, improved growing conditions. Biogeographical models may under some circumstances predict that a species will become locally extinct, despite improved growing conditions, because they are based on an assumption of equilibrium and this forces the species range to match the species-specific macroclimatic thresholds. We argue that such model predictions should be rejected unless there is evidence either that competition influences the position of the range margins or that a certain physiological mechanism associated with the apparent improvement in growing conditions negatively affects the species performance. We illustrate how a process-based vegetation model can be used to ascertain whether such a physiological cause exists. To avoid potential modelling errors of this type, we propose a method that constrains the scenario predictions of the envelope models by changing the geographical distribution of the dominant plant functional type. Consistent modelling results are very important for evaluating how changes in species areas affect local functional trait diversity and hence ecosystem functioning and resilience, and for inferring the implications for conservation management in the face of climate change. PMID:22991500

  13. Corridors Increase Plant Species Richness at Large Scales

    SciTech Connect

    Damschen, Ellen I.; Haddad, Nick M.; Orrock,John L.; Tewksbury, Joshua J.; Levey, Douglas J.

    2006-09-01

    Habitat fragmentation is one of the largest threats to biodiversity. Landscape corridors, which are hypothesized to reduce the negative consequences of fragmentation, have become common features of ecological management plans worldwide. Despite their popularity, there is little evidence documenting the effectiveness of corridors in preserving biodiversity at large scales. Using a large-scale replicated experiment, we showed that habitat patches connected by corridors retain more native plant species than do isolated patches, that this difference increases over time, and that corridors do not promote invasion by exotic species. Our results support the use of corridors in biodiversity conservation.

  14. Climate change is affecting altitudinal migrants and hibernating species.

    PubMed

    Inouye, D W; Barr, B; Armitage, K B; Inouye, B D

    2000-02-15

    Calendar date of the beginning of the growing season at high altitude in the Colorado Rocky Mountains is variable but has not changed significantly over the past 25 years. This result differs from growing evidence from low altitudes that climate change is resulting in a longer growing season, earlier migrations, and earlier reproduction in a variety of taxa. At our study site, the beginning of the growing season is controlled by melting of the previous winter's snowpack. Despite a trend for warmer spring temperatures the average date of snowmelt has not changed, perhaps because of the trend for increased winter precipitation. This disjunction between phenology at low and high altitudes may create problems for species, such as many birds, that migrate over altitudinal gradients. We present data indicating that this already may be true for American robins, which are arriving 14 days earlier than they did in 1981; the interval between arrival date and the first date of bare ground has grown by 18 days. We also report evidence for an effect of climate change on hibernation behavior; yellow-bellied marmots are emerging 38 days earlier than 23 years ago, apparently in response to warmer spring air temperatures. Migrants and hibernators may experience problems as a consequence of these changes in phenology, which may be exacerbated if climate models are correct in their predictions of increased winter snowfall in our study area. The trends we report for earlier formation of permanent snowpack and for a longer period of snow cover also have implications for hibernating species. PMID:10677510

  15. Sampling Plant Diversity and Rarity at Landscape Scales: Importance of Sampling Time in Species Detectability

    PubMed Central

    Zhang, Jian; Nielsen, Scott E.; Grainger, Tess N.; Kohler, Monica; Chipchar, Tim; Farr, Daniel R.

    2014-01-01

    Documenting and estimating species richness at regional or landscape scales has been a major emphasis for conservation efforts, as well as for the development and testing of evolutionary and ecological theory. Rarely, however, are sampling efforts assessed on how they affect detection and estimates of species richness and rarity. In this study, vascular plant richness was sampled in 356 quarter hectare time-unlimited survey plots in the boreal region of northeast Alberta. These surveys consisted of 15,856 observations of 499 vascular plant species (97 considered to be regionally rare) collected by 12 observers over a 2 year period. Average survey time for each quarter-hectare plot was 82 minutes, ranging from 20 to 194 minutes, with a positive relationship between total survey time and total plant richness. When survey time was limited to a 20-minute search, as in other Alberta biodiversity methods, 61 species were missed. Extending the survey time to 60 minutes, reduced the number of missed species to 20, while a 90-minute cut-off time resulted in the loss of 8 species. When surveys were separated by habitat type, 60 minutes of search effort sampled nearly 90% of total observed richness for all habitats. Relative to rare species, time-unlimited surveys had ∼65% higher rare plant detections post-20 minutes than during the first 20 minutes of the survey. Although exhaustive sampling was attempted, observer bias was noted among observers when a subsample of plots was re-surveyed by different observers. Our findings suggest that sampling time, combined with sample size and observer effects, should be considered in landscape-scale plant biodiversity surveys. PMID:24740179

  16. Soil sand content can alter effects of different taxa of mycorrhizal fungi on plant biomass production of grassland species

    PubMed Central

    Zaller, Johann G.; Frank, Thomas; Drapela, Thomas

    2011-01-01

    In this greenhouse experiment we tested whether (i) ubiquitous arbuscular mycorrhizal fungi (AMF) taxa (Glomus claroideum, Glomus geosporum, Glomus intraradices, Glomus mosseae) singly and in a mixture differently affect growth and biomass production of four co-occurring grassland species (grass: Arrhenatherum elatius, non-leguminous forbs: Plantago lanceolata, Salvia pratensis and leguminous forb Trifolium pratense), and (ii) different soil sand contents alter AMF influence. We hypothesized that AMF effects on plants will increase with an increased AMF diversity and with increasing sand content. Percent AMF colonization of roots differed between plant species and AMF taxa and was higher with higher sand content. Plant growth responses to AMF were species-specific both regarding plants and AMF. Generally, biomass production of the non-leguminous forbs was the most responsive, the grass species the least and the legume intermediate both for AMF treatments and sand content. Across species, AMF influence on plant biomass increased with increasing soil sand content. Plant species growing in soil containing a mix of four AMF taxa showed similar growth responses than species in soil containing only one AMF taxon. These results suggest that both interference among AMF taxa and soil sand content can trigger the influence of AMF on plant production in grassland species. PMID:26109837

  17. New evidence for electrotropism in some plant species

    NASA Astrophysics Data System (ADS)

    Gorgolewski, S.; Rozej, B.

    The ever-present global Atmospheric Electrical F ield (AEF) is used by many plant species. There are many natural habitats with electrotropic plants and habitats with no AEF. The plants growing there are not electrotropic, like the plants growing under the canopies of the trees or the Arecibo radio telescope. Examples are given of different plants which belong to one or the other class, and the criteria how to distinguish them. In addition to natural habitat observations, laboratory experiments were run in search of the sensitivity to electrotropic effect in different electric field intensities and directions. It was established that in very strong fields (of the order of 1 MV/m) all plants respond immediately to the field. This type of reaction is due to the Coulomb forces, but electrotropism depends on electric field interaction with ions in plant tissues. We use a "reference field" (130 V/m) and stronger fields in the several kV/m range which enhance plant growth rate and size similar to plant growth hormones. Surprising effects were also observed with reversed field polarity. In conclusion electrotropic pl nts deprived of the electrical field do not develop asa expected, as can be seen in BIOSPHERE 2. It was a sad example of what happens when one forgets to provide the plants with this vital natural environmental factor. Electrical fields of different intensity and direction are cheap and easy to generate. More plants were investigated in order to verify their response to electrical fields. Effect of several kV/m horizontal fields, was compared with the vertical 130 V/m field (ued as a reference) and it was shown that electrotropic sensitivity can be found easily. Surprisingly even the nonelectrotropic plants, whose initial growth rate does not depend on the field strength, when they develop leaves begin to lean towards the positive electrode, and become elect rotropic. Ground based fitotron experiments enable us to select cheaply plants which shall be suitable

  18. Content and distribution of flavonoids among 91 edible plant species.

    PubMed

    Yang, Ray-Yu; Lin, Shou; Kuo, George

    2008-01-01

    Flavonoid contents as aglycones (for quercetin, kaempherol, isorhamnetin, luteolin and apigenin) were reported for 115 edible plants (91 species). Plant materials mostly originated in tropical zones were grown and harvested from AVRDC, Taiwan. Acid extraction and HPLC were used as analytical methods. Total flavonoid contents ranged from 0 to 254 mg/100g fresh weight. About 75% of samples were found to contain flavonoids > 0.5 mg/100g with the group mean 33 +/- 48 mg/100g. Data for only 30 samples (20 species) in this study are also available (measured as raw vegetables) in the USDA flavonoid database. This study can expand the flavonoid database and contribute to measurement of flavonoid intake, especially for populations consuming tropical and underutilized vegetables. PMID:18296355

  19. Hybrid Viability and Fertility in Co-occuring Plant Species

    NASA Astrophysics Data System (ADS)

    Hernandez, E.; Garcia, C.; Yost, J.

    2012-12-01

    Similar species of plants can co-exist due to reproductive barriers that keep them from hybridizing. In the case of Lasthenia gracilis and L. californica, certain reproductive barriers allow them to co-exist at Jasper Ridge without hybridization. The two species are locally adapted to different regions of the same hillside, and have slight differences in flowering time but hybrids can be created at low rate in the green house. We tested the viability and fertility of green house produced hybrids to quantify post-zygotic reproductive isolation at Jasper Ridge. We planted 10 hybrid seeds and 10 control seeds from 11 different families. We measured the percent germination, survival to flowering and pollen fertility of the seeds. We expect lower germination, lower survival to flowering, and lower pollen viability of hybrid seeds as compared to control seeds.

  20. Origin of floral isolation between ornithophilous and sphingophilous plant species.

    PubMed Central

    Grant, V

    1993-01-01

    Three plant groups in temperate western North America contain closely related ornithophilous and sphingophilous species: the Aquilegia formosa/Aquilegia caerulea group (Ranunculaceae), the Ipomopsis aggregata group (Polemoniaceae), and the Diplacus longiflorus group (Scrophulariaceae). The ornithophilous and sphingophilous species are products of allopatric speciation on the diploid level. Geographical races which are adapted to one class of pollinators in one area where these pollinators are abundant and effective and to another class of pollinators in another geographically isolated area (pollination races) represent a probable intermediate stage in the process of allopatric speciation. Mechanical and ethological isolation (collectively, floral isolation) is a byproduct of the divergence in pollination systems. Selection for reproductive isolation per se has not played any detectable role in the origin of the floral isolation in the three plant groups. PMID:11607421

  1. Climate change threatens endangered plant species by stronger and interacting water-related stresses

    NASA Astrophysics Data System (ADS)

    Bartholomeus, Ruud P.; Witte, Jan-Philip M.; van Bodegom, Peter M.; van Dam, Jos C.; Aerts, Rien

    2011-12-01

    Atmospheric CO2-concentration, temperature and rainfall variability are all expected to increase in the near future. The resulting increased dynamics of soil moisture contents, together with increased plant physiological demands for both oxygen and water, will lead to an increased occurrence of wet and dry extremes of plant stresses, i.e., of oxygen and drought stress, respectively, alone and in interaction. The use of indirect environmental variables in previous studies and a focus on individual stresses rather than their combined effects has hampered understanding of the causal impact of climate change on plant species composition through changes in abiotic site conditions. Here, we use process-based simulations of oxygen and drought stresses in conjunction with a downscaled national version of IPCC scenarios in order to show that these stresses will increase (on average by ˜20% at sites where both stresses occur) in a warmer and more variable future (2050) climate. These two types of stresses will increasingly coincide, i.e. both stresses will occur more often (but not at the same time) within a single vegetation plot. We further show that this increased coincidence of water-related stresses will negatively affect the future occurrence of currently endangered plant species (causing a reduction of ˜16%), while apparently no such decrease will occur among common species. Individual stresses did not appear to affect the occurrence of endangered plant species. Consequently, our study demonstrates that species that are already threatened under the current climate will suffer most from the effects of climate change.

  2. Unpreferred plants affect patch choice and spatial distribution of European brown hares

    NASA Astrophysics Data System (ADS)

    Kuijper, D. P. J.; Bakker, J. P.

    2008-11-01

    Many herbivore species prefer to forage on patches of intermediate biomass. Plant quality and forage efficiency are predicted to decrease with increasing plant standing crop which explains the lower preference of the herbivore. However, often is ignored that on the long-term, plant species composition is predicted to change with increasing plant standing crop. The amount of low-quality, unpreferred food plants increases with increasing plant standing crop. In the present study the effects of unpreferred plants on patch choice and distribution of European brown hare in a salt-marsh system were studied. In one experiment, unpreferred plants were removed from plots. In the second experiment, plots were planted with different densities of an unpreferred artificial plant. Removal of unpreferred plants increased hare-grazing pressure more than fivefold compared to unmanipulated plots. Planting of unpreferred plants reduced hare-grazing pressure, with a significant reduction of grazing already occurring at low unpreferred plant density. Spatial distribution of hares within this salt-marsh system was related to spatial arrangement of unpreferred plants. Hare-grazing intensity decreased strongly with increasing abundance of unpreferred plants despite a high abundance of principal food plants. The results of this study indicate that plant species replacement is an important factor determining patch choice and spatial distribution of hares next to changing plant quality. Increasing abundance of unpreferred plant species can strengthen the decreasing patch quality with increasing standing crop and can decrease grazing intensity when preferred food plants are still abundantly present.

  3. Constrained preferences in nitrogen uptake across plant species and environments.

    PubMed

    Wang, Lixin; Macko, Stephen A

    2011-03-01

    Knowledge of determining factors for nitrogen uptake preferences and how they are modified in changing environments are critical to understand ecosystem nitrogen cycling and to predict plant responses to future environmental changes. Two ¹⁵N tracer experiments utilizing a unique differential labelled nitrogen source were employed in both African savannas and greenhouse settings. The results demonstrated that nitrogen uptake preferences were constrained by the climatic conditions. As mainly indicated by root δ¹⁵N signatures at 1:1 ammonium/nitrate ratio, in the drier environments, plants preferred nitrate and in the wetter environments they preferred ammonium. Nitrogen uptake preferences were different across different ecosystems (e.g. from drier to wetter environments) even for the same species. More significantly, our experiments showed that the plant progeny continued to exhibit the same nitrogen preference as the parent plants in the field, even when removed from their native environment and the nitrogen source was changed dramatically. The climatic constraint of nitrogen uptake preference is likely influenced by ammonium/nitrate ratios in the native habitats of the plants. The constancy in nitrogen preference has important implications in predicting the success of plant communities in their response to climate change, to seed bank use and to reforestation efforts. PMID:21118424

  4. Biodegradation of 2,4-dinitrotoluene by different plant species.

    PubMed

    Podlipná, Radka; Pospíšilová, Blanka; Vaněk, Tomáš

    2015-02-01

    Over the past century, rapid growth of population, mining and industrialization significantly contributed to extensive soil, air and water contamination. The 2,4-dinitrotoluene (2,4-DNT), used mostly as explosive, belongs to the hazardous xenobiotics. Soils and waters contaminated with 2,4-DNT may be cleaned by phytoremediation using suitable plant species. The ability of crop plants (hemp, flax, sunflower and mustard) to germinate and grow on soils contaminated with 2,4-DNT was compared. Stimulation of their growth was found at 0.252 mg/g 2,4-DNT. The lethal concentration for the growth for these species was around 1 mg/g. In hydropony, the above mentioned species were able to survive 200 mg/l 2,4-DNT, the concentration close to maximal solubility of 2,4-DNT in water. Metabolism of 2,4-DNT was tested using suspension culture of soapwort and reed. The degradation products 2-aminonitrotoluene and 4-aminonitrotoluene were found both in the medium and in the acetone extract of plant cells. The test showed that the toxicity of these metabolites was higher than the toxicity of the parent compound, but 2,4-diaminotoluene, the product of next reduction step, was less toxic in the concentration range tested (0-200 mg/l). PMID:25463853

  5. Consequences of plant invasions on compartmentalization and species' roles in plant-pollinator networks.

    PubMed

    Albrecht, Matthias; Padrón, Benigno; Bartomeus, Ignasi; Traveset, Anna

    2014-08-01

    Compartmentalization-the organization of ecological interaction networks into subsets of species that do not interact with other subsets (true compartments) or interact more frequently among themselves than with other species (modules)-has been identified as a key property for the functioning, stability and evolution of ecological communities. Invasions by entomophilous invasive plants may profoundly alter the way interaction networks are compartmentalized. We analysed a comprehensive dataset of 40 paired plant-pollinator networks (invaded versus uninvaded) to test this hypothesis. We show that invasive plants have higher generalization levels with respect to their pollinators than natives. The consequences for network topology are that-rather than displacing native species from the network-plant invaders attracting pollinators into invaded modules tend to play new important topological roles (i.e. network hubs, module hubs and connectors) and cause role shifts in native species, creating larger modules that are more connected among each other. While the number of true compartments was lower in invaded compared with uninvaded networks, the effect of invasion on modularity was contingent on the study system. Interestingly, the generalization level of the invasive plants partially explains this pattern, with more generalized invaders contributing to a lower modularity. Our findings indicate that the altered interaction structure of invaded networks makes them more robust against simulated random secondary species extinctions, but more vulnerable when the typically highly connected invasive plants go extinct first. The consequences and pathways by which biological invasions alter the interaction structure of plant-pollinator communities highlighted in this study may have important dynamical and functional implications, for example, by influencing multi-species reciprocal selection regimes and coevolutionary processes. PMID:24943368

  6. Traffic noise affects forest bird species in a protected tropical forest.

    PubMed

    Arévalo, J Edgardo; Newhard, Kimberly

    2011-06-01

    have conservation as well as management implications. A decrease in bird species richness and bird abundance due to intrusive road noise could negatively affect the use of trails by visitors. Alternatives for noise attenuation in the affected forest area include the enforcement of speed limits and the planting of live barriers. PMID:21717861

  7. Reactive oxygen species, essential molecules, during plant-pathogen interactions.

    PubMed

    Camejo, Daymi; Guzmán-Cedeño, Ángel; Moreno, Alexander

    2016-06-01

    Reactive oxygen species (ROS) are continually generated as a consequence of the normal metabolism in aerobic organisms. Accumulation and release of ROS into cell take place in response to a wide variety of adverse environmental conditions including salt, temperature, cold stresses and pathogen attack, among others. In plants, peroxidases class III, NADPH oxidase (NOX) locates in cell wall and plasma membrane, respectively, may be mainly enzymatic systems involving ROS generation. It is well documented that ROS play a dual role into cells, acting as important signal transduction molecules and as toxic molecules with strong oxidant power, however some aspects related to its function during plant-pathogen interactions remain unclear. This review focuses on the principal enzymatic systems involving ROS generation addressing the role of ROS as signal molecules during plant-pathogen interactions. We described how the chloroplasts, mitochondria and peroxisomes perceive the external stimuli as pathogen invasion, and trigger resistance response using ROS as signal molecule. PMID:26950921

  8. Sulphur phytoaccumulation in plant species characteristic of Gypsiferous soils.

    PubMed

    Ruiz, Juan M; López-Cantarero, Inmaculada; Rivero, Rosa M; Romero, Luis

    2003-01-01

    The SO4= toxicity in gypsiferous soils, which represent more than 100 million hectares worldwide, constitutes one of the major problems limiting world agricultural output. Currently, phytoremediation of SO4= is regarded, from agricultural and environmental standpoints, as one of the most effective alternatives for the decontamination and recovery of these soils. In this study, we analyzed the behavior of five plant species characteristic of gypsiferous soils (Gypsophila struthium, Helianthemun alypoides, H. squamatum, H. syriacum, and Lepidium subulatum) in order to establish the variability of these plants in terms of S-extraction mechanisms. Our results indicate that the species best adapted and with the densest population was Lepidium subulatum. This plant showed the highest concentration of total S and the greatest organic S, as well as the highest levels of amino acids and proteins. In this study, we propose that the incorporation of S into organic compounds is the essential metabolic process determining the tolerance of Lepidium subulatum to gypsiferous soils. In conclusion, the foliar accumulation of organic S could be defined a priori as one of the key characteristics in developing plants with a potential for regenerating zones with high SO4= concentrations. PMID:14750428

  9. ANTIFUNGAL POTENTIAL OF PLANT SPECIES FROM BRAZILIAN CAATINGA AGAINST DERMATOPHYTES.

    PubMed

    Biasi-Garbin, Renata Perugini; Demitto, Fernanda de Oliveira; Amaral, Renata Claro Ribeiro do; Ferreira, Magda Rhayanny Assunção; Soares, Luiz Alberto Lira; Svidzinski, Terezinha Inez Estivalet; Baeza, Lilian Cristiane; Yamada-Ogatta, Sueli Fumie

    2016-01-01

    Trichophyton rubrum and Trichophyton mentagrophytes complex, or Trichophyton spp. are the main etiologic agents of dermatophytosis, whose treatment is limited by the high cost of antifungal treatments, their various side effects, and the emergence of resistance amongst these species. This study evaluated the in vitro antidermatophytic activity of 23 crude extracts from nine plant species of semiarid vegetation (caatinga) found in Brazil. The extracts were tested at concentrations ranging from 1.95 to 1,000.0 mg/mL by broth microdilution assay against the reference strains T. rubrum ATCC 28189 and T. mentagrophytes ATCC 11481, and 33 clinical isolates of dermatophytes. All plants showed a fungicidal effect against both fungal species, with MIC/MFC values of the active extracts ranging from 15.6 to 250.0 µg/mL. Selected extracts of Eugenia uniflora (AcE), Libidibia ferrea (AE), and Persea americana (AcE) also exhibited a fungicidal effect against all clinical isolates of T. rubrum and T. mentagrophytes complex. This is the first report of the antifungal activity of Schinus terebinthifolius, Piptadenia colubrina, Parapiptadenia rigida, Mimosa ophthalmocentra, and Persea americana against both dermatophyte species. PMID:27007561

  10. Unmanned Aerial Vehicles for Alien Plant Species Detection and Monitoring

    NASA Astrophysics Data System (ADS)

    Dvořák, P.; Müllerová, J.; Bartaloš, T.; Brůna, J.

    2015-08-01

    Invasive species spread rapidly and their eradication is difficult. New methods enabling fast and efficient monitoring are urgently needed for their successful control. Remote sensing can improve early detection of invading plants and make their management more efficient and less expensive. In an ongoing project in the Czech Republic, we aim at developing innovative methods of mapping invasive plant species (semi-automatic detection algorithms) by using purposely designed unmanned aircraft (UAV). We examine possibilities for detection of two tree and two herb invasive species. Our aim is to establish fast, repeatable and efficient computer-assisted method of timely monitoring, reducing the costs of extensive field campaigns. For finding the best detection algorithm we test various classification approaches (object-, pixel-based and hybrid). Thanks to its flexibility and low cost, UAV enables assessing the effect of phenological stage and spatial resolution, and is most suitable for monitoring the efficiency of eradication efforts. However, several challenges exist in UAV application, such as geometrical and radiometric distortions, high amount of data to be processed and legal constrains for the UAV flight missions over urban areas (often highly invaded). The newly proposed UAV approach shall serve invasive species researchers, management practitioners and policy makers.

  11. ANTIFUNGAL POTENTIAL OF PLANT SPECIES FROM BRAZILIAN CAATINGA AGAINST DERMATOPHYTES

    PubMed Central

    BIASI-GARBIN, Renata Perugini; DEMITTO, Fernanda de Oliveira; do AMARAL, Renata Claro Ribeiro; FERREIRA, Magda Rhayanny Assunção; SOARES, Luiz Alberto Lira; SVIDZINSKI, Terezinha Inez Estivalet; BAEZA, Lilian Cristiane; YAMADA-OGATTA, Sueli Fumie

    2016-01-01

    Trichophyton rubrum and Trichophyton mentagrophytes complex, or Trichophyton spp. are the main etiologic agents of dermatophytosis, whose treatment is limited by the high cost of antifungal treatments, their various side effects, and the emergence of resistance amongst these species. This study evaluated the in vitro antidermatophytic activity of 23 crude extracts from nine plant species of semiarid vegetation (caatinga) found in Brazil. The extracts were tested at concentrations ranging from 1.95 to 1,000.0 mg/mL by broth microdilution assay against the reference strains T. rubrum ATCC 28189 and T. mentagrophytesATCC 11481, and 33 clinical isolates of dermatophytes. All plants showed a fungicidal effect against both fungal species, with MIC/MFC values of the active extracts ranging from 15.6 to 250.0 µg/mL. Selected extracts of Eugenia uniflora (AcE), Libidibia ferrea (AE), and Persea americana (AcE) also exhibited a fungicidal effect against all clinical isolates of T. rubrum and T. mentagrophytes complex. This is the first report of the antifungal activity of Schinus terebinthifolius, Piptadenia colubrina, Parapiptadenia rigida, Mimosa ophthalmocentra, and Persea americana against both dermatophyte species. PMID:27007561

  12. Climate change hampers endangered species through intensified moisture-related plant stresses

    NASA Astrophysics Data System (ADS)

    (Ruud) Bartholomeus, R. P.; (Flip) Witte, J. P. M.; (Peter) van Bodegom, P. M.; (Jos) van Dam, J. C.; (Rien) Aerts, R.

    2010-05-01

    With recent climate change, extremes in meteorological conditions are forecast and observed to increase globally, and to affect vegetation composition. More prolonged dry periods will alternate with more intensive rainfall events, both within and between years, which will change soil moisture dynamics. In temperate climates, soil moisture, in concert with nutrient availability and soil acidity, is the most important environmental filter in determining local plant species composition, as it determines the availability of both oxygen and water to plant roots. These resources are indispensable for meeting the physiological demands of plants. The consequences of climate change for our natural environment are among the most pressing issues of our time. The international research community is beginning to realise that climate extremes may be more powerful drivers of vegetation change and species extinctions than slow-and-steady climatic changes, but the causal mechanisms of such changes are presently unknown. The roles of amplitudes in water availability as drivers of vegetation change have been particularly elusive owing to the lack of integration of the key variables involved. Here we show that the combined effect of increased rainfall variability, temperature and atmospheric CO2-concentration will lead to an increased variability in both wet and dry extremes in stresses faced by plants (oxygen and water stress, respectively). We simulated these plant stresses with a novel, process-based approach, incorporating in detail the interacting processes in the soil-plant-atmosphere interface. In order to quantify oxygen and water stress with causal measures, we focused on interacting meteorological, soil physical, microbial, and plant physiological processes in the soil-plant-atmosphere system. The first physiological process inhibited at high soil moisture contents is plant root respiration, i.e. oxygen consumption in the roots, which responds to increased temperatures. High

  13. Valuing the Endangered Species Antirrhinum lopesianum: Neuroprotective Activities and Strategies for in vitro Plant Propagation

    PubMed Central

    Gomes, Andreia; Fortalezas, Sofia; Pimpão, Rui; Figueira, Inês; Maroco, João; Aguiar, Carlos; Ferreira, Ricardo B.; Miguel, Célia; Santos, Cláudia N.

    2013-01-01

    Plant phytochemicals are described as possessing considerable neuroprotective properties, due to radical scavenging capacity and acetylcholinesterase inhibitory activity, important bioactivities in neurodegeneration. Antirrhinum lopesianum is a rare endemism from the Iberian Peninsula, occurring at the northeastern border between Portugal and Spain. It is classified as Endangered, due to its highly fragmented geographical occupation, facing a high risk of extinction in the Portuguese territory, within 20 years. Here, we describe for the first time the chemical characterization of extracts of the species concerning total phenol content, flavonoid content and antioxidant properties. The profile of high performance liquid chromatography with diode array detector (HPLC-DAD) of the polyphenol-enriched fraction of plant extracts was also performed, showing the great potential of the species as a source of bioactive phytochemical compounds. A. lopesianum’s potential for neuroprotection was revealed by a significant acetylcholinesterase inhibitory activity and also by a neuroprotective effect on a human cell model of neurodegeneration. Moreover, this is the first report describing a successful procedure for the in vitro propagation of this endangered species. The comparison of phenolic content and the HPLC-DAD profile of wild and in vitro propagated plants revealed that in vitro plants maintain the ability to produce secondary metabolites, but the profiles are differentially affected by the growth regulators. The results presented here greatly contribute to the value for this species regarding its potential as a source of phytochemicals with prospective neuroprotective health benefits. PMID:26784465

  14. Valuing the Endangered Species Antirrhinum lopesianum: Neuroprotective Activities and Strategies for in vitro Plant Propagation.

    PubMed

    Gomes, Andreia; Fortalezas, Sofia; Pimpão, Rui; Figueira, Inês; Maroco, João; Aguiar, Carlos; Ferreira, Ricardo B; Miguel, Célia; Santos, Cláudia N

    2013-01-01

    Plant phytochemicals are described as possessing considerable neuroprotective properties, due to radical scavenging capacity and acetylcholinesterase inhibitory activity, important bioactivities in neurodegeneration. Antirrhinum lopesianum is a rare endemism from the Iberian Peninsula, occurring at the northeastern border between Portugal and Spain. It is classified as Endangered, due to its highly fragmented geographical occupation, facing a high risk of extinction in the Portuguese territory, within 20 years. Here, we describe for the first time the chemical characterization of extracts of the species concerning total phenol content, flavonoid content and antioxidant properties. The profile of high performance liquid chromatography with diode array detector (HPLC-DAD) of the polyphenol-enriched fraction of plant extracts was also performed, showing the great potential of the species as a source of bioactive phytochemical compounds. A. lopesianum's potential for neuroprotection was revealed by a significant acetylcholinesterase inhibitory activity and also by a neuroprotective effect on a human cell model of neurodegeneration. Moreover, this is the first report describing a successful procedure for the in vitro propagation of this endangered species. The comparison of phenolic content and the HPLC-DAD profile of wild and in vitro propagated plants revealed that in vitro plants maintain the ability to produce secondary metabolites, but the profiles are differentially affected by the growth regulators. The results presented here greatly contribute to the value for this species regarding its potential as a source of phytochemicals with prospective neuroprotective health benefits. PMID:26784465

  15. Chemical recognition of partner plant species by foundress ant queens in Macaranga-Crematogaster myrmecophytism.

    PubMed

    Inui, Y; Itioka, T; Murase, K; Yamaoka, R; Itino, T

    2001-10-01

    The partnership in the Crematogaster-Macaranga ant-plant interaction is highly species-specific. Because a mutualistic relationship on a Macaranga plant starts with colonization by a foundress queen of a partner Crematogaster species, we hypothesized that the foundress queens select their partner plant species by chemical recognition. We tested this hypothesis with four sympatric Macaranga species and their Crematogaster plant-ant species. We demonstrated that foundress Crematogaster queens can recognize their partner Macaranga species by contact with the surface of the seedlings, that they can recognize compounds from the stem surface of seedlings of their partner plant species, and that the gas chromatographic profiles are characteristic of the plant species. These findings support the hypothesis that foundress queens of the Crematogaster plant-ant species select their partner Macaranga species by recognizing nonvolatile chemical characteristics of the stem surfaces of seedlings. PMID:11710609

  16. Ecological context and metapopulation dynamics affect sex-ratio variation among dioecious plant populations

    PubMed Central

    Field, David L.; Pickup, Melinda; Barrett, Spencer C. H.

    2013-01-01

    Background and Aims Populations of dioecious flowering plants commonly exhibit heterogeneity in sex ratios and deviations from the equilibrium expectation of equal numbers of females and males. Yet the role of ecological and demographic factors in contributing towards biased sex ratios is currently not well understood. Methods Species-level studies from the literature were analysed to investigate ecological correlates of among-population sex-ratio variation and metapopulation models and empirical data were used to explore the influence of demography and non-equilibrium conditions on flowering sex ratios. Key Results The survey revealed significant among-population heterogeneity in sex ratios and this was related to the degree of sampling effort. For some species, sex-ratio bias was associated with the proportion of non-reproductive individuals, with greater male bias in populations with a lower proportion of individuals that were flowering. Male-biased ratios were also found at higher altitudes and latitudes, and in more xeric sites. Simulations and empirical data indicated that clonal species exhibited greater heterogeneity in sex ratios than non-clonal species as a result of their slower approach to equilibrium. The simulations also indicated the importance of interactions between reproductive mode and founder effects, with greater departures from equilibrium in clonal populations with fewer founding individuals. Conclusions The results indicate that sex-based differences in costs of reproduction and non-equilibrium conditions can each play important roles in affecting flowering sex ratios in populations of dioecious plants. PMID:23444124

  17. Proliferation of diversified clostridial species during biological soil disinfestation incorporated with plant biomass under various conditions.

    PubMed

    Mowlick, Subrata; Takehara, Toshiaki; Kaku, Nobuo; Ueki, Katsuji; Ueki, Atsuko

    2013-09-01

    Biological soil disinfestation (BSD) involves the anaerobic decomposition of plant biomass by microbial communities leading to control of plant pathogens. We analyzed bacterial communities in soil of a model experiment of BSD, as affected by biomass incorporation under various conditions, to find out the major anaerobic bacterial groups which emerged after BSD treatments. The soil was treated with Brassica juncea plants, wheat bran, or Avena strigosa plants, irrigated at 20 or 30 % moisture content and incubated at 25-30 °C for 17 days. The population of Fusarium oxysporum f. sp. spinaciae incorporated at the start of the experiment declined markedly for some BSD conditions and rather high concentrations of acetate and butyrate were detected from these BSD-treated soils. The polymerase chain reaction-denaturing gradient gel electrophoresis analysis based on the V3 region of 16S rRNA gene sequences from the soil DNA revealed that bacterial profiles greatly changed according to the treatment conditions. Based on the clone library analysis, phylogenetically diverse clostridial species appeared exceedingly dominant in the bacterial community of BSD soil incorporated with Brassica plants or wheat bran, in which the pathogen was suppressed completely. Species in the class Clostridia such as Clostridium saccharobutylicum, Clostridium acetobutylicum, Clostridium xylanovorans, Oxobacter pfennigii, Clostridium pasteurianum, Clostridium sufflavum, Clostridium cylindrosporum, etc. were commonly recognized as closely related species of the dominant clone groups from these soil samples. PMID:23132344

  18. Species-Specific Seed Dispersal in an Obligate Ant-Plant Mutualism

    PubMed Central

    Youngsteadt, Elsa; Baca, Jeniffer Alvarez; Osborne, Jason; Schal, Coby

    2009-01-01

    Throughout lowland Amazonia, arboreal ants collect seeds of specific plants and cultivate them in nutrient-rich nests, forming diverse yet obligate and species-specific symbioses called Neotropical ant-gardens (AGs). The ants depend on their symbiotic plants for nest stability, and the plants depend on AGs for substrate and nutrients. Although the AGs are limited to specific participants, it is unknown at what stage specificity arises, and seed fate pathways in AG epiphytes are undocumented. Here we examine the specificity of the ant-seed interaction by comparing the ant community observed at general food baits to ants attracted to and removing seeds of the AG plant Peperomia macrostachya. We also compare seed removal rates under treatments that excluded vertebrates, arthropods, or both. In the bait study, only three of 70 ant species collected P. macrostachya seeds, and 84% of observed seed removal by ants was attributed to the AG ant Camponotus femoratus. In the exclusion experiment, arthropod exclusion significantly reduced seed removal rates, but vertebrate exclusion did not. We provide the most extensive empirical evidence of species specificity in the AG mutualism and begin to quantify factors that affect seed fate in order to understand conditions that favor its departure from the typical diffuse model of plant-animal mutualism. PMID:19194502

  19. Species-specific seed dispersal in an obligate ant-plant mutualism.

    PubMed

    Youngsteadt, Elsa; Baca, Jeniffer Alvarez; Osborne, Jason; Schal, Coby

    2009-01-01

    Throughout lowland Amazonia, arboreal ants collect seeds of specific plants and cultivate them in nutrient-rich nests, forming diverse yet obligate and species-specific symbioses called Neotropical ant-gardens (AGs). The ants depend on their symbiotic plants for nest stability, and the plants depend on AGs for substrate and nutrients. Although the AGs are limited to specific participants, it is unknown at what stage specificity arises, and seed fate pathways in AG epiphytes are undocumented. Here we examine the specificity of the ant-seed interaction by comparing the ant community observed at general food baits to ants attracted to and removing seeds of the AG plant Peperomia macrostachya. We also compare seed removal rates under treatments that excluded vertebrates, arthropods, or both. In the bait study, only three of 70 ant species collected P. macrostachya seeds, and 84% of observed seed removal by ants was attributed to the AG ant Camponotus femoratus. In the exclusion experiment, arthropod exclusion significantly reduced seed removal rates, but vertebrate exclusion did not. We provide the most extensive empirical evidence of species specificity in the AG mutualism and begin to quantify factors that affect seed fate in order to understand conditions that favor its departure from the typical diffuse model of plant-animal mutualism. PMID:19194502

  20. Honeydew feeding in the solitary bee Osmia bicornis as affected by aphid species and nectar availability.

    PubMed

    Konrad, Roger; Wäckers, Felix L; Romeis, Jörg; Babendreier, Dirk

    2009-12-01

    Like honey bees (Apis mellifera), non-Apis bees could exploit honeydew as a carbohydrate source. In addition to providing carbohydrates, this may expose them to potentially harmful plant products secreted in honeydew. However, knowledge on honeydew feeding by solitary bees is very scarce. Here we determine whether the polylectic solitary bee Osmia bicornis (=O. rufa) collects honeydew under semi-field conditions, and whether this is affected by aphid species and presence of floral nectar. Bees were provided with oilseed rape plants containing flowers and/or colonies of either Myzus persicae or Brevicoryne brassicae. We used the total sugar level of the bee crop as a measure of the individual's nutritional state and the oligosaccharide erlose as indicator for honeydew consumption. Erlose was present in honeydews from both aphid species, while absent in oilseed rape nectar, nor being synthesized by O. bicornis. When bees were confined to a single honeydew type as the only carbohydrate source, consumption of M. persicae honeydew was confirmed for 47% of the bees and consumption of B. brassicae honeydew for only 3%. Increased mortality in the latter treatment provided further evidence that B. brassicae honeydew is an unsuitable food source for O. bicornis. All bees that were given the choice between honeydew and floral nectar showed significantly increased total sugar levels. However, the fact that no erlose was detected in these bees indicates that honeydew was not consumed when suitable floral nectar was available. This study demonstrates that honeydew exploitation by O. bicornis is dependent on honeydew type and the presence of floral nectar. PMID:19699745

  1. Native Americans' choice of species for medicinal use is dependent on plant family: confirmation with meta-significance analysis.

    PubMed

    Moerman, Daniel E; Estabrook, George F

    2003-07-01

    We test the hypothesis that the choice by traditional people of species of plants for medicinal use does or does not depend on the families to which those species belong. Our geographic context is continental North America north of the Rio Grande River. Our plant context is flowering plants. Our ethnological context is Native American traditions. Our null hypothesis is that the probability of any species being medicinal is the fraction of all species that are medicinal, no matter the family to which that species may belong. Classical statistical techniques and the experience of ethnobiologists had already made it clear that among very large plant families, most have either very many or very few medicinal species. Here we use intense computation to simulate thousands of data sets to create predictions to compare with the observed data for medium and small families. Our results clearly show that a surprising number of medium and small families also have very many or very few medicinal species. Recent molecular, fossil and cytological studies have confirmed the evolutionary naturalness of most plant families. This suggests that species in the same family may have inherited from common ancestors similar ecological adaptations, such as ways to protect themselves from herbivores, pathogens or decomposers. Some of these adaptations affect the physiology of the attacking organisms, suggesting an explanation for the clear preferences of Native American traditions to choose medicinal species from some families much more than from others, regardless of the size of those families. PMID:12787954

  2. Invasive Plant Species: Inventory, Mapping, and Monitoring - A National Strategy

    USGS Publications Warehouse

    Ludke, J. Larry; D'Erchia, Frank; Coffelt, Jan; Hanson, Leanne

    2002-01-01

    America is under siege by invasive species of plants and animals, and by diseases. The current environmental, economic, and health-related costs of invasive species could exceed $138 billion per year-more than all other natural disasters combined. Notorious examples include West Nile virus, Dutch elm disease, chestnut blight, and purple loose- strife in the Northeast; kudzu, Brazilian peppertree, water hyacinth, nutria, and fire ants in the Southeast; zebra mussels, leafy spurge, and Asian long-horn beetles in the Midwest; salt cedar, Russian olive, and Africanized bees in the Southwest; yellow star thistle, European wild oats, oak wilt disease, Asian clams, and white pine blister rust in California; cheatgrass, various knapweeds, and thistles in the Great Basin; whirling disease of salmonids in the Northwest; hundreds of invasive species from microbes to mammals in Hawaii; and the brown tree snake in Guam. Thousands of species from other countries are introduced intentionally or accidentally into the United States each year. Based on past experience, 10-15 percent can be expected to establish free-living populations and about 1 percent can be expected to cause significant impacts to ecosystems, native species, economic productivity, and (or) human health.

  3. Effects of ‘Target’ Plant Species Body Size on Neighbourhood Species Richness and Composition in Old-Field Vegetation

    PubMed Central

    Schamp, Brandon S.; Aarssen, Lonnie W.; Wight, Stephanie

    2013-01-01

    Competition is generally regarded as an important force in organizing the structure of vegetation, and evidence from several experimental studies of species mixtures suggests that larger mature plant size elicits a competitive advantage. However, these findings are at odds with the fact that large and small plant species generally coexist, and relatively smaller species are more common in virtually all plant communities. Here, we use replicates of ten relatively large old-field plant species to explore the competitive impact of target individual size on their surrounding neighbourhoods compared to nearby neighbourhoods of the same size that are not centred by a large target individual. While target individuals of the largest of our test species, Centaurea jacea L., had a strong impact on neighbouring species, in general, target species size was a weak predictor of the number of other resident species growing within its immediate neighbourhood, as well as the number of resident species that were reproductive. Thus, the presence of a large competitor did not restrict the ability of neighbouring species to reproduce. Lastly, target species size did not have any impact on the species size structure of neighbouring species; i.e. they did not restrict smaller, supposedly poorer competitors, from growing and reproducing close by. Taken together, these results provide no support for a size-advantage in competition restricting local species richness or the ability of small species to coexist and successfully reproduce in the immediate neighbourhood of a large species. PMID:24349177

  4. Soil modification by invasive plants: Effects on native and invasive species of mixed-grass prairies

    USGS Publications Warehouse

    Jordan, N.R.; Larson, D.L.; Huerd, S.C.

    2008-01-01

    Invasive plants are capable of modifying attributes of soil to facilitate further invasion by conspecifics and other invasive species. We assessed this capability in three important plant invaders of grasslands in the Great Plains region of North America: leafy spurge (Euphorbia esula), smooth brome (Bromus inermis) and crested wheatgrass (Agropyron cristatum). In a glasshouse, these three invasives or a group of native species were grown separately through three cycles of growth and soil conditioning in both steam-pasteurized and non-pasteurized soils, after which we assessed seedling growth in these soils. Two of the three invasive species, Bromus and Agropyron, exhibited significant self-facilitation via soil modification. Bromus and Agropyron also had significant facilitative effects on other invasives via soil modification, while Euphorbia had significant antagonistic effects on the other invasives. Both Agropyron and Euphorbia consistently suppressed growth of two of three native forbs, while three native grasses were generally less affected. Almost all intra- and interspecific effects of invasive soil conditioning were dependent upon presence of soil biota from field sites where these species were successful invaders. Overall, these results suggest that that invasive modification of soil microbiota can facilitate plant invasion directly or via 'cross-facilitation' of other invasive species, and moreover has potential to impede restoration of native communities after removal of an invasive species. However, certain native species that are relatively insensitive to altered soil biota (as we observed in the case of the forb Linum lewisii and the native grasses), may be valuable as 'nurse'species in restoration efforts. ?? 2007 Springer Science+Business Media B.V.

  5. Seed trait-mediated selection by rodents affects mutualistic interactions and seedling recruitment of co-occurring tree species.

    PubMed

    Zhang, Hongmao; Yan, Chuan; Chang, Gang; Zhang, Zhibin

    2016-02-01

    As mutualists, seed dispersers may significantly affect mutualistic interactions and seedling recruitment of sympatric plants that share similar seed dispersers, but studies are rare. Here, we compared seed dispersal fitness in two co-occurring plant species (Armeniaca sibirica and Amygdalus davidiana) that inhabit warm temperate deciduous forest in northern China. We tested the hypothesis that seed trait-mediated selection by rodents may influence mutualistic interactions with rodents and then seedling establishment of co-occurring plant species. A. davidiana seeds are larger and harder (thick endocarps) than A. sibirica seeds, but they have similar levels of nutrients (crude fat, crude protein), caloric value and tannin. More A. sibirica seedlings are found in the field. Semi-natural enclosure tests indicated that the two seed species were both harvested by the same six rodent species, but that A. sibirica had mutualistic interactions (scatter hoarding) with four rodent species (Apodemus peninsulae, A. agrarius, Sciurotamias davidianus, Tamias sibiricus), and A. davidiana with only one (S. davidianus). Tagged seed dispersal experiments in the field indicated that more A. sibirica seeds were scatter-hoarded by rodents, and more A. sibirica seeds survived to the next spring and became seedlings. A. sibirica seeds derive more benefit from seed dispersal by rodents than A. davidiana seeds, particularly in years with limited seed dispersers, which well explained the higher seedling recruitment of A. sibirica compared with that of A. davidiana under natural conditions. Our results suggest that seed dispersers may play a significant role in seedling recruitment and indirect competition between co-occurring plant species. PMID:26546082

  6. Genetic control of invasive plants species using selfish genetic elements

    PubMed Central

    Hodgins, Kathryn A; Rieseberg, Loren; Otto, Sarah P

    2009-01-01

    Invasive plants cause substantial environmental damage and economic loss. Here, we explore the possibility that a selfish genetic element found in plants called cytoplasmic male sterility (CMS) could be exploited for weed control. CMS is caused by mutations in the mitochondrial genome that sterilize male reproductive organs. We developed an analytical model and a spatial simulation to assess the use of CMS alleles to manage weed populations. Specifically, we examined how fertility, selfing, pollen limitation and dispersal influenced extinction rate and time until extinction in populations where CMS arises. We found that the introduction of a CMS allele can cause rapid population extinction, but only under a restricted set of conditions. Both models suggest that the CMS strategy will be appropriate for species where pollen limitation is negligible, inbreeding depression is high and the fertility advantage of females over hermaphrodites is substantial. In general, spatial structure did not have a strong influence on the simulation outcome, although low pollen dispersal and intermediate levels of seed dispersal tended to reduce population extinction rates. Given these results, the introduction of CMS alleles into a population of invasive plants probably represents an effective control method for only a select number of species. PMID:25567898

  7. Hydroperiod regime controls the organization of plant species in wetlands.

    PubMed

    Foti, Romano; del Jesus, Manuel; Rinaldo, Andrea; Rodriguez-Iturbe, Ignacio

    2012-11-27

    With urban, agricultural, and industrial needs growing throughout the past decades, wetland ecosystems have experienced profound changes. Most critically, the biodiversity of wetlands is intimately linked to its hydrologic dynamics, which in turn are being drastically altered by ongoing climate changes. Hydroperiod regimes, e.g., percentage of time a site is inundated, exert critical control in the creation of niches for different plant species in wetlands. However, the spatial signatures of the organization of plant species in wetlands and how the different drivers interact to yield such signatures are unknown. Focusing on Everglades National Park (ENP) in Florida, we show here that cluster sizes of each species follow a power law probability distribution and that such clusters have well-defined fractal characteristics. Moreover, we individuate and model those signatures via the interplay between global forcings arising from the hydroperiod regime and local controls exerted by neighboring vegetation. With power law clustering often associated with systems near critical transitions, our findings are highly relevant for the management of wetland ecosystems. In addition, our results show that changes in climate and land management have a quantifiable predictable impact on the type of vegetation and its spatial organization in wetlands. PMID:23150589

  8. Hydroperiod regime controls the organization of plant species in wetlands

    PubMed Central

    Foti, Romano; del Jesus, Manuel; Rinaldo, Andrea; Rodriguez-Iturbe, Ignacio

    2012-01-01

    With urban, agricultural, and industrial needs growing throughout the past decades, wetland ecosystems have experienced profound changes. Most critically, the biodiversity of wetlands is intimately linked to its hydrologic dynamics, which in turn are being drastically altered by ongoing climate changes. Hydroperiod regimes, e.g., percentage of time a site is inundated, exert critical control in the creation of niches for different plant species in wetlands. However, the spatial signatures of the organization of plant species in wetlands and how the different drivers interact to yield such signatures are unknown. Focusing on Everglades National Park (ENP) in Florida, we show here that cluster sizes of each species follow a power law probability distribution and that such clusters have well-defined fractal characteristics. Moreover, we individuate and model those signatures via the interplay between global forcings arising from the hydroperiod regime and local controls exerted by neighboring vegetation. With power law clustering often associated with systems near critical transitions, our findings are highly relevant for the management of wetland ecosystems. In addition, our results show that changes in climate and land management have a quantifiable predictable impact on the type of vegetation and its spatial organization in wetlands. PMID:23150589

  9. Multiple phenological responses to climate change among 42 plant species in Xi'an, China

    NASA Astrophysics Data System (ADS)

    Dai, Junhu; Wang, Huanjiong; Ge, Quansheng

    2013-09-01

    Phenological data of 42 woody plants in a temperate deciduous forest from the Chinese Phenological Observation Network (CPON) and the corresponding meteorological data from 1963 to 2011 in Xi'an, Shaanxi Province, China were collected and analyzed. The first leaf date (FLD), leaf coloring date (LCD) and first flower date (FFD) are revealed as strong biological signals of climatic change. The FLD, LCD and FFD of most species are sensitive to average temperature during a certain period before phenophase onset. Regional precipitation also has a significant impact on phenophases of about half of the species investigated. Affected by climate change, the FLD and FFD of these species have advanced by 5.54 days and 10.20 days on average during 2003-2011 compared with the period 1963-1996, respectively. Meanwhile, the LCD has delayed by 10.59 days, and growing season length has extended 16.13 days. Diverse responses of phenology commonly exist among different species and functional groups during the study period. Especially for FFD, the deviations between the above two periods ranged from -20.68 to -2.79 days; biotic pollination species showed a significantly greater advance than abiotic pollination species. These results were conducive to the understanding of possible changes in both the structure of plant communities and interspecific relationships in the context of climate change.

  10. Diet selection variation of a large herbivore in a feeding experiment with increasing species numbers and different plant functional group combinations

    NASA Astrophysics Data System (ADS)

    Wang, Ling; Wang, Deli; Liu, Jushan; Huang, Yue; Hodgkinson, Ken C.

    2011-05-01

    The grazing of domestic herbivores affects the biodiversity of rangeland. Knowledge on the feedback of changed plant diversity on diet selection by domestic herbivores is poor even though it is at the core of the effects of herbivores on biodiversity of rangeland. We investigated the influence of increasing species numbers and different plant functional group combinations on the dynamics of diet preference and foraging selectivity by sheep. Sheep were given 16 consecutive meals at each sequential level of plant species richness. Three combinations of species, selected for functional types, were presented to sheep. The results showed that sheep did not usually maintain stable diet preference patterns for the 16 consecutive meals of the plant species combinations offered. The magnitude of meal to meal variation in the preference index for each species increased significantly with plant species richness. There was no obvious effect of post-ingestive learning on the meal variation in diet preference. The magnitude of sheep foraging selectivity within each meal significantly reduced with plant species richness. These results indicated that, when plant diversity was high, the diet selection pattern of herbivore may be more beneficial to maintaining high plant diversity. Thus, there may be a weak positive feedback between plant species richness and herbivore foraging. We suggested that increasing plant diversity, especially for plant functional group diversity, can reduce herbivore selectivity and promote more uniform use of different plant species in rangeland.

  11. Plot shape effects on plant species diversity measurements

    USGS Publications Warehouse

    Keeley, J.E.; Fotheringham, C.J.

    2005-01-01

    Question: Do rectangular sample plots record more plant species than square plots as suggested by both empirical and theoretical studies? Location: Grasslands, shrublands and forests in the Mediterranean-climate region of California, USA. Methods: We compared three 0.1-ha sampling designs that differed in the shape and dispersion of 1-m2 and 100-m2 nested subplots. We duplicated an earlier study that compared the Whittaker sample design, which had square clustered subplots, with the modified Whittaker design, which had dispersed rectangular subplots. To sort out effects of dispersion from shape we used a third design that overlaid square subplots on the modified Whittaker design. Also, using data from published studies we extracted species richness values for 400-m2 subplots that were either square or 1:4 rectangles partially overlaid on each other from desert scrub in high and low rainfall years, chaparral, sage scrub, oak savanna and coniferous forests with and without fire. Results: We found that earlier empirical reports of more than 30% greater richness with rectangles were due to the confusion of shape effects with spatial effects, coupled with the use of cumulative number of species as the metric for comparison. Average species richness was not significantly different between square and 1:4 rectangular sample plots at either 1-or 100-m2. Pairwise comparisons showed no significant difference between square and rectangular samples in all but one vegetation type, and that one exhibited significantly greater richness with squares. Our three intensive study sites appear to exhibit some level of self-similarity at the scale of 400 m2, but, contrary to theoretical expectations, we could not detect plot shape effects on species richness at this scale. Conclusions: At the 0.1-ha scale or lower there is no evidence that plot shape has predictable effects on number of species recorded from sample plots. We hypothesize that for the mediterranean-climate vegetation types

  12. Salt tolerant plants increase nitrogen removal from biofiltration systems affected by saline stormwater.

    PubMed

    Szota, Christopher; Farrell, Claire; Livesley, Stephen J; Fletcher, Tim D

    2015-10-15

    Biofiltration systems are used in urban areas to reduce the concentration and load of nutrient pollutants and heavy metals entering waterways through stormwater runoff. Biofilters can, however be exposed to salt water, through intrusion of seawater in coastal areas which could decrease their ability to intercept and retain pollutants. We measured the effect of adding saline stormwater on pollutant removal by six monocotyledonous species with different levels of salt-tolerance. Carex appressa, Carex bichenoviana, Ficinia nodosa, Gahnia filum, Juncus kraussii and Juncus usitatus were exposed to six concentrations of saline stormwater, equivalent to electrical conductivity readings of: 0.09, 2.3, 5.5, 10.4, 20.0 and 37.6 mS cm(-1). Salt-sensitive species: C. appressa, C. bichenoviana and J. usitatus did not survive ≥10.4 mS cm(-1), removing their ability to take up nitrogen (N). Salt-tolerant species, such as F. nodosa and J. kraussii, maintained N-removal even at the highest salt concentration. However, their levels of water stress and stomatal conductance suggest that N-removal would not be sustained at concentrations ≥10.4 mS cm(-1). Increasing salt concentration indirectly increased phosphorus (P) removal, by converting dissolved forms of P to particulate forms which were retained by filter media. Salt concentrations ≥10 mS cm(-1) also reduced removal efficiency of zinc, manganese and cadmium, but increased removal of iron and lead, regardless of plant species. Our results suggest that biofiltration systems exposed to saline stormwater ≤10 mS cm(-1) can only maintain N-removal when planted with salt-tolerant species, while P removal and immobilisation of heavy metals is less affected by species selection. PMID:26150068

  13. Monitoring the Impacts of Severe Drought on Plant Species in Southern California Chaparral

    NASA Astrophysics Data System (ADS)

    Dennison, P. E.; Coates, A.; Roberts, D. A.; Roth, K. L.

    2015-12-01

    Airborne imaging spectrometer and thermal infrared image data acquired for the Hyperspectral Infrared Imager (HyspIRI) preparatory campaign were used to measure changes in green vegetation fraction and land surface temperature for twelve dominant plant species affected by drought in the Santa Barbara region of California. Relative green vegetation fraction was calculated from seasonally-acquired Airborne Visible Infrared Imaging Spectrometer (AVIRIS) data using pre-drought 2011 AVIRIS data as a baseline. Land surface temperature was retrieved from MODIS-ASTER Simulator (MASTER) data. Deeply rooted tree species, tree species found on more mesic north-facing slopes, and tree species found in riparian areas had the least change in relative green vegetation fraction in 2013 and 2014 (e.g. QUAG and UMCA in the figure below). Coastal sage scrub and chaparral shrub species demonstrated greater variability as well as a long-term decline in relative green vegetation fraction. Three Ceanothus species (CECU, CEME, and CESP in the figure below) had more severe reductions in relative green vegetation fraction in comparison to another common chaparral shrub species, Adenostoma fasciculatum (ADFA). Species formed clusters in the space defined by land surface temperature and relative green vegetation fraction. Declining relative green vegetation fraction corresponded with increasing land surface temperature. Combined, routine acquisition of imaging spectrometer and thermal infrared imagery should provide new opportunities for monitoring drought impacts on ecosystems.

  14. Variation within and between Frankliniella Thrips Species in Host Plant Utilization

    PubMed Central

    Baez, Ignacio; Reitz, Stuart R.; Funderburk, Joseph E.; Olson, Steve M.

    2011-01-01

    Anthophilous flower thrips in the genus Frankliniella (Thysanoptera: Thripidae) exploit ephemeral plant resources and therefore must be capable of successfully locating appropriate hosts on a repeated basis, yet little is known of interspecific and intraspecific variation in responses to host plant type and nutritional quality. Field trials were conducted over two seasons to determine if the abundance of males and females of three common Frankliniella species, F. occidentalis (Pergande), F. tritici (Fitch) and F. bispinosa (Morgan), their larvae, and a key predator, Orius insidiosus (Say) (Hemiptera: Anthocoridae) were affected by host plant type and plant nutritional quality. Two host plants, pepper, Capsicum annuum L. (Solanales: Solanaceae) and tomato, Solanum lycopersicum L. that vary in suitability for these species were examined, and their nutritional quality was manipulated by applying three levels of nitrogen fertilization (101 kg/ha, 202 kg/ha, 404 kg/ha). F. occidentalis females were more abundant in pepper than in tomato, but males did not show a differential response. Both sexes of F. tritici and F. bispinosa were more abundant in tomato than in pepper. Larval thrips were more abundant in pepper than in tomato. Likewise, O. insidiosus females and nymphs were more abundant in pepper than in tomato. Only F. occidentalis females showed a distinct response to nitrogen fertilization, with abundance increasing with fertilization. These results show that host plant utilization patterns vary among Frankliniella spp. and should not be generalized from results of the intensively studied F. occidentalis. Given the different pest status of these species and their differential abundance in pepper and tomato, it is critical that scouting programs include species identifications for proper management. PMID:21539418

  15. The Gastropod Menace: Slugs on Brassica Plants Affect Caterpillar Survival through Consumption and Interference with Parasitoid Attraction.

    PubMed

    Desurmont, Gaylord A; Zemanova, Miriam A; Turlings, Ted C J

    2016-03-01

    Terrestrial molluscs and insect herbivores play a major role as plant consumers in a number of ecosystems, but their direct and indirect interactions have hardly been explored. The omnivorous nature of slugs makes them potential disrupters of predator-prey relationships, as a direct threat to small insects and through indirect, plant-mediated effects. Here, we examined the effects of the presence of two species of slugs, Arion rufus (native) and A. vulgaris (invasive) on the survivorship of young Pieris brassicae caterpillars when feeding on Brassica rapa plants, and on plant attractiveness to the main natural enemy of P. brassicae, the parasitoid Cotesia glomerata. In two separate predation experiments, caterpillar mortality was significantly higher on plants co-infested with A. rufus or A. vulgaris. Moreover, caterpillar mortality correlated positively with slug mass and leaf consumption by A. vulgaris. At the third trophic level, plants infested with slugs and plants co-infested with slugs and caterpillars were far less attractive to parasitoids than plants damaged by caterpillars only, independently of slug species. Chemical analyses confirmed that volatile emissions, which provide foraging cues for parasitoids, were strongly reduced in co-infested plants. Our study shows that the presence of slugs has the potential to affect insect populations, directly via consumptive effects, and indirectly via changes in plant volatiles that result in a reduced attraction of natural enemies. The fitness cost for P. brassicae imposed by increased mortality in presence of slugs may be counterbalanced by the benefit of escaping its parasitoids. PMID:27002323

  16. Telling plant species apart with DNA: from barcodes to genomes

    PubMed Central

    Li, De-Zhu; van der Bank, Michelle

    2016-01-01

    Land plants underpin a multitude of ecosystem functions, support human livelihoods and represent a critically important component of terrestrial biodiversity—yet many tens of thousands of species await discovery, and plant identification remains a substantial challenge, especially where material is juvenile, fragmented or processed. In this opinion article, we tackle two main topics. Firstly, we provide a short summary of the strengths and limitations of plant DNA barcoding for addressing these issues. Secondly, we discuss options for enhancing current plant barcodes, focusing on increasing discriminatory power via either gene capture of nuclear markers or genome skimming. The former has the advantage of establishing a defined set of target loci maximizing efficiency of sequencing effort, data storage and analysis. The challenge is developing a probe set for large numbers of nuclear markers that works over sufficient phylogenetic breadth. Genome skimming has the advantage of using existing protocols and being backward compatible with existing barcodes; and the depth of sequence coverage can be increased as sequencing costs fall. Its non-targeted nature does, however, present a major informatics challenge for upscaling to large sample sets. This article is part of the themed issue ‘From DNA barcodes to biomes’. PMID:27481790

  17. Telling plant species apart with DNA: from barcodes to genomes.

    PubMed

    Hollingsworth, Peter M; Li, De-Zhu; van der Bank, Michelle; Twyford, Alex D

    2016-09-01

    Land plants underpin a multitude of ecosystem functions, support human livelihoods and represent a critically important component of terrestrial biodiversity-yet many tens of thousands of species await discovery, and plant identification remains a substantial challenge, especially where material is juvenile, fragmented or processed. In this opinion article, we tackle two main topics. Firstly, we provide a short summary of the strengths and limitations of plant DNA barcoding for addressing these issues. Secondly, we discuss options for enhancing current plant barcodes, focusing on increasing discriminatory power via either gene capture of nuclear markers or genome skimming. The former has the advantage of establishing a defined set of target loci maximizing efficiency of sequencing effort, data storage and analysis. The challenge is developing a probe set for large numbers of nuclear markers that works over sufficient phylogenetic breadth. Genome skimming has the advantage of using existing protocols and being backward compatible with existing barcodes; and the depth of sequence coverage can be increased as sequencing costs fall. Its non-targeted nature does, however, present a major informatics challenge for upscaling to large sample sets.This article is part of the themed issue 'From DNA barcodes to biomes'. PMID:27481790

  18. Antimicrobial potentials of some plant species of the Bignoniaceae family.

    PubMed

    Binutu, O A; Lajubutu, B A

    1994-09-01

    The methanol extracts of the leaves and stem bark of four Bignoniaceae plants Jacaranda mimosifolia D. Dol., Tecoma stans Linn., Tabebuia rosea (Bertol) D.C., and Crescentia cujete Linn. were studied for their antimicrobial activity using a wide range of Gram-positive and Gram-negative bacteria and fungi. Extracts of both the leaves and stem bark of majority of plant species studied showed variable but remarkable broad spectrum antimicrobial activity. However, methanol extracts of Tecoma stans leaves was found to be effective against only Candida albicans at the concentrations employed. It was observed that the extracts of stem bark generally showed better antimicrobial activity than those of the leaves and some organisms were selectively more sensitive to the extracts than others. Preliminary phytochemical screening of these plants revealed the presence of tannins, flavonoids, alkaloids, quinones and traces of saponins. The antimicrobial activity observed are discussed in relation to the chemical constituents reportedly isolated from these plants and their traditional uses. PMID:7604753

  19. ELEVATED CO2 AND PLANT PLANT SPECIES RICHNESS IMPACT ARBUSCULAR MYCORRHIZAL FUNGAL SPORE COMMUNITIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We enumerated arbuscular mycorrhizal fungal spore communities for three years as part of a long-term Free-Air CO2 Enrichment experiment (BioCON) at Cedar Creek, Minnesota, USA. Complete factorial combinations of two levels of CO2 and N, and sixteen perennial plant species grown in monoculture and si...

  20. Reactive oxygen species generation and signaling in plants

    PubMed Central

    Tripathy, Baishnab Charan; Oelmüller, Ralf

    2012-01-01

    The introduction of molecular oxygen into the atmosphere was accompanied by the generation of reactive oxygen species (ROS) as side products of many biochemical reactions. ROS are permanently generated in plastids, peroxisomes, mitochiondria, the cytosol and the apoplast. Imbalance between ROS generation and safe detoxification generates oxidative stress and the accumulating ROS are harmful for the plants. On the other hand, specific ROS function as signaling molecules and activate signal transduction processes in response to various stresses. Here, we summarize the generation of ROS in the different cellular compartments and the signaling processes which are induced by ROS. PMID:23072988

  1. 45 CFR 670.25 - Designation of specially protected species of native mammals, birds, and plants.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... native mammals, birds, and plants. 670.25 Section 670.25 Public Welfare Regulations Relating to Public... Protected Species of Mammals, Birds, and Plants § 670.25 Designation of specially protected species of native mammals, birds, and plants. The following species has been designated as Specially...

  2. 45 CFR 670.25 - Designation of specially protected species of native mammals, birds, and plants.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... native mammals, birds, and plants. 670.25 Section 670.25 Public Welfare Regulations Relating to Public... Protected Species of Mammals, Birds, and Plants § 670.25 Designation of specially protected species of native mammals, birds, and plants. The following species has been designated as Specially...

  3. 45 CFR 670.25 - Designation of specially protected species of native mammals, birds, and plants.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... native mammals, birds, and plants. 670.25 Section 670.25 Public Welfare Regulations Relating to Public... Protected Species of Mammals, Birds, and Plants § 670.25 Designation of specially protected species of native mammals, birds, and plants. The following species has been designated as Specially...

  4. Screening of aquatic and wetland plant species for phytoremediation of explosives-contaminated groundwater from the Iowa Army Ammunition Plant.

    PubMed

    Best, E P; Zappi, M E; Fredrickson, H L; Sprecher, S L; Larson, S L; Ochman, M

    1997-11-21

    The results of this study indicate that the presence of plants did enhance TNT and TNB removal from IAAP groundwater. Most effective at 25 degrees C were reed canary grass, coontail and pondweed. Groundwater and plant tissue analyses indicate that in presence of the plants tested TNT is degraded to reduced by-products and to other metabolites that were not analyzed. TNT removal was best modeled using first order kinetics, with rate constants at 25 degrees C incubations ranging from 0.038 microgram L-1 h-1 for reed canary grass to 0.012 microgram L-1 h-1 for parrot-feather. These kinetics predict hydraulic retention times (HRTs) ranging from 4.9 days to 19.8 days to reach a TNT concentration of 2 micrograms L-1. Decreasing incubation temperature to 10 degrees C affected reed canary grass more than parrot-feather, increasing estimated HRTs by factors of four and two, respectively. The plant species tested showed a far lower potential for RDX removal from the IAAP groundwater. Most effective at 25 degrees C were reed canary grass and fox sedge. Analyses of plant material indicated the presence of RDX in under-water plant portions and in aerial plant portions, and RDX accumulation in the latter. RDX removal was best modeled using zero order kinetics, with rate constants for the 25 degrees C incubation ranging from 13.45 micrograms L-1 h-1 for reed canary grass to no removal in four species. Based on these kinetics, estimated HRTs to reach 2 micrograms L-1 RDX increased from 39 days. Decreasing the temperature to 10 degrees C increased HRT 24-fold for reed canary grass. By using the biomass-normalized K value, submersed plants are identified as having the highest explosives-removing activity (microgram explosive L-1 h-1 g DW-1). However, biomass production of submersed plants is normally five to ten times less than that of emergent plants per unit area, and, thus, in plant selection for wetland construction, both, explosives removal potential and biomass production are

  5. Copper phytotoxicity in native and agronomical plant species.

    PubMed

    Lamb, Dane T; Naidu, Ravi; Ming, Hui; Megharaj, Mallavarapu

    2012-11-01

    Copper (Cu) is a widespread soil contaminant that is known to be highly toxic to soil biota. Limited information is available on the response of wild endemic species to Cu in the literature, which hinders ecological risk assessments and revegetation. In the present study, the phytotoxicity of Cu in nutrient solution was studied in five Australian endemic plant species (Acacia decurrens, Austrodanthonia richardsonii (Wallaby Grass), Bothriochloa macra (Redgrass), Eucalyptus camaldulensis var. camaldulensis (River Red-Gum) and Dichanthium sericeum (Bluegrass) and two vegetable plants species (Lactuca sativa L. 'Great lakes' and Raphanus sativa L.). Vegetable species were grown in a more concentrated nutrient solution. The response of B. macra was also compared between the two nutrient solutions (dilute and concentrated nutrient solution). In the first experiment, D. sericeum and E. camaldulensis were found to be highly sensitive to Cu exposure in nutrient culture. Critical exogenous Cu concentrations (50 percent reduction in roots) for E. camaldulensis, D. sericeum, A. richardsonii, B. macra (dilute), L. sativa, B. macra (concentrated), R. sativa and A. decurrens were, respectively, (μg/L) 16, 35, 83, 88, 97, 105, 128 and 186. Copper tolerance in B. macra was observed to be higher in the more concentrated nutrient solution despite the estimated Cu(2+) concentration being very similar in treatment solutions. Additional short-term rhizo-accumulation studies showed that neither Ca(2+) not K(+) was responsible for reduced uptake at the roots. However, the estimated maximum shoot Cu was reduced from 41 to 24mg/kg in the more concentrated solution. PMID:22995781

  6. Potential for using native plant species in stormwater wetlands.

    PubMed

    Bonilla-Warford, Cristina M; Zedler, Joy B

    2002-03-01

    Spartina pectinata (prairie cordgrass) was grown under five hydroperiods (wet-dry cycles) to determine its potential for use in stormwater wetlands, particularly as an alternative to the highly invasive Phalaris arundinacea (an exotic grass). Rhizomes planted in outdoor microcosms grew vigorously in all treatments, namely, weekly flooding in early summer, weekly flooding in late summer, flooding every three weeks throughout the summer, weekly flooding throughout the summer, and no flooding. Neither the timing nor frequency of 24-hour floods (10-20 cm deep) affected total stem length (grand mean 1003 +/- 188.8 cm per pot, n = 140) or above-ground biomass (46.5 +/- 8.3 g per pot, equivalent to approximately 360 g/m2). However, by late summer, fewer new tillers were found in unflooded microcosms, indicating that vegetative expansion is drought-sensitive. The growth of Spartina plants was further assessed with and without Glyceria striata (a native grass) and Phalaris arundinacea. Glyceria growth was not affected by hydrologic treatment. Glyceria reduced Spartina growth by approximately 11%, suggesting potential as a cover crop that might reduce establishment and growth of Phalaris seedlings. Seeds of Phalaris did not germinate, but branch fragments established where soil was moist from flooding, regardless of the presence of Glyceria. The ability of Spartina to establish vegetatively and grow well under variable water levels leads us to recommend further testing in stormwater wetlands, along with early planting of Glyceria to reduce weed invasions. PMID:11830768

  7. Cross-Species Affective Neuroscience Decoding of the Primal Affective Experiences of Humans and Related Animals

    PubMed Central

    Panksepp, Jaak

    2011-01-01

    Background The issue of whether other animals have internally felt experiences has vexed animal behavioral science since its inception. Although most investigators remain agnostic on such contentious issues, there is now abundant experimental evidence indicating that all mammals have negatively and positively-valenced emotional networks concentrated in homologous brain regions that mediate affective experiences when animals are emotionally aroused. That is what the neuroscientific evidence indicates. Principal Findings The relevant lines of evidence are as follows: 1) It is easy to elicit powerful unconditioned emotional responses using localized electrical stimulation of the brain (ESB); these effects are concentrated in ancient subcortical brain regions. Seven types of emotional arousals have been described; using a special capitalized nomenclature for such primary process emotional systems, they are SEEKING, RAGE, FEAR, LUST, CARE, PANIC/GRIEF and PLAY. 2) These brain circuits are situated in homologous subcortical brain regions in all vertebrates tested. Thus, if one activates FEAR arousal circuits in rats, cats or primates, all exhibit similar fear responses. 3) All primary-process emotional-instinctual urges, even ones as complex as social PLAY, remain intact after radical neo-decortication early in life; thus, the neocortex is not essential for the generation of primary-process emotionality. 4) Using diverse measures, one can demonstrate that animals like and dislike ESB of brain regions that evoke unconditioned instinctual emotional behaviors: Such ESBs can serve as ‘rewards’ and ‘punishments’ in diverse approach and escape/avoidance learning tasks. 5) Comparable ESB of human brains yield comparable affective experiences. Thus, robust evidence indicates that raw primary-process (i.e., instinctual, unconditioned) emotional behaviors and feelings emanate from homologous brain functions in all mammals (see Appendix S1), which are regulated by higher

  8. Enantioselective Separation of 4,8-DHT and Phytotoxicity of the Enantiomers on Various Plant Species.

    PubMed

    Yang, Li; Ma, Xiao-Yan; Ruan, Xiao; Jiang, De-An; Pan, Cun-De; Wang, Qiang

    2016-01-01

    As a candidate for bioherbicide, 4,8-dihydroxy-1-tetralone (4,8-DHT) was isolated from Caryospora callicarpa epicarp and its two enantiomers, S-(+)-isosclerone and R-(-)-regiolone, were separated by chiral high-performance liquid chromatography (HPLC) on a Chiralcel OD column with chiral stationary phase (CSP)-coated cellulose-tris(3,5-dimethylphenylcarbamate). Then, the phytotoxicity of 4,8-DHT and its enantiomers toward the seeds germination and seedling growth of the five tested plant species, including lettuce (Latuca sativa), radish (Raphanus sativus), cucumber (Cucumis sativus), onion (Allium cepa), and wheat (Triticum aestivum), were investigated and the results indicated a hormesis at low concentration of 4,8-DHT and its enantiomers, but a retardant effect at high concentration. Between the two enantiomers of 4,8-DHT, the S-(+)-isosclerone was more toxic to seeds germination and seedling growth of the five tested plant species than the R-(-)-regiolone, and also the phytotoxicity of S-(+)-isosclerone varied with different plants. For example, S-(+)-isosclerone was the most active to seedling growth of lettuce, indicating that S-(+)-isosclerone had specific effects on different organisms. Thus, all of the chirality and concentration of 4,8-DHT, as well as the affected plant species, need to be taken into consideration in the development and utilization of 4,8-DHT. PMID:27110760

  9. Emission of isoprene from common Indian plant species and its implications for regional air quality.

    PubMed

    Singh, Rashmi; Singh, Abhai Pratap; Singh, M P; Kumar, Animesh; Varshney, C K

    2008-09-01

    Isoprene is most dominant volatile organic compounds (VOC) emitted by many plants. In this study 40 common Indian plant species were examined for isoprene emission using dynamic flow through enclosure chamber technique. Isoprene emission rates of plants species were found to vary from undetectable to 69.5 microg g(-1) h(-1) (Madhuca latifolia). Besides, an attempt has been made to evaluate suitability of 80 common Indian plant species for planting programmes. Out of 80 species, 29 species were moderate to high emitters (10 to < or =25 microg g(-1) h(-1)), 12 species were low emitter emitters (1 to < or =10 microg g(-1) h(-1)) and remaining 39 species were found to be negligible or non emitters (<1 microg g(-1) h(-1)) of isoprene. About 50% plant species selected for planting programmes in India were found to be moderate to high emitters of isoprene. PMID:17952698

  10. Similarities and differences in rubber biochemistry among plant species.

    PubMed

    Cornish, K

    2001-08-01

    This report reviews aspects of the biochemical regulation of rubber yield and rubber quality in three contrasting rubber-producing species, Hevea brasiliensis, Parthenium argentatum and Ficus elastica. Although many similarities are revealed, considerable differences also exist in enzymatic mechanisms regulating biosynthetic rate and the molecular weight of the rubber biopolymers produced. In all three species, rubber molecule initiation, biosynthetic rate and molecular weight, in vitro, are dependent upon substrate concentration and the ratio of isopentenyl pyrophosphate (IPP, the elongation substrate, or monomer) and farnesyl pyrophosphate (FPP, an initiator), but these parameters are affected by intrinsic properties of the rubber transferases as well. All three rubber transferases are capable of producing a wide range of rubber molecular weight, depending upon substrate concentration, clearly demonstrating that the transferases are not the prime determinants of product size in vivo. However, despite these commonalities, considerable differences exist between the species with respect to cosubstrate effects, binding constants, effective concentration ranges, and the role of negative cooperativity in vitro. The P. argentatum rubber transferase appears to exert more control over the molecular weight it produces than the other two species and may, therefore, provide the best prospect for the source of genes for transformation of annual crop species. The kinetic data, from the three contrasting rubber-producing species, also were used to develop a model of the rubber transferase active site in which, in addition to separate IPP and allylic-PP binding sites, there exists a hydrophobic region that interacts with the linear portion of allylic-PP initiator proximal to the pyrophosphate. Substrate affinity increases until the active site is traversed and the rubber interior of the rubber particle is reached. The kinetic data suggest that the hydrophobic region in H

  11. Duck productivity in restored species-rich native and species-poor non-native plantings.

    PubMed

    Haffele, Ryan D; Eichholz, Michael W; Dixon, Cami S

    2013-01-01

    Conservation efforts to increase duck production have led the United States Fish and Wildlife Service to restore grasslands with multi-species (3-5) mixtures of introduced cool season vegetation often termed dense nesting cover (DNC). The effectiveness of DNC to increase duck production has been variable, and maintenance of the cover type is expensive. In an effort to decrease the financial and ecological costs (increased carbon emissions from plowing and reseeding) of maintaining DNC and provide a long-term, resilient cover that will support a diversity of grassland fauna, restoration of multi-species (16-32) plantings of native plants has been explored. We investigated the vegetation characteristics, nesting density and nest survival between the 2 aforementioned cover types in the Prairie Pothole Region of North Dakota, USA from 2010-2011 to see if restored-native plantings provide similar benefits to nesting hens as DNC. We searched 14 fields (7 DNC, 271 ha; and 7 restored native, 230 ha) locating 3384 nests (1215 in restored-native vegetation and 2169 in DNC) in 2010-2011. Nest survival was similar between cover types in 2010, while DNC had greater survival than native plantings in 2011. Densities of nests adjusted for detection probability were not different between cover types in either year. We found no structural difference in vegetation between cover types in 2010; however, a difference was detected during the late sampling period in 2011 with DNC having deeper litter and taller vegetation. Our results indicate restored-native plantings are able to support similar nesting density as DNC; however, nest survival is more stable between years in DNC. It appears the annual variation in security between cover types goes undetected by hens as hens selected cover types at similar levels both years. PMID:23840898

  12. Duck Productivity in Restored Species-Rich Native and Species-Poor Non-Native Plantings

    PubMed Central

    Haffele, Ryan D.; Eichholz, Michael W.; Dixon, Cami S.

    2013-01-01

    Conservation efforts to increase duck production have led the United States Fish and Wildlife Service to restore grasslands with multi-species (3-5) mixtures of introduced cool season vegetation often termed dense nesting cover (DNC). The effectiveness of DNC to increase duck production has been variable, and maintenance of the cover type is expensive. In an effort to decrease the financial and ecological costs (increased carbon emissions from plowing and reseeding) of maintaining DNC and provide a long-term, resilient cover that will support a diversity of grassland fauna, restoration of multi-species (16-32) plantings of native plants has been explored. We investigated the vegetation characteristics, nesting density and nest survival between the 2 aforementioned cover types in the Prairie Pothole Region of North Dakota, USA from 2010–2011 to see if restored-native plantings provide similar benefits to nesting hens as DNC. We searched 14 fields (7 DNC, 271 ha; and 7 restored native, 230 ha) locating 3384 nests (1215 in restored-native vegetation and 2169 in DNC) in 2010-2011. Nest survival was similar between cover types in 2010, while DNC had greater survival than native plantings in 2011. Densities of nests adjusted for detection probability were not different between cover types in either year. We found no structural difference in vegetation between cover types in 2010; however, a difference was detected during the late sampling period in 2011 with DNC having deeper litter and taller vegetation. Our results indicate restored-native plantings are able to support similar nesting density as DNC; however, nest survival is more stable between years in DNC. It appears the annual variation in security between cover types goes undetected by hens as hens selected cover types at similar levels both years. PMID:23840898

  13. Biochar mitigates negative effects of salt additions on two herbaceous plant species.

    PubMed

    Thomas, Sean C; Frye, Susan; Gale, Nigel; Garmon, Matthew; Launchbury, Rebecca; Machado, Natasha; Melamed, Sarah; Murray, Jessica; Petroff, Alexandre; Winsborough, Carolyn

    2013-11-15

    Addition of pyrolyzed biomass ("biochar") to soils has commonly been shown to increase crop yields and alleviate plant stresses associated with drought and exposure to toxic materials. Here we investigate the ability of biochar (at two dosages: 5 and 50 t ha(-1)) to mitigate salt-induced stress, simulating road salt additions in a factorial glasshouse experiment involving the broadleaved herbaceous plants Abutilon theophrasti and Prunella vulgaris. Salt additions of 30 g m(-2) NaCl to unamended soils resulted in high mortality rates for both species. Biochar (Fagus grandifolia sawdust pyrolyzed at 378 °C), when applied at 50 t ha(-1) as a top dressing, completely alleviated salt-induced mortality in A. theophrasti and prolonged survival of P. vulgaris. Surviving A. theophrasti plants that received both 50 t ha(-1) biochar and salt addition treatments showed growth rates and physiological performance similar to plants without salt addition. Biochar treatments alone also substantially increased biomass of P. vulgaris, with a ∼50% increase relative to untreated controls at both biochar dosages. Biochar did not significantly affect photosynthetic carbon gain (Amax), water use efficiency, or chlorophyll fluorescence (Fv/Fm) in either species. Our results indicate that biochar can ameliorate salt stress effects on plants through salt sorption, suggesting novel applications of biochar to mitigate effects of salinization in agricultural, urban, and contaminated soils. PMID:23796889

  14. A century of ecosystem change: human and seabird impacts on plant species extirpation and invasion on islands

    PubMed Central

    Bennett, Joseph R.; Blight, Louise K.; Giesen, Marissa; Janssen, Michael H.; Schaminée, Joop J.H.J.; Arcese, Peter

    2016-01-01

    We used 116 years of floral and faunal records from Mandarte Island, British Columbia, Canada, to estimate the indirect effects of humans on plant communities via their effects on the population size of a surface-nesting, colonial seabird, the Glaucous-winged gull (Larus glaucescens). Comparing current to historical records revealed 18 extirpations of native plant species (32% of species historically present), 31 exotic species introductions, and one case of exotic introduction followed by extirpation. Contemporary surveys indicated that native species cover declined dramatically from 1986 to 2006, coincident with the extirpation of ‘old-growth’ conifers. Because vegetation change co-occurred with an increasing gull population locally and regionally, we tested several predictions from the hypothesis that the presence and activities of seabirds help to explain those changes. Specifically, we predicted that on Mandarte and nearby islands with gull colonies, we should observe higher nutrient loading and exotic plant species richness and cover than on nearby islands without gull colonies, as a consequence of competitive dominance in species adapted to high soil nitrogen and trampling. As predicted, we found that native plant species cover and richness were lower, and exotic species cover and richness higher, on islands with versus without gull colonies. In addition, we found that soil carbon and nitrogen on islands with nesting gulls were positively related to soil depth and exotic species richness and cover across plots and islands. Our results support earlier suggestions that nesting seabirds can drive rapid change in insular plant communities by increasing nutrients and disturbing vegetation, and that human activities that affect seabird abundance may therefore indirectly affect plant community composition on islands with seabird colonies. PMID:27547531

  15. A century of ecosystem change: human and seabird impacts on plant species extirpation and invasion on islands.

    PubMed

    Lameris, Thomas K; Bennett, Joseph R; Blight, Louise K; Giesen, Marissa; Janssen, Michael H; Schaminée, Joop J H J; Arcese, Peter

    2016-01-01

    We used 116 years of floral and faunal records from Mandarte Island, British Columbia, Canada, to estimate the indirect effects of humans on plant communities via their effects on the population size of a surface-nesting, colonial seabird, the Glaucous-winged gull (Larus glaucescens). Comparing current to historical records revealed 18 extirpations of native plant species (32% of species historically present), 31 exotic species introductions, and one case of exotic introduction followed by extirpation. Contemporary surveys indicated that native species cover declined dramatically from 1986 to 2006, coincident with the extirpation of 'old-growth' conifers. Because vegetation change co-occurred with an increasing gull population locally and regionally, we tested several predictions from the hypothesis that the presence and activities of seabirds help to explain those changes. Specifically, we predicted that on Mandarte and nearby islands with gull colonies, we should observe higher nutrient loading and exotic plant species richness and cover than on nearby islands without gull colonies, as a consequence of competitive dominance in species adapted to high soil nitrogen and trampling. As predicted, we found that native plant species cover and richness were lower, and exotic species cover and richness higher, on islands with versus without gull colonies. In addition, we found that soil carbon and nitrogen on islands with nesting gulls were positively related to soil depth and exotic species richness and cover across plots and islands. Our results support earlier suggestions that nesting seabirds can drive rapid change in insular plant communities by increasing nutrients and disturbing vegetation, and that human activities that affect seabird abundance may therefore indirectly affect plant community composition on islands with seabird colonies. PMID:27547531

  16. Effect of plant species on nitrogen recovery in aquaponics.

    PubMed

    Hu, Zhen; Lee, Jae Woo; Chandran, Kartik; Kim, Sungpyo; Brotto, Ariane Coelho; Khanal, Samir Kumar

    2015-01-01

    Nitrogen transformations in aquaponics with different edible plant species, i.e., tomato (Lycopersicon esculentum) and pak choi (Brassica campestris L. subsp. chinensis) were systematically examined and compared. Results showed that nitrogen utilization efficiencies (NUE) of tomato- and pak choi-based aquaponic systems were 41.3% and 34.4%, respectively. The abundance of nitrifying bacteria in tomato-based aquaponics was 4.2-folds higher than that in pak choi-based aquaponics, primarily due to its higher root surface area. In addition, tomato-based aquaponics had better water quality than that of pak choi-based aquaponics. About 1.5-1.9% of nitrogen input were emitted to atmosphere as nitrous oxide (N2O) in tomato- and pak choi-based aquaponic systems, respectively, suggesting that aquaponics is a potential anthropogenic source of N2O emission. Overall, this is the first intensive study that examined the role plant species played in aquaponics, which could provide new strategy in designing and operating an aquaponic system. PMID:25650140

  17. Plant Functional Diversity and Species Diversity in the Mongolian Steppe

    PubMed Central

    Liu, Guofang; Xie, Xiufang; Ye, Duo; Ye, Xuehua; Tuvshintogtokh, Indree; Mandakh, Bayart; Huang, Zhenying; Dong, Ming

    2013-01-01

    Background The Mongolian steppe is one of the most important grasslands in the world but suffers from aridization and damage from anthropogenic activities. Understanding structure and function of this community is important for the ecological conservation, but has seldom been investigated. Methodology/Principal Findings In this study, a total of 324 quadrats located on the three main types of Mongolian steppes were surveyed. Early-season perennial forbs (37% of total importance value), late-season annual forbs (33%) and late-season perennial forbs (44%) were dominant in meadow, typical and desert steppes, respectively. Species richness, diversity and plant functional type (PFT) richness decreased from the meadow, via typical to desert steppes, but evenness increased; PFT diversity in the desert and meadow steppes was higher than that in typical steppe. However, above-ground net primary productivity (ANPP) was far lower in desert steppe than in the other two steppes. In addition, the slope of the relationship between species richness and PFT richness increased from the meadow, via typical to desert steppes. Similarly, with an increase in species diversity, PFT diversity increased more quickly in both the desert and typical steppes than that in meadow steppe. Random resampling suggested that this coordination was partly due to a sampling effect of diversity. Conclusions/Significance These results indicate that desert steppe should be strictly protected because of its limited functional redundancy, which its ecological functioning is sensitive to species loss. In contrast, despite high potential forage production shared by the meadow and typical steppes, management of these two types of steppes should be different: meadow steppe should be preserved due to its higher conservation value characterized by more species redundancy and higher spatial heterogeneity, while typical steppe could be utilized moderately because its dominant grass genus Stipa is resistant to

  18. How grazing and soil quality affect native and exotic plant diversity in Rocky Mountain grasslands

    USGS Publications Warehouse

    Stohlgren, T.J.; Schell, L.D.; Vanden, Heuvel B.

    1999-01-01

    (adjacent and distant 1000-m2 plots) in the same vegetation type overlapped just 48.6 ?? 3.6%, and the ungrazed plots and distant grazed plots overlapped 49.4 ?? 3.6%. Differences in vegetation and soils between grazed and ungrazed sites were minimal in most cases, but soil characteristics and elevation were strongly correlated with native and exotic plant diversity in the study region. For the 78 1000-m2 plots, 59.4% of the variance in total species richness was explained by percentage of silt (coefficient = 0.647, t = 5.107, P < 0.001), elevation (coefficient = 0.012, t = 5.084, P < 0.001), and total foliar cover (coefficient = 0.110, t = 2.104, P < 0.039). Only 12.8% of the variance in exotic species cover (log10cover) was explained by percentage of clay (coefficient = -0.011, t = -2.878, P < 0.005), native species richness (coefficient = -0.011, t = -2.156, P < 0.034), and log10N (coefficient = 2.827, t = 1.860, P < 0.067). Native species cover and exotic species richness and frequency were also significantly positively correlated with percentage of soil N at the 1000-m2 plot scale. Our research led to five broad generalizations about current levels of grazing in these Rocky Mountain grasslands: (1) grazing probably has little effect on native species richness at landscape scales; (2) grazing probably has little effect on the accelerated spread of most exotic plant species at landscape scales; (3) grazing affects local plant species and life-form composition and cover, but spatial variation is considerable; (4) soil characteristics, climate, and disturbances may have a greater effect on plant species diversity than do current levels of grazing; and (5) few plant species show consistent, directional responses to grazing or cessation of grazing.

  19. The Roles of Mitochondrial Reactive Oxygen Species in Cellular Signaling and Stress Response in Plants.

    PubMed

    Huang, Shaobai; Van Aken, Olivier; Schwarzländer, Markus; Belt, Katharina; Millar, A Harvey

    2016-07-01

    Mitochondria produce ATP via respiratory oxidation of organic acids and transfer of electrons to O2 via the mitochondrial electron transport chain. This process produces reactive oxygen species (ROS) at various rates that can impact respiratory and cellular function, affecting a variety of signaling processes in the cell. Roles in redox signaling, retrograde signaling, plant hormone action, programmed cell death, and defense against pathogens have been attributed to ROS generated in plant mitochondria (mtROS). The shortcomings of the black box-idea of mtROS are discussed in the context of mechanistic considerations and the measurement of mtROS The overall aim of this update is to better define our current understanding of mtROS and appraise their potential influence on cellular function in plants. Furthermore, directions for future research are provided, along with suggestions to increase reliability of mtROS measurements. PMID:27021189

  20. Comprehensive Cooling Water Study: Volume 6, Federally endangered species, Savannah River Plant: Final report

    SciTech Connect

    Mackey, H.E.

    1987-09-01

    The Comprehensive Cooling Water Study (CCWS) was initiated in 1983 to evaluate the environmental effects of the intake and release of cooling water on the structure and function of aquatic ecosystems at the Savannah River Plant. The initial report described the results from the first year of the study. This document is the final report and concludes the program. The report comprises eight volumes. The Endangered Species Act requires that Federal agencies use their authorities to conduct programs for the conservation of endangered and threatened species and to ensure that agency actions do not jeopardize the continued existence of or result in the destruction or adverse modification of critical habitat of protected species. Those Federally endangered or threatened species that occur on the Savannah River Plant (SRP) include the American alligator, the red-cockaded woodpecker, the shortnose sturgeon, the wood stork, and the bald eagle. Of these species, the alligator, sturgeon, wood stork, and the bald eagle are likely to be affected directly and/or indirectly by the intake or release of cooling water at the SRP. 81 refs., 76 figs., 35 tabs.

  1. Imperfect replacement of native species by non-native species as pollinators of endemic Hawaiian plants.

    PubMed

    Aslan, Clare E; Zavaleta, Erika S; Tershy, Bernie; Croll, Don; Robichaux, Robert H

    2014-04-01

    Native plant species that have lost their mutualist partners may require non-native pollinators or seed dispersers to maintain reproduction. When natives are highly specialized, however, it appears doubtful that introduced generalists will partner effectively with them. We used visitation observations and pollination treatments (experimental manipulations of pollen transfer) to examine relationships between the introduced, generalist Japanese White-eye (Zosterops japonicus) and 3 endemic Hawaiian plant species (Clermontia parviflora, C. montis-loa, and C. hawaiiensis). These plants are characterized by curved, tubular flowers, apparently adapted for pollination by curve-billed Hawaiian honeycreepers. Z. japonicus were responsible for over 80% of visits to flowers of the small-flowered C. parviflora and the midsize-flowered C. montis-loa. Z. japonicus-visited flowers set significantly more seed than did bagged flowers. Z. japonicus also demonstrated the potential to act as an occasional Clermontia seed disperser, although ground-based frugivory by non-native mammals likely dominates seed dispersal. The large-flowered C. hawaiiensis received no visitation by any birds during observations. Unmanipulated and bagged C. hawaiiensis flowers set similar numbers of seeds. Direct examination of Z. japonicus and Clermontia morphologies suggests a mismatch between Z. japonicus bill morphology and C. hawaiiensis flower morphology. In combination, our results suggest that Z. japonicus has established an effective pollination relationship with C. parviflora and C. montis-loa and that the large flowers of C. hawaiiensis preclude effective visitation by Z. japonicus. PMID:24372761

  2. Colorimetric Method for Identifying Plant Essential Oil Components That Affect Biofilm Formation and Structure

    PubMed Central

    Niu, C.; Gilbert, E. S.

    2004-01-01

    The specific biofilm formation (SBF) assay, a technique based on crystal violet staining, was developed to locate plant essential oils and their components that affect biofilm formation. SBF analysis determined that cinnamon, cassia, and citronella oils differentially affected growth-normalized biofilm formation by Escherichia coli. Examination of the corresponding essential oil principal components by the SBF assay revealed that cinnamaldehyde decreased biofilm formation compared to biofilms grown in Luria-Bertani broth, eugenol did not result in a change, and citronellol increased the SBF. To evaluate these results, two microscopy-based assays were employed. First, confocal laser scanning microscopy (CLSM) was used to examine E. coli biofilms cultivated in flow cells, which were quantitatively analyzed by COMSTAT, an image analysis program. The overall trend for five parameters that characterize biofilm development corroborated the findings of the SBF assay. Second, the results of an assay measuring growth-normalized adhesion by direct microscopy concurred with the results of the SBF assay and CLSM imaging. Viability staining indicated that there was reduced toxicity of the essential oil components to cells in biofilms compared to the toxicity to planktonic cells but revealed morphological damage to E. coli after cinnamaldehyde exposure. Cinnamaldehyde also inhibited the swimming motility of E. coli. SBF analysis of three Pseudomonas species exposed to cinnamaldehyde, eugenol, or citronellol revealed diverse responses. The SBF assay could be useful as an initial step for finding plant essential oils and their components that affect biofilm formation and structure. PMID:15574886

  3. Antifungal Effect of Plant Essential Oils on Controlling Phytophthora Species

    PubMed Central

    Amini, Jahanshir; Farhang, Vahid; Javadi, Taimoor; Nazemi, Javad

    2016-01-01

    In this study, antifungal activity of essential oils of Cymbopogon citratus and Ocimum basilicum and two fungicides Mancozeb and Metalaxyl-Mancozeb in six different concentrations were investigated for controlling three species of Phytophthora, including P. capsici, P. drechsleri and P. melonis on pepper, cucumber and melon under in vitro and greenhouse conditions, respectively. Under the in vitro condition, the median effective concen- tration (EC50) values (ppm) of plant essential oils and fungicides were measured. In greenhouse, soil infested with Phytophthora species was treated by adding 50 ml of essential oils and fungicides (100 ppm). Disease severity was determined after 28 days. Among two tested plant essential oils, C. citratus had the lowest EC50 values for inhibition of the mycelial growth of P. capsici (31.473), P. melonis (33.097) and P. drechsleri (69.112), respectively. The mean EC50 values for Metalaxyl-Mancozeb on these pathogens were 20.87, 20.06 and 17.70, respectively. Chemical analysis of plant essential oils by GC-MS showed that, among 42 compounds identified from C. citratus, two compounds β-geranial (α-citral) (39.16%) and z-citral (30.95%) were the most abundant. Under the greenhouse condition, Metalaxyl-Mancozeb caused the greatest reduction in disease severity, 84.2%, 86.8% and 92.1% on melon, cucumber, and pepper, respectively. The C. citratus essential oil reduced disease severity from 47.4% to 60.5% compared to the untreated control (p≤0.05). Essential oils of O. basilicum had the lowest effects on the pathogens under in vitro and greenhouse conditions. These results show that essential oils may contribute to the development of new antifungal agents to protect the crops from Phytophthora diseases. PMID:26889111

  4. Antifungal Effect of Plant Essential Oils on Controlling Phytophthora Species.

    PubMed

    Amini, Jahanshir; Farhang, Vahid; Javadi, Taimoor; Nazemi, Javad

    2016-02-01

    In this study, antifungal activity of essential oils of Cymbopogon citratus and Ocimum basilicum and two fungicides Mancozeb and Metalaxyl-Mancozeb in six different concentrations were investigated for controlling three species of Phytophthora, including P. capsici, P. drechsleri and P. melonis on pepper, cucumber and melon under in vitro and greenhouse conditions, respectively. Under the in vitro condition, the median effective concen- tration (EC50) values (ppm) of plant essential oils and fungicides were measured. In greenhouse, soil infested with Phytophthora species was treated by adding 50 ml of essential oils and fungicides (100 ppm). Disease severity was determined after 28 days. Among two tested plant essential oils, C. citratus had the lowest EC50 values for inhibition of the mycelial growth of P. capsici (31.473), P. melonis (33.097) and P. drechsleri (69.112), respectively. The mean EC50 values for Metalaxyl-Mancozeb on these pathogens were 20.87, 20.06 and 17.70, respectively. Chemical analysis of plant essential oils by GC-MS showed that, among 42 compounds identified from C. citratus, two compounds β-geranial (α-citral) (39.16%) and z-citral (30.95%) were the most abundant. Under the greenhouse condition, Metalaxyl-Mancozeb caused the greatest reduction in disease severity, 84.2%, 86.8% and 92.1% on melon, cucumber, and pepper, respectively. The C. citratus essential oil reduced disease severity from 47.4% to 60.5% compared to the untreated control (p≤0.05). Essential oils of O. basilicum had the lowest effects on the pathogens under in vitro and greenhouse conditions. These results show that essential oils may contribute to the development of new antifungal agents to protect the crops from Phytophthora diseases. PMID:26889111

  5. Tree species and functional traits but not species richness affect interrill erosion processes in young subtropical forests

    NASA Astrophysics Data System (ADS)

    Seitz, S.; Goebes, P.; Song, Z.; Bruelheide, H.; Härdtle, W.; Kühn, P.; Li, Y.; Scholten, T.

    2016-01-01

    Soil erosion is seriously threatening ecosystem functioning in many parts of the world. In this context, it is assumed that tree species richness and functional diversity of tree communities can play a critical role in improving ecosystem services such as erosion control. An experiment with 170 micro-scale run-off plots was conducted to investigate the influence of tree species and tree species richness as well as functional traits on interrill erosion in a young forest ecosystem. An interrill erosion rate of 47.5 Mg ha-1 a-1 was calculated. This study provided evidence that different tree species affect interrill erosion differently, while tree species richness did not affect interrill erosion in young forest stands. Thus, different tree morphologies have to be considered, when assessing soil erosion under forest. High crown cover and leaf area index reduced interrill erosion in initial forest ecosystems, whereas rising tree height increased it. Even if a leaf litter cover was not present, the remaining soil surface cover by stones and biological soil crusts was the most important driver for soil erosion control. Furthermore, soil organic matter had a decreasing influence on interrill erosion. Long-term monitoring of soil erosion under closing tree canopies is necessary, and a wide range of functional tree traits should be considered in future research.

  6. Analysis of the Prefoldin Gene Family in 14 Plant Species

    PubMed Central

    Cao, Jun

    2016-01-01

    Prefoldin is a hexameric molecular chaperone complex present in all eukaryotes and archaea. The evolution of this gene family in plants is unknown. Here, I identified 140 prefoldin genes in 14 plant species. These prefoldin proteins were divided into nine groups through phylogenetic analysis. Highly conserved gene organization and motif distribution exist in each prefoldin group, implying their functional conservation. I also observed the segmental duplication of maize prefoldin gene family. Moreover, a few functional divergence sites were identified within each group pairs. Functional network analyses identified 78 co-expressed genes, and most of them were involved in carrying, binding and kinase activity. Divergent expression profiles of the maize prefoldin genes were further investigated in different tissues and development periods and under auxin and some abiotic stresses. I also found a few cis-elements responding to abiotic stress and phytohormone in the upstream sequences of the maize prefoldin genes. The results provided a foundation for exploring the characterization of the prefoldin genes in plants and will offer insights for additional functional studies. PMID:27014333

  7. Reactive oxygen species in response of plants to gravity stress

    NASA Astrophysics Data System (ADS)

    Jadko, Sergiy

    2016-07-01

    Reactive oxygen species (ROS) as second messengers can induce stress response of plants. Thioredoxins (Trx) and peroxiredoxins (Prx) can function as sensors and transmitters of the ROS in stress signaling and antioxidant response. 12-14 days old tissue culture of Arabidopsis thaliana have been investigated. Hypergravity stress was induced by centrifugation at 10 and 20 g during 30 and 90 min and than intensity of spontaneous chemiluminescence (SChL/ROS content), Trx and Prx activities were determined. All experiments were repeated from 3 to 5 times and the obtained data were statistically treated. In the tissue culture under development of the stress there were an increase in intensity of SChL and Trx and Prx activities. Thus, under hypergravity stress in the plant occurred early increase in the ROS level and the ROS induced the increase in the Trx and Prx activities. Prx and Trx can also participate in the formation of stress respons as acceptors and transducers of the redox signals. Increase in the activity of these enzymes primarily aimed at increasing of the total antioxidant activity in the cells to prevent of the plant to development of oxidative degradation by ROS.

  8. Optical Parameters of Leaves of 30 Plant Species 1

    PubMed Central

    Gausman, H. W.; Allen, W. A.

    1973-01-01

    Optical parameters (absorption coefficient k, infinite reflectance R∞, scattering coefficient 8) are tabulated for seven wavelengths and analyzed for statistical differences for 30 plant species. The wavelengths are: 550 nm (green reflectance peak), 650 nm (chlorophyll absorption band), 850 nm (infrared reflectance plateau), 1450 nm (water absorption band), 1650 nm (reflectance peak following water absorption band at 1450 nm), 1950 nm (water absorption band), and 2200 nm (reflectance peak following water absorption band at 1950 nm). Thick, complex dorsiventral (bifacial mesophyll) leaves such as rubber plant, begonia, sedum, and privet had lower R∞ values than thinner, less complex dorsiventral leaves (i.e., soybean, peach, bean, rose) or essentially centric (undifferentiated mesophyll) sorghum and corn leaves. Infinite reflectance was negatively correlated with leaf thickness (−0.734**). Thick, complex dorsiventral leaves (crinum, oleander, privet, rubber plant, sedum) had higher (p 0.01) k values than thinner, less complex dorsiventral leaves (i.e., soybean, rose, peach) or essentially centric sorghum, sugarcane, and corn leaves. A coefficient of 0.718** was obtained for the correlation of k values with leaf thickness values. Complex dorsiventral oleander, orange, and crinum leaves had higher (p 0.01) 8 values than less complex dorsiventral (i.e., onion, begonia, banana) or centric leaves (i.e., corn and sugarcane). The scattering coefficient was not correlated with leaf thickness. PMID:16658499

  9. Ground Layer Plant Species Turnover and Beta Diversity in Southern-European Old-Growth Forests

    PubMed Central

    Sabatini, Francesco Maria; Burrascano, Sabina; Tuomisto, Hanna; Blasi, Carlo

    2014-01-01

    Different assembly processes may simultaneously affect local-scale variation of species composition in temperate old-growth forests. Ground layer species diversity reflects chance colonization and persistence of low-dispersal species, as well as fine-scale environmental heterogeneity. The latter depends on both purely abiotic factors, such as soil properties and topography, and factors primarily determined by overstorey structure, such as light availability. Understanding the degree to which plant diversity in old-growth forests is associated with structural heterogeneity and/or to dispersal limitation will help assessing the effectiveness of silvicultural practices that recreate old-growth patterns and structures for the conservation or restoration of plant diversity. We used a nested sampling design to assess fine-scale species turnover, i.e. the proportion of species composition that changes among sampling units, across 11 beech-dominated old-growth forests in Southern Europe. For each stand, we also measured a wide range of environmental and structural variables that might explain ground layer species turnover. Our aim was to quantify the relative importance of dispersal limitation in comparison to that of stand structural heterogeneity while controlling for other sources of environmental heterogeneity. For this purpose, we used multiple regression on distance matrices at the within-stand extent, and mixed effect models at the extent of the whole dataset. Species turnover was best predicted by structural and environmental heterogeneity, especially by differences in light availability and in topsoil nutrient concentration and texture. Spatial distances were significant only in four out of eleven stands with a relatively low explanatory power. This suggests that structural heterogeneity is a more important driver of local-scale ground layer species turnover than dispersal limitation in southern European old-growth beech forests. PMID:24748155

  10. Ozone affects gas exchange, growth and reproductive development in Brassica campestris (Wisconsin fast plants).

    PubMed

    Black, V J; Stewart, C A; Roberts, J A; Black, C R

    2007-01-01

    Exposure to ozone (O(3)) may affect vegetative and reproductive development, although the consequences for yield depend on the effectiveness of the compensatory processes induced. This study examined the impact on reproductive development of exposing Brassica campestris (Wisconsin Fast Plants) to ozone during vegetative growth. Plants were exposed to 70 ppb ozone for 2 d during late vegetative growth or 10 d spanning most of the vegetative phase. Effects on gas exchange, vegetative growth, reproductive development and seed yield were determined. Impacts on gas exchange and foliar injury were related to pre-exposure stomatal conductance. Exposure for 2 d had no effect on growth or reproductive characteristics, whereas 10-d exposure reduced vegetative growth and reproductive site number on the terminal raceme. Mature seed number and weight per pod and per plant were unaffected because seed abortion was reduced. The observation that mature seed yield per plant was unaffected by exposure during the vegetative phase, despite adverse effects on physiological, vegetative and reproductive processes, shows that indeterminate species such as B. campestris possess sufficient compensatory flexibility to avoid reductions in seed production. PMID:17803646

  11. Seasonality and host preference of arbuscular mycorrhizal fungi of five plant species in the inner mongolia steppe, china

    PubMed Central

    Su, Yuan-Ying; Sun, Xin; Guo, Liang-Dong

    2011-01-01

    The seasonal change and host preference of arbuscular mycorrhizal (AM) colonization and community composition of five common plant species Agropyron cristatum, Anemarrhena asphodeloides, Cleistogenes squarrosa, Leymus chinensis, and Stipa grandis in the Inner Mongolia steppe were investigated. The AM root length colonization rates were different among the five plant species and were generally high in early (May and June) and late (September) growth seasons and low in August. A total of 18 AM fungal species representing five genera were isolated from rhizosphere soils of the five plant species, and most AM fungi had not host specificity, except that Acaulospora sp., Glomus constrictum, G. diaphanum and Glomus sp. showed a certain degree of host preference. Glomus albidum, G. etunicatum and G. geosporum were the dominant species and showed various sporulation patterns in the five plants during the growth seasons. The AM fungal spore densities and species richness increased from May to September and decreased in October and were different in the same month in the five plants. Multivariate analyses revealed that season and host significantly co-affected the AM fungal spore density, species richness, and Shannon-Wiener diversity index, and the season had higher influence than the host. PMID:24031605

  12. Patterns of fine-scale plant species richness in dry grasslands across the eastern Balkan Peninsula

    NASA Astrophysics Data System (ADS)

    Palpurina, Salza; Chytrý, Milan; Tzonev, Rossen; Danihelka, Jiří; Axmanová, Irena; Merunková, Kristina; Duchoň, Mário; Karakiev, Todor

    2015-02-01

    Fine-scale plant species richness varies across habitats, climatic and biogeographic regions, but the large-scale context of this variation is insufficiently explored. The patterns at the borders between biomes harbouring rich but different floras are of special interest. Dry grasslands of the eastern Balkan Peninsula, situated in the Eurasian forest-steppe zone and developed under Mediterranean influence, are a specific case of such biome transition. However, there are no studies assessing the patterns of fine-scale species richness and their underlying factors across the eastern Balkans. To explore these patterns, we sampled dry and semi-dry grasslands (phytosociological class Festuco-Brometea) across Bulgaria and SE Romania. In total, 172 vegetation plots of 10 × 10 m2 were sampled, in which all vascular plant species were recorded, soil depth was measured, and soil samples were collected and analysed in a laboratory for pH and plant-available nutrients. Geographic coordinates were used to extract selected climatic variables. Regression trees and linear regressions were used to quantify the relationships between species richness and environmental variables. Climatic factors were identified as the main drivers of species richness: (1) Species richness was strongly positively correlated with the mean temperature of the coldest month: sub-Mediterranean areas of S and E Bulgaria, characterized by warmer winters, were more species-rich. (2) Outside the sub-Mediterranean areas, species richness strongly increased with annual precipitation, which was primarily controlled by altitude. (3) Bedrock type and soil pH also significantly affected dry grassland richness outside the sub-Mediterranean areas. These results suggest that fine-scale species richness of dry grasslands over large areas is driven by processes at the regional level, especially by the difference in the species pools of large regions, in our case the Continental and Mediterranean biogeographic regions

  13. A new non-indigenous Crassostrea species in Southwest Atlantic salt marshes affects mortality of the cordgrass Spartina alterniflora

    NASA Astrophysics Data System (ADS)

    Lomovasky, Betina J.; Alvarez, Graciela; Addino, Mariana; Montemayor, Diana I.; Iribarne, Oscar

    2014-07-01

    Biological invasions in marine and coastal systems may produce new trophic and nontrophic interactions influencing the structure of the invaded community. In the intertidal salt marshes of Samborombón Bay (36°19‧20″S, 56°46‧26″W; mouth of La Plata River; Argentina), there is a new non-indigenous oyster species, Crassostrea sp., which settles on the dominant smooth cordgrass Spartina alterniflora. Here, we analyzed if the oyster affects S. alterniflora. Sampling showed that density of live plant was similar across intertidal levels, but there were higher density of dead plant stems at low intertidal levels. This pattern coincides with higher density and larger shell size of Crassostrea sp. at the low intertidal where oysters are attached to the basal part of the plant stems. An experiment manipulating oysters attached to S. alterniflora stems and oyster mimics shows that Crassostrea sp. can indeed increase mortality of S. alterniflora. The negative effect of bivalves on plant could be because several oysters settle around the Spartina stem, and by growing during the year, strangle the plants increasing their mortality rate. Together, all these evidences strongly suggest that these non-indigenous oysters can control the lower intertidal level of plant distribution in this system.

  14. Beneath the veil: Plant growth form influences the strength of species richness-productivity relationships in forests

    USGS Publications Warehouse

    Oberle, B.; Grace, J.B.; Chase, J.M.

    2009-01-01

    Aim: Species richness has been observed to increase with productivity at large spatial scales, though the strength of this relationship varies among functional groups. In forests, canopy trees shade understorey plants, and for this reason we hypothesize that species richness of canopy trees will depend on macroclimate, while species richness of shorter growth forms will additionally be affected by shading from the canopy. In this study we test for differences in species richness-productivity relationships (SRPRs) among growth forms (canopy trees, shrubs, herbaceous species) in small forest plots. Location: We analysed 231 plots ranging from 34.0?? to 48.3?? N latitude and from 75.0?? to 124.2?? W longitude in the United States. Methods: We analysed data collected by the USDA Forest Inventory and Analysis program for plant species richness partitioned into different growth forms, in small plots. We used actual evapotranspiration as a macroclimatic estimate of regional productivity and calculated the area of light-blocking tissue in the immediate area surrounding plots for an estimate of the intensity of local shading. We estimated and compared SRPRs for different partitions of the species richness dataset using generalized linear models and we incorporated the possible indirect effects of shading using a structural equation model. Results: Canopy tree species richness increased strongly with regional productivity, while local shading primarily explained the variation in herbaceous plant richness. Shrub species richness was related to both regional productivity and local shading. Main conclusions: The relationship between total forest plant species richness and productivity at large scales belies strong effects of local interactions. Counter to the pattern for overall richness, we found that understorey herbaceous plant species richness does not respond to regional productivity gradients, and instead is strongly influenced by canopy density, while shrub species

  15. The predominance of inorganic arsenic species in plants from Yellowknife, Northwest Territories, Canada

    SciTech Connect

    Koch, I.; Wang, L.; Ollson, C.A.; Cullen, W.R.; Reimer, K.J.

    2000-01-01

    Elevated levels of arsenic in Yellowknife, NWT, Canada, from historic and recent gold mine operations, are of increasing concern to Yellowknife residents. The study of arsenic in Yellowknife plants is a part of ongoing bioavailability and food chain research. A variety of plants from Yellowknife were analyzed for total arsenic and water soluble arsenic species. The plants included vascular plants and bryophytes (mosses). Total amounts of arsenic were greatest in mosses and varied greatly within specimens of the same plant species from different locations. Mostly inorganic arsenic species were extracted from plants using methanol/water (1:1). This result is very important from a toxicological point of view, since inorganic species are relatively toxic arsenic species. Small amounts of methylated arsenic species, as well as arsenosugars, were present in some plants. On average, greater than 50% of arsenic in these plants was not extracted; the chemical and toxicological characteristics of this fraction remain a topic for further study.

  16. Affective imagery and acceptance of replacing nuclear power plants.

    PubMed

    Keller, Carmen; Visschers, Vivianne; Siegrist, Michael

    2012-03-01

    This study examined the relationship between the content of spontaneous associations with nuclear power plants and the acceptance of using new-generation nuclear power plants to replace old ones. The study also considered gender as a variable. A representative sample of the German- and French-speaking population of Switzerland (N= 1,221) was used. Log-linear models revealed significant two-way interactions between the association content and acceptance, association content and gender, and gender and acceptance. Correspondence analysis revealed that participants who were opposed to nuclear power plants mainly associated nuclear power plants with risk, negative feelings, accidents, radioactivity, waste disposal, military use, and negative consequences for health and environment; whereas participants favoring nuclear power plants mainly associated them with energy, appearance descriptions of nuclear power plants, and necessity. Thus, individuals opposing nuclear power plants had both more concrete and more diverse associations with them than people who were in favor of nuclear power plants. In addition, participants who were undecided often mentioned similar associations to those participants who were in favor. Males more often expressed associations with energy, waste disposal, and negative health effects. Females more often made associations with appearance descriptions, negative feelings, and negative environmental effects. The results further suggest that acceptance of replacing nuclear power plants was higher in the German-speaking part of the country, where all of the Swiss nuclear power plants are physically located. Practical implications for risk communication are discussed. PMID:21977961

  17. Metabolism of reactive oxygen species and reactive nitrogen species in pepper (Capsicum annuum L.) plants under low temperature stress.

    PubMed

    Airaki, Morad; Leterrier, Marina; Mateos, Rosa M; Valderrama, Raquel; Chaki, Mounira; Barroso, Juan B; Del Río, Luis A; Palma, José M; Corpas, Francisco J

    2012-02-01

    Low temperature is an environmental stress that affects crop production and quality and regulates the expression of many genes, and the level of a number of proteins and metabolites. Using leaves from pepper (Capsicum annum L.) plants exposed to low temperature (8 °C) for different time periods (1 to 3 d), several key components of the metabolism of reactive nitrogen and oxygen species (RNS and ROS, respectively) were analysed. After 24 h of exposure at 8 °C, pepper plants exhibited visible symptoms characterized by flaccidity of stems and leaves. This was accompanied by significant changes in the metabolism of RNS and ROS with an increase of both protein tyrosine nitration (NO(2) -Tyr) and lipid peroxidation, indicating that low temperature induces nitrosative and oxidative stress. During the second and third days at low temperature, pepper plants underwent cold acclimation by adjusting their antioxidant metabolism and reverting the observed nitrosative and oxidative stress. In this process, the levels of the soluble non-enzymatic antioxidants ascorbate and glutathione, and the activity of the main NADPH-generating dehydrogenases were significantly induced. This suggests that ascorbate, glutathione and the NADPH-generating dehydrogenases have a role in the process of cold acclimation through their effect on the redox state of the cell. PMID:21414013

  18. Similar local and landscape processes affect both a common and a rare newt species.

    PubMed

    Denoël, Mathieu; Perez, Amélie; Cornet, Yves; Ficetola, Gentile Francesco

    2013-01-01

    Although rare species are often the focus of conservation measures, more common species may experience similar decline and suffer from the same threatening processes. We tested this hypothesis by examining, through an information-theoretic approach, the importance of ecological processes at multiple scales in the great crested newt Triturus cristatus, regionally endangered and protected in Europe, and the more common smooth newt, Lissotriton vulgaris. Both species were similarly affected by the same processes, i.e. suitability of aquatic and terrestrial components of their habitat at different scales, connectivity among breeding sites, and the presence of introduced fish. T. cristatus depended more on water depth and aquatic vegetation than L. vulgaris. The results show that environmental pressures threaten both common and rare species, and therefore the more widespread species should not be neglected in conservation programs. Because environmental trends are leading to a deterioration of aquatic and terrestrial habitat features required by newt populations, populations of the common species may follow the fate of the rarest species. This could have substantial conservation implications because of the numerical importance of common species in ecosystems and because commonness could be a transient state moving towards rarity. On the other hand, in agreement with the umbrella species concept, targeting conservation efforts on the most demanding species would also protect part of the populations of the most common species. PMID:23658765

  19. Sitona lineatus (Coleoptera: Curculionidae) Larval Feeding on Pisum sativum L. Affects Soil and Plant Nitrogen.

    PubMed

    Cárcamo, Héctor A; Herle, Carolyn E; Lupwayi, Newton Z

    2015-01-01

    Adults of Sitona lineatus (pea leaf weevil, PLW) feed on foliage of several Fabaceae species but larvae prefer to feed on nodules of Pisum sativum L. and Vicia faba L. Indirectly, through their feeding on rhizobia, weevils can reduce soil and plant available nitrogen (N). However, initial soil N can reduce nodulation and damage by the weevil and reduce control requirements. Understanding these interactions is necessary to make integrated pest management recommendations for PLW. We conducted a greenhouse study to quantify nodulation, soil and plant N content, and nodule damage by weevil larvae in relation to soil N amendment with urea, thiamethoxam insecticide seed coating and crop stage. PLWs reduced the number of older tumescent (multilobed) nodules and thiamethoxam addition increased them regardless of other factors. Nitrogen amendment significantly increased soil available N (>99% nitrate) as expected and PLW presence was associated with significantly lower levels of soil N. PLW decreased plant N content at early flower and thiamethoxam increased it, particularly at late flower. The study illustrated the complexity of interactions that determine insect herbivory effects on plant and soil nutrition for invertebrates that feed on N-fixing root nodules. We conclude that effects of PLW on nodulation and subsequent effects on plant nitrogen are more pronounced during the early growth stages of the plant. This suggests the importance of timing of PLW infestation and may explain the lack of yield depression in relation to this pest observed in many field studies. Also, pea crops in soils with high levels of soil N are unlikely to be affected by this herbivore and should not require insecticide inputs. PMID:26106086

  20. Sitona lineatus (Coleoptera: Curculionidae) Larval Feeding on Pisum sativum L. Affects Soil and Plant Nitrogen

    PubMed Central

    Cárcamo, Héctor A.; Herle, Carolyn E.; Lupwayi, Newton Z.

    2015-01-01

    Adults of Sitona lineatus (pea leaf weevil, PLW) feed on foliage of several Fabaceae species but larvae prefer to feed on nodules of Pisum sativum L. and Vicia faba L. Indirectly, through their feeding on rhizobia, weevils can reduce soil and plant available nitrogen (N). However, initial soil N can reduce nodulation and damage by the weevil and reduce control requirements. Understanding these interactions is necessary to make integrated pest management recommendations for PLW. We conducted a greenhouse study to quantify nodulation, soil and plant N content, and nodule damage by weevil larvae in relation to soil N amendment with urea, thiamethoxam insecticide seed coating and crop stage. PLWs reduced the number of older tumescent (multilobed) nodules and thiamethoxam addition increased them regardless of other factors. Nitrogen amendment significantly increased soil available N (>99% nitrate) as expected and PLW presence was associated with significantly lower levels of soil N. PLW decreased plant N content at early flower and thiamethoxam increased it, particularly at late flower. The study illustrated the complexity of interactions that determine insect herbivory effects on plant and soil nutrition for invertebrates that feed on N-fixing root nodules. We conclude that effects of PLW on nodulation and subsequent effects on plant nitrogen are more pronounced during the early growth stages of the plant. This suggests the importance of timing of PLW infestation and may explain the lack of yield depression in relation to this pest observed in many field studies. Also, pea crops in soils with high levels of soil N are unlikely to be affected by this herbivore and should not require insecticide inputs. PMID:26106086

  1. Climate and soil factors influencing seedling recruitment of plant species used for dryland restoration

    NASA Astrophysics Data System (ADS)

    Muñoz-Rojas, Miriam; Erickson, Todd E.; Martini, Dylan C.; Dixon, Kingsley W.; Merritt, David J.

    2016-06-01

    Land degradation affects 10-20 % of drylands globally. Intensive land use and management, large-scale disturbances such as extractive operations, and global climate change, have contributed to degradation of these systems worldwide. Restoring these damaged environments is critical to improving ecosystem services and functions, conserve biodiversity, and contribute to climate resilience, food security, and landscape sustainability. Here, we present a case study on plant species of the mining intensive semi-arid Pilbara region in Western Australia that examines the effects of climate and soil factors on the restoration of drylands. We analysed the effects of a range of rainfall and temperature scenarios and the use of alternative soil materials on seedling recruitment of key native plant species from this area. Experimental studies were conducted in controlled environment facilities where conditions simulated those found in the Pilbara. Soil from topsoil (T) stockpiles and waste materials (W) from an active mine site were mixed at different proportions (100 % T, 100 % W, and two mixes of topsoil and waste at 50 : 50 and 25 : 75 ratios) and used as growth media. Our results showed that seedling recruitment was highly dependent on soil moisture and emergence was generally higher in the topsoil, which had the highest available water content. In general, responses to the climate scenarios differed significantly among the native species which suggest that future climate scenarios of increasing drought might affect not only seedling recruitment but also diversity and structure of native plant communities. The use of waste materials from mining operations as growth media could be an alternative to the limited topsoil. However, in the early stages of plant establishment successful seedling recruitment can be challenging in the absence of water. These limitations could be overcome by using soil amendments but the cost associated to these solutions at large landscape scales

  2. Effects of polybrominated diphenyl ethers and plant species on nitrification, denitrification and anammox in mangrove soils.

    PubMed

    Chen, Juan; Zhou, Hai Chao; Pan, Ying; Shyla, Farzana Shazia; Tam, Nora Fung-Yee

    2016-05-15

    Little is known about polybrominated diphenyl ethers (PBDEs) and planting affect biogeochemical processes, and their impact on microbial nitrogen (N) transformation in soil. A 12-month microcosm experiment was conducted to understand the effects of a mixture of PBDEs at two contamination levels, 2 and 20 mg kg(-1)dry weight representing low and high soil contamination, respectively, using two mangrove plant species, namely Kandelia obovata (Ko) and Bruguiera gymnorrhiza (Bg), on nitrification, denitrification and anammox in mangrove soils. No significant changes in these N transformation processes were found at month 3 and at a low level of PBDEs in both plant species, suggesting that short-term exposure to 2 mg kg(-1) contamination did not affect microbial N transformation. At month 12, a high level of PBDE contamination significantly decreased the nitrification potential activity and the copy numbers of archaeal amoA and bacterial amoA gene in Ko soil, but such inhibitory effect was not significant in Bg soil. On the contrary, the denitrification-related parameters, including the activities of nitrate reductase and nitrite reductase, potential denitrification activity and copy numbers of nirK, nirS and nosZ gene, were stimulated by a high level of PBDE contamination in both Ko and Bg soils, and the stimulation was higher in the more anaerobic Bg soil. Different from denitrification, a high level of PBDE contamination decreased the copy numbers of anammox bacterial 16S rRNA gene in Bg soil but not in Ko soil; this was possibly related to the lower nitrate concentration in Bg soil that might inhibit the growth of anammox bacteria. These results indicated that the effects of PBDEs on microbial N transformation were plant species-specific, with the nitrifying microorganisms in Ko soil more susceptible to PBDE contamination, while denitrification and anammox in Bg soil were more sensitive. PMID:26901803

  3. Biological control of invasive plant species: a reassessment for the Anthropocene.

    PubMed

    Seastedt, Timothy R

    2015-01-01

    The science of finding, testing and releasing herbivores and pathogens to control invasive plant species has achieved a level of maturity and success that argues for continued and expanded use of this program. The practice, however, remains unpopular with some conservationists, invasion biologists, and stakeholders. The ecological and economic benefits of controlling densities of problematic plant species using biological control agents can be quantified, but the risks and net benefits of biological control programs are often derived from social or cultural rather than scientific criteria. Management of invasive plants is a 'wicked problem', and local outcomes to wicked problems have both positive and negative consequences differentially affecting various groups of stakeholders. The program has inherent uncertainties; inserting species into communities that are experiencing directional or even transformational changes can produce multiple outcomes due to context-specific factors that are further confounded by environmental change drivers. Despite these uncertainties, biological control could play a larger role in mitigation and adaptation strategies used to maintain biological diversity as well as contribute to human well-being by protecting food and fiber resources. PMID:25303317

  4. Nitrogen and phosphorus additions negatively affect tree species diversity in tropical forest regrowth trajectories.

    PubMed

    Siddique, Ilyas; Vieira, Ima Célia Guimarães; Schmidt, Susanne; Lamb, David; Carvalho, Cláudio José Reis; Figueiredo, Ricardo de Oliveira; Blomberg, Simon; Davidson, Eric A

    2010-07-01

    Nutrient enrichment is increasingly affecting many tropical ecosystems, but there is no information on how this affects tree biodiversity. To examine dynamics in vegetation structure and tree species biomass and diversity, we annually remeasured tree species before and for six years after repeated additions of nitrogen (N) and phosphorus (P) in permanent plots of abandoned pasture in Amazonia. Nitrogen and, to a lesser extent, phosphorus addition shifted growth among woody species. Nitrogen stimulated growth of two common pioneer tree species and one common tree species adaptable to both high- and low-light environments, while P stimulated growth only of the dominant pioneer tree Rollinia exsucca (Annonaceae). Overall, N or P addition reduced tree assemblage evenness and delayed tree species accrual over time, likely due to competitive monopolization of other resources by the few tree species responding to nutrient enrichment with enhanced establishment and/or growth rates. Absolute tree growth rates were elevated for two years after nutrient addition. However, nutrient-induced shifts in relative tree species growth and reduced assemblage evenness persisted for more than three years after nutrient addition, favoring two nutrient-responsive pioneers and one early-secondary tree species. Surprisingly, N + P effects on tree biomass and species diversity were consistently weaker than N-only and P-only effects, because grass biomass increased dramatically in response to N + P addition. The resulting intensified competition probably prevented an expected positive N + P synergy in the tree assemblage. Thus, N or P enrichment may favor unknown tree functional response types, reduce the diversity of coexisting species, and delay species accrual during structurally and functionally complex tropical rainforest secondary succession. PMID:20715634

  5. Productivity Is a Poor Predictor of Plant Species Richness.

    SciTech Connect

    Peter B. Adler; et al.

    2011-09-22

    For more than 30 years, the relationship between net primary productivity and species richness has generated intense debate in ecology about the processes regulating local diversity. The original view, which is still widely accepted, holds that the relationship is hump-shaped, with richness first rising and then declining with increasing productivity. Although recent meta-analyses questioned the generality of hump-shaped patterns, these syntheses have been criticized for failing to account for methodological differences among studies. We addressed such concerns by conducting standardized sampling in 48 herbaceous-dominated plant communities on five continents. We found no clear relationship between productivity and fine-scale (meters-2) richness within sites, within regions, or across the globe. Ecologists should focus on fresh, mechanistic approaches to understanding the multivariate links between productivity and richness.

  6. Productivity is a poor predictor of plant species richness

    USGS Publications Warehouse

    Adler, Peter B.; Seabloom, Eric W.; Borer, Elizabeth T.; Hillebrand, Helmut; Hautier, Yann; Hector, Andy; Harpole, W. Stanley; O'Halloran, Lydia R.; Grace, James B.; Anderson, T. Michael; Bakker, Jonathan D.; Biederman, Lori A.; Brown, Cynthia S.; Buckley, Yvonne M.; Calabrese, Laura B.; Chu, Cheng-Jin; Cleland, Elsa E.; Collins, Scott L.; Cottingham, Kathryn L.; Crawley, Michael J.; Damschen, Ellen Ingman; Davies, Kendi F.; DeCrappeo, Nicole M.; Fay, Philip A.; Firn, Jennifer; Frater, Paul; Gasarch, Eve I.; Gruner, Daneil S.; Hagenah, Nicole; Lambers, Janneke Hille Ris; Humphries, Hope; Jin, Virginia L.; Kay, Adam D.; Kirkman, Kevin P.; Klein, Julia A.; Knops, Johannes M.H.; La Pierre, Kimberly J.; Lambrinos, John G.; Li, Wei; MacDougall, Andrew S.; McCulley, Rebecca L.; Melbourne, Brett A.; Mitchell, Charles E.; Moore, Joslin L.; Morgan, John W.; Mortensen, Brent; Orrock, John L.; Prober, Suzanne M.; Pyke, David A.; Risch, Anita C.; Schuetz, Martin; Smith, Melinda D.; Stevens, Carly J.; Sullivan, Lauren L.; Wang, Gang; Wragg, Peter D.; Wright, Justin P.; Yang, Louie H.

    2011-01-01

    For more than 30 years, the relationship between net primary productivity and species richness has generated intense debate in ecology about the processes regulating local diversity. The original view, which is still widely accepted, holds that the relationship is hump-shaped, with richness first rising and then declining with increasing productivity. Although recent meta-analyses questioned the generality of hump-shaped patterns, these syntheses have been criticized for failing to account for methodological differences among studies. We addressed such concerns by conducting standardized sampling in 48 herbaceous-dominated plant communities on five continents. We found no clear relationship between productivity and fine-scale (meters-2) richness within sites, within regions, or across the globe. Ecologists should focus on fresh, mechanistic approaches to understanding the multivariate links between productivity an

  7. Positive effects of plant genotypic and species diversity on anti-herbivore defenses in a tropical tree species.

    PubMed

    Moreira, Xoaquín; Abdala-Roberts, Luis; Parra-Tabla, Víctor; Mooney, Kailen A

    2014-01-01

    Despite increasing evidence that plant intra- and inter-specific diversity increases primary productivity, and that such effect may in turn cascade up to influence herbivores, there is little information about plant diversity effects on plant anti-herbivore defenses, the relative importance of different sources of plant diversity, and the mechanisms for such effects. For example, increased plant growth at high diversity may lead to reduced investment in defenses via growth-defense trade-offs. Alternatively, positive effects of plant diversity on plant growth may lead to increased herbivore abundance which in turn leads to a greater investment in plant defenses. The magnitude of trait variation underlying diversity effects is usually greater among species than among genotypes within a given species, so plant species diversity effects on resource use by producers as well as on higher trophic levels should be stronger than genotypic diversity effects. Here we compared the relative importance of plant genotypic and species diversity on anti-herbivore defenses and whether such effects are mediated indirectly via diversity effects on plant growth and/or herbivore damage. To this end, we performed a large-scale field experiment where we manipulated genotypic diversity of big-leaf mahogany (Swietenia macrophylla) and tree species diversity, and measured effects on mahogany growth, damage by the stem-boring specialist caterpillar Hypsipyla grandella, and defensive traits (polyphenolics and condensed tannins in stem and leaves). We found that both forms of plant diversity had positive effects on stem (but not leaf) defenses. However, neither source of diversity influenced mahogany growth, and diversity effects on defenses were not mediated by either growth-defense trade-offs or changes in stem-borer damage. Although the mechanism(s) of diversity effects on plant defenses are yet to be determined, our study is one of the few to test for and show producer diversity effects on

  8. Positive Effects of Plant Genotypic and Species Diversity on Anti-Herbivore Defenses in a Tropical Tree Species

    PubMed Central

    Moreira, Xoaquín; Abdala-Roberts, Luis; Parra-Tabla, Víctor; Mooney, Kailen A.

    2014-01-01

    Despite increasing evidence that plant intra- and inter-specific diversity increases primary productivity, and that such effect may in turn cascade up to influence herbivores, there is little information about plant diversity effects on plant anti-herbivore defenses, the relative importance of different sources of plant diversity, and the mechanisms for such effects. For example, increased plant growth at high diversity may lead to reduced investment in defenses via growth-defense trade-offs. Alternatively, positive effects of plant diversity on plant growth may lead to increased herbivore abundance which in turn leads to a greater investment in plant defenses. The magnitude of trait variation underlying diversity effects is usually greater among species than among genotypes within a given species, so plant species diversity effects on resource use by producers as well as on higher trophic levels should be stronger than genotypic diversity effects. Here we compared the relative importance of plant genotypic and species diversity on anti-herbivore defenses and whether such effects are mediated indirectly via diversity effects on plant growth and/or herbivore damage. To this end, we performed a large-scale field experiment where we manipulated genotypic diversity of big-leaf mahogany (Swietenia macrophylla) and tree species diversity, and measured effects on mahogany growth, damage by the stem-boring specialist caterpillar Hypsipyla grandella, and defensive traits (polyphenolics and condensed tannins in stem and leaves). We found that both forms of plant diversity had positive effects on stem (but not leaf) defenses. However, neither source of diversity influenced mahogany growth, and diversity effects on defenses were not mediated by either growth-defense trade-offs or changes in stem-borer damage. Although the mechanism(s) of diversity effects on plant defenses are yet to be determined, our study is one of the few to test for and show producer diversity effects on

  9. Concentration-dependent NH 3 deposition processes for moorland plant species with and without stomata

    NASA Astrophysics Data System (ADS)

    Jones, M. R.; Leith, I. D.; Raven, J. A.; Fowler, D.; Sutton, M. A.; Nemitz, E.; Cape, J. N.; Sheppard, L. J.; Smith, R. I.

    Currently, in operational modelling of NH 3 deposition a fixed value of canopy resistance ( Rc) is generally applied, irrespective of the plant species and NH 3 concentration. This study determined the effect of NH 3 concentration on deposition processes to individual moorland species. An innovative flux chamber system was used to provide accurate continuous measurements of NH 3 deposition to Deschampsia cespitosa (L.) Beauv., Calluna vulgaris (L.) Hull, Eriophorum vaginatum L., Cladonia spp., Sphagnum spp., and Pleurozium schreberi (Brid.) Mitt. Measurements were conducted across a wide range of NH 3 concentrations (1-140 μg m -3). NH 3 concentration directly affects the deposition processes to the vegetation canopy, with Rc, and cuticular resistance ( Rw) increasing with increasing NH 3 concentration, for all the species and vegetation communities tested. For example, the Rc for C. vulgaris increased from 14 s m -1 at 2 μg m -3 to 112 s m -1 at 80 μg m -3. Diurnal variations in NH 3 uptake were observed for higher plants, due to stomatal uptake; however, no diurnal variations were shown for non-stomatal plants. Rc for C. vulgaris at 80 μg m -3 was 66 and 112 s m -1 during day and night, respectively. Differences were found in NH 3 deposition between plant species and vegetation communities: Sphagnum had the lowest Rc (3 s m -1 at 2 μg m -3 to 23 at 80 μg m -3), and D. cespitosa had the highest nighttime value (18 s m -1 at 2 μg m -3 to 197 s m -1 at 80 μg m -3).

  10. Endangered and threatened plant species on the Department of Energy Oak Ridge Reservation: an update

    SciTech Connect

    Parr, P.D.

    1984-10-01

    Plant species considered endangered or threatened on the Department of Energy-Oak Ridge Reservation (DOE-ORR) were identified through a review of pertinent literature and evaluation of herbarium voucher specimens. Thirteen plant species are on the official Tennessee list of endangered and threatened plants. Three of those species have been proposed for inclusion on the Federal list as rare in Tennessee. These rare plants will be given careful consideration in land-use planning. Protection of endangered and threatened species in their native habitat is considered the best method of ensuring their survival. In addition to habitat preservation, natural history studies of the rare species is important in determ

  11. Plant ecology. Worldwide evidence of a unimodal relationship between productivity and plant species richness.

    PubMed

    Fraser, Lauchlan H; Pither, Jason; Jentsch, Anke; Sternberg, Marcelo; Zobel, Martin; Askarizadeh, Diana; Bartha, Sandor; Beierkuhnlein, Carl; Bennett, Jonathan A; Bittel, Alex; Boldgiv, Bazartseren; Boldrini, Ilsi I; Bork, Edward; Brown, Leslie; Cabido, Marcelo; Cahill, James; Carlyle, Cameron N; Campetella, Giandiego; Chelli, Stefano; Cohen, Ofer; Csergo, Anna-Maria; Díaz, Sandra; Enrico, Lucas; Ensing, David; Fidelis, Alessandra; Fridley, Jason D; Foster, Bryan; Garris, Heath; Goheen, Jacob R; Henry, Hugh A L; Hohn, Maria; Jouri, Mohammad Hassan; Klironomos, John; Koorem, Kadri; Lawrence-Lodge, Rachael; Long, Ruijun; Manning, Pete; Mitchell, Randall; Moora, Mari; Müller, Sandra C; Nabinger, Carlos; Naseri, Kamal; Overbeck, Gerhard E; Palmer, Todd M; Parsons, Sheena; Pesek, Mari; Pillar, Valério D; Pringle, Robert M; Roccaforte, Kathy; Schmidt, Amanda; Shang, Zhanhuan; Stahlmann, Reinhold; Stotz, Gisela C; Sugiyama, Shu-ichi; Szentes, Szilárd; Thompson, Don; Tungalag, Radnaakhand; Undrakhbold, Sainbileg; van Rooyen, Margaretha; Wellstein, Camilla; Wilson, J Bastow; Zupo, Talita

    2015-07-17

    The search for predictions of species diversity across environmental gradients has challenged ecologists for decades. The humped-back model (HBM) suggests that plant diversity peaks at intermediate productivity; at low productivity few species can tolerate the environmental stresses, and at high productivity a few highly competitive species dominate. Over time the HBM has become increasingly controversial, and recent studies claim to have refuted it. Here, by using data from coordinated surveys conducted throughout grasslands worldwide and comprising a wide range of site productivities, we provide evidence in support of the HBM pattern at both global and regional extents. The relationships described here provide a foundation for further research into the local, landscape, and historical factors that maintain biodiversity. PMID:26185249

  12. From facilitation to competition: temperature-driven shift in dominant plant interactions affects population dynamics in seminatural grasslands.

    PubMed

    Olsen, Siri L; Töpper, Joachim P; Skarpaas, Olav; Vandvik, Vigdis; Klanderud, Kari

    2016-05-01

    Biotic interactions are often ignored in assessments of climate change impacts. However, climate-related changes in species interactions, often mediated through increased dominance of certain species or functional groups, may have important implications for how species respond to climate warming and altered precipitation patterns. We examined how a dominant plant functional group affected the population dynamics of four co-occurring forb species by experimentally removing graminoids in seminatural grasslands. Specifically, we explored how the interaction between dominants and subordinates varied with climate by replicating the removal experiment across a climate grid consisting of 12 field sites spanning broad-scale temperature and precipitation gradients in southern Norway. Biotic interactions affected population growth rates of all study species, and the net outcome of interactions between dominants and subordinates switched from facilitation to competition with increasing temperature along the temperature gradient. The impacts of competitive interactions on subordinates in the warmer sites could primarily be attributed to reduced plant survival. Whereas the response to dominant removal varied with temperature, there was no overall effect of precipitation on the balance between competition and facilitation. Our findings suggest that global warming may increase the relative importance of competitive interactions in seminatural grasslands across a wide range of precipitation levels, thereby favouring highly competitive dominant species over subordinate species. As a result, seminatural grasslands may become increasingly dependent on disturbance (i.e. traditional management such as grazing and mowing) to maintain viable populations of subordinate species and thereby biodiversity under future climates. Our study highlights the importance of population-level studies replicated under different climatic conditions for understanding the underlying mechanisms of climate

  13. Factors Affecting Location Decisions of Food Processing Plants

    NASA Astrophysics Data System (ADS)

    Turhan, Sule; Canan Ozbag, Basak; Cetin, Bahattin

    The main aim of this study is to examine the determinants of location choices for food processing plants using the results of 59 personal surveys. The 61.3% of the food processing plants that were interviewed are small scale plants, 9.1% are large scale plants and 29.6% are medium scale plants. Sixteen of the firms process vegetables, 12 process poultry, 12 process dairy and 9 process seafood products. Business climate factors are divided into six categories (market, infrastructure, raw material, labor, personal and environmental) and 17 specific location factors are considered. The survey responses are analyzed by types of raw materials processed and by plant size. 43.7, 55.3 and 42.2% of the respondents cited categories of Market, Raw Material and Infrastructure respectively as important, while 44.3, 50.7 and 74.4% of the respondents cited, labor, personal and environmental regulation categories of as not important. Thus survey findings indicate that plant location choices are mainly driven by market, raw material and infra structural factors. Environmental factors such as environmental regulations and permissions are relatively insignificant.

  14. Factors affecting plant growth in membrane nutrient delivery

    NASA Technical Reports Server (NTRS)

    Dreschel, T. W.; Wheeler, R. M.; Sager, J. C.; Knott, W. M.

    1990-01-01

    The development of the tubular membrane plant growth unit for the delivery of water and nutrients to roots in microgravity has recently focused on measuring the effects of changes in physical variables controlling solution availability to the plants. Significant effects of membrane pore size and the negative pressure used to contain the solution were demonstrated. Generally, wheat grew better in units with a larger pore size but equal negative pressure and in units with the same pore size but less negative pressure. Lettuce also exhibited better plant growth at less negative pressure.

  15. Plant species invasions along the latitudinal gradient in the United States

    USGS Publications Warehouse

    Stohlgren, T.J.; Barnett, D.; Flather, C.; Kartesz, J.; Peterjohn, B.

    2005-01-01

    It has been long established that the richness of vascular plant species and many animal taxa decreases with increasing latitude, a pattern that very generally follows declines in actual and potential evapotranspiration, solar radiation, temperature, and thus, total productivity. Using county-level data on vascular plants from the United States (3000 counties in the conterminous 48 states), we used the Akaike Information Criterion (AIC) to evaluate competing models predicting native and nonnative plant species density (number of species per square kilometer in a county) from various combinations of biotic variables (e.g., native bird species density, vegetation carbon, normalized difference vegetation index), environmental/topographic variables (elevation, variation in elevation, the number of land cover classes in the county; radiation, mean precipitation, actual evapotranspiration, and potential evapotranspiration), and human variables (human population density, crop-land, and percentage of disturbed lands in a county). We found no evidence of a latitudinal gradient for the density of native plant species and a significant, slightly positive latitudinal gradient for the density of nonnative plant species. We found stronger evidence of a significant, positive productivity gradient (vegetation carbon) for the density of native plant species and nonnative plant species. We found much stronger significant relationships when biotic, environmental/topographic, and human variables were used to predict native plant species density and nonnative plant species density. Biotic variables generally had far greater influence in multivariate models than human or environmental/topographic variables. Later, we found that the best, single, positive predictor of the density of nonnative plant species in a county was the density of native plant species in a county. While further study is needed, it may be that, while humans facilitate the initial establishment invasions of nonnative

  16. Modularity Reveals the Tendency of Arbuscular Mycorrhizal Fungi To Interact Differently with Generalist and Specialist Plant Species in Gypsum Soils

    PubMed Central

    Torrecillas, Emma; del Mar Alguacil, Maria; Roldán, Antonio; Díaz, Gisela; Montesinos-Navarro, Alicia

    2014-01-01

    Patterns in plant–soil biota interactions could be influenced by the spatial distribution of species due to soil conditions or by the functional traits of species. Gypsum environments usually constitute a mosaic of heterogeneous soils where gypsum and nongypsum soils are imbricated at a local scale. A case study of the interactions of plants with arbuscular mycorrhizal fungi (AMF) in gypsum environments can be illustrative of patterns in biotic interactions. We hypothesized that (i) soil characteristics might affect the AMF community and (ii) there are differences between the AMF communities (modules) associated with plants exclusive to gypsum soils (gypsophytes) and those associated with plants that show facultative behavior on gypsum and/or marly-limestone soils (gypsovags). We used indicator species and network analyses to test for differences between the AMF communities harbored in gypsophyte and gypsovag plants. We recorded 46 operational taxonomic units (OTUs) belonging to nine genera of Glomeromycota. The indicator species analysis showed two OTUs preferentially associating with gypsum soils and three OTUs preferentially associating with marly-limestone soils. Modularity analysis revealed that soil type can be a major factor shaping AMF communities, and some AMF groups showed a tendency to interact differently with plants that had distinct ecological strategies (gypsophytes and gypsovags). Characterization of ecological networks can be a valuable tool for ascertaining the potential influence of above- and below-ground biotic interactions (plant-AMF) on plant community composition. PMID:24973074

  17. Alkaloid Quantities in Endophyte-Infected Tall Fescue are Affected by the Plant-Fungus Combination and Environment.

    PubMed

    Helander, M; Phillips, T; Faeth, S H; Bush, L P; McCulley, R; Saloniemi, I; Saikkonen, K

    2016-02-01

    Many grass species are symbiotic with systemic, vertically-transmitted, asymptomatic Epichloë endophytic fungi. These fungi often produce alkaloids that defend the host against herbivores. We studied how environmental variables affect alkaloids in endophyte-infected tall fescue (Schedonorus phoenix) from three Northern European wild origins and the widely planted US cultivar 'Kentucky-31' (KY31). The plants were grown in identical common garden experiments in Finland and Kentucky for two growing seasons. Plants were left as controls (C) or given water (W), nutrient (N) or water and nutrient (WN) treatments. For 8-10 replications of each plant origin and treatment combination in both experiments, we analyzed ergot alkaloids, lysergic acid, and lolines. In Finland, tall fescue plants produced 50 % more ergot alkaloids compared to plants of the same origin and treatments in Kentucky. Origin of the plants affected the ergot alkaloid concentration at both study sites: the wild origin plants produced 2-4 times more ergot alkaloids than KY31, but the ergot alkaloid concentration of KY31 plants was the same at both locations. Overall lysergic acid content was 60 % higher in plants grown in Kentucky than in those grown in Finland. Nutrient treatments (N, WN) significantly increased ergot alkaloid concentrations in plants from Finland but not in plants from Kentucky. These results suggest that the success of KY31 in US is not due to selection for high ergot alkaloid production but rather other traits associated with the endophyte. In addition, the environmental effects causing variation in alkaloid production of grass-endophyte combinations should be taken into account when using endophyte-infected grasses agriculturally. PMID:26815170

  18. Plant toxins that affect nicotinic acetylcholine receptors: A review

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plants produce wide variety of chemical compounds termed secondary metabolites that are not involved in basic metabolism, photosynthesis or reproduction. These compounds are used as flavors, fragrances, insecticides, dyes, hallucinogens, nutritional supplements, poisons, and pharmaceutical agents. ...

  19. A novel family of small proteins that affect plant development

    SciTech Connect

    John Charles Walker

    2011-04-29

    The DVL genes represent a new group of plant proteins that influence plant growth and development. Overexpression of DVL1, and other members of the DVL family, causes striking phenotypic changes. The DVL proteins share sequence homology in their C-terminal half. Point mutations in the C-terminal domain show it is necessary and deletion studies demonstrate the C-terminal domain is sufficient to confer the overexpression phenotypes. The phenotypes observed, and the conservation of the protein sequence in the plant kingdom, does suggest the DVL proteins have a role in modulating plant growth and development. Our working hypothesis is the DVL proteins function as regulators of cellular signaling pathways that control growth and development.

  20. Burkholderia cenocepacia Lipopolysaccharide Modification and Flagellin Glycosylation Affect Virulence but Not Innate Immune Recognition in Plants

    PubMed Central

    Khodai-Kalaki, Maryam; Andrade, Angel; Fathy Mohamed, Yasmine

    2015-01-01

    ABSTRACT Burkholderia cenocepacia causes opportunistic infections in plants, insects, animals, and humans, suggesting that “virulence” depends on the host and its innate susceptibility to infection. We hypothesized that modifications in key bacterial molecules recognized by the innate immune system modulate host responses to B. cenocepacia. Indeed, modification of lipopolysaccharide (LPS) with 4-amino-4-deoxy-l-arabinose and flagellin glycosylation attenuates B. cenocepacia infection in Arabidopsis thaliana and Galleria mellonella insect larvae. However, B. cenocepacia LPS and flagellin triggered rapid bursts of nitric oxide and reactive oxygen species in A. thaliana leading to activation of the PR-1 defense gene. These responses were drastically reduced in plants with fls2 (flagellin FLS2 host receptor kinase), Atnoa1 (nitric oxide-associated protein 1), and dnd1-1 (reduced production of nitric oxide) null mutations. Together, our results indicate that LPS modification and flagellin glycosylation do not affect recognition by plant receptors but are required for bacteria to establish overt infection. PMID:26045541

  1. Soil biota can change after exotic plant invasion: Does this affect ecosystem processes?

    USGS Publications Warehouse

    Belnap, J.; Phillips, S.L.; Sherrod, S.K.; Moldenke, A.

    2005-01-01

    Invasion of the exotic annual grass Bromus tectorum into stands of the native perennial grass Hilaria jamesii significantly reduced the abundance of soil biota, especially microarthropods and nematodes. Effects of invasion on active and total bacterial and fungal biomass were variable, although populations generally increased after 50+ years of invasion. The invasion of Bromus also resulted in a decrease in richness and a species shift in plants, microarthropods, fungi, and nematodes. However, despite the depauperate soil fauna at the invaded sites, no effects were seen on cellulose decomposition rates, nitrogen mineralization rates, or vascular plant growth. When Hilaria was planted into soils from not-invaded, recently invaded, and historically invaded sites (all currently or once dominated by Hilaria), germination and survivorship were not affected. In contrast, aboveground Hilaria biomass was significantly greater in recently invaded soils than in the other two soils. We attributed the Hilaria response to differences in soil nutrients present before the invasion, especially soil nitrogen, phosphorus, and potassium, as these nutrients were elevated in the soils that produced the greatest Hilaria biomass. Our data suggest that it is not soil biotic richness per se that determines soil process rates or plant productivity, but instead that either (1) the presence of a few critical soil food web taxa can keep ecosystem function high, (2) nutrient loss is very slow in this ecosystem, and/or (3) these processes are microbially driven. However, the presence of Bromus may reduce key soil nutrients over time and thus may eventually suppress native plant success. ?? 2005 by the Ecological Society of America.

  2. Rhizosphere microbiome assemblage is affected by plant development

    PubMed Central

    Chaparro, Jacqueline M; Badri, Dayakar V; Vivanco, Jorge M

    2014-01-01

    There is a concerted understanding of the ability of root exudates to influence the structure of rhizosphere microbial communities. However, our knowledge of the connection between plant development, root exudation and microbiome assemblage is limited. Here, we analyzed the structure of the rhizospheric bacterial community associated with Arabidopsis at four time points corresponding to distinct stages of plant development: seedling, vegetative, bolting and flowering. Overall, there were no significant differences in bacterial community structure, but we observed that the microbial community at the seedling stage was distinct from the other developmental time points. At a closer level, phylum such as Acidobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria and specific genera within those phyla followed distinct patterns associated with plant development and root exudation. These results suggested that the plant can select a subset of microbes at different stages of development, presumably for specific functions. Accordingly, metatranscriptomics analysis of the rhizosphere microbiome revealed that 81 unique transcripts were significantly (P<0.05) expressed at different stages of plant development. For instance, genes involved in streptomycin synthesis were significantly induced at bolting and flowering stages, presumably for disease suppression. We surmise that plants secrete blends of compounds and specific phytochemicals in the root exudates that are differentially produced at distinct stages of development to help orchestrate rhizosphere microbiome assemblage. PMID:24196324

  3. Selenium bioavailability and uptake as affected by four different plants in a loamy clay soil with particular attention to mycorrhizae inoculated ryegrass.

    PubMed

    Munier-Lamy, C; Deneux-Mustin, S; Mustin, C; Merlet, D; Berthelin, J; Leyval, C

    2007-01-01

    The aim of this study was to investigate the influence of plant species, especially of their rhizosphere soil, and of inoculation with an arbuscular mycorrhizal (AM) fungus on the bioavailability of selenium and its transfer in soil-plant systems. A pot experiment was performed with a loamy clay soil and four plant species: maize, lettuce, radish and ryegrass, the last one being inoculated or not with an arbuscular mycorrhizal fungus (Glomus mosseae). Plant biomass and Se concentration in shoots and roots were estimated at harvest. Se bioavailability in rhizosphere and unplanted soil was evaluated using sequential extractions. Plant biomass and selenium uptake varied with plant species. The quantity of rhizosphere soil also differed between plants and was not proportional to plant biomass. The highest plant biomass, Se concentration in plants, and soil to plant transfer factor were obtained with radish. The lowest Se transfer factors were obtained with ryegrass. For the latter, mycorrhizal inoculation did not significantly affect plant growth, but reduced selenium transfer from soil to plant by 30%. In unplanted soil after 65 days aging, more than 90% of added Se was water-extractable. On the contrary, Se concentration in water extracts of rhizosphere soil represented less than 1% and 20% of added Se for ryegrass and maize, respectively. No correlation was found between the water-extractable fraction and Se concentration in plants. The speciation of selenium in the water extracts indicated that selenate was reduced, may be under organic forms, in the rhizosphere soil. PMID:17544553

  4. Regression analysis of technical parameters affecting nuclear power plant performances

    SciTech Connect

    Ghazy, R.; Ricotti, M. E.; Trueco, P.

    2012-07-01

    Since the 80's many studies have been conducted in order to explicate good and bad performances of commercial nuclear power plants (NPPs), but yet no defined correlation has been found out to be totally representative of plant operational experience. In early works, data availability and the number of operating power stations were both limited; therefore, results showed that specific technical characteristics of NPPs were supposed to be the main causal factors for successful plant operation. Although these aspects keep on assuming a significant role, later studies and observations showed that other factors concerning management and organization of the plant could instead be predominant comparing utilities operational and economic results. Utility quality, in a word, can be used to summarize all the managerial and operational aspects that seem to be effective in determining plant performance. In this paper operational data of a consistent sample of commercial nuclear power stations, out of the total 433 operating NPPs, are analyzed, mainly focusing on the last decade operational experience. The sample consists of PWR and BWR technology, operated by utilities located in different countries, including U.S. (Japan)) (France)) (Germany)) and Finland. Multivariate regression is performed using Unit Capability Factor (UCF) as the dependent variable; this factor reflects indeed the effectiveness of plant programs and practices in maximizing the available electrical generation and consequently provides an overall indication of how well plants are operated and maintained. Aspects that may not be real causal factors but which can have a consistent impact on the UCF, as technology design, supplier, size and age, are included in the analysis as independent variables. (authors)

  5. Species-driven changes in nitrogen cycling can provide a mechanism for plant invasions.

    PubMed

    Laungani, Ramesh; Knops, Johannes M H

    2009-07-28

    Traits that permit successful invasions have often seemed idiosyncratic, and the key biological traits identified vary widely among species. This fundamentally limits our ability to determine the invasion potential of a species. However, ultimately, successful invaders must have positive growth rates that longer term result in higher biomass accumulation than competing established species. In many terrestrial ecosystems nitrogen limits plant growth, and is a key factor determining productivity and the outcome of competition among species. Plant nitrogen use may provide a powerful framework to evaluate the invasive potential of a species in nitrogen-limiting ecosystems. Six mechanisms influence plant nitrogen use or acquisition: photosynthetic tissue allocation, photosynthetic nitrogen use efficiency, nitrogen fixation, nitrogen-leaching losses, gross nitrogen mineralization, and plant nitrogen residence time. Here we show that among these alternatives, the key mechanism allowing invasion for Pinus strobus into nitrogen limited grasslands was its higher nitrogen residence time. This higher nitrogen residence time created a positive feedback that redistributed nitrogen from the soil into the plant. This positive feedback allowed P. strobus to accumulate twice as much nitrogen in its tissues and four times as much nitrogen to photosynthetic tissues, as compared with other plant species. In turn, this larger leaf nitrogen pool increased total plant carbon gain of P. strobus two- to sevenfold as compared with other plant species. Thus our data illustrate that plant species can change internal ecosystem nitrogen cycling feedbacks and this mechanism can allow them to gain a competitive advantage over other plant species. PMID:19592506

  6. Plant Trait-Species Abundance Relationships Vary with Environmental Properties in Subtropical Forests in Eastern China

    PubMed Central

    Yan, En-Rong; Yang, Xiao-Dong; Chang, Scott X.; Wang, Xi-Hua

    2013-01-01

    Understanding how plant trait-species abundance relationships change with a range of single and multivariate environmental properties is crucial for explaining species abundance and rarity. In this study, the abundance of 94 woody plant species was examined and related to 15 plant leaf and wood traits at both local and landscape scales involving 31 plots in subtropical forests in eastern China. Further, plant trait-species abundance relationships were related to a range of single and multivariate (PCA axes) environmental properties such as air humidity, soil moisture content, soil temperature, soil pH, and soil organic matter, nitrogen (N) and phosphorus (P) contents. At the landscape scale, plant maximum height, and twig and stem wood densities were positively correlated, whereas mean leaf area (MLA), leaf N concentration (LN), and total leaf area per twig size (TLA) were negatively correlated with species abundance. At the plot scale, plant maximum height, leaf and twig dry matter contents, twig and stem wood densities were positively correlated, but MLA, specific leaf area, LN, leaf P concentration and TLA were negatively correlated with species abundance. Plant trait-species abundance relationships shifted over the range of seven single environmental properties and along multivariate environmental axes in a similar way. In conclusion, strong relationships between plant traits and species abundance existed among and within communities. Significant shifts in plant trait-species abundance relationships in a range of environmental properties suggest strong environmental filtering processes that influence species abundance and rarity in the studied subtropical forests. PMID:23560114

  7. Plant trait-species abundance relationships vary with environmental properties in subtropical forests in eastern china.

    PubMed

    Yan, En-Rong; Yang, Xiao-Dong; Chang, Scott X; Wang, Xi-Hua

    2013-01-01

    Understanding how plant trait-species abundance relationships change with a range of single and multivariate environmental properties is crucial for explaining species abundance and rarity. In this study, the abundance of 94 woody plant species was examined and related to 15 plant leaf and wood traits at both local and landscape scales involving 31 plots in subtropical forests in eastern China. Further, plant trait-species abundance relationships were related to a range of single and multivariate (PCA axes) environmental properties such as air humidity, soil moisture content, soil temperature, soil pH, and soil organic matter, nitrogen (N) and phosphorus (P) contents. At the landscape scale, plant maximum height, and twig and stem wood densities were positively correlated, whereas mean leaf area (MLA), leaf N concentration (LN), and total leaf area per twig size (TLA) were negatively correlated with species abundance. At the plot scale, plant maximum height, leaf and twig dry matter contents, twig and stem wood densities were positively correlated, but MLA, specific leaf area, LN, leaf P concentration and TLA were negatively correlated with species abundance. Plant trait-species abundance relationships shifted over the range of seven single environmental properties and along multivariate environmental axes in a similar way. In conclusion, strong relationships between plant traits and species abundance existed among and within communities. Significant shifts in plant trait-species abundance relationships in a range of environmental properties suggest strong environmental filtering processes that influence species abundance and rarity in the studied subtropical forests. PMID:23560114

  8. The regulatory roles of ethylene and reactive oxygen species (ROS) in plant salt stress responses.

    PubMed

    Zhang, Ming; Smith, J Andrew C; Harberd, Nicholas P; Jiang, Caifu

    2016-08-01

    Soil salinity is one of the most commonly encountered environmental stresses affecting plant growth and crop productivity. Accordingly, plants have evolved a variety of morphological, physiological and biochemical strategies that enable them to adapt to saline growth conditions. For example, it has long been known that salinity-stress increases both the production of the gaseous stress hormone ethylene and the in planta accumulation of reactive oxygen species (ROS). Recently, there has been significant progress in understanding how the fine-tuning of ethylene biosynthesis and signaling transduction can promote salinity tolerance, and how salinity-induced ROS accumulation also acts as a signal in the mediation of salinity tolerance. Furthermore, recent advances have indicated that ethylene signaling modulates salinity responses largely via regulation of ROS-generating and ROS-scavenging mechanisms. This review focuses on these recent advances in understanding the linked roles of ethylene and ROS in salt tolerance. PMID:27233644

  9. Plant species richness and shrub cover attenuate drought effects on ecosystem functioning across Patagonian rangelands.

    PubMed

    Gaitán, Juan J; Bran, Donaldo; Oliva, Gabriel; Maestre, Fernando T; Aguiar, Martín R; Jobbágy, Esteban; Buono, Gustavo; Ferrante, Daniela; Nakamatsu, Viviana; Ciari, Georgina; Salomone, Jorge; Massara, Virginia

    2014-10-01

    Drought is an increasingly common phenomenon in drylands as a consequence of climate change. We used 311 sites across a broad range of environmental conditions in Patagonian rangelands to evaluate how drought severity and temperature (abiotic factors) and vegetation structure (biotic factors) modulate the impact of a drought event on the annual integral of normalized difference vegetation index (NDVI-I), our surrogate of ecosystem functioning. We found that NDVI-I decreases were larger with both increasing drought severity and temperature. Plant species richness (SR) and shrub cover (SC) attenuated the effects of drought on NDVI-I. Grass cover did not affect the impacts of drought on NDVI-I. Our results suggest that warming and species loss, two important imprints of global environmental change, could increase the vulnerability of Patagonian ecosystems to drought. Therefore, maintaining SR through appropriate grazing management can attenuate the adverse effects of climate change on ecosystem functioning. PMID:25339654

  10. Germination and root elongation bioassays in six different plant species for testing Ni contamination in soil.

    PubMed

    Visioli, Giovanna; Conti, Federica D; Gardi, Ciro; Menta, Cristina

    2014-04-01

    In vitro short-term chronic phytotoxicity germination and root elongation test were applied to test the effects of nickel (Ni) in seed germination and root elongation in six plants species: Cucumis sativus (Cucurbitaceae), Lepidium sativum and Brassica nigra (Brassicaceae), Trifolium alexandrinum and Medicago sativa (Fabaceae), Phacelia tanacetifolia (Boraginaceae). A naturally Ni rich soil was used to compare the results obtained. Unlike root elongation, germination was not affected by Ni in any of the six species tested. EC50 values, calculated on the root elongation, showed that Ni toxicity decreases in the following order: P. tanacetifolia > B. nigra > C. sativus > L. sativum > M. sativa > T. alexandrinum. The test conducted using soil elutriate revealed a significantly lower effect in both seed germination and root elongation when compared to the results obtained using untreated soil. Conversely, the test performed on soil confirmed the high sensitivity of C. sativus, P. tanacetifolia and L. sativum to Ni. PMID:24288040

  11. Plant species richness and shrub cover attenuate drought effects on ecosystem functioning across Patagonian rangelands

    PubMed Central

    Gaitán, Juan J.; Bran, Donaldo; Oliva, Gabriel; Maestre, Fernando T.; Aguiar, Martín R.; Jobbágy, Esteban; Buono, Gustavo; Ferrante, Daniela; Nakamatsu, Viviana; Ciari, Georgina; Salomone, Jorge; Massara, Virginia

    2014-01-01

    Drought is an increasingly common phenomenon in drylands as a consequence of climate change. We used 311 sites across a broad range of environmental conditions in Patagonian rangelands to evaluate how drought severity and temperature (abiotic factors) and vegetation structure (biotic factors) modulate the impact of a drought event on the annual integral of normalized difference vegetation index (NDVI-I), our surrogate of ecosystem functioning. We found that NDVI-I decreases were larger with both increasing drought severity and temperature. Plant species richness (SR) and shrub cover (SC) attenuated the effects of drought on NDVI-I. Grass cover did not affect the impacts of drought on NDVI-I. Our results suggest that warming and species loss, two important imprints of global environmental change, could increase the vulnerability of Patagonian ecosystems to drought. Therefore, maintaining SR through appropriate grazing management can attenuate the adverse effects of climate change on ecosystem functioning. PMID:25339654

  12. Species and tissue type regulate long-term decomposition of brackish marsh plants grown under elevated CO2 conditions

    NASA Astrophysics Data System (ADS)

    Jones, Joshua A.; Cherry, Julia A.; McKee, Karen L.

    2016-02-01

    Organic matter accumulation, the net effect of plant production and decomposition, contributes to vertical soil accretion in coastal wetlands, thereby playing a key role in whether they keep pace with sea-level rise. Any factor that affects decomposition may affect wetland accretion, including atmospheric CO2 concentrations. Higher CO2 can influence decomposition rates by altering plant tissue chemistry or by causing shifts in plant species composition or biomass partitioning. A combined greenhouse-field experiment examined how elevated CO2 affected plant tissue chemistry and subsequent decomposition of above- and belowground tissues of two common brackish marsh species, Schoenoplectus americanus (C3) and Spartina patens (C4). Both species were grown in monoculture and in mixture under ambient (350-385 μL L-1) or elevated (ambient + 300 μL L-1) atmospheric CO2 conditions, with all other growth conditions held constant, for one growing season. Above- and belowground tissues produced under these treatments were decomposed under ambient field conditions in a brackish marsh in the Mississippi River Delta, USA. Elevated CO2 significantly reduced nitrogen content of S. americanus, but not sufficiently to affect subsequent decomposition. Instead, long-term decomposition (percent mass remaining after 280 d) was controlled by species composition and tissue type. Shoots of S. patens had more mass remaining (41 ± 2%) than those of S. americanus (12 ± 2%). Belowground material decomposed more slowly than that placed aboveground (62 ± 1% vs. 23 ± 3% mass remaining), but rates belowground did not differ between species. Increases in atmospheric CO2 concentration will likely have a greater effect on overall decomposition in this brackish marsh community through shifts in species dominance or biomass allocation than through effects on tissue chemistry. Consequent changes in organic matter accumulation may alter marsh capacity to accommodate sea-level rise through vertical

  13. Tree cover at fine and coarse spatial grains interacts with shade tolerance to shape plant species distributions across the Alps

    PubMed Central

    Nieto-Lugilde, Diego; Lenoir, Jonathan; Abdulhak, Sylvain; Aeschimann, David; Dullinger, Stefan; Gégout, Jean-Claude; Guisan, Antoine; Pauli, Harald; Renaud, Julien; Theurillat, Jean-Paul; Thuiller, Wilfried; Van Es, Jérémie; Vittoz, Pascal; Willner, Wolfgang; Wohlgemuth, Thomas; Zimmermann, Niklaus E.; Svenning, Jens-Christian

    2015-01-01

    The role of competition for light among plants has long been recognised at local scales, but its importance for plant species distributions at larger spatial scales has generally been ignored. Tree cover modifies the local abiotic conditions below the canopy, notably by reducing light availability, and thus, also the performance of species that are not adapted to low-light conditions. However, this local effect may propagate to coarser spatial grains, by affecting colonisation probabilities and local extinction risks of herbs and shrubs. To assess the effect of tree cover at both the plot- and landscape-grain sizes (approximately 10-m and 1-km), we fit Generalised Linear Models (GLMs) for the plot-level distributions of 960 species of herbs and shrubs using 6,935 vegetation plots across the European Alps. We ran four models with different combinations of variables (climate, soil and tree cover) at both spatial grains for each species. We used partial regressions to evaluate the independent effects of plot- and landscape-grain tree cover on plot-level plant communities. Finally, the effects on species-specific elevational range limits were assessed by simulating a removal experiment comparing the species distributions under high and low tree cover. Accounting for tree cover improved the model performance, with the probability of the presence of shade-tolerant species increasing with increasing tree cover, whereas shade-intolerant species showed the opposite pattern. The tree cover effect occurred consistently at both the plot and landscape spatial grains, albeit most strongly at the former. Importantly, tree cover at the two grain sizes had partially independent effects on plot-level plant communities. With high tree cover, shade-intolerant species exhibited narrower elevational ranges than with low tree cover whereas shade-tolerant species showed wider elevational ranges at both limits. These findings suggest that forecasts of climate-related range shifts for herb

  14. Changes in Semi-Arid Plant Species Associations along a Livestock Grazing Gradient

    PubMed Central

    Saiz, Hugo; Alados, Concepción L.

    2012-01-01

    In semi-arid ecosystems, vegetation is heterogeneously distributed, with plant species often associating in patches. These associations between species are not constant, but depend on the particular response of each species to environmental factors. Here, we investigated how plant species associations change in response to livestock grazing in a semi-arid ecosystem, Cabo de Gata-Níjar Natural Park in South East Spain. We established linear point-intercept transects at four sites with different grazing intensity, and recorded all species at each point. We investigated plant associations by comparing the number of times that each pair of species occurred at the same spatial point (co-occurrences), with the expected number of times based on species abundances. We also assessed associations for each shrub and grass species by considering all their pairs of associations and for the whole plant community by considering all pairs of associations on each site. At all sites, the plant community had a negative pattern of association, with fewer co-occurrences than expected. Negative association in the plant community increased at maximum grazing intensity. Most species associated as expected, particularly grass species, and positive associations were most important at intermediate grazing intensities. No species changed its type of association along the grazing gradient. We conclude that in the present plant community, grazing-resistant species compete among themselves and segregate in space. Some shrub species act as refuges for grazing-sensitive species that benefit from being spatially associated with shrub species, particularly at intermediate grazing intensities where positive associations were highest. At high grazing intensity, these shrubs can no longer persist and positive associations decrease due to the disappearance of refuges. Spatial associations between plant species and their response to grazing help identify the factors that organize plant communities, and

  15. Tree species identity and functional traits but not species richness affect interrill erosion processes in young subtropical forests

    NASA Astrophysics Data System (ADS)

    Seitz, S.; Goebes, P.; Song, Z.; Bruelheide, H.; Härdtle, W.; Kühn, P.; Li, Y.; Scholten, T.

    2015-06-01

    Soil erosion is seriously threatening ecosystem functioning in many parts of the world. In this context, it is assumed that tree species richness and functional diversity of tree communities can play a critical role in improving ecosystem services such as erosion control. An experiment with 170 micro-scale runoff plots was conducted to investigate the influence of tree species richness and identity as well as tree functional traits on interrill erosion in a young forest ecosystem. An interrill erosion rate of 47.5 t ha-1 a-1 was calculated. This study provided evidence that different tree species affect interrill erosion, but higher tree species richness did not mitigate soil losses in young forest stands. Thus, different tree morphologies have to be considered, when assessing erosion under forest. High crown cover and leaf area index reduced soil losses in initial forest ecosystems, whereas rising tree height increased them. Even if a leaf litter cover was not present, remaining soil surface cover by stones and biological soil crusts was the most important driver for soil erosion control. Furthermore, soil organic matter had a decreasing influence on soil loss. Long-term monitoring of soil erosion under closing tree canopies is necessary and a wide range of functional tree traits should be taken into consideration in future research.

  16. Thermal tolerance affects mutualist attendance in an ant-plant protection mutualism

    PubMed Central

    Fitzpatrick, Ginny; Lanan, Michele C.; Bronstein, Judith L.

    2014-01-01

    Mutualism is an often-complex interaction among multiple species, each of which may respond differently to abiotic conditions. The effects of temperature on the formation, dissolution, and success of these and other species interactions remain poorly understood. We studied the thermal ecology of the mutualism between the cactus Ferocactus wislizeni and its ant defenders (Forelius pruinosus, Crematogaster opuntiae, Solenopsis aurea, and Solenopsis xyloni) in the Sonoran Desert, USA. The ants are attracted to extrafloral nectar produced by the plants and in exchange protect the plants from herbivores; there is a hierarchy of mutualist effectiveness based on aggression toward herbivores. We determined the relationship between temperature and ant activity on plants, the thermal tolerance of each ant species, and ant activity in relation to the thermal environment of plants. Temperature played a role in determining which species interact as mutualists. Three of the four ant species abandoned the plants during the hottest part of the day (up to 40°C), returning when surface temperature began to decrease in the afternoon. The least effective ant mutualist, F. pruinosus, had a significantly higher critical thermal maximum than the other three species, was active across the entire range of plant surface temperatures observed (13.8-57.0°C), and visited plants that reached the highest temperatures. F. pruinosus occupied some plants full-time and invaded plants occupied by more dominant species when those species were thermally excluded. Combining data on thermal tolerance and mutualist effectiveness provides a potentially powerful tool for predicting the effects of temperature on mutualisms and mutualistic species. PMID:25012597

  17. Thermal tolerance affects mutualist attendance in an ant-plant protection mutualism.

    PubMed

    Fitzpatrick, Ginny; Lanan, Michele C; Bronstein, Judith L

    2014-09-01

    Mutualism is an often complex interaction among multiple species, each of which may respond differently to abiotic conditions. The effects of temperature on the formation, dissolution, and success of these and other species interactions remain poorly understood. We studied the thermal ecology of the mutualism between the cactus Ferocactus wislizeni and its ant defenders (Forelius pruinosus, Crematogaster opuntiae, Solenopsis aurea, and Solenopsis xyloni) in the Sonoran Desert, USA. The ants are attracted to extrafloral nectar produced by the plants and, in exchange, protect the plants from herbivores; there is a hierarchy of mutualist effectiveness based on aggression toward herbivores. We determined the relationship between temperature and ant activity on plants, the thermal tolerance of each ant species, and ant activity in relation to the thermal environment of plants. Temperature played a role in determining which species interact as mutualists. Three of the four ant species abandoned the plants during the hottest part of the day (up to 40 °C), returning when surface temperature began to decrease in the afternoon. The least effective ant mutualist, F. pruinosus, had a significantly higher critical thermal maximum than the other three species, was active across the entire range of plant surface temperatures observed (13.8-57.0 °C), and visited plants that reached the highest temperatures. F. pruinosus occupied some plants full-time and invaded plants occupied by more dominant species when those species were thermally excluded. Combining data on thermal tolerance and mutualist effectiveness provides a potentially powerful tool for predicting the effects of temperature on mutualisms and mutualistic species. PMID:25012597

  18. Cadmium content of plants as affected by soil cadmium concentration

    SciTech Connect

    Lehoczky, E.; Szabados, I.; Marth, P.

    1996-12-31

    Pot experiments were conducted in greenhouse conditions to study the effects of increasing cadmium (Cd) levels on biomass production and Cd contents in corn, (Zea mays L.), garlic (Allium sativum L.), and spinach (Spinacia oleracea L.). Plants were grown in two soil types: Eutric cambisol soil and A gleyic luvisol soil. Spinach proved to be the most sensitive to Cd treatments as its biomass considerably decreased with the increasing Cd levels. Cadmium contents of the three crops increased with increasing levels of Cd applications. Statistical differences were observed in the Cd contents of crops depending on soil type. With the same Cd rates, Cd tissue concentration of test plants grown in the strongly acidic Gleyic luvisol soil were many times higher than that of plants grown in a neutral Eutric cambisol soil. 14 refs., 4 tabs.

  19. Plant species distributions along environmental gradients: do belowground interactions with fungi matter?

    PubMed Central

    Pellissier, Loïc; Pinto-Figueroa, Eric; Niculita-Hirzel, Hélène; Moora, Mari; Villard, Lucas; Goudet, Jérome; Guex, Nicolas; Pagni, Marco; Xenarios, Ioannis; Sanders, Ian; Guisan, Antoine

    2013-01-01

    The distribution of plants along environmental gradients is constrained by abiotic and biotic factors. Cumulative evidence attests of the impact of biotic factors on plant distributions, but only few studies discuss the role of belowground communities. Soil fungi, in particular, are thought to play an important role in how plant species assemble locally into communities. We first review existing evidence, and then test the effect of the number of soil fungal operational taxonomic units (OTUs) on plant species distributions using a recently collected dataset of plant and metagenomic information on soil fungi in the Western Swiss Alps. Using species distribution models (SDMs), we investigated whether the distribution of individual plant species is correlated to the number of OTUs of two important soil fungal classes known to interact with plants: the Glomeromycetes, that are obligatory symbionts of plants, and the Agaricomycetes, that may be facultative plant symbionts, pathogens, or wood decayers. We show that including the fungal richness information in the models of plant species distributions improves predictive accuracy. Number of fungal OTUs is especially correlated to the distribution of high elevation plant species. We suggest that high elevation soil show greater variation in fungal assemblages that may in turn impact plant turnover among communities. We finally discuss how to move beyond correlative analyses, through the design of field experiments manipulating plant and fungal communities along environmental gradients. PMID:24339830

  20. Political Systems Affect Mobile and Sessile Species Diversity – A Legacy from the Post-WWII Period

    PubMed Central

    Cousins, Sara A. O.; Kaligarič, Mitja; Bakan, Branko; Lindborg, Regina

    2014-01-01

    Political ideologies, policies and economy affect land use which in turn may affect biodiversity patterns and future conservation targets. However, few studies have investigated biodiversity in landscapes with similar physical properties but governed by different political systems. Here we investigate land use and biodiversity patterns, and number and composition of birds and plants, in the borderland of Austria, Slovenia and Hungary. It is a physically uniform landscape but managed differently during the last 70 years as a consequence of the political “map” of Europe after World War I and II. We used a historical map from 1910 and satellite data to delineate land use within three 10-kilometre transects starting from the point where the three countries meet. There was a clear difference between countries detectable in current biodiversity patterns, which relates to land use history. Mobile species richness was associated with current land use whereas diversity of sessile species was more associated with past land use. Heterogeneous landscapes were positively and forest cover was negatively correlated to bird species richness. Our results provide insights into why landscape history is important to understand present and future biodiversity patterns, which is crucial for designing policies and conservation strategies across the world. PMID:25084154

  1. Ecological traits affect the response of tropical forest bird species to land-use intensity.

    PubMed

    Newbold, Tim; Scharlemann, Jörn P W; Butchart, Stuart H M; Sekercioğlu, Cağan H; Alkemade, Rob; Booth, Hollie; Purves, Drew W

    2013-01-01

    Land-use change is one of the main drivers of current and likely future biodiversity loss. Therefore, understanding how species are affected by it is crucial to guide conservation decisions. Species respond differently to land-use change, possibly related to their traits. Using pan-tropical data on bird occurrence and abundance across a human land-use intensity gradient, we tested the effects of seven traits on observed responses. A likelihood-based approach allowed us to quantify uncertainty in modelled responses, essential for applying the model to project future change. Compared with undisturbed habitats, the average probability of occurrence of bird species was 7.8 per cent and 31.4 per cent lower, and abundance declined by 3.7 per cent and 19.2 per cent in habitats with low and high human land-use intensity, respectively. Five of the seven traits tested affected the observed responses significantly: long-lived, large, non-migratory, primarily frugivorous or insectivorous forest specialists were both less likely to occur and less abundant in more intensively used habitats than short-lived, small, migratory, non-frugivorous/insectivorous habitat generalists. The finding that species responses to land use depend on their traits is important for understanding ecosystem functioning, because species' traits determine their contribution to ecosystem processes. Furthermore, the loss of species with particular traits might have implications for the delivery of ecosystem services. PMID:23173205

  2. Interactive effects of plant-available soil silicon and herbivory on competition between two grass species

    PubMed Central

    Garbuzov, Mihail; Reidinger, Stefan; Hartley, Susan E.

    2011-01-01

    Background and Aims The herbivore defence system of true grasses (Poaceae) is predominantly based on silicon that is taken up from the soil and deposited in the leaves in the form of abrasive phytoliths. Silicon uptake mechanisms can be both passive and active, with the latter suggesting that there is an energetic cost to silicon uptake. This study assessed the effects of plant-available soil silicon and herbivory on the competitive interactions between the grasses Poa annua, a species that has previously been reported to accumulate only small amounts of silicon, and Lolium perenne, a high silicon accumulator. Methods Plants were grown in mono- and mixed cultures under greenhouse conditions. Plant-available soil silicon levels were manipulated by adding silicon to the soil in the form of sodium silicate. Subsets of mixed culture pots were exposed to above-ground herbivory by desert locusts (Schistocerca gregaria). Key Results In the absence of herbivory, silicon addition increased biomass of P. annua but decreased biomass of L. perenne. Silicon addition increased foliar silicon concentrations of both grass species >4-fold. Under low soil-silicon availability the herbivores removed more leaf biomass from L. perenne than from P. annua, whereas under high silicon availability the reverse was true. Consequently, herbivory shifted the competitive balance between the two grass species, with the outcome depending on the availability of soil silicon. Conclusions It is concluded that a complex interplay between herbivore abundance, growth–defence trade-offs and the availability of soil silicon in the grasses' local environment affects the outcome of inter-specific competition, and so has the potential to impact on plant community structure. PMID:21868406

  3. Clonal Plasticity of Aquatic Plant Species Submitted to Mechanical Stress: Escape versus Resistance Strategy

    PubMed Central

    Puijalon, Sara; Bouma, Tjeerd J.; Van Groenendael, Jan; Bornette, Gudrun

    2008-01-01

    Background and Aims The plastic alterations of clonal architecture are likely to have functional consequences, as they affect the spatial distribution of ramets over patchy environments. However, little is known about the effect of mechanical stresses on the clonal growth. The aim of the present study was to investigate the clonal plasticity induced by mechanical stress consisting of continuous water current encountered by aquatic plants. More particularly, the aim was to test the capacity of the plants to escape this stress through clonal plastic responses. Methods The transplantation of ramets of the same clone in two contrasting flow velocity conditions was carried out for two species (Potamogeton coloratus and Mentha aquatica) which have contrasting clonal growth forms. Relative allocation to clonal growth, to creeping stems in the clonal biomass, number and total length of creeping stems, spacer length and main creeping stem direction were measured. Key Results For P. coloratus, plants exposed to water current displayed increased total length of creeping stems, increased relative allocation to creeping stems within the clonal dry mass and increased spacer length. For M. aquatica, plants exposed to current displayed increased number and total length of creeping stems. Exposure to current induced for both species a significant increase of the proportion of creeping stems in the downstream direction to the detriment of creeping stems perpendicular to flow. Conclusions This study demonstrates that mechanical stress from current flow induced plastic variation in clonal traits for both species. The responses of P. coloratus could lead to an escape strategy, with low benefits with respect to sheltering and anchorage. The responses of M. aquatica that may result in a denser canopy and enhancement of anchorage efficiency could lead to a resistance strategy. PMID:18854376

  4. Toward breeding new land-sea plant hybrid species irrigable with seawater for dry regions.

    PubMed

    Moustafa, Khaled

    2015-01-01

    A plant species growing in sea or coastal saltmarsh is greatly tolerant to high concentrations of salts, and a plant species growing in desert or dry regions is highly tolerant to drought. Breeding a new plant hybrid species from both species by means of cellular grafting, genome fusion or nuclear transfer would generate, at least in theory, a hybrid plant species that should be strongly tolerant to harsh aridity and salinity and would be potentially irrigable with seawater. Such prospective species can be used for example as a fodder, biofuel crop or stabilizer species to protect soil from wind erosion and sandy storms in dry regions. Breeding such species would change the surface of the world and help to solve major challenges of starvation, malnutrition and poverty. Here, I propose potential approaches that would be worthy of investigation toward this purpose. PMID:25806436

  5. Toward breeding new land-sea plant hybrid species irrigable with seawater for dry regions

    PubMed Central

    Moustafa, Khaled

    2015-01-01

    A plant species growing in sea or coastal saltmarsh is greatly tolerant to high concentrations of salts, and a plant species growing in desert or dry regions is highly tolerant to drought. Breeding a new plant hybrid species from both species by means of cellular grafting, genome fusion or nuclear transfer would generate, at least in theory, a hybrid plant species that should be strongly tolerant to harsh aridity and salinity and would be potentially irrigable with seawater. Such prospective species can be used for example as a fodder, biofuel crop or stabilizer species to protect soil from wind erosion and sandy storms in dry regions. Breeding such species would change the surface of the world and help to solve major challenges of starvation, malnutrition and poverty. Here, I propose potential approaches that would be worthy of investigation toward this purpose. PMID:25806436

  6. Plant extracts affect in vitro rumen microbial fermentation.

    PubMed

    Busquet, M; Calsamiglia, S; Ferret, A; Kamel, C

    2006-02-01

    Different doses of 12 plant extracts and 6 secondary plant metabolites were incubated for 24 h in diluted ruminal fluid with a 50:50 forage:concentrate diet. Treatments were: control (no additive), plant extracts (anise oil, cade oil, capsicum oil, cinnamon oil, clove bud oil, dill oil, fenugreek, garlic oil, ginger oil, oregano oil, tea tree oil, and yucca), and secondary plant metabolites (anethol, benzyl salicylate, carvacrol, carvone, cinnamaldehyde, and eugenol). Each treatment was supplied at 3, 30, 300, and 3,000 mg/L of culture fluid. At 3,000 mg/L, most treatments decreased total volatile fatty acid concentration, but cade oil, capsicum oil, dill oil, fenugreek, ginger oil, and yucca had no effect. Different doses of anethol, anise oil, carvone, and tea tree oil decreased the proportion of acetate and propionate, which suggests that these compounds may not be nutritionally beneficial to dairy cattle. Garlic oil (300 and 3,000 mg/L) and benzyl salicylate (300 and 3,000 mg/L) reduced acetate and increased propionate and butyrate proportions, suggesting that methane production was inhibited. At 3,000 mg/L, capsicum oil, carvacrol, carvone, cinnamaldehyde, cinnamon oil, clove bud oil, eugenol, fenugreek, and oregano oil resulted in a 30 to 50% reduction in ammonia N concentration. Careful selection and combination of these extracts may allow the manipulation of rumen microbial fermentation. PMID:16428643

  7. Maximizing plant density affects broccoli yield and quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increased demand for fresh market bunch broccoli (Brassica oleracea L. var. italica) has led to increased production along the United States east coast. Maximizing broccoli yields is a primary concern for quickly expanding southeastern commercial markets. This broccoli plant density study was carr...

  8. Interactions of plant zinc and plant species on the bioavailability of plant cadmium to Japanese quail fed lettuce and spinach

    SciTech Connect

    McKenna, I.M.; Keach, R.M. Jr; Williams, F.M. ); Chaney, R.L. Dept. of Agriculture, Beltsville, MD ); Tao, Shyy-Hwa )

    1992-02-01

    Many cadmium-contaminated environments contain high levels of zinc. The effects of plant Zn and plant species on plant Cd bioavailability were tested in Japanese quail fed lettuce and spinach. Four groups of birds received 10% of their diets as lettuce or spinach leaves intrinsically labeled with {sup 109}Cd and containing low or high intrinsic Zn. Two other groups were fed control diets containing {sup 109}Cd as CdSO{sub 4} and low or high Zn as ZnCO{sub 3}. Cadmium concentrations in diets ranged from 0.857 to 1.05 {mu}g/g dry wt. Zinc concentrations in low-Zn diets ranged from 21.2 to 22.8, and in high-Zn diets from 56.0 to 63.3 {mu}g/g dry wt. Increased lettuce and spinach Zn decreased plant Cd retention in kidney, liver, and jejunum-ileum of Japanese quail. Spinach Cd was less absorbed than lettuce Cd at both Zn levels. Inorganic Zn produced a lesser decrease in Cd retention in kidney, liver, and jejunum-ileum than did plant Zn. The authors conclude that (1) crops that transport Zn and Cd readily into edible tissues show lower Cd bioavailability when grown in Zn-Cd contaminated environments than in Cd-only polluted sites, (2) plant species differ in Cd bioavailability for identical concentrations of Zn and Cd in edible tissues, and (3) toxicological studies with animals exposed to Cd salts and Zn supplements do not assess Cd bioavailability of Zn-Cd contaminated crops.

  9. Vascular plant and vertebrate species richness in national parks of the eastern United States

    USGS Publications Warehouse

    Hatfield, Jeffrey S.; Myrick, Kaci E.; Huston, Michael A.; Weckerly, Floyd W.; Green, M. Clay

    2013-01-01

    Given the estimates that species diversity is diminishing at 50-100 times the normal rate, it is critical that we be able to evaluate changes in species richness in order to make informed decisions for conserving species diversity. In this study, we examined the potential of vascular plant species richness to be used as a surrogate for vertebrate species richness in the classes of amphibians, reptiles, birds, and mammals. Vascular plants, as primary producers, represent the biotic starting point for ecological community structure and are the logical place to start for understanding vertebrate species associations. We used data collected by the United States (US) National Park Service (NPS) on species presence within parks in the eastern US to estimate simple linear regressions between plant species richness and vertebrate richness. Because environmental factors may also influence species diversity, we performed simple linear regressions of species richness versus natural logarithm of park area, park latitude, mean annual precipitation, mean annual temperature, and human population density surrounding the parks. We then combined plant species richness and environmental variables in multiple regressions to determine the variables that remained as significant predictors of vertebrate species richness. As expected, we detected significant relationships between plant species richness and amphibian, bird, and mammal species richness. In some cases, plant species richness was predicted by park area alone. Species richness of mammals was only related to plant species richness. Reptile species richness, on the other hand, was related to plant species richness, park latitude and annual precipitation, while amphibian species richness was related to park latitude, park area, and plant species richness. Thus, plant species richness predicted species richness of different vertebrate groups to varying degrees and should not be used exclusively as a surrogate for vertebrate

  10. Seasonal Changes Affect Root Prunasin Concentration in Prunus serotina and Override Species Interactions between P. serotina and Quercus petraea.

    PubMed

    Robakowski, Piotr; Bielinis, Ernest; Stachowiak, Jerzy; Mejza, Iwona; Bułaj, Bartosz

    2016-03-01

    The allocation of resources to chemical defense can decrease plant growth and photosynthesis. Prunasin is a cyanogenic glycoside known for its role in defense against herbivores and other plants. In the present study, fluctuations of prunasin concentrations in roots of Prunus serotina seedlings were hypothesized to be: (1) dependent on light, air temperature, and humidity; (2) affected by competition between Prunus serotina and Quercus petraea seedlings, with mulching with Prunus serotina leaves; (3) connected with optimal allocation of resources. For the first time, we determined prunasin concentration in roots on several occasions during the vegetative season. The results indicate that seasonal changes have more pronounced effects on prunasin concentration than light regime and interspecific competition. Prunus serotina invested more nitrogen in the synthesis of prunasin under highly restricted light conditions than in higher light environments. In full sun, prunasin in roots of Prunus serotina growing in a monoculture was correlated with growth and photosynthesis, whereas these relationships were not found when interspecific competition with mulching was a factor. The study demonstrates that prunasin concentration in Prunus serotina roots is the result of species-specific adaptation, light and temperature conditions, ontogenetic shift, and, to a lesser extent, interspecific plant-plant interactions. PMID:26961681

  11. Reactive oxygen species mediate growth and death in submerged plants

    PubMed Central

    Steffens, Bianka; Steffen-Heins, Anja; Sauter, Margret

    2013-01-01

    Aquatic and semi-aquatic plants are well adapted to survive partial or complete submergence which is commonly accompanied by oxygen deprivation. The gaseous hormone ethylene controls a number of adaptive responses to submergence including adventitious root growth and aerenchyma formation. Reactive oxygen species (ROS) act as signaling intermediates in ethylene-controlled submergence adaptation and possibly also independent of ethylene. ROS levels are controlled by synthesis, enzymatic metabolism, and non-enzymatic scavenging. While the actors are by and large known, we still have to learn about altered ROS at the subcellular level and how they are brought about, and the signaling cascades that trigger a specific response. This review briefly summarizes our knowledge on the contribution of ROS to submergence adaptation and describes spectrophotometrical, histochemical, and live cell imaging detection methods that have been used to study changes in ROS abundance. Electron paramagnetic resonance (EPR) spectroscopy is introduced as a method that allows identification and quantification of specific ROS in cell compartments. The use of advanced technologies such as EPR spectroscopy will be necessary to untangle the intricate and partially interwoven signaling networks of ethylene and ROS. PMID:23761805

  12. Invasive plant species as potential bioenergy producers and carbon contributors.

    SciTech Connect

    Young, S.; Gopalakrishnan, G.; Keshwani, D.

    2011-03-01

    Current cellulosic bioenergy sources in the United States are being investigated in an effort to reduce dependence on foreign oil and the associated risks to national security and climate change (Koh and Ghazoul 2008; Demirbas 2007; Berndes et al. 2003). Multiple sources of renewable plant-based material have been identified and include agricultural and forestry residues, municipal solid waste, industrial waste, and specifically grown bioenergy crops (Demirbas et al. 2009; Gronowska et al. 2009). These sources are most commonly converted to energy through direct burning, conversion to gas, or conversion to ethanol. Annual crops, such as corn (Zea Mays L.) and sorghum grain, can be converted to ethanol through fermentation, while soybean and canola are transformed into fatty acid methyl esters (biodiesel) by reaction with an alcohol (Demirbas 2007). Perennial grasses are one of the more viable sources for bioenergy due to their continuous growth habit, noncrop status, and multiple use products (Lewandowski el al. 2003). In addition, a few perennial grass species have very high water and nutrient use efficiencies producing large quantities of biomass on an annual basis (Dohleman et al. 2009; Grantz and Vu 2009).

  13. Exogenous abscisic acid significantly affects proteome in tea plant (Camellia sinensis) exposed to drought stress

    PubMed Central

    Zhou, Lin; Xu, Hui; Mischke, Sue; Meinhardt, Lyndel W; Zhang, Dapeng; Zhu, Xujun; Li, Xinghui; Fang, Wanping

    2014-01-01

    Tea [Camellia sinensis (L.) O. Kuntze] is an important economic crop, and drought is the most important abiotic stress affecting yield and quality. Abscisic acid (ABA) is an important phytohormone responsible for activating drought resistance. Increased understanding of ABA effects on tea plant under drought stress is essential to develop drought-tolerant tea genotypes, along with crop management practices that can mitigate drought stress. The objective of the present investigation is evaluation of effects of exogenous ABA on the leaf proteome in tea plant exposed to drought stress. Leaf protein patterns of tea plants under simulated drought stress [(polyethylene glycol (PEG)-treated] and exogenous ABA treatment were analyzed in a time-course experiment using two-dimensional electrophoresis (2-DE), followed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). Among the 72 protein spots identified by MALDI-TOF MS, 16 proteins were downregulated and two were upregulated by exogenous ABA. The upregulated proteins have roles in glycolysis and photosystem II stabilization. Twenty-one protein spots were responsive to drought stress and most participate in carbohydrate and nitrogen metabolism, control of reactive oxygen species (ROS), defense, signaling or nucleic acid metabolism. The combined treatments of exogenous ABA and drought showed upregulation of 10 protein spots at 12 h and upregulation of 11 proteins at 72 h after initiation of drought stress. The results support the importance of the role that ABA plays in the tea plant during drought stress, by improving protein transport, carbon metabolism and expression of resistance proteins. PMID:27076915

  14. Do vineyards in contrasting landscapes contribute to conserve plant species of dry calcareous grasslands?

    PubMed

    Nascimbene, Juri; Zottini, Michela; Ivan, Diego; Casagrande, Valentina; Marini, Lorenzo

    2016-03-01

    The increasing development of vineyards in Mediterranean areas worldwide is considered a major driver of conversion of several habitats of conservation concern, including calcareous dry grasslands that are targeted for biodiversity conservation by the European Union, according to Natura 2000 policies. Here, we aim at evaluating the potential of extensive vineyards located in contrasting landscapes (semi-natural vs crop-dominated) for providing suitable habitat conditions to plant species associated with dry grasslands. This study was carried out in one of the economically most important winemaking districts of Italy, characterized by a hilly landscape with steep slope vineyards. We compared plant communities of vineyards in contrasting landscapes with those of the remnants of dry grasslands. Our study demonstrates that landscape composition strongly affects local plant communities in vineyards, with a positive effect of semi-natural habitats bordering the cultivated areas. Our findings thus supply an additional tool for improving the effectiveness of viticultural landscapes for nature conservation. In particular, our results indicate that vineyards on steep slopes could provide moderate chance for the conservation of plant specialists inhabiting calcareous dry grasslands, depending on the landscape composition: vineyards embedded in semi-natural landscapes have more potential for conservation than those in crop-dominated landscapes. Our study also indicates that conservation efforts should aim at (a) decreasing the current management intensity that likely hampers the beneficial effects of semi-natural habitats in the surrounding landscape on local plant assemblages, and (b) strictly conserving the remnants of dry grasslands that are irreplaceable refugia for habitat specialists and species of conservation concern. PMID:26747988

  15. Climate change may threaten habitat suitability of threatened plant species within Chinese nature reserves

    PubMed Central

    Wan, Jizhong

    2016-01-01

    Climate change has the potential to alter the distributions of threatened plant species, and may therefore diminish the capacity of nature reserves to protect threatened plant species. Chinese nature reserves contain a rich diversity of plant species that are at risk of becoming more threatened by climate change. Hence, it is urgent to identify the extent to which future climate change may compromise the suitability of threatened plant species habitats within Chinese nature reserves. Here, we modelled the climate suitability of 82 threatened plant species within 168 nature reserves across climate change scenarios. We used Maxent modelling based on species occurrence localities and evaluated climate change impacts using the magnitude of change in climate suitability and the degree of overlap between current and future climatically suitable habitats. There was a significant relationship between overlap with current and future climate suitability of all threatened plant species habitats and the magnitude of changes in climate suitability. Our projections estimate that the climate suitability of more than 60 threatened plant species will decrease and that climate change threatens the habitat suitability of plant species in more than 130 nature reserves under the low, medium, and high greenhouse gas concentration scenarios by both 2050s and 2080s. Furthermore, future climate change may substantially threaten tree plant species through changes in annual mean temperature. These results indicate that climate change may threaten plant species that occur within Chinese nature reserves. Therefore, we suggest that climate change projections should be integrated into the conservation and management of threatened plant species within nature reserves. PMID:27326373

  16. Decoupling factors affecting plant diversity and cover on extensive green roofs.

    PubMed

    MacIvor, J Scott; Margolis, Liat; Puncher, Curtis L; Carver Matthews, Benjamin J

    2013-11-30

    Supplemental irrigation systems are often specified on green roofs to ensure plant cover and growth, both important components of green roof performance and aesthetics. Properties of the growing media environment too can alter the assemblage of plant species able to thrive. In this study we determine how plant cover, above ground biomass and species diversity are influenced by irrigation and growing media. Grass and forb vegetative cover and biomass were significantly greater in organic based growing media but there was no effect of supplemental irrigation, with two warm season grasses dominating in those treatments receiving no supplemental irrigation. On the other hand, plant diversity declined without irrigation in organic media, and having no irrigation in inorganic growing media resulted in almost a complete loss of cover. Sedum biomass was less in inorganic growing media treatments and species dominance shifted when growing media organic content increased. Our results demonstrate that supplemental irrigation is required to maintain plant diversity on an extensive green roof, but not necessarily plant cover or biomass. These results provide evidence that planting extensive green roofs with a mix of plant species can ensure the survival of some species; maintaining cover and biomass when supplemental irrigation is turned off to conserve water, or during extreme drought. PMID:24100190

  17. Salt tolerance and stress level affect plant biomass-density relationships and neighbor effects

    NASA Astrophysics Data System (ADS)

    Yu, Zhenxing; Chen, Wenwen; Zhang, Qian; Yang, Haishui; Tang, Jianjun; Weiner, Jacob; Chen, Xin

    2014-07-01

    It has been shown that plant biomass-density relationships are altered under extreme or stressed conditions. We do not know whether variation in biomass-density relationships is a direct result of stress tolerance or occurs via changes in plant-plant interactions. Here, we evaluated biomass-density relationships and neighbor effects in six plant species that differ in salt tolerance in a salt marsh, and conducted a literature review of biomass-density relationship under higher and lower stress levels. Our field study showed that both neighbor effects and the exponent of the biomass-density relationship (α) varied among plant species with different degrees of salt tolerance. There was a positive relationship between neighbor effects (measured as relative interaction index) and α-value among the tested species. The literature review showed that α and its variation increased under higher stress. Our results indicate that plant species with different salinity tolerance differ in the direction and strength of neighbor effects, resulting in variation in biomass-density relationships. Our results support the hypothesis that differences in biomass-density relationships among species are not due to differences in stress tolerance alone, they are mediated by changes in plant-plant interactions.

  18. Effects of environmental change on plant species density: Comparing predictions with experiments

    USGS Publications Warehouse

    Gough, L.; Grace, J.B.

    1999-01-01

    Ideally, general ecological relationships may be used to predict responses of natural communities to environmental change, but few attempts have been made to determine the reliability of predictions based on descriptive data. Using a previously published structural equation model (SEM) of descriptive data from a coastal marsh landscape, we compared these predictions against observed changes in plant species density resulting from field experiments (manipulations of soil fertility, flooding, salinity, and mammalian herbivory) in two areas within the same marsh. In general, observed experimental responses were fairly consistent with predictions. The largest discrepancy occurred when sods were transplanted from high- to low-salinity sites and herbivores selectively consumed a particularly palatable plant species in the transplanted sods. Individual plot responses to some treatments were predicted more accurately than others. Individual fertilized plot responses were not consistent with predictions (P > 0.05), nor were fenced plots (herbivore exclosures; R2 = 0.15) compared to unfenced plots (R2 = 0.53). For the remaining treatments, predictions reasonably matched responses (R2 = 0.63). We constructed an SEM for the experimental data; it explained 60% of the variance in species density and showed that fencing and fertilization led to decreases in species density that were not predicted from treatment effects on community biomass or observed disturbance levels. These treatments may have affected the ratio of live to dead biomass, and competitive exclusion likely decreased species density in fenced and fertilized plots. We conclude that experimental validation is required to determine the predictive value of comparative relationships derived from descriptive data.

  19. The ozone component of global changes: Potential effects on agricultural and horticultural plant yield, product quality and interactions with invasive species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The performance and quality of agricultural and horticultural plants in many regions of the world are adversely affected by current and anticipated concentrations of ground-level, tropospheric ozone (O3). Numerous studies with a variety of plant species and experimental approaches lead to similar ...

  20. Is the use-impact on native caatinga species in Brazil reduced by the high species richness of medicinal plants?

    PubMed

    de Albuquerque, Ulysses Paulino; de Oliveira, Rosilane Ferreira

    2007-08-15

    A study of the diversity of uses of medicinal plants and the traditional knowledge associated with the caatinga vegetation was undertaken in the semi-arid region of Pernambuco State, NE Brazil. We tested the utilitarian redundancy model (as an analogy to the ecological redundancy hypothesis) in evaluating the implications of the use of medicinal plants by rural communities to examine whether the presence of numerous species with analogous functions (identical therapeutic applications, for example) would reduce the use-impact on native species in the neighboring caatinga vegetation. Various techniques were used to collect information concerning medicinal plants and their applications from 19 residents considered "local specialists". The vegetation was sampled to determine the abundance of woody plants. Approximately 106 plants that fall into 67 local therapeutic categories were identified. Despite the fact that exotic species compose a significant fraction of the local medicinal flora, the native species represented the greatest percentage of local uses and indications. Amburana cearensis, Myracrodruon urundeuva, Anadenanthera colubrina, Sideroxylon obtusifolium, and Ziziphus joazeiro, for example, are highly sought after plants, and represent key species in terms of conservation and sustainable management. Our model of utilitarian redundancy has important consequences for testing ethnobotanical hypotheses, as well as for indicating strategies for biodiversity conservation. PMID:17616289

  1. Tree species composition affects the abundance of rowan (Sorbus aucuparia L.) in urban forests in Finland.

    PubMed

    Hamberg, Leena; Lehvävirta, Susanna; Kotze, D Johan; Heikkinen, Juha

    2015-03-15

    Recent studies have shown a considerable increase in the abundance of rowan (Sorbus aucuparia) saplings in urban forests in Finland, yet the reasons for this increase are not well understood. Here we investigated whether canopy cover or tree species composition, i.e., the basal areas of different tree species in Norway spruce dominated urban forests, affects the abundances of rowan seedlings, saplings and trees. Altogether 24 urban forest patches were investigated. We sampled the number of rowan and other saplings, and calculated the basal areas of trees. We showed that rowan abundance was affected by tree species composition. The basal area of rowan trees (≥ 5 cm in diameter at breast height, dbh) decreased with increasing basal area of Norway spruce, while the cover of rowan seedlings increased with an increase in Norway spruce basal area. However, a decrease in the abundance of birch (Betula pendula) and an increase in the broad-leaved tree group (Acer platanoides, Alnus glutinosa, Alnus incana, Amelanchier spicata, Prunus padus, Quercus robur, Rhamnus frangula and Salix caprea) coincided with a decreasing number of rowans. Furthermore, rowan saplings were scarce in the vicinity of mature rowan trees. Although it seems that tree species composition has an effect on rowan, the relationship between rowan saplings and mature trees is complex, and therefore we conclude that regulating tree species composition is not an easy way to keep rowan thickets under control in urban forests in Finland. PMID:25588119

  2. Species by environment interactions affect pyrrolizidine alkaloid expression in Senecio jacobaea, Senecio aquaticus, and their hybrids.

    PubMed

    Kirk, Heather; Vrieling, Klaas; Van Der Meijden, Eddy; Klinkhamer, Peter G L

    2010-04-01

    We examined the effects of water and nutrient availability on the expression of the defense pyrrolizidine alkaloids (PAs) in Senecio jacobaea and S. aquaticus. Senecio jacobaea, and S. aquaticus are adapted to different natural habitats, characterized by differing abiotic conditions and different selection pressures from natural enemies. We tested if PA concentration and diversity are plastic over a range of water and nutrient treatments, and also whether such plasticity is dependent on plant species. We also tested the hypothesis that hybridization may contribute to PA diversity within plants, by comparing PA expression in parental species to that in artificially generated F(1) hybrids, and also in later generation natural hybrids between S. jacobaea and S. aquaticus. We showed that total PA concentration in roots and shoots is not dependent on species, but that species determines the pattern of PA diversification. Pyrrolizidine alkaloid diversity and concentration are both dependent on environmental factors. Hybrids produce a putatively novel PA, and this PA is conserved in natural hybrids, that are backcrossed to S. jacobaea. Natural hybrids that are backcrossed several times to S. jacobaea are with regard to PA diversity significantly different from S. jacobaea but not from S. aquaticus, while F(1) hybrids are in all cases more similar to S. jacobaea. These results collectively suggest that PA diversity is under the influence of natural selection. PMID:20309618

  3. Volatile Exchange between Undamaged Plants - a New Mechanism Affecting Insect Orientation in Intercropping

    PubMed Central

    Ninkovic, Velemir; Dahlin, Iris; Vucetic, Andja; Petrovic-Obradovic, Olivera; Glinwood, Robert; Webster, Ben

    2013-01-01

    Changes in plant volatile emission can be induced by exposure to volatiles from neighbouring insect-attacked plants. However, plants are also exposed to volatiles from unattacked neighbours, and the consequences of this have not been explored. We investigated whether volatile exchange between undamaged plants affects volatile emission and plant-insect interaction. Consistently greater quantities of two terpenoids were found in the headspace of potato previously exposed to volatiles from undamaged onion plants identified by mass spectrometry. Using live plants and synthetic blends mimicking exposed and unexposed potato, we tested the olfactory response of winged aphids, Myzus persicae. The altered potato volatile profile deterred aphids in laboratory experiments. Further, we show that growing potato together with onion in the field reduces the abundance of winged, host-seeking aphids. Our study broadens the ecological significance of the phenomenon; volatiles carry not only information on whether or not neighbouring plants are under attack, but also information on the emitter plants themselves. In this way responding plants could obtain information on whether the neighbouring plant is a competitive threat and can accordingly adjust their growth towards it. We interpret this as a response in the process of adaptation towards neighbouring plants. Furthermore, these physiological changes in the responding plants have significant ecological impact, as behaviour of aphids was affected. Since herbivore host plants are potentially under constant exposure to these volatiles, our study has major implications for the understanding of how mechanisms within plant communities affect insects. This knowledge could be used to improve plant protection and increase scientific understanding of communication between plants and its impact on other organisms. PMID:23922710

  4. How do soil texture, plant community composition and earthworms affected the infiltration rate in a grassland plant diversity experiment depending on season?

    NASA Astrophysics Data System (ADS)

    Fischer, Christine; Britta, Merkel; Nico, Eisenhauer; Christiane, Roscher; Sabine, Attinger; Stefan, Scheu; Anke, Hildebrandt

    2013-04-01

    Background and aims: In this study we analyzed the influences of plant community characteristics, soil texture and earthworm presence on infiltration rates on a managed grassland plant diversity experiment assessing the role of biotic and abiotic factors on soil hydrology. Methods: We measured infiltration using a hood infiltrometer in subplots with ambient and reduced earthworm density (earthworm extraction) nested in plots of different plant species richness (1, 4, and 16), plant functional group number and composition (1 to 4; legumes, grasses, small herbs, tall herbs) in early summer (June) and autumn (September, October) 2011. Results: The presence of certain plant functional groups such as grasses and legumes influenced infiltration rates and this effect enhanced during the growing season. Infiltration was significantly higher in plots containing legumes than in plots without, and it was significantly lower in the presence of grasses than in their absence. In early summer, earthworm presence and biomass increased the infiltration rates, independently of plant species richness. In October, plant species richness only affected infiltration rates in reduced earthworm plots. At the end of the growing season earthworm populations were negatively influenced by grasses and positively by legumes. In September, infiltration rates were positive related to the proportion of finer grains. The correlation disappears when removing all plots containing legumes from the sample. For all measurements the infiltration rates decreases from early summer to autumn at the matric potentials at pressure zero and -0.02 m, but not for smaller macropores at matric potentials -0.04 and -0.06m. Conclusions: Considering infiltration rates as ecosystem function, this function will largely depend on the ecosystem composition and season, not on biodiversity per se. Our results indicate that biotic factors are of overriding influence for shaping infiltration rates mainly for larger macropores

  5. Effects of Arbuscular-Mycorrhizal Glomus Species on Drought Tolerance: Physiological and Nutritional Plant Responses

    PubMed Central

    Ruiz-Lozano, J. M.; Azcon, R.; Gomez, M.

    1995-01-01

    The tolerance of lettuce plants (Lactuca sativa L. cv. Romana) to drought stress differed with the arbuscular-mycorrhizal fungal isolate with which the plants were associated. Seven fungal species belonging to the genus Glomus were studied for their ability to enhance the drought tolerance of lettuce plants. These fungi had different traits that affected the drought resistance of host plants. The ranking of arbuscular-mycorrhizal fungal effects on drought tolerance, based on the relative decreases in shoot dry weight, was as follows: Glomus deserticola > Glomus fasciculatum > Glomus mosseae > Glomus etunicatum > Glomus intraradices > Glomus caledonium > Glomus occultum. In this comparative study specific mycorrhizal fungi had consistent effects on plant growth, mineral uptake, the CO(inf2) exchange rate, water use efficiency, transpiration, stomatal conductance, photosynthetic phosphorus use efficiency, and proline accumulation under either well-watered or drought-stressed conditions. The ability of the isolates to maintain plant growth effectively under water stress conditions was related to higher transpiration rates, levels of leaf conductance, and proline, N, and P contents. Differences in proline accumulation in leaves among the fungal symbioses suggested that the fungi were able to induce different degrees of osmotic adjustment. The detrimental effects of drought were not related to decreases in photosynthesis or water use efficiency. Neither of these parameters was related to P nutrition. The differences in P and K acquisition, transpiration, and stomatal conductance were related to the mycorrhizal efficiencies of the different fungi. Our observations revealed the propensities of different Glomus species to assert their protective effects during plant water stress. The greater effectiveness of G. deserticola in improving water deficit tolerance was associated with the lowest level of growth reduction (9%) under stress conditions. The growth of plants

  6. Evolutionary factors affecting the cross-species utility of newly developed microsatellite markers in seabirds.

    PubMed

    Moodley, Yoshan; Masello, Juan F; Cole, Theresa L; Calderon, Luciano; Munimanda, Gopi K; Thali, Marco R; Alderman, Rachael; Cuthbert, Richard J; Marin, Manuel; Massaro, Melanie; Navarro, Joan; Phillips, Richard A; Ryan, Peter G; Suazo, Cristián G; Cherel, Yves; Weimerskirch, Henri; Quillfeldt, Petra

    2015-09-01

    Microsatellite loci are ideal for testing hypotheses relating to genetic segregation at fine spatio-temporal scales. They are also conserved among closely related species, making them potentially useful for clarifying interspecific relationships between recently diverged taxa. However, mutations at primer binding sites may lead to increased nonamplification, or disruptions that may result in decreased polymorphism in nontarget species. Furthermore, high mutation rates and constraints on allele size may also with evolutionary time, promote an increase in convergently evolved allele size classes, biasing measures of interspecific genetic differentiation. Here, we used next-generation sequencing to develop microsatellite markers from a shotgun genome sequence of the sub-Antarctic seabird, the thin-billed prion (Pachyptila belcheri), that we tested for cross-species amplification in other Pachyptila and related sub-Antarctic species. We found that heterozygosity decreased and the proportion of nonamplifying loci increased with phylogenetic distance from the target species. Surprisingly, we found that species trees estimated from interspecific FST provided better approximations of mtDNA relationships among the studied species than those estimated using DC , even though FST was more affected by null alleles. We observed a significantly nonlinear second order polynomial relationship between microsatellite and mtDNA distances. We propose that the loss of linearity with increasing mtDNA distance stems from an increasing proportion of homoplastic allele size classes that are identical in state, but not identical by descent. Therefore, despite high cross-species amplification success and high polymorphism among the closely related Pachyptila species, we caution against the use of microsatellites in phylogenetic inference among distantly related taxa. PMID:25594938

  7. Remnant Trees Affect Species Composition but Not Structure of Tropical Second-Growth Forest

    PubMed Central

    Sandor, Manette E.; Chazdon, Robin L.

    2014-01-01

    Remnant trees, spared from cutting when tropical forests are cleared for agriculture or grazing, act as nuclei of forest regeneration following field abandonment. Previous studies on remnant trees were primarily conducted in active pasture or old fields abandoned in the previous 2–3 years, and focused on structure and species richness of regenerating forest, but not species composition. Our study is among the first to investigate the effects of remnant trees on neighborhood forest structure, biodiversity, and species composition 20 years post-abandonment. We compared the woody vegetation around individual remnant trees to nearby plots without remnant trees in the same second-growth forests (“control plots”). Forest structure beneath remnant trees did not differ significantly from control plots. Species richness and species diversity were significantly higher around remnant trees. The species composition around remnant trees differed significantly from control plots and more closely resembled the species composition of nearby old-growth forest. The proportion of old-growth specialists and generalists around remnant trees was significantly greater than in control plots. Although previous studies show that remnant trees may initially accelerate secondary forest growth, we found no evidence that they locally affect stem density, basal area, and seedling density at later stages of regrowth. Remnant trees do, however, have a clear effect on the species diversity, composition, and ecological groups of the surrounding woody vegetation, even after 20 years of forest regeneration. To accelerate the return of diversity and old-growth forest species into regrowing forest on abandoned land, landowners should be encouraged to retain remnant trees in agricultural or pastoral fields. PMID:24454700

  8. The Plant Communities and Environmental Gradients of Pitcairn Island: The Significance of Invasive Species and the Need for Conservation Management

    PubMed Central

    KINGSTON, N.; WALDREN, S.

    2003-01-01

    Quantitative surveys of the vegetation of south‐east Polynesian Islands are rarely undertaken owing to time and logistical restrictions; however they are fundamental in determining the conservation status of fragile island ecosystems. The aim of the research was to document quantitatively the vegetation of Pitcairn Island by investigating whether clearly definable plant communities existed on the island, and the underlying environmental gradients influencing these communities. Initially, 10 × 10 m quadrats were taken from all areas of the island, with environmental parameters recorded for each quadrat. The vegetation was then mapped from high altitude vantage points. Two‐way indicator species analysis was used to identify distinct plant communities, and canonical correspondence analysis was used to determine the underlying environmental gradients. The vegetation consists of 14 plant communities: four coastal, six forest, two fernland and two scrub communities. Large areas are covered by non‐native scrub vegetation, and by monospecific Syzygium jambos (rose‐apple) plantations. Less than 30 % of the island is covered by native forest, and these areas are limited to remote valleys. Fernlands also cover large areas, including both eroding areas and ridge tops. Coastal vegetation comprises rock and cliff communities with limited strand vegetation. The major environmental gradient affecting the composition of the plant communities is altitude, but anthropogenic influences also have a large effect, owing to forest clearance and introduced species. The light environment is affected by the canopy species, and determines what ground flora can develop. Identification of distinct plant communities has allowed for a system of nature reserves to be suggested, which conserve all of these plant communities and a significant proportion of the threatened plant species. PMID:12824069

  9. Factors affecting post-control reinvasion by seed of an invasive species, Phragmites australis, in the central Platte River, Nebraska.

    USGS Publications Warehouse

    Galatowitsch, Susan M.; Larson, Diane L.; Larson, Jennifer L.

    2016-01-01

    Invasive plants, such as Phragmites australis, can profoundly affect channel environments of large rivers by stabilizing sediments and altering water flows. Invasive plant removal is considered necessary where restoration of dynamic channels is needed to provide critical habitat for species of conservation concern. However, these programs are widely reported to be inefficient. Post-control reinvasion is frequent, suggesting increased attention is needed to prevent seed regeneration. To develop more effective responses to this invader in the Central Platte River (Nebraska, USA), we investigated several aspects of Phragmites seed ecology potentially linked to post-control reinvasion, in comparison to other common species: extent of viable seed production, importance of water transport, and regeneration responses to hydrology. We observed that although Phragmites seed does not mature until very late in the ice-free season, populations produce significant amounts of viable seed (>50 % of filled seed). Most seed transported via water in the Platte River are invasive perennial species, although Phragmites abundances are much lower than species such as Lythrum salicaria, Cyperus esculentus and Phalaris arundinacea. Seed regeneration of Phragmites varies greatly depending on hydrology, especially timing of water level changes. Flood events coinciding with the beginning of seedling emergence reduced establishment by as much as 59 % compared to flood events that occurred a few weeks later. Results of these investigations suggest that prevention of seed set (i.e., by removal of flowering culms) should be a priority in vegetation stands not being treated annually. After seeds are in the seedbank, preventing reinvasion using prescribed flooding has a low chance of success given that Phragmites can regenerate in a wide variety of hydrologic microsites.

  10. Solanum malacoxylon: a toxic plant which affects animal calcium metabolism.

    PubMed

    Boland, R L

    1988-12-01

    The "enteque seco" is a disease of calcinosis, i.e., pathological deposition of calcium phosphate in soft tissues, which occurs in grazing cattle in Argentina and is of considerable economic importance. The ingestion of leaves of Solanum malacoxylon has been identified as the cause of the disease. Hypercalcemia and/or hyperphosphatemia and mineralization of the cardiovascular and pulmonary systems are usually seen in bovines or experimental animals exposed to this plant. The symptoms of the disease resemble those of vitamin D intoxication. In agreement with these observations, a glycoside derivative of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), the hormonally active form of vitamin D in animals, has been identified as the toxic principle of S. malacoxylon. Glycoside conjugates of its precursors, 25-hydroxyvitamin D3 and vitamin D3, may also be present. Recent studies indicate that the plant factor is modified in the rumen of bovines through cleavage of the glycosidic linkage and further conversion of the released 1,25(OH)2D3 to a more polar metabolite, possibly 1,24,25-trihydroxyvitamin D3. Excess free 1,25(OH)2D3 may alter extracellular and intracellular Ca homeostasis in intoxicated animals through a receptor-mediated mechanism and activation of membrane Ca channels. In addition, 1,24,25(OH)3D3 may potentiate the effects of 1,25(OH)2D3 on intestinal Ca transport. PMID:3077267

  11. Bayesian species delimitation reveals generalist and specialist parasitic wasps on Galerucella beetles (Chrysomelidae): sorting by herbivore or plant host

    PubMed Central

    2013-01-01

    Background To understand the ecological and evolutionary consequences of species interactions in food webs necessitates that interactions are properly identified. Genetic analyses suggest that many supposedly generalist parasitoid species should rather be defined as multiple species with a more narrow diet, reducing the probability that such species may mediate indirect interactions such as apparent competition among hosts. Recent studies showed that the parasitoid Asecodes lucens mediate apparent competition between two hosts, Galerucella tenella and G. calmariensis, affecting both interaction strengths and evolutionary feedbacks. The same parasitoid was also recorded from other species in the genus Galerucella, suggesting that similar indirect effects may also occur for other species pairs. Methods To explore the possibility of such interactions, we sequenced mitochondrial and nuclear genetic markers to resolve the phylogeny of both host and parasitoid and to test the number of parasitoid species involved. We thus collected 139 Galerucella larvae from 8 host plant species and sequenced 31 adult beetle and 108 parasitoid individuals. Results The analysis of the Galerucella data, that also included sequences from previous studies, verified the five species previously documented as reciprocally monophyletic, but the Bayesian species delimitation for A. lucens suggested 3–4 cryptic taxa with a more specialised host use than previously suggested. The gene data analyzed under the multispecies coalescent model allowed us to reconstruct the species tree phylogeny for both host and parasitoid and we found a fully congruent coevolutionary pattern suggesting that parasitoid speciation followed upon host speciation. Conclusion Using multilocus sequence data in a Bayesian species delimitation analysis we propose that hymenopteran parasitoids of the genus Asecodes that infest Galerucella larvae constitute at least three species with narrow diet breath. The evolution of

  12. Species richness of arbuscular mycorrhizal fungi: associations with grassland plant richness and biomass.

    PubMed

    Hiiesalu, Inga; Pärtel, Meelis; Davison, John; Gerhold, Pille; Metsis, Madis; Moora, Mari; Öpik, Maarja; Vasar, Martti; Zobel, Martin; Wilson, Scott D

    2014-07-01

    Although experiments show a positive association between vascular plant and arbuscular mycorrhizal fungal (AMF) species richness, evidence from natural ecosystems is scarce. Furthermore, there is little knowledge about how AMF richness varies with belowground plant richness and biomass. We examined relationships among AMF richness, above- and belowground plant richness, and plant root and shoot biomass in a native North American grassland. Root-colonizing AMF richness and belowground plant richness were detected from the same bulk root samples by 454-sequencing of the AMF SSU rRNA and plant trnL genes. In total we detected 63 AMF taxa. Plant richness was 1.5 times greater belowground than aboveground. AMF richness was significantly positively correlated with plant species richness, and more strongly with below- than aboveground plant richness. Belowground plant richness was positively correlated with belowground plant biomass and total plant biomass, whereas aboveground plant richness was positively correlated only with belowground plant biomass. By contrast, AMF richness was negatively correlated with belowground and total plant biomass. Our results indicate that AMF richness and plant belowground richness are more strongly related with each other and with plant community biomass than with the plant aboveground richness measures that have been almost exclusively considered to date. PMID:24641509

  13. Investigating Effects of Invasive Species on Plant Community Structure

    ERIC Educational Resources Information Center

    Franklin, Wilfred

    2008-01-01

    In this article, the author presents a field study project that explores factors influencing forest community structure and lifts the veil off of "plant blindness." This ecological study consists of three laboratories: (1) preliminary field trip to the study site; (2) plant survey; and (3) analyzing plant community structure with descriptive…

  14. Nutritional and cultural aspects of plant species selection for a controlled ecological life support system

    NASA Technical Reports Server (NTRS)

    Hoff, J. E.; Howe, J. M.; Mitchell, C. A.

    1982-01-01

    The feasibility of using higher plants in a controlled ecological life support system is discussed. Aspects of this system considered important in the use of higher plants include: limited energy, space, and mass, and problems relating to cultivation and management of plants, food processing, the psychological impact of vegetarian diets, and plant propagation. A total of 115 higher plant species are compared based on 21 selection criteria.

  15. Beyond the EDGE with EDAM: Prioritising British Plant Species According to Evolutionary Distinctiveness, and Accuracy and Magnitude of Decline

    PubMed Central

    Pearse, William D.; Chase, Mark W.; Crawley, Michael J.; Dolphin, Konrad; Fay, Michael F.; Joseph, Jeffrey A.; Powney, Gary; Preston, Chris D.; Rapacciuolo, Giovanni; Roy, David B.; Purvis, Andy

    2015-01-01

    Conservation biologists have only finite resources, and so must prioritise some species over others. The EDGE-listing approach ranks species according to their combined evolutionary distinctiveness and degree of threat, but ignores the uncertainty surrounding both threat and evolutionary distinctiveness. We develop a new family of measures for species, which we name EDAM, that incorporates evolutionary distinctiveness, the magnitude of decline, and the accuracy with which decline can be predicted. Further, we show how the method can be extended to explore phyogenetic uncertainty. Using the vascular plants of Britain as a case study, we find that the various EDAM measures emphasise different species and parts of Britain, and that phylogenetic uncertainty can strongly affect the prioritisation scores of some species. PMID:26018568

  16. Beyond the EDGE with EDAM: Prioritising British Plant Species According to Evolutionary Distinctiveness, and Accuracy and Magnitude of Decline.

    PubMed

    Pearse, William D; Chase, Mark W; Crawley, Michael J; Dolphin, Konrad; Fay, Michael F; Joseph, Jeffrey A; Powney, Gary; Preston, Chris D; Rapacciuolo, Giovanni; Roy, David B; Purvis, Andy

    2015-01-01

    Conservation biologists have only finite resources, and so must prioritise some species over others. The EDGE-listing approach ranks species according to their combined evolutionary distinctiveness and degree of threat, but ignores the uncertainty surrounding both threat and evolutionary distinctiveness. We develop a new family of measures for species, which we name EDAM, that incorporates evolutionary distinctiveness, the magnitude of decline, and the accuracy with which decline can be predicted. Further, we show how the method can be extended to explore phyogenetic uncertainty. Using the vascular plants of Britain as a case study, we find that the various EDAM measures emphasise different species and parts of Britain, and that phylogenetic uncertainty can strongly affect the prioritisation scores of some species. PMID:26018568

  17. Plant performance on Mediterranean green roofs: interaction of species-specific hydraulic strategies and substrate water relations

    PubMed Central

    Raimondo, Fabio; Trifilò, Patrizia; Lo Gullo, Maria A.; Andri, Sergio; Savi, Tadeja; Nardini, Andrea

    2015-01-01

    Recent studies have highlighted the ecological, economic and social benefits assured by green roof technology to urban areas. However, green roofs are very hostile environments for plant growth because of shallow substrate depths, high temperatures and irradiance and wind exposure. This study provides experimental evidence for the importance of accurate selection of plant species and substrates for implementing green roofs in hot and arid regions, like the Mediterranean area. Experiments were performed on two shrub species (Arbutus unedo L. and Salvia officinalis L.) grown in green roof experimental modules with two substrates slightly differing in their water retention properties, as derived from moisture release curves. Physiological measurements were performed on both well-watered and drought-stressed plants. Gas exchange, leaf and xylem water potential and also plant hydraulic conductance were measured at different time intervals following the last irrigation. The substrate type significantly affected water status. Arbutus unedo and S. officinalis showed different hydraulic responses to drought stress, with the former species being substantially isohydric and the latter one anisohydric. Both A. unedo and S. officinalis were found to be suitable species for green roofs in the Mediterranean area. However, our data suggest that appropriate choice of substrate is key to the success of green roof installations in arid environments, especially if anisohydric species are employed. PMID:25603968

  18. Plant performance on Mediterranean green roofs: interaction of species-specific hydraulic strategies and substrate water relations.

    PubMed

    Raimondo, Fabio; Trifilò, Patrizia; Lo Gullo, Maria A; Andri, Sergio; Savi, Tadeja; Nardini, Andrea

    2015-01-01

    Recent studies have highlighted the ecological, economic and social benefits assured by green roof technology to urban areas. However, green roofs are very hostile environments for plant growth because of shallow substrate depths, high temperatures and irradiance and wind exposure. This study provides experimental evidence for the importance of accurate selection of plant species and substrates for implementing green roofs in hot and arid regions, like the Mediterranean area. Experiments were performed on two shrub species (Arbutus unedo L. and Salvia officinalis L.) grown in green roof experimental modules with two substrates slightly differing in their water retention properties, as derived from moisture release curves. Physiological measurements were performed on both well-watered and drought-stressed plants. Gas exchange, leaf and xylem water potential and also plant hydraulic conductance were measured at different time intervals following the last irrigation. The substrate type significantly affected water status. Arbutus unedo and S. officinalis showed different hydraulic responses to drought stress, with the former species being substantially isohydric and the latter one anisohydric. Both A. unedo and S. officinalis were found to be suitable species for green roofs in the Mediterranean area. However, our data suggest that appropriate choice of substrate is key to the success of green roof installations in arid environments, especially if anisohydric species are employed. PMID:25603968

  19. Plant Species Diversity and Distribution in Pastures of the Northeastern USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grazed pastures in the northeastern United contain far more than planted forage species. These species may contribute to forage production, but they may also detract from forage production or palatability. As the first step toward identifying the role of plant diversity in forage systems, we collect...

  20. Spatial environmental heterogeneity affects plant growth and thermal performance on a green roof.

    PubMed

    Buckland-Nicks, Michael; Heim, Amy; Lundholm, Jeremy

    2016-05-15

    Green roofs provide ecosystem services, including stormwater retention and reductions in heat transfer through the roof. Microclimates, as well as designed features of green roofs, such as substrate and vegetation, affect the magnitude of these services. Many green roofs are partially shaded by surrounding buildings, but the effects of this within-roof spatial environmental heterogeneity on thermal performance and other ecosystem services have not been examined. We quantified the effects of spatial heterogeneity in solar radiation, substrate depth and other variables affected by these drivers on vegetation and ecosystem services in an extensive green roof. Spatial heterogeneity in substrate depth and insolation were correlated with differential growth, survival and flowering in two focal plant species. These effects were likely driven by the resulting spatial heterogeneity in substrate temperature and moisture content. Thermal performance (indicated by heat flux and substrate temperature) was influenced by spatial heterogeneity in vegetation cover and substrate depth. Areas with less insolation were cooler in summer and had greater substrate moisture, leading to more favorable conditions for plant growth and survival. Spatial variation in substrate moisture (7%-26% volumetric moisture content) and temperature (21°C-36°C) during hot sunny conditions in summer could cause large differences in stormwater retention and heat flux within a single green roof. Shaded areas promote smaller heat fluxes through the roof, leading to energy savings, but lower evapotranspiration in these areas should reduce stormwater retention capacity. Spatial heterogeneity can thus result in trade-offs between different ecosystem services. The effects of these spatial heterogeneities are likely widespread in green roofs. Structures that provide shelter from sun and wind may be productively utilized to design higher functioning green roofs and increase biodiversity by providing habitat

  1. How does biomass distribution change with size and differ among species? An analysis for 1200 plant species from five continents.

    PubMed

    Poorter, Hendrik; Jagodzinski, Andrzej M; Ruiz-Peinado, Ricardo; Kuyah, Shem; Luo, Yunjian; Oleksyn, Jacek; Usoltsev, Vladimir A; Buckley, Thomas N; Reich, Peter B; Sack, Lawren

    2015-11-01

    We compiled a global database for leaf, stem and root biomass representing c. 11 000 records for c. 1200 herbaceous and woody species grown under either controlled or field conditions. We used this data set to analyse allometric relationships and fractional biomass distribution to leaves, stems and roots. We tested whether allometric scaling exponents are generally constant across plant sizes as predicted by metabolic scaling theory, or whether instead they change dynamically with plant size. We also quantified interspecific variation in biomass distribution among plant families and functional groups. Across all species combined, leaf vs stem and leaf vs root scaling exponents decreased from c. 1.00 for small plants to c. 0.60 for the largest trees considered. Evergreens had substantially higher leaf mass fractions (LMFs) than deciduous species, whereas graminoids maintained higher root mass fractions (RMFs) than eudicotyledonous herbs. These patterns do not support the hypothesis of fixed allometric exponents. Rather, continuous shifts in allometric exponents with plant size during ontogeny and evolution are the norm. Across seed plants, variation in biomass distribution among species is related more to function than phylogeny. We propose that the higher LMF of evergreens at least partly compensates for their relatively low leaf area : leaf mass ratio. PMID:26197869

  2. Macroinvertebrate abundance, water chemistry, and wetland characteristics affect use of wetlands by avian species in Maine

    USGS Publications Warehouse

    Longcore, J.R.; McAuley, D.G.; Pendleton, G.W.; Bennatti, C.R.; Mingo, T.M.; Stromborg, K.L.

    2006-01-01

    Our objective was to determine use by avian species (e.g., piscivores, marsh birds, waterfowl, selected passerines) of 29 wetlands in areas with low ( 5.51. All years combined use of wetlands by broods was greater on wetlands with pH 5.51 that supported 21.8% of the broods. High mean brood density was associated with mean number of Insecta per wetland. For lentic wetlands created by beaver, those habitats contained vegetative structure and nutrients necessary to provide cover to support invertebrate populations that are prey of omnivore and insectivore species. The fishless status of a few wetlands may have affected use by some waterfowl species and obligate piscivores.

  3. Macroinvertebrate abundance, water chemistry, and wetland characteristics affect use of wetlands by avian species in Maine

    USGS Publications Warehouse

    Longcore, J.R.; McAuley, D.G.; Pendelton, G.W.; Bennatti, C.R.; Mingo, T.M.; Stromborg, K.L.

    2006-01-01

    Our objective was to determine use by avian species (e.g., piscivores, marsh birds, waterfowl, selected passerines) of 29 wetlands in areas with low ( 5.51. All years combined use of wetlands by broods was greater on wetlands with pH ??? 5.51 (77.4%) in contract to wetlands with pH > 5.51 that supported 21.8% of the broods. High mean brood density was associated with mean number of Insecta per wetland. For lentic wetlands created by beaver, those habitats contained vegetative structure and nutrients necessary to provide cover to support invertebrate populations that are prey of omnivore and insectivore species. The fishless status of a few wetlands may have affected use by some waterfowl species and obligate piscivores. ?? Springer 2006.

  4. Effect of smoke derivatives on in vitro pollen germination and pollen tube elongation of species from different plant families.

    PubMed

    Kumari, A; Papenfus, H B; Kulkarni, M G; Pošta, M; Van Staden, J

    2015-07-01

    Plant-derived smoke stimulates seed germination in numerous plant species. Smoke also has a positive stimulatory effect on pollen germination and pollen tube growth. The range of plant families affected my smoke still needs to be established since the initial study was restricted to only three species from the Amaryllidaceae. The effects of smoke-water (SW) and the smoke-derived compounds, karrikinolide (KAR1 ) and trimethylbutenolide (TMB) on pollen growth characteristics were evaluated in seven different plant families. Smoke-water (1:1000 and 1:2000 v:v) combined with either Brewbaker and Kwack's (BWK) medium or sucrose and boric acid (SB) medium significantly improved pollen germination and pollen tube growth in Aloe maculata All., Kniphofia uvaria Oken, Lachenalia aloides (L.f.) Engl. var. aloides and Tulbaghia simmleri P. Beauv. Karrikinolide (10(-6) and 10(-7) m) treatment significantly improved pollen tube growth in A. maculata, K. uvaria, L. aloides and Nematanthus crassifolius (Schott) Wiehle compared to the controls. BWK or SB medium containing TMB (10(-3) m) produced significantly longer pollen tubes in A. maculata, K. uvaria and N. crassifolius. These results indicate that plant-derived smoke and the smoke-isolated compounds may stimulate pollen growth in a wide range of plant species. PMID:25545791

  5. Are non-native plants perceived to be more risky? Factors influencing horticulturists' risk perceptions of ornamental plant species.

    PubMed

    Humair, Franziska; Kueffer, Christoph; Siegrist, Michael

    2014-01-01

    Horticultural trade is recognized as an important vector in promoting the introduction and dispersal of harmful non-native plant species. Understanding horticulturists' perceptions of biotic invasions is therefore important for effective species risk management. We conducted a large-scale survey among horticulturists in Switzerland (N = 625) to reveal horticulturists' risk and benefit perceptions from ornamental plant species, their attitudes towards the regulation of non-native species, as well as the factors decisive for environmental risk perceptions and horticulturists' willingness to engage in risk mitigation behavior. Our results suggest that perceived familiarity with a plant species had a mitigating effect on risk perceptions, while perceptions of risk increased if a species was perceived to be non-native. However, perceptions of the non-native origin of ornamental plant species were often not congruent with scientific classifications. Horticulturists displayed positive attitudes towards mandatory trade regulations, particularly towards those targeted against known invasive species. Participants also expressed their willingness to engage in risk mitigation behavior. Yet, positive effects of risk perceptions on the willingness to engage in risk mitigation behavior were counteracted by perceptions of benefits from selling non-native ornamental species. Our results indicate that the prevalent practice in risk communication to emphasize the non-native origin of invasive species can be ineffective, especially in the case of species of high importance to local industries and people. This is because familiarity with these plants can reduce risk perceptions and be in conflict with scientific concepts of non-nativeness. In these cases, it might be more effective to focus communication on well-documented environmental impacts of harmful species. PMID:25003195

  6. Are Non-Native Plants Perceived to Be More Risky? Factors Influencing Horticulturists' Risk Perceptions of Ornamental Plant Species

    PubMed Central

    Humair, Franziska; Kueffer, Christoph; Siegrist, Michael

    2014-01-01

    Horticultural trade is recognized as an important vector in promoting the introduction and dispersal of harmful non-native plant species. Understanding horticulturists' perceptions of biotic invasions is therefore important for effective species risk management. We conducted a large-scale survey among horticulturists in Switzerland (N = 625) to reveal horticulturists' risk and benefit perceptions from ornamental plant species, their attitudes towards the regulation of non-native species, as well as the factors decisive for environmental risk perceptions and horticulturists' willingness to engage in risk mitigation behavior. Our results suggest that perceived familiarity with a plant species had a mitigating effect on risk perceptions, while perceptions of risk increased if a species was perceived to be non-native. However, perceptions of the non-native origin of ornamental plant species were often not congruent with scientific classifications. Horticulturists displayed positive attitudes towards mandatory trade regulations, particularly towards those targeted against known invasive species. Participants also expressed their willingness to engage in risk mitigation behavior. Yet, positive effects of risk perceptions on the willingness to engage in risk mitigation behavior were counteracted by perceptions of benefits from selling non-native ornamental species. Our results indicate that the prevalent practice in risk communication to emphasize the non-native origin of invasive species can be ineffective, especially in the case of species of high importance to local industries and people. This is because familiarity with these plants can reduce risk perceptions and be in conflict with scientific concepts of non-nativeness. In these cases, it might be more effective to focus communication on well-documented environmental impacts of harmful species. PMID:25003195

  7. Discriminating plant species across California's diverse ecosystems using airborne VSWIR and TIR imagery

    NASA Astrophysics Data System (ADS)

    Meerdink, S.; Roberts, D. A.; Roth, K. L.

    2015-12-01

    Accurate knowledge of the spatial distribution of plant species is required for many research and management agendas that track ecosystem health. Because of this, there is continuous development of research focused on remotely-sensed species classifications for many diverse ecosystems. While plant species have been mapped using airborne imaging spectroscopy, the geographic extent has been limited due to data availability and spectrally similar species continue to be difficult to separate. The proposed Hyperspectral Infrared Imager (HyspIRI) space-borne mission, which includes a visible near infrared/shortwave infrared (VSWIR) imaging spectrometer and thermal infrared (TIR) multi-spectral imager, would present an opportunity to improve species discrimination over a much broader scale. Here we evaluate: 1) the capability of VSWIR and/or TIR spectra to discriminate plant species; 2) the accuracy of species classifications within an ecosystem; and 3) the potential for discriminating among species across a range of ecosystems. Simulated HyspIRI imagery was acquired in spring/summer of 2013 spanning from Santa Barbara to Bakersfield, CA with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and the MODIS/ASTER Airborne Simulator (MASTER) instruments. Three spectral libraries were created from these images: AVIRIS (224 bands from 0.4 - 2.5 µm), MASTER (8 bands from 7.5 - 12 µm), and AVIRIS + MASTER. We used canonical discriminant analysis (CDA) as a dimension reduction technique and then classified plant species using linear discriminant analysis (LDA). Our results show the inclusion of TIR spectra improved species discrimination, but only for plant species with emissivities departing from that of a gray body. Ecosystems with species that have high spectral contrast had higher classification accuracies. Mapping plant species across all ecosystems resulted in a classification with lower accuracies than a single ecosystem due to the complex nature of

  8. Threatened and Endangered Species Evaluation for Operating Commercial Nuclear Power Generating Plants

    SciTech Connect

    Sackschewsky, Michael R.

    2004-01-15

    &E species take, consultations, and evaluations of potential effects of operation on T&E species. This search recovered a total of approximately 100 documents from 13 sites. Sites that were in the relicensing or decommissioning processes were excluded from the ADAMS search. In general the ADAMS search did not reveal any serious deficiencies or compliance problems. The most notable finds were reports of takes of green sea turtles at Diablo Canyon. While these events were reported to both the NRC and to NOAA Fisheries, no record of interaction between the two federal agencies was found. Species potentially present at each site were determined via querying the Geographical, Environmental, and Siting Information System (GEn&SIS) database developed for the NRC by Lawrence Livermore National Laboratory. The results of these queries were compared against the 1997 review, and in the cases of sites that were in the relicensing process, with the results of those site specific evaluations. A total of 452 T&E species were identified as potentially occurring near one or more of the operating commercial nuclear power generating plants. Information about each of these species was gathered to support an assessment of the probability of occurrence at each of the reactor sites. Based on the assessments of which species are potentially affected at each site, and the information gathered through the ADAMS search, each site was assigned a priority value for follow-up evaluations. The priority listing did not include any sites that had entered the relicensing process, those where the licensee has indicated that they intend to enter the relicensing process before the end of 2005, or those that have entered the decommissioning process. Of the 39 remaining sites, those that were identified as the highest priority for follow-on evaluations are: Diablo Canyon, San Onofre, Crystal River, Harris, and Vogtle, followed by South Texas, Palo Verde, Salem, and Cooper.

  9. Phytophthora niederhauserii sp. nov., a polyphagous species associated with ornamentals, fruit trees and native plants in 13 countries.

    PubMed

    Abad, Z Gloria; Abad, Jorge A; Cacciola, Santa Olga; Pane, Antonella; Faedda, Roberto; Moralejo, Eduardo; Pérez-Sierra, Ana; Abad-Campos, Paloma; Alvarez-Bernaola, Luis A; Bakonyi, József; Józsa, András; Herrero, Maria Luz; Burgess, Treena I; Cunnington, James H; Smith, Ian W; Balci, Yilmaz; Blomquist, Cheryl; Henricot, Béatrice; Denton, Geoffrey; Spies, Chris; Mcleod, Adele; Belbahri, Lassaad; Cooke, David; Kageyama, Koji; Uematsu, Seiji; Kurbetli, Ilker; Değirmenci, Kemal

    2014-01-01

    A non-papillate, heterothallic Phytophthora species first isolated in 2001 and subsequently from symptomatic roots, crowns and stems of 33 plant species in 25 unrelated botanical families from 13 countries is formally described here as a new species. Symptoms on various hosts included crown and stem rot, chlorosis, wilting, leaf blight, cankers and gumming. This species was isolated from Australia, Hungary, Israel, Italy, Japan, the Netherlands, Norway, South Africa, Spain, Taiwan, Turkey, the United Kingdom and United States in association with shrubs and herbaceous ornamentals grown mainly in greenhouses. The most prevalent hosts are English ivy (Hedera helix) and Cistus (Cistus salvifolius). The association of the species with acorn banksia (Banksia prionotes) plants in natural ecosystems in Australia, in affected vineyards (Vitis vinifera) in South Africa and almond (Prunus dulcis) trees in Spain and Turkey in addition to infection of shrubs and herbaceous ornamentals in a broad range of unrelated families are a sign of a wide ecological adaptation of the species and its potential threat to agricultural and natural ecosystems. The morphology of the persistent non-papillate ellipsoid sporangia, unique toruloid lobate hyphal swellings and amphigynous antheridia does not match any of the described species. Phylogenetic analysis based on sequences of the ITS rDNA, EF-1α, and β-tub supported that this organism is a hitherto unknown species. It is closely related to species in ITS clade 7b with the most closely related species being P. sojae. The name Phytophthora niederhauserii has been used in previous studies without the formal description of the holotype. This name is validated in this manuscript with the formal description of Phytophthora niederhauserii Z.G. Abad et J.A. Abad, sp. nov. The name is coined to honor Dr John S. Niederhauser, a notable plant pathologist and the 1990 World Food Prize laureate. PMID:24871599

  10. How microRNA172 affects fruit growth in different species is dependent on fruit type.

    PubMed

    Yao, Jia-Long; Tomes, Sumathi; Xu, Juan; Gleave, Andrew P

    2016-04-01

    microRNA172 (miR172) expression has been shown to have a positive effect on Arabidopsis fruit (siliques) growth. In contrast, over-expression of miR172 has a negative influence on fruit growth in apple, resulting in a dramatic reduction in fruit size. This negative influence is supported by the results of analyzing a transposable element (TE) insertional allele of a MIR172 gene that has reduced expression of the miRNA and is associated with an increase in fruit size. Arabidopsis siliques are a dry fruit derived from ovary tissues, whereas apple is a fleshy pome fruit derived mostly from hypanthium tissues. A model has been developed to explain the contrasting impact of miR172 expression in these two plant species based on the differences in their fruit structure. Transgenic apple plants with extremely high levels of miR172 overexpression produced flowers consisting of carpel tissues only, which failed to produce fruit. By comparison, in tomato, a fleshy berry fruit derived from the ovary, high level over-expression of the same miR172 resulted in carpel-only flowers which developed into parthenocarpic fruit. These results further indicate that the influence of miR172 on fruit growth in different plant species depends on its fruit type. PMID:26926448

  11. Contrasting nurse plants and nurse rocks: The spatial distribution of seedlings of two sub-Antarctic species

    NASA Astrophysics Data System (ADS)

    Haussmann, N. S.; McGeoch, M. A.; Boelhouwers, J. C.

    2010-05-01

    Positive plant interactions, such as those associated with nurse plants, have been suggested to dominate over negative interactions in environments with high abiotic stress. Here we demonstrate that the sub-Antarctic cushion plant species, Azorella selago (Apiaceae), positively affects the distribution of both its own seedlings and those of the perennial grass, Agrostis magellanica (Poaceae). As a result of the light weight and small size of seeds of both species, coupled with strong winds experienced in the study area, we consider it unlikely that these patterns are the result of very localized seed dispersal from the study cushions themselves. Instead, we suggest that both cushions and rocks act as seed traps, trapping seeds dispersed by wind, runoff and/or downslope sediment transport through frost creep. In addition, increased A. selago seedling numbers around cushions, but not around rocks, suggest that cushions provide a biological nurse effect, such as improving soil nutrient status or providing mychorrizae, to seedlings of their own kind.

  12. Shrub encroachment affects mammalian carnivore abundance and species richness in semiarid rangelands

    NASA Astrophysics Data System (ADS)

    Blaum, Niels; Rossmanith, Eva; Popp, Alexander; Jeltsch, Florian

    2007-01-01

    Shrub encroachment due to overgrazing has led to dramatic changes of savanna landscapes and is considered to be one of the most threatening forms of rangeland degradation e.g. via habitat fragmentation. Mammalian carnivores are particularly vulnerable to local extinction in fragmented landscapes. However, our understanding of how shrub encroachment affects mammalian carnivores is poor. Here we investigated the relative sensitivities of ten native carnivores to different levels of shrub cover ranging from low (<5%) to high shrub cover (>25%) in 20 southern Kalahari rangeland sites. Relative abundance of carnivores was monitored along 40 sand transects (5 m × 250 m) for each site. Our results show that increasing shrub cover affects carnivore species differently. African wild cats, striped polecats, cape foxes and suricates were negatively affected, whereas we found hump-shaped responses for yellow mongooses, bat-eared foxes and small-spotted genets with maximum abundance at shrub covers between 10 and 18%. In contrast, black-backed jackals, slender mongooses and small spotted cats were not significantly affected by increasing shrub cover. However, a negative impact of high shrub cover above 18% was congruent for all species. We conclude that intermediate shrub cover (10-18%) in savanna landscapes sustain viable populations of small carnivores.

  13. Reassessment of selected factors affecting siting of Nuclear Power Plants

    SciTech Connect

    Davis, R.E.; Hanson, A.L.; Mubayi, V.; Nourbakhsh, H.P.

    1997-02-01

    Brookhaven National Laboratory has performed a series of probabilistic consequence assessment calculations for nuclear reactor siting. This study takes into account recent insights into severe accident source terms and examines consequences in a risk based format consistent with the quantitative health objectives (QHOs) of the NRC`s Safety Goal Policy. Simplified severe accident source terms developed in this study are based on the risk insights of NUREG-1150. The results of the study indicate that both the quantity of radioactivity released in a severe accident as well as the likelihood of a release are lower than those predicted in earlier studies. The accident risks using the simplified source terms are examined at a series of generic plant sites, that vary in population distribution, meteorological conditions, and exclusion area boundary distances. Sensitivity calculations are performed to evaluate the effects of emergency protective action assumptions on the risk of prompt fatality and latent cancers fatality, and population relocation. The study finds that based on the new source terms the prompt and latent fatality risks at all generic sites meet the QHOs of the NRC`s Safety Goal Policy by margins ranging from one to more than three orders of magnitude. 4 refs., 17 figs., 24 tabs.

  14. Quantitative Analysis of Plant Consumption and Preference by Oedaleus asiaticus (Acrididae: Oedipodinae) in Changed Plant Communities Consisting of Three Grass Species.

    PubMed

    Huang, X; McNeill, M; Zhang, Z

    2016-02-01

    We used Oedaleus asiaticus Bey-Bienko (Acrididae: Oedipodinae) as a model species to examine how plant community composition influenced grasshopper population densities and feeding habits. Our results show that in the Xinli Gol Grassland ecosystem, both plant community composition and grasshopper density vary considerably over fairly small distances, and that O. asiaticus density was directly related to the proportional abundance of specific plant species. A 60-d field-cage study showed that O. asiaticus food preference and consumption differed when the ratios of three dominant grass species (Leymus chinensis (Trin.) Tzvel, Stipa krylovii Roshev, and Cleistogenes squarrosa (Trin.) Keng) differed. The consumption of both S. krylovii and C. squarrosa increased with a corresponding increase in their respective biomass availability. Although O. asiaticus preferred S. krylovii and ate only small amounts of L. chinensis, a specific amount of L. chinensis was always consumed. Feeding of these three plant species could be divided into three levels based on diet selectivity index (SI), with O. asiaticus showing a strong preference for S. krylovii (SI > 1), over that for C. squarrosa (0.5 < SI ≤ 1), and a low acceptance for L. chinensis (0 < SI ≤ 0.5). Plant consumption and preference by O. asiaticus was in decreasing order S. krylovii>C. squarrosa>L. chinensis. This study shows that small-scale changes in plant community composition can have large affects on grasshopper diets and populations. As such, this study is useful for developing guidelines for the monitoring of O. asiaticus impacts against the background of vegetation succession and changing plant communities in response to grazing or human activities. PMID:26577863

  15. The effect of AMF suppression on plant species composition in a nutrient-poor dry grassland.

    PubMed

    Dostálek, Tomáš; Pánková, Hana; Münzbergová, Zuzana; Rydlová, Jana

    2013-01-01

    Arbuscular mycorrhizal fungi (AMF) are expected to be one of the key drivers determining the diversity of natural plant communities, especially in nutrient-poor and dry habitats. Several previous studies have explored the importance of AMF for the composition of plant communities in various types of habitats. Surprisingly, studies of the role of AMF in nutrient-poor dry grassland communities dominated by less mycotrophic plant species are still relatively rare. We present the results of a 3-year study in which a plant community in a species-rich dry grassland was subjected to the fungicide carbendazim to suppress AMF colonization. We tested the effect of the fungicide on the following parameters: the plant species composition; the number of plant species; the cover of the rare, highly mycorrhiza-dependent species Aster amellus; the cover of the dominant, less mycorrhiza-dependent species Brachypodium pinnatum; and the cover of graminoids and perennial forbs. In addition, we examined the mycorrhizal inoculation potential of the soil. We found that the suppression of AMF with fungicide resulted in substantial changes in plant species composition and significant decrease in species richness, the cover of A. amellus and the cover of perennial forbs. In contrast the species increasing their cover after fungicide application were graminoids--the C3 grasses B. pinnatum and Bromus erectus and the sedge Carex flacca. These species appear to be less mycorrhiza dependent. Moreover, due to their clonal growth and efficient nutrient usage, they are, most likely, better competitors than perennial forbs under fungicide application. Our results thus suggest that AMF are an essential part of the soil communities supporting a high diversity of plant species in species-rich dry grasslands in nutrient-poor habitats. The AMF are especially important for the maintenance of the populations of perennial forbs, many of which are rare and endangered in the area. PMID:24265829

  16. The Effect of AMF Suppression on Plant Species Composition in a Nutrient-Poor Dry Grassland

    PubMed Central

    Dostálek, Tomáš; Pánková, Hana; Münzbergová, Zuzana; Rydlová, Jana

    2013-01-01

    Arbuscular mycorrhizal fungi (AMF) are expected to be one of the key drivers determining the diversity of natural plant communities, especially in nutrient-poor and dry habitats. Several previous studies have explored the importance of AMF for the composition of plant communities in various types of habitats. Surprisingly, studies of the role of AMF in nutrient-poor dry grassland communities dominated by less mycotrophic plant species are still relatively rare. We present the results of a 3-year study in which a plant community in a species-rich dry grassland was subjected to the fungicide carbendazim to suppress AMF colonization. We tested the effect of the fungicide on the following parameters: the plant species composition; the number of plant species; the cover of the rare, highly mycorrhiza-dependent species Aster amellus; the cover of the dominant, less mycorrhiza-dependent species Brachypodium pinnatum; and the cover of graminoids and perennial forbs. In addition, we examined the mycorrhizal inoculation potential of the soil. We found that the suppression of AMF with fungicide resulted in substantial changes in plant species composition and significant decrease in species richness, the cover of A. amellus and the cover of perennial forbs. In contrast the species increasing their cover after fungicide application were graminoids—the C3 grasses B. pinnatum and Bromus erectus and the sedge Carex flacca. These species appear to be less mycorrhiza dependent. Moreover, due to their clonal growth and efficient nutrient usage, they are, most likely, better competitors than perennial forbs under fungicide application. Our results thus suggest that AMF are an essential part of the soil communities supporting a high diversity of plant species in species-rich dry grasslands in nutrient-poor habitats. The AMF are especially important for the maintenance of the populations of perennial forbs, many of which are rare and endangered in the area. PMID:24265829

  17. Moose as a vector for non-indigenous plant species in Alaska

    Technology Transfer Automated Retrieval System (TEKTRAN)

    White sweetclover and narrowleaf hawksbeard are non-indigenous invasive plant species in Alaska that are rapidly spreading, including into areas that are otherwise free of non-indigenous plants. There has been concern that native moose could be dispersing viable seed from these plants after ingestio...

  18. Collection and Domestication of Rangeland Plant Species with Emphasis on Mongolia and China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Changing economic and social conditions are threatening plant diversity on rangelands in Mongolia and China. Teams of collaborating scientists from the U.S.A., Mongolia, and China collected seed of rangeland plant species in Mongolia and Inner Mongolia, China, to preserve plant biodiversity from th...

  19. Herbivore species richness and feeding complementarity affect community structure and function on a coral reef

    PubMed Central

    Burkepile, Deron E.; Hay, Mark E.

    2008-01-01

    Consumer effects on prey are well known for cascading through food webs and producing dramatic top-down effects on community structure and ecosystem function. Bottom-up effects of prey (primary producer) biodiversity are also well known. However, the role of consumer diversity in affecting community structure or ecosystem function is not well understood. Here, we show that herbivore species richness can be critical for maintaining the structure and function of coral reefs. In two experiments over 2 years, we constructed large cages enclosing single herbivore species, equal densities of mixed species of herbivores, or excluding herbivores and assessed effects on both seaweeds and corals. When compared with single-herbivore treatments, mixed-herbivore treatments lowered macroalgal abundance by 54–76%, enhanced cover of crustose coralline algae (preferred recruitment sites for corals) by 52–64%, increased coral cover by 22%, and prevented coral mortality. Complementary feeding by herbivorous fishes drove the herbivore richness effects, because macroalgae were unable to effectively deter fishes with different feeding strategies. Maintaining herbivore species richness appears critical for preserving coral reefs, because complementary feeding by diverse herbivores produces positive, but indirect, effects on corals, the foundation species for the ecosystem. PMID:18845686

  20. Factors affecting reproductive success in three entomophilous orchid species in Hungary.

    PubMed

    Vojtkó, Anna E; Sonkoly, Judit; Lukács, Balázs András; Molnár V, Attila

    2015-06-01

    The reproductive success of orchids is traditionally estimated by determining the fruit-set of individuals. Here, we investigated both the fruit and the seed production of three orchid species and the factors that may affect individual fruit-set, like pollination strategy, individual traits or the annual amount of precipitation. The species [Dactylorhiza sambucina (L.) Soó, Dactylorhiza majalis (Rchb.) P. F. Hunt & Summerhayes and Platanthera bifolia (L.) L. C. M. Richard] were studied in three consecutive years (2010-2012) in the Bükk Mountains, Hungary. All three species were proved to be non-autogamous by a bagging experiment. Data analyses showed significant differences between seed numbers but not between fruit-sets of species. There was no statistical difference in individual reproductive success between wet and dry years, however, the effect of the annual amount of precipitation is significant on the population level. Comparison of published fruit-set data revealed accordance with our results in P. bifolia, but not in D. sambucina and D. majalis. We assume that the surprisingly high fruit-set values of the two Dactylorhiza species may be due to the fact that the pollination crisis reported from Western European countries is not an actual problem in the Bükk Mountains, Hungary. PMID:26081278

  1. Use of plant woody species electrical potential for irrigation scheduling.

    PubMed

    Ríos-Rojas, Liliana; Morales-Moraga, David; Alcalde, José A; Gurovich, Luis A

    2015-01-01

    The electrical response of plants to environmental stimuli can be measured and quantitatively related to the intensity of several stimulating sources, like temperature, solar radiation, soil water content, evapotranspiration rates, sap flow and dendrometric cycles. These relations can be used to assess the influence of different environmental situations on soil water availability to plants, defined as a steady state condition between leaf transpirative flow and soil water flow to plant roots. A restricted soil water flow due to soil dryness can trigger water stress in plants, if the atmospheric evaporative demand is high, causing partial stomata closure as a physiological response to avoid plant dehydration; water stressed and unstressed plants manifest a differential electrical response. Real time plant electrical response measurements can anticipate actions that prevent the plant reaching actual stress conditions, optimizing stomata gas exchange and photosynthetic rates. An electrophysiological sensor developed in this work, allows remote real-time recording information on plant electrical potential (EP) in the field, which is highly related to EP measurements obtained with a laboratory Keithley voltmeter sensor used in an highly controlled experimental setup. Our electrophysiological sensor is a wireless, autonomous devise, which transmits EP information via Internet to a data server. Using both types of sensors (EP electrodes with a Keithley voltmeter and the electrophysiological sensor), we measured in real time the electrical responses of Persea americana and Prunus domestica plants, to induced water deficits. The differential response for 2 scenarios: irrigation and water restriction is identified by a progressive change in slope on the daily maximal and minimal electric signal values in stressed plants, and a zero-slope for similar signals for well-watered plants. Results show a correspondence between measured signals obtained by our electrophysiological

  2. Use of plant woody species electrical potential for irrigation scheduling

    PubMed Central

    Ríos-Rojas, Liliana; Morales-Moraga, David; Alcalde, José A; Gurovich, Luis A

    2015-01-01

    The electrical response of plants to environmental stimuli can be measured and quantitatively related to the intensity of several stimulating sources, like temperature, solar radiation, soil water content, evapotranspiration rates, sap flow and dendrometric cycles. These relations can be used to assess the influence of different environmental situations on soil water availability to plants, defined as a steady state condition between leaf transpirative flow and soil water flow to plant roots. A restricted soil water flow due to soil dryness can trigger water stress in plants, if the atmospheric evaporative demand is high, causing partial stomata closure as a physiological response to avoid plant dehydration; water stressed and unstressed plants manifest a differential electrical response. Real time plant electrical response measurements can anticipate actions that prevent the plant reaching actual stress conditions, optimizing stomata gas exchange and photosynthetic rates. An electrophysiological sensor developed in this work, allows remote real-time recording information on plant electrical potential (EP) in the field, which is highly related to EP measurements obtained with a laboratory Keithley voltmeter sensor used in an highly controlled experimental setup. Our electrophysiological sensor is a wireless, autonomous devise, which transmits EP information via Internet to a data server. Using both types of sensors (EP electrodes with a Keithley voltmeter and the electrophysiological sensor), we measured in real time the electrical responses of Persea americana and Prunus domestica plants, to induced water deficits. The differential response for 2 scenarios: irrigation and water restriction is identified by a progressive change in slope on the daily maximal and minimal electric signal values in stressed plants, and a zero-slope for similar signals for well-watered plants. Results show a correspondence between measured signals obtained by our electrophysiological

  3. Allocation, stress tolerance and carbon transport in plants: how does phloem physiology affect plant ecology?

    PubMed

    Savage, Jessica A; Clearwater, Michael J; Haines, Dustin F; Klein, Tamir; Mencuccini, Maurizio; Sevanto, Sanna; Turgeon, Robert; Zhang, Cankui

    2016-04-01

    Despite the crucial role of carbon transport in whole plant physiology and its impact on plant-environment interactions and ecosystem function, relatively little research has tried to examine how phloem physiology impacts plant ecology. In this review, we highlight several areas of active research where inquiry into phloem physiology has increased our understanding of whole plant function and ecological processes. We consider how xylem-phloem interactions impact plant drought tolerance and reproduction, how phloem transport influences carbon allocation in trees and carbon cycling in ecosystems and how phloem function mediates plant relations with insects, pests, microbes and symbiotes. We argue that in spite of challenges that exist in studying phloem physiology, it is critical that we consider the role of this dynamic vascular system when examining the relationship between plants and their biotic and abiotic environment. PMID:26147312

  4. Roads in northern hardwood forests affect adjacent plant communities and soil chemistry in proportion to the maintained roadside area.

    PubMed

    Neher, Deborah A; Asmussen, David; Lovell, Sarah Taylor

    2013-04-01

    The spatial extent of the transported materials from three road types was studied in forest soil and vegetative communities in Vermont. Hypotheses were two-fold: 1) soil chemical concentrations above background environment would reflect traffic volume and road type (highway>2-lane paved>gravel), and 2) plant communities close to the road and near roads with greater traffic will be disturbance-tolerant and adept at colonization. Soil samples were gathered from 12 randomly identified transects for each of three road types classified as "highway," "two-lane paved," and "gravel." Using GIS mapping, transects were constructed perpendicular to the road, and samples were gathered at the shoulder, ditch, backslope, 10 m from the edge of the forest, and 50 m from road center. Sample locations were analyzed for a suite of soil elements and parameters, as well as percent area coverage by plant species. The main effects from roads depended on the construction modifications required for a roadway (i.e., vegetation clearing and topography modification). The cleared area defined the type of plant community and the distance that road pollutants travel. Secondarily, road presence affected soil chemistry. Metal concentrations (e.g., Pb, Cd, Cu, and Zn) correlated positively with road type. Proximity to all road types made the soils more alkaline (pH 7.7) relative to the acidic soil of the adjacent native forest (pH 5.6). Roadside microtopography had marked effects on the composition of plant communities based on the direction of water flow. Ditch areas supported wetland plant species, greater soil moisture and sulfur content, while plant communities closer to the road were characteristic of drier upland zones. The area beyond the edge of the forest did not appear to be affected chemically or physically by any of the road types, possibly due to the dense vegetation that typically develops outside of the managed right-of-way. PMID:23435063

  5. Classification and identification of metal-accumulating plant species by cluster analysis.

    PubMed

    Yang, Wenhao; Li, He; Zhang, Taoxiang; Sen, Lin; Ni, Wuzhong

    2014-09-01

    Identification and classification of metal-accumulating plant species is essential for phytoextraction. Cluster analysis is used for classifying individuals based on measured characteristics. In this study, classification of plant species for metal accumulation was conducted using cluster analysis based on a practical survey. Forty plant samples belonging to 21 species were collected from an ancient silver-mining site. Five groups such as hyperaccumulator, potential hyperaccumulator, accumulator, potential accumulator, and normal accumulating plant were graded. For Cd accumulation, the ancient silver-mining ecotype of Sedum alfredii was treated as a Cd hyperaccumulator, and the others were normal Cd-accumulating plants. For Zn accumulation, S. alfredii was considered as a potential Zn hyperaccumulator, Conyza canadensis and Artemisia lavandulaefolia were Zn accumulators, and the others were normal Zn-accumulating plants. For Pb accumulation, S. alfredii and Elatostema lineolatum were potential Pb hyperaccumulators, Rubus hunanensis, Ajuga decumbens, and Erigeron annuus were Pb accumulators, C. canadensis and A. lavandulaefolia were potential Pb accumulators, and the others were normal Pb-accumulating plants. Plant species with the potential for phytoextraction were identified such as S. alfredii for Cd and Zn, C. canadensis and A. lavandulaefolia for Zn and Pb, and E. lineolatum, R. hunanensis, A. decumbens, and E. annuus for Pb. Cluster analysis is effective in the classification of plant species for metal accumulation and identification of potential species for phytoextraction. PMID:24888623

  6. Assessment of heavy metal tolerance in native plant species from soils contaminated with electroplating effluent.

    PubMed

    Sainger, Poonam Ahlawat; Dhankhar, Rajesh; Sainger, Manish; Kaushik, Anubha; Singh, Rana Pratap

    2011-11-01

    Heavy metals concentrations of (Cr, Zn, Fe, Cu and Ni) were determined in plants and soils contaminated with electroplating industrial effluent. The ranges of total soil Cr, Zn, Fe, Cu and Ni concentrations were found to be 1443-3240, 1376-3112, 683-2228, 263-374 and 234-335 mg kg⁻¹, respectively. Metal accumulation, along with hyperaccumulative characteristics of the screened plants was investigated. Present study highlighted that metal accumulation in different plants varied with species, tissues and metals. Only one plant (Amaranthus viridis) accumulated Fe concentrations over 1000 mg kg⁻¹. On the basis of TF, eight plant species for Zn and Fe, three plant species for Cu and two plant species for Ni, could be used in phytoextraction technology. Although BAF of all plant species was lesser than one, these species exhibited high metal adaptability and could be considered as potential hyperaccumulators. Phytoremediation potential of these plants can be used to remediate metal contaminated soils, though further investigation is still needed. PMID:21820739

  7. Race to Displace: A Game to Model the Effects of Invasive Species on Plant Communities

    ERIC Educational Resources Information Center

    Hopwood, Jennifer L.; Flowers, Susan K.; Seidler, Katie J.; Hopwood, Erica L.

    2013-01-01

    Invasive species are a substantial threat to biodiversity. Educating students about invasive species introduces fundamental concepts in biology, ecology, and environmental science. In the Race to Displace game, students assume the characteristics of select native or introduced plants and experience first hand the influences of species interactions…

  8. Phytochemicals of selected plant species of the Apocynaceae and Asclepiadaceae from Western Ghats, Tamil Nadu, India

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A concern about the declining supply of petroleum products has led to a renewed interest in evaluating plant species as potential alternate sources of energy. Five species of the Apocynaceae and three species of the Asclepiadaceae from the Western Ghats were evaluated as alternative sources of energ...

  9. Does deciduous tree species identity affect carbon storage in temperate soils?

    NASA Astrophysics Data System (ADS)

    Jungkunst, Hermann; Schleuß, Per; Heitkamp, Felix

    2015-04-01

    Forest soils contribute roughly 70 % to the global terrestrial soil organic carbon (SOC) pool and thus play a vital role in the global carbon cycle. It is less clear, however, whether temperate tree species identity affects SOC storage beyond the coarse differentiation between coniferous and deciduous trees. The most important driver for soil SOC storage definitely is the fine mineral fraction (clay and fine silt) because of its high sorption ability. It is difficult to disentangle any additional biotic effects since clay and silt vary considerably in nature. For experimental approaches, the process of soil carbon accumulation is too slow and, therefore, sound results cannot be expected for decades. Here we will present our success to distinguish between the effects of fine particle content (abiotic) and tree species composition (biotic) on the SOC pool in an old-growth broad-leaved forest plots along a tree diversity gradient , i.e., 1- (beech), 3- (plus ash and lime tree)- and 5-(plus maple and hornbeam) species. The particle size fractions were separated first and then the carbon concentrations of each fraction was measured. Hence, the carbon content per unit clay was not calculated, as usually done, but directly measured. As expected, the variation in SOC content was mainly explained by the variations in clay content but not entirely. We found that the carbon concentration per unit clay and fine silt in the subsoil was by 30-35% higher in mixed than in monospecific stands indicating a significant species identity or species diversity effect on C stabilization. In contrast to the subsoil, no tree species effects was identified for the topsoil. Indications are given that the mineral phase was already carbon saturated and thus left no more room for a possible biotic effect. Underlying processes must remain speculative, but we will additionally present our latest microcosm results, including isotopic signatures, to underpin the proposed deciduous tree species

  10. Seasonal polyphenism in wing coloration affects species recognition in rubyspot damselflies (Hetaerina spp.).

    PubMed

    Drury, J P; Anderson, C N; Grether, G F

    2015-08-01

    Understanding how phenotypic plasticity evolves and in turn affects the course of evolution is a major challenge in modern biology. By definition, biological species are reproductively isolated, but many animals fail to distinguish between conspecifics and closely related heterospecifics. In some cases, phenotypic plasticity may interfere with species recognition. Here, we document a seasonal polyphenism in the degree of dark wing pigmentation in smoky rubyspot damselflies (Hetaerina titia) - a shift so pronounced that it led early researchers to classify different forms of H. titia as separate species. We further show how the seasonal colour shift impacts species recognition with the sympatric congener Hetaerina occisa. Interspecific aggression (territorial fights) and reproductive interference (mating attempts) are much more frequent early in the year, when H. titia more closely resembles H. occisa, compared to later in the year when the dark phase of H. titia predominates. Using wing colour manipulations of tethered damselflies, we show that the seasonal changes in interspecific interactions are caused not only by the seasonal colour shift but also by shifts in discriminatory behaviour in both species. We also experimentally tested and rejected the hypothesis that learning underlies the behavioural shifts in H. occisa. An alternative hypothesis, which remains to be tested, is that the seasonal polyphenism in H. titia wing coloration has resulted in the evolution of a corresponding seasonal polyphenism in species recognition in H. occisa. This study illustrates one of the many possible ways that plasticity in species recognition cues may influence the evolution of interspecific interactions. PMID:26033550

  11. Conflicting genomic signals affect phylogenetic inference in four species of North American pines.

    PubMed

    Koralewski, Tomasz E; Mateos, Mariana; Krutovsky, Konstantin V

    2016-01-01

    Adaptive evolutionary processes in plants may be accompanied by episodes of introgression, parallel evolution and incomplete lineage sorting that pose challenges in untangling species evolutionary history. Genus Pinus (pines) is one of the most abundant and most studied groups among gymnosperms, and a good example of a lineage where these phenomena have been observed. Pines are among the most ecologically and economically important plant species. Some, such as the pines of the southeastern USA (southern pines in subsection Australes), are subjects of intensive breeding programmes. Despite numerous published studies, the evolutionary history of Australes remains ambiguous and often controversial. We studied the phylogeny of four major southern pine species: shortleaf (Pinus echinata), slash (P. elliottii), longleaf (P. palustris) and loblolly (P. taeda), using sequences from 11 nuclear loci and maximum likelihood and Bayesian methods. Our analysis encountered resolution difficulties similar to earlier published studies. Although incomplete lineage sorting and introgression are two phenomena presumptively underlying our results, the phylogenetic inferences seem to be also influenced by the genes examined, with certain topologies supported by sets of genes sharing common putative functionalities. For example, genes involved in wood formation supported the clade echinata-taeda, genes linked to plant defence supported the clade echinata-elliottii and genes linked to water management properties supported the clade echinata-palustris The support for these clades was very high and consistent across methods. We discuss the potential factors that could underlie these observations, including incomplete lineage sorting, hybridization and parallel or adaptive evolution. Our results likely reflect the relatively short evolutionary history of the subsection that is thought to have begun during the middle Miocene and has been influenced by climate fluctuations. PMID:27060161

  12. Conflicting genomic signals affect phylogenetic inference in four species of North American pines

    PubMed Central

    Koralewski, Tomasz E.; Mateos, Mariana; Krutovsky, Konstantin V.

    2016-01-01

    Adaptive evolutionary processes in plants may be accompanied by episodes of introgression, parallel evolution and incomplete lineage sorting that pose challenges in untangling species evolutionary history. Genus Pinus (pines) is one of the most abundant and most studied groups among gymnosperms, and a good example of a lineage where these phenomena have been observed. Pines are among the most ecologically and economically important plant species. Some, such as the pines of the southeastern USA (southern pines in subsection Australes), are subjects of intensive breeding programmes. Despite numerous published studies, the evolutionary history of Australes remains ambiguous and often controversial. We studied the phylogeny of four major southern pine species: shortleaf (Pinus echinata), slash (P. elliottii), longleaf (P. palustris) and loblolly (P. taeda), using sequences from 11 nuclear loci and maximum likelihood and Bayesian methods. Our analysis encountered resolution difficulties similar to earlier published studies. Although incomplete lineage sorting and introgression are two phenomena presumptively underlying our results, the phylogenetic inferences seem to be also influenced by the genes examined, with certain topologies supported by sets of genes sharing common putative functionalities. For example, genes involved in wood formation supported the clade echinata–taeda, genes linked to plant defence supported the clade echinata–elliottii and genes linked to water management properties supported the clade echinata–palustris. The support for these clades was very high and consistent across methods. We discuss the potential factors that could underlie these observations, including incomplete lineage sorting, hybridization and parallel or adaptive evolution. Our results likely reflect the relatively short evolutionary history of the subsection that is thought to have begun during the middle Miocene and has been influenced by climate fluctuations. PMID

  13. 40 CFR 230.75 - Actions affecting plant and animal populations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... populations. 230.75 Section 230.75 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) OCEAN... Actions To Minimize Adverse Effects § 230.75 Actions affecting plant and animal populations. Minimization of adverse effects on populations of plants and animals can be achieved by: (a) Avoiding changes...

  14. 40 CFR 230.75 - Actions affecting plant and animal populations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... populations. 230.75 Section 230.75 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) OCEAN... Actions To Minimize Adverse Effects § 230.75 Actions affecting plant and animal populations. Minimization of adverse effects on populations of plants and animals can be achieved by: (a) Avoiding changes...

  15. 40 CFR 230.75 - Actions affecting plant and animal populations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... populations. 230.75 Section 230.75 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) OCEAN... Actions To Minimize Adverse Effects § 230.75 Actions affecting plant and animal populations. Minimization of adverse effects on populations of plants and animals can be achieved by: (a) Avoiding changes...

  16. 40 CFR 230.75 - Actions affecting plant and animal populations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... populations. 230.75 Section 230.75 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) OCEAN... Actions To Minimize Adverse Effects § 230.75 Actions affecting plant and animal populations. Minimization of adverse effects on populations of plants and animals can be achieved by: (a) Avoiding changes...

  17. 40 CFR 230.75 - Actions affecting plant and animal populations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... populations. 230.75 Section 230.75 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) OCEAN... Actions To Minimize Adverse Effects § 230.75 Actions affecting plant and animal populations. Minimization of adverse effects on populations of plants and animals can be achieved by: (a) Avoiding changes...

  18. Nitrogen and water affect direct and indirect plant systemic induced defense in cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We tested the affects of nitrogen levels and water availability on the ability of cotton plants to deter feeding by Spodoptera exigua larvae through induction of anti-feedant chemicals by the cotton plant, and to attract the biological control agent, Micropitis crociepes through induction of chemica...

  19. Population rules can apply to individual plants and affect their architecture: an evaluation on the cushion plant Mulinum spinosum (Apiaceae)

    PubMed Central

    Puntieri, Javier G.; Damascos, María A.; Llancaqueo, Yanina; Svriz, Maya

    2010-01-01

    Background and aims Plants are regarded as populations of modules such as axes and growth units (GUs, i.e. seasonally produced axis segments). Due to their dense arrays of GUs, cushion plants may resemble crowded plant populations in the way the number of components (GUs in plants, individuals in populations) relates to their individual sizes. Methodology The morphological differentiation of GUs and its relationship with biomass accumulation and plant size were studied for the cushion subshrub Mulinum spinosum (Apiaceae), a widespread species in dry areas of Patagonia. In 2009, GUs were sampled from one-quarter of each of 24 adult plants. Within- and between-plant variations in GU length, diameter, number of nodes and biomass were analysed and related to whole-plant size. Principal results Each year, an M. spinosum cushion develops flowering GUs and vegetative GUs. Flowering GUs are larger, twice as numerous and contain two to four times more dry mass (excluding reproductive structures) than vegetative GUs. The hemispherical area of the cushions was positively correlated with the biomass of last-year GUs. The biomass of flowering GUs was negatively correlated with the density of GUs. Mulinum spinosum plants exhibited a notable differentiation between flowering and vegetative GUs, but their axes, i.e. the sequences of GUs, were not differentiated throughout the plants. Flowering GUs comprised a major proportion of each plant's photosynthetic tissues. Conclusions A decrease in the size of flowering GUs and in their number relative to the total number of GUs per plant, parallel to an increase in GU density, is predicted as M. spinosum plants age over years. The assimilative role of vegetative GUs is expected to increase in summer because of their less exposed position in the cushion. These GUs would therefore gain more from warm and dry conditions than flowering GUs. PMID:22476077

  20. Past and present effectiveness of protected areas for conservation of naturally and anthropogenically rare plant species.

    PubMed

    Vellak, Ain; Tuvi, Eva-Liis; Reier, Ülle; Kalamees, Rein; Roosaluste, Elle; Zobel, Martin; Pärtel, Meelis

    2009-06-01

    The Global Strategy of Plant Conservation states that at least 60% of threatened plant species should be within protected areas. This goal has been met in some regions with long traditions of plant protection. We used gap analysis to explore how particular groups of species of conservation interest, representing different types of natural or anthropogenic rarity, have been covered by protected areas on a national scale in Estonia during the last 100 years. Species-accumulation curves indicated that plant species that are naturally rare (restricted global or local distribution, always small populations, or very rare habitat requirements) needed almost twice as many protected areas to reach the 60% target as plant species that are rare owing to lack of suitable management (species depending on grassland management, moderate forest disturbances, extensive traditional agriculture, or species potentially threatened by collecting). Temporal analysis of the establishment of protected areas suggested that grouping plant species according to the predominant cause of rarity accurately reflected the history of conservation decision making. Species found in very rare habitats have previously received special conservation attention; species dependent on traditional extensive agriculture have been largely ignored until recently. Legislative initiative and new nature-protection schemes (e.g., Natura 2000, network of protected areas in the European Union) have had a positive influence on all species groups. Consequently, the species groups needing similar action for their conservation are sensitive indicators of the effectiveness of protected-area networks. Different species groups, however, may not be uniformly conserved within protected areas, and all species groups should fulfill the target of 60% coverage within protected areas. PMID:19128324

  1. Development and reproduction of Panonychus citri (Prostigmata: Tetranychidae) on different species and varieties of citrus plants.

    PubMed

    Zanardi, Odimar Zanuzo; Bordini, Gabriela Pavan; Franco, Aline Aparecida; de Morais, Matheus Rovere; Yamamoto, Pedro Takao

    2015-12-01

    The species and varieties of citrus plants that are currently grown can favor the population growth of the citrus red mite Panonychus citri (McGregor) (Prostigmata: Tetranychidae) and alter the pest management programs in citrus groves. In this study we evaluated, in the laboratory, the development and reproduction of P. citri and estimated its life table parameters when reared on four varieties of Citrus sinensis (L.) Osbeck (Valencia, Pera, Natal, and Hamlin), one variety of Citrus reticulata Blanco (Ponkan) and one variety of Citrus limon (L.) Burm. (Sicilian). The incubation period and egg viability were not affected by the host plant. However, the development and survival of the immature stage were significantly lower on Hamlin orange than on Valencia, Pera and Natal oranges, Ponkan mandarin and Sicilian lemon. The fecundity and oviposition period of females were lower on Hamlin orange than on the other hosts. Mites reared on Valencia orange and Sicilian lemon had a higher net reproductive rate (R 0 ), intrinsic growth rate (r) and finite rate of increase (λ), and a shorter interval between generations (T) than on Pera, Natal and Hamlin oranges and Ponkan mandarin. On the other hand, mites reared on Hamlin orange had the lowest R 0 , r and λ and the highest T among the hosts. Based on the results obtained we recommend that for Valencia orange and Sicilian lemon, the mite monitoring programs should be more intense to detect the initial infestation of pest, avoiding the damage in plants and the increase in production costs. PMID:26459376

  2. Urban habitat complexity affects species richness but not environmental filtering of morphologically-diverse ants

    PubMed Central

    Nash, Michael A.; Christie, Fiona J.; Hahs, Amy K.; Livesley, Stephen J.

    2015-01-01

    Habitat complexity is a major determinant of structure and diversity of ant assemblages. Following the size-grain hypothesis, smaller ant species are likely to be advantaged in more complex habitats compared to larger species. Habitat complexity can act as an environmental filter based on species size and morphological traits, therefore affecting the overall structure and diversity of ant assemblages. In natural and semi-natural ecosystems, habitat complexity is principally regulated by ecological successions or disturbance such as fire and grazing. Urban ecosystems provide an opportunity to test relationships between habitat, ant assemblage structure and ant traits using novel combinations of habitat complexity generated and sustained by human management. We sampled ant assemblages in low-complexity and high-complexity parks, and high-complexity woodland remnants, hypothesizing that (i) ant abundance and species richness would be higher in high-complexity urban habitats, (ii) ant assemblages would differ between low- and high-complexity habitats and (iii) ants living in high-complexity habitats would be smaller than those living in low-complexity habitats. Contrary to our hypothesis, ant species richness was higher in low-complexity habitats compared to high-complexity habitats. Overall, ant assemblages were significantly different among the habitat complexity types investigated, although ant size and morphology remained the same. Habitat complexity appears to affect the structure of ant assemblages in urban ecosystems as previously observed in natural and semi-natural ecosystems. However, the habitat complexity filter does not seem to be linked to ant morphological traits related to body size. PMID:26528416

  3. Urban habitat complexity affects species richness but not environmental filtering of morphologically-diverse ants.

    PubMed

    Ossola, Alessandro; Nash, Michael A; Christie, Fiona J; Hahs, Amy K; Livesley, Stephen J

    2015-01-01

    Habitat complexity is a major determinant of structure and diversity of ant assemblages. Following the size-grain hypothesis, smaller ant species are likely to be advantaged in more complex habitats compared to larger species. Habitat complexity can act as an environmental filter based on species size and morphological traits, therefore affecting the overall structure and diversity of ant assemblages. In natural and semi-natural ecosystems, habitat complexity is principally regulated by ecological successions or disturbance such as fire and grazing. Urban ecosystems provide an opportunity to test relationships between habitat, ant assemblage structure and ant traits using novel combinations of habitat complexity generated and sustained by human management. We sampled ant assemblages in low-complexity and high-complexity parks, and high-complexity woodland remnants, hypothesizing that (i) ant abundance and species richness would be higher in high-complexity urban habitats, (ii) ant assemblages would differ between low- and high-complexity habitats and (iii) ants living in high-complexity habitats would be smaller than those living in low-complexity habitats. Contrary to our hypothesis, ant species richness was higher in low-complexity habitats compared to high-complexity habitats. Overall, ant assemblages were significantly different among the habitat complexity types investigated, although ant size and morphology remained the same. Habitat complexity appears to affect the structure of ant assemblages in urban ecosystems as previously observed in natural and semi-natural ecosystems. However, the habitat complexity filter does not seem to be linked to ant morphological traits related to body size. PMID:26528416

  4. Australian native plant species Carpobrotus rossii (Haw.) Schwantes shows the potential of cadmium phytoremediation.

    PubMed

    Zhang, Chengjun; Sale, Peter W G; Doronila, Augustine I; Clark, Gary J; Livesay, Caitlin; Tang, Caixian

    2014-01-01

    Many polluted sites are typically characterized by contamination with multiple heavy metals, drought, salinity, and nutrient deficiencies. Here, an Australian native succulent halophytic plant species, Carpobrotus rossii (Haw.) Schwantes (Aizoaceae) was investigated to assess its tolerance and phytoextraction potential of Cd, Zn, and the combination of Cd and Zn, when plants were grown in soils spiked with various concentrations of Cd (20-320 mg kg(-1) Cd), Zn (150-2,400 mg kg(-1) Zn) or Cd + Zn (20 + 150, 40 + 300, 80 + 600 mg kg(-1)). The concentration of Cd in plant parts followed the order of roots > stems > leaves, resulting in Cd translocation factor (TF, concentration ratio of shoots to roots) less than one. In contrast, the concentration of Zn was in order of leaves > stems > roots, with a Zn TF greater than one. However, the amount of Cd and Zn were distributed more in leaves than in stems or roots, which was attributed to higher biomass of leaves than stems or roots. The critical value that causes 10% shoot biomass reduction was 115 μg g(-1) for Cd and 1,300 μg g(-1) for Zn. The shoot Cd uptake per plant increased with increasing Cd addition while shoot Zn uptake peaked at 600 mg kg(-1) Zn addition. The combined addition of Cd and Zn reduced biomass production more than Cd or Zn alone and significantly increased Cd concentration, but did not affect Zn concentration in plant parts. The results suggest that C. rossii is able to hyperaccumulate Cd and can be a promising candidate for phytoextraction of Cd from polluted soils. PMID:24777324

  5. Floral display size, conspecific density and florivory affect fruit set in natural populations of Phlox hirsuta, an endangered species

    PubMed Central

    Ruane, Lauren G.; Rotzin, Andrew T.; Congleton, Philip H.

    2014-01-01

    Background and Aims Natural variation in fruit and seed set may be explained by factors that affect the composition of pollen grains on stigmas. Self-incompatible species require compatible outcross pollen grains to produce seeds. The siring success of outcross pollen grains, however, can be hindered if self (or other incompatible) pollen grains co-occur on stigmas. This study identifies factors that determine fruit set in Phlox hirsuta, a self-sterile endangered species that is prone to self-pollination, and its associated fitness costs. Methods Multiple linear regressions were used to identify factors that explain variation in percentage fruit set within three of the five known populations of this endangered species. Florivorous beetle density, petal colour, floral display size, local conspecific density and pre-dispersal seed predation were quantified and their effects on the ability of flowers to produce fruits were assessed. Key Results In all three populations, percentage fruit set decreased as florivorous beetle density increased and as floral display size increased. The effect of floral display size on fruit set, however, often depended on the density of nearby conspecific plants. High local conspecific densities offset – even reversed – the negative effects of floral display size on percentage fruit set. Seed predation by mammals decreased fruit set in one population. Conclusions The results indicate that seed production in P. hirsuta can be maximized by selectively augmenting populations in areas containing isolated large plants, by reducing the population sizes of florivorous beetles and by excluding mammals that consume unripe fruits. PMID:24557879

  6. Ecophysiology of wetland plant roots: A modelling comparison of aeration in relation to species distribution

    USGS Publications Warehouse

    Sorrell, B.K.; Mendelssohn, I.A.; McKee, K.L.; Woods, R.A.

    2000-01-01

    This study examined the potential for inter-specific differences in root aeration to determine wetland plant distribution in nature. We compared aeration in species that differ in the type of sediment and depth of water they colonize. Differences in root anatomy, structure and physiology were applied to aeration models that predicted the maximum possible aerobic lengths and development of anoxic zones in primary adventitious roots. Differences in anatomy and metabolism that provided higher axial fluxes of oxygen allowed deeper root growth in species that favour more reducing sediments and deeper water. Modelling identified factors that affected growth in anoxic soils through their effects on aeration. These included lateral root formation, which occurred at the expense of extension of the primary root because of the additional respiratory demand they imposed, reducing oxygen fluxes to the tip and stele, and the development of stelar anoxia. However, changes in sediment oxygen demand had little detectable effect on aeration in the primary roots due to their low wall permeability and high surface impedance, but appeared to reduce internal oxygen availability by accelerating loss from laterals. The development of pressurized convective gas flow in shoots and rhizomes was also found to be important in assisting root aeration, as it maintained higher basal oxygen concentrations at the rhizome-root junctions in species growing into deep water. (C) 2000 Annals of Botany Company.

  7. Plant Growth and Phosphorus Uptake of Three Riparian Grass Species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Riparian buffers can significantly reduce sediment-bound phosphorus (P) entering surface water, but control of dissolved P inputs is more challenging. Because plant roots remove P from soil solution, it follows that plant uptake will reduce dissolved P losses. We evaluated P uptake of smooth bromegr...

  8. Uptake of gaseous nitrous acid (HONO) by several plant species

    NASA Astrophysics Data System (ADS)

    Schimang, Ralf; Folkers, Achim; Kleffmann, Jörg; Kleist, Einhard; Miebach, Marco; Wildt, Jürgen

    Uptake of gaseous nitrous acid (HONO) by sunflower ( Heliantus annuus L. var. gigantheus), tobacco ( Nicotiana tabacum L. var. Bel W3), castor ( Rhicinus communis L. var. Carmencita), and birch ( Betula pendula L.) was studied under controlled conditions in a continuously stirred tank reactor. Exposing plants to HONO at concentrations between 60 ppt and 10 ppb led to significant uptake by the plants. The uptake was proportional to HONO concentrations and linearly related to stomatal conductivity. HONO losses at the cuticle were of minor importance. Our data imply a quick metabolism of HONO and it is concluded that the uptake of HONO by plants is only limited by diffusion of HONO through the plants stomata. Comparing results from measurements with and without plants in the chamber it is furthermore concluded that a compensation point for HONO uptake is below 20 ppt if it exists at all. Heterogeneous formation of HONO by reactions of NO 2 on the plant surfaces was either not effective or compensated by the stomatal uptake of HONO. The data of the present study imply that plant surfaces represent a sink for HONO. Therefore, it was concluded that processes on plant surfaces cannot explain HONO formation on ground surfaces as observed in field studies.

  9. Aminomethylphosphonic acid accumulation in plant species treated with glyphosate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aminomethylphosphonic acid (AMPA) is the most frequently detected metabolite of glyphosate in plants. Greenhouse studies were conducted to determine the glyphosate I50 values (rate required to cause a 50% reduction in plant growth) and to quantify AMPA and shikimate concentrations in selected legum...

  10. 50 CFR 402.45 - Alternative consultation on FIFRA actions that are not likely to adversely affect listed species...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... that are not likely to adversely affect listed species or critical habitat. 402.45 Section 402.45... habitat. (a) Consultation obligations for FIFRA actions that are not likely to adversely affect listed species or critical habitat when alternative consultation agreement is in effect. If EPA and the...

  11. 50 CFR 402.45 - Alternative consultation on FIFRA actions that are not likely to adversely affect listed species...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... that are not likely to adversely affect listed species or critical habitat. 402.45 Section 402.45... habitat. (a) Consultation obligations for FIFRA actions that are not likely to adversely affect listed species or critical habitat when alternative consultation agreement is in effect. If EPA and the...

  12. 50 CFR 402.45 - Alternative consultation on FIFRA actions that are not likely to adversely affect listed species...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... that are not likely to adversely affect listed species or critical habitat. 402.45 Section 402.45... habitat. (a) Consultation obligations for FIFRA actions that are not likely to adversely affect listed species or critical habitat when alternative consultation agreement is in effect. If EPA and the...

  13. Avian vacuolar myelinopathy linked to exotic aquatic plants and a novel cyanobacterial species.

    PubMed

    Wilde, Susan B; Murphy, Thomas M; Hope, Charlotte P; Habrun, Sarah K; Kempton, Jason; Birrenkott, Anna; Wiley, Faith; Bowerman, William W; Lewitus, Alan J

    2005-06-01

    Invasions of exotic species have created environmental havoc through competition and displacement of native plants and animals. The introduction of hydrilla (Hydrilla verticillata) into the United States in the 1960s has been detrimental to navigation, power generation, water intake, and water quality (McCann et al., 1996). Our field surveys and feeding studies have now implicated exotic hydrilla and associated epiphytic cyanobacterial species as a link to avian vacuolar myelinopathy (AVM), an emerging avian disease affecting herbivorous waterbirds and their avian predators. AVM, first reported in 1994, has caused the death of at least 100 bald eagles (Haliaeetus leucocephalus) and thousands of American coots (Fulica americana) at 11 sites from Texas to North Carolina (Thomas et al., 1998; Rocke et al., 2002). Our working hypothesis is that the agent of this disease is an uncharacterized neurotoxin produced by a novel cyanobacterial epiphyte of the order Stigonematales. This undescribed species covers up to 95% of the surface area of leaves in reservoirs where bird deaths have occurred from the disease. In addition, this species is rare or not found on hydrilla collected at sites where AVM disease has not been diagnosed. Laboratory feeding trials and a sentinel bird study using naturally occurring blooms of cyanobacteria on hydrilla leaves and farm-raised mallard ducks (Anas platyrhynchos) induced the disease experimentally. Since 1994 AVM has been diagnosed in additional sites from Texas to North Carolina. Specific site characteristics that produce the disjunct distribution of AVM are unknown, but it is probable that the incidence of this disease will increase with the introduction of hydrilla and associated cyanobacterial species into additional ponds, lakes, and reservoirs. PMID:15892059

  14. Functional Diversity of Boreal Bog Plant Species Decreases Seasonal Variation of Ecosystem Carbon Sink Function

    NASA Astrophysics Data System (ADS)

    Korrensalo, A.

    2015-12-01

    Species diversity has been found to decrease the temporal variance of productivity of a plant community, and diversity in species responses to environmental factors seems to make a plant community more stable in changing conditions. Boreal bogs are nutrient poor peatland ecosystems where the number of plant species is low but the species differ greatly in their growth form. In here we aim to assess the role of the variation in photosynthesis between species for the temporal variation in ecosystem carbon sink function. To quantify the photosynthetic properties and their seasonal variation for different bog plant species we measured photosynthetic parameters and stress-inducing chlorophyll fluorescence of vascular plant and Sphagnum moss species in a boreal bog over a growing season. We estimated monthly gross photosynthesis (PG) of the whole study site based on species level light response curves and leaf area development. The estimated PG was further compared with a gross primary production (GPP) estimate measured by eddy covariance (EC) technique. The sum of upscaled PG estimates agreed well with the GPP estimate measured by the EC technique. The contributions of the species and species groups to the ecosystem level PG changed over the growing season. The sharp mid-summer peak in sedge PG was balanced by more stable PG of evergreen shrubs and Sphagna. Species abundance rather than differences in photosynthetic properties between species and growth forms determined the most productive plants on the ecosystem scale. Sphagna had lower photosynthesis and clorophyll fluorescence than vascular plants but were more productive on the ecosystem scale throughout the growing season due to their high areal coverage. These results show that the diversity of growth forms stabilizes the seasonal variation of the ecosystem level PG in an ombrotrophic bog ecosystem. This may increase the resilience of the ecosystem to changing environmental conditions.

  15. Productivity is a poor predictor of plant species richness

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For 30 years, the relationship between net primary productivity and species richness has generated intense debate in ecology about the processes regulating fine-scale species richness. The true relationship was thought to be hump-shaped, with richness peaking at intermediate levels of productivity, ...

  16. Batch Isolation of Microsatellites for Tropical Plant Species Pyrosequencing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microsatellites were developed for ten tropical species using a method recently developed in our laboratory that involves a combination of two adapters at the SSR-enrichment stage and allows for cost saving and simultaneous loading of samples. The species for which microsatellites were isolated are...

  17. Life history influences how fire affects genetic diversity in two lizard species.

    PubMed

    Smith, Annabel L; Bull, C Michael; Gardner, Michael G; Driscoll, Don A

    2014-05-01

    'Fire mosaics' are often maintained in landscapes to promote successional diversity in vegetation with little understanding of how this will affect ecological processes in animal populations such as dispersal, social organization and re-establishment. To investigate these processes, we conducted a replicated, spatiotemporal landscape genetics study of two Australian woodland lizard species [Amphibolurus norrisi (Agamidae) and Ctenotus atlas (Scincidae)]. Agamids have a more complex social and territory structure than skinks, so fire might have a greater impact on their population structure and thus genetic diversity. Genetic diversity increased with time since fire in C. atlas and decreased with time since fire in A. norrisi. For C. atlas, this might reflect its increasing population size after fire, but we could not detect increased gene flow that would reduce the loss of genetic diversity through genetic drift. Using landscape resistance analyses, we found no evidence that postfire habitat succession or topography affected gene flow in either species and we were unable to distinguish between survival and immigration as modes of postfire re-establishment. In A. norrisi, we detected female-biased dispersal, likely reflecting its territorial social structure and polygynous mating system. The increased genetic diversity in A. norrisi in recently burnt habitat might reflect a temporary disruption of its territoriality and increased male dispersal, a hypothesis that was supported with a simulation experiment. Our results suggest that the effects of disturbance on genetic diversity will be stronger for species with territorial social organization. PMID:24750427

  18. Herbaceous plant species invading natural areas tend to have stronger adaptive root foraging than other naturalized species.

    PubMed

    Keser, Lidewij H; Visser, Eric J W; Dawson, Wayne; Song, Yao-Bin; Yu, Fei-Hai; Fischer, Markus; Dong, Ming; van Kleunen, Mark

    2015-01-01

    Although plastic root-foraging responses are thought to be adaptive, as they may optimize nutrient capture of plants, this has rarely been tested. We investigated whether nutrient-foraging responses are adaptive, and whether they pre-adapt alien species to become natural-area invaders. We grew 12 pairs of congeneric species (i.e., 24 species) native to Europe in heterogeneous and homogeneous nutrient environments, and compared their foraging responses and performance. One species in each pair is a USA natural-area invader, and the other one is not. Within species, individuals with strong foraging responses, measured as plasticity in root diameter and specific root length, had a higher biomass. Among species, the ones with strong foraging responses, measured as plasticity in root length and root biomass, had a higher biomass. Our results therefore suggest that root foraging is an adaptive trait. Invasive species showed significantly stronger root-foraging responses than non-invasive species when measured as root diameter. Biomass accumulation was decreased in the heterogeneous vs. the homogeneous environment. In aboveground, but not belowground and total biomass, this decrease was smaller in invasive than in non-invasive species. Our results show that strong plastic root-foraging responses are adaptive, and suggest that it might aid in pre-adapting species to becoming natural-area invaders. PMID:25964790

  19. Herbaceous plant species invading natural areas tend to have stronger adaptive root foraging than other naturalized species

    PubMed Central

    Keser, Lidewij H.; Visser, Eric J. W.; Dawson, Wayne; Song, Yao-Bin; Yu, Fei-Hai; Fischer, Markus; Dong, Ming; van Kleunen, Mark

    2015-01-01

    Although plastic root-foraging responses are thought to be adaptive, as they may optimize nutrient capture of plants, this has rarely been tested. We investigated whether nutrient-foraging responses are adaptive, and whether they pre-adapt alien species to become natural-area invaders. We grew 12 pairs of congeneric species (i.e., 24 species) native to Europe in heterogeneous and homogeneous nutrient environments, and compared their foraging responses and performance. One species in each pair is a USA natural-area invader, and the other one is not. Within species, individuals with strong foraging responses, measured as plasticity in root diameter and specific root length, had a higher biomass. Among species, the ones with strong foraging responses, measured as plasticity in root length and root biomass, had a higher biomass. Our results therefore suggest that root foraging is an adaptive trait. Invasive species showed significantly stronger root-foraging responses than non-invasive species when measured as root diameter. Biomass accumulation was decreased in the heterogeneous vs. the homogeneous environment. In aboveground, but not belowground and total biomass, this decrease was smaller in invasive than in non-invasive species. Our results show that strong plastic root-foraging responses are adaptive, and suggest that it might aid in pre-adapting species to becoming natural-area invaders. PMID:25964790

  20. Individual species-area relationship of woody plant communities in a heterogeneous subtropical monsoon rainforest.

    PubMed

    Tsai, Cheng-Han; Lin, Yi-Ching; Wiegand, Thorsten; Nakazawa, Takefumi; Su, Sheng-Hsin; Hsieh, Chih-Hao; Ding,