Understanding the impact of plant competition on the coupling between vegetation and the atmosphere

Glyphosate-based herbicides are used extensively in forestry and agriculture to control broadleaf plant competition. A review of the literature offers conflicting results regarding the impact of glyphosate on fungal growth. This study investigated the effects of 7 glyphosate concentrations (1, 2, 5, 10, 50, 100, and 1000 µg·mL–1) of Roundup (35.6% glyphosate) on the number of colony-forming units (CFUs) of soilborne microfungi from a boreal forest soil sample and on the in vitro linear growth of 20 selected species of microfungi representative of this boreal forest soil. Concentrations of glyphosate at 50 µg·mL–1and higher significantly decreased the number of CFUs observed. At glyphosate concentrations equal to 5 µg·mL–1, 13 fungal species exhibited colony diameters less than 50% than that of their respective controls. Several species showed an inhibition of pigmentation and sporulation when subjected to glyphosate concentrations of 1 µg·mL–1. Differential sensitivity was observed among species at the various concentrations, suggesting the possibility of a shift towards tolerant species of fungi when they are exposed to glyphosate.

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Interactions between Plant Competition and Herbivory on the Growth of Hypericum Species: a Comparison of Glasshouse and Field Results

Australian Journal of Botany ◽

10.1071/bt97025 ◽

1998 ◽

Vol 46 (6) ◽

pp. 707 ◽

Cited By ~ 15

Author(s):

Anthony J. Willis ◽

Richard H. Groves ◽

Julian E. Ash

Keyword(s):

Biological Control ◽

Field Experiment ◽

Native Species ◽

Field Experiments ◽

Plant Competition ◽

Plant Productivity ◽

Combined Effects ◽

The Impact ◽

Hypericum Species

The combined effects of interspecific plant competition and herbivory by a mite, Aculus hyperici Liro, on the growth of two Hypericum species were compared in separate glasshouse and field experiments. The impact of mites on H. perforatum L. was slightly greater than their effect on H. gramineum Forst. In both the glasshouse and the field, competition affected Hypericum growth more adversely than herbivory. There was little evidence that combinations of competition and herbivory caused complex synergistic reductions in plant productivity. In combination, herbivory and competition caused proportional reductions in growth, approximately equivalent to the product of the proportional growth under competition and herbivory individually. Broadly similar results were achieved in both the glasshouse and the field experiment. The results are discussed in relation to the biological control of H. perforatum by A. hyperici, and the impact of this arthropod on the growth of H. gramineum, a non-target native species.

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Interactions between plant genome size, nutrients and herbivory by rabbits, molluscs and insects on a temperate grassland

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2018.2619 ◽

2019 ◽

Vol 286 (1899) ◽

pp. 20182619 ◽

Cited By ~ 3

Author(s):

Maïté S. Guignard ◽

Michael J. Crawley ◽

Dasha Kovalenko ◽

Richard A. Nichols ◽

Mark Trimmer ◽

...

Keyword(s):

Plant Species ◽

Plant Competition ◽

Plant Genome ◽

Total Biomass ◽

Nutrient Inputs ◽

Nutrient Quality ◽

Path Analyses ◽

Plant Herbivore ◽

Herbivore Pressure ◽

The Impact

Angiosperm genome sizes (GS) vary ca 2400-fold. Recent research has shown that GS influences plant abundance, and plant competition. There are also tantalizing reports that herbivores may select plants as food dependent on their GS. To test the hypothesis that GS plays a role in shaping plant communities under herbivore pressure, we exploit a grassland experiment that has experimentally excluded herbivores and applied nutrient over 8 years. Using phylogenetically informed statistical models and path analyses, we show that under rabbit grazing, plant species with small GS generated the most biomass. By contrast, on mollusc and insect-grazed plots, it was the plant species with larger GS that increased in biomass. GS was also shown to influence plant community properties (e.g. competitive strategy, total biomass) although the impact varied between different herbivore guilds (i.e. rabbits versus invertebrates) and nutrient inputs. Overall, we demonstrate that GS plays a role in influencing plant–herbivore interactions, and suggest potential reasons for this response, which include the impact of GS on a plant's response to different herbivore guilds, and on a plant's nutrient quality. The inclusion of GS in ecological models has the potential to expand our understanding of plant productivity and community ecology under nutrient and herbivore stress.

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Opposing community assembly patterns for dominant and non-dominant plant species in herbaceous ecosystems globally

10.22541/au.162486571.19454366/v1 ◽

2021 ◽

Author(s):

Carlos Alberto Arnillas ◽

Elizabeth Borer ◽

Eric Seabloom ◽

Juan Alberti ◽

Selene Baez ◽

...

Keyword(s):

Dominant Species ◽

Plant Competition ◽

Environmental Filtering ◽

Environmental Drivers ◽

Environmental Constraints ◽

Dominant Plant Species ◽

Evolutionary Consequences ◽

Abiotic Influences ◽

The Impact ◽

Phylogenetic Dispersion

Dominant and non-dominant plants could be subject to different biotic and abiotic influences, partially because dominant plants modify the environment where non-dominant plants grow, causing an interaction asymmetry. Among other possibilities, if dominant plants compete strongly, they should deplete most resources forcing non-dominant plants into a more constrained niche space. Conversely, if dominant plants are constrained by the environment, they might not fully deplete available resources but instead ameliorate some of the environmental constraints limiting non-dominants. Hence, the nature of the interactions between the non-dominants could be modified by dominant species. However, when plant competition and environmental constraints have similar effects on dominant and non-dominant species no difference is expected. By estimating phylogenetic dispersion in 78 grasslands across five continents, we found that dominant species were clustered (underdispersed), suggesting dominant species are likely organized by environmental filtering, and that non-dominant species were either randomly assembled or overdispersed. Traits showed similar trends, but insufficient data prevented further analyses. Furthermore, several lineages scattered in the phylogeny had more non-dominant species, suggesting that traits related to non-dominants are phylogenetically conserved and have evolved multiple times. We found some environmental drivers of the dominant—non-dominant disparity. Our results indicate that assembly patterns for dominants and non-dominants are different, consistent with asymmetries in assembly mechanisms. Among the different mechanisms we evaluated, the results suggest two complementary hypotheses seldom explored: (1) Non-dominant species include lineages adapted to thrive in the environment generated by the dominant species. (2) Even when dominant species reduce resources to non-dominant ones, dominant species could have a stronger effect on—at least—some non-dominants by ameliorating the impact of the environment on them, than by depleting resources and increasing the environmental stress to those non-dominants. The results show that the dominant–non-dominant asymmetry has ecological and evolutionary consequences fundamental to understand plant communities.

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Impact of Competition on the Growth of Pinus Tabulaeformis in Response to Climate on the Loess Plateau of China

10.21203/rs.3.rs-619294/v1 ◽

2021 ◽

Author(s):

Rumeng He ◽

Xuhu Wang ◽

Tao Liu ◽

Lijun Guo ◽

Baitian Wang ◽

...

Keyword(s):

Plant Competition ◽

Small Diameter ◽

Stand Density ◽

Climate Variation ◽

Pinus Tabulaeformis ◽

Biotic Factor ◽

Small Diameter Trees ◽

Stand Density Index ◽

The Impact ◽

The Relationship

Abstract With climate change, understanding tree responses to climate is important for predicting trees’ growth, and plant competition as a nonnegligible biotic factor plays a key role in such response. However, few studies have investigated how competition affects the response of Pinus tabulaeformis plantations to climate . In our study, we investigated nine 29-year-old P. tabulaeformis plantation plots (three density gradients). The dendroecological method was used to analyze the impact of competition on trees response to drought and interannual climate variation. Stand density index was used to indicate the intensity of competition. The results showed that competition modified the climate-growth relationship. Competition increased trees’ sensitivity to drought but the relationship between competition and sensitivity to drought was nonlinear. The competition effect slightly increased under intense competition conditions. Additionally, competition reduced trees’ sensitivity to interannual climate variation. After 1999, the effect of competition was obvious. The sensitivity of small-diameter trees, especially those in middle- and high-density stands, declined. Thus, in the future these trees presumably may exhibit a reduced sensitivity to interannual climate variation and a greater sensitivity to drought.

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Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

Symposium - International Astronomical Union ◽

10.1017/s0074180900178404 ◽

1962 ◽

Vol 14 ◽

pp. 415-418

Author(s):

K. P. Stanyukovich ◽

V. A. Bronshten

Keyword(s):

Explosive Charge ◽

The Moon ◽

Meteorite Impacts ◽

The Earth ◽

Lunar Craters ◽

The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

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The Geosciences Applied to Lunar Exploration

Symposium - International Astronomical Union ◽

10.1017/s0074180900178222 ◽

1962 ◽

Vol 14 ◽

pp. 169-257 ◽

Cited By ~ 9

Author(s):

J. Green

Keyword(s):

Lunar Surface ◽

Probable Mechanism ◽

Point Of View ◽

Lunar Exploration ◽

Geological Model ◽

Apply Geophysics ◽

Surface Features ◽

The Impact

The term geo-sciences has been used here to include the disciplines geology, geophysics and geochemistry. However, in order to apply geophysics and geochemistry effectively one must begin with a geological model. Therefore, the science of geology should be used as the basis for lunar exploration. From an astronomical point of view, a lunar terrain heavily impacted with meteors appears the more reasonable; although from a geological standpoint, volcanism seems the more probable mechanism. A surface liberally marked with volcanic features has been advocated by such geologists as Bülow, Dana, Suess, von Wolff, Shaler, Spurr, and Kuno. In this paper, both the impact and volcanic hypotheses are considered in the application of the geo-sciences to manned lunar exploration. However, more emphasis is placed on the volcanic, or more correctly the defluidization, hypothesis to account for lunar surface features.

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Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

International Astronomical Union Colloquium ◽

10.1017/s0252921100014718 ◽

1997 ◽

Vol 161 ◽

pp. 197-201 ◽

Cited By ~ 1

Author(s):

Duncan Steel

Keyword(s):

Probability Distributions ◽

Regions Of Interest ◽

Significant Fraction ◽

Organic Chemicals ◽

Impact Speed ◽

The Mean ◽

The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

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Organic Syntheses During the Impact of a Comet with a Gaseous Planet

International Astronomical Union Colloquium ◽

10.1017/s0252921100014706 ◽

1997 ◽

Vol 161 ◽

pp. 189-195

Author(s):

Cesare Guaita ◽

Roberto Crippa ◽

Federico Manzini

Keyword(s):

Polymeric Material ◽

Molecular Form ◽

Parent Compound ◽

Blue Filter ◽

Organic Syntheses ◽

The Impact

AbstractA large amount of CO has been detected above many SL9/Jupiter impacts. This gas was never detected before the collision. So, in our opinion, CO was released from a parent compound during the collision. We identify this compound as POM (polyoxymethylene), a formaldehyde (HCHO) polymer that, when suddenly heated, reformes monomeric HCHO. At temperatures higher than 1200°K HCHO cannot exist in molecular form and the most probable result of its decomposition is the formation of CO. At lower temperatures, HCHO can react with NH3 and/or HCN to form high UV-absorbing polymeric material. In our opinion, this kind of material has also to be taken in to account to explain the complex evolution of some SL9 impacts that we observed in CCD images taken with a blue filter.

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