Patterns of initial saprophytic fungal colonization of grass roots from two severely disturbed soils

1984 ◽  
Vol 62 (3) ◽  
pp. 596-602 ◽  
Author(s):  
John C. Zak ◽  
Dennis Parkinson
Keyword(s):  
Rare Species ◽  
Oil Sands ◽  
Species Turnover ◽  
Species Abundance ◽  
Growing Season ◽  
Root Surface ◽  
Fungal Colonization ◽  
Nodal Roots ◽  
Fungal Assemblages ◽  
Root Surfaces

Development of the root-surface fungal assemblages of Agropyron trachycaulum grown on amended oil-sands tailings and a subalpine coal-mine spoil from Alberta (Canada) was followed over one growing season. Fungi were isolated, using a root-washing procedure, from the region of main seminal and nodal roots 4 cm from the root–hypocotyl axis. Fungal colonization of the root surfaces was rapid, with equilibrium numbers of species reached 2 weeks after plant emergence. Although the application of either fertilizer, peat, or sewage sludge to these spoils had no effect on the general form of the colonization curve, peat amendation did result in significantly higher numbers of species on the root surfaces. Species turnover within all assemblages was high throughout the growing season. The amount of species replacement ranged from a low of 67% to a high of 91% between consecutive 4-week sampling periods. Thus, although the number of species was relatively constant, species composition changed considerably. The structure of the root-surface fungal assemblages was characterized by a large proportion of rare species. The species abundance distributions were essentially negative exponential. Neither time nor amendation had any significant effect on these distributions. The large incidence of rare species within the assemblages suggests that these root surfaces represent nonequilibrium systems with respect to species occurrences.

Redevelopment of biological activity in strip-mine spoils: saprotrophic fungal assemblages of grass roots

1988 ◽  
Vol 94 ◽  
pp. 73-83
Author(s):  
John C. Zak
Keyword(s):  
Species Composition ◽  
Species Abundance ◽  
Typical Feature ◽  
Fungal Species ◽  
Oil Sand ◽  
Mine Spoils ◽  
Species Abundance Distributions ◽  
Strip Mine ◽  
Fungal Assemblages ◽  
Root Surfaces

SynopsisThe development of fungal assemblages on root-surfaces of Agropyron trachycaulum growing in control, peat, fertiliser, or sewage-amended oil sand tailings was followed over a four-year period. Although the number of fungal species isolated from the root-surfaces differed significantly among the amendments, species numbers did not change significantly within treatments over the four years. The species composition of the assemblages, however, changed considerably from year to year. Species abundance distributions for fungal assemblages from the control, peat, and fertiliser amended spoil were best described by logarithmic functions. Distributions from the sewage-treated spoil were best fitted by exponential functions. Although species composition changed over time, the forms of the species abundance distributions were not altered. The observed structure and dynamic nature of fungal assemblages on root-surfaces may not be a consequence of disturbance, but may be a typical feature of such assemblages. High nutrient addition to mine spoils can result in altered species abundance patterns, and may lead to a decrease in community stability.

scholarly journals Bog plant/lichen tissue nitrogen and sulfur concentrations as indicators of emissions from oil sands development in Alberta, Canada

2021 ◽  
Vol 193 (4) ◽  
Author(s):  
R. Kelman Wieder ◽  
Melanie A. Vile ◽  
Kimberli D. Scott ◽  
Cara M. Albright ◽  
James C. Quinn ◽  
...  
Keyword(s):  
Oil Sands ◽  
Growing Season ◽  
N Deposition ◽  
Point Sources ◽  
Gaseous Emissions ◽  
Spatial And Temporal Patterns ◽  
Sphagnum Fuscum ◽  
S Cycling ◽  
S Deposition ◽  
Tissue Chemistry

AbstractIncreasing gaseous emissions of nitrogen (N) and sulfur (S) associated with oil sands development in northern Alberta (Canada) has led to changing regional wet and dry N and S deposition regimes. We assessed the potential for using bog plant/lichen tissue chemistry (N and S concentrations, C:N and C:S ratios, in 10 plant/lichen species) to monitor changing atmospheric N and S deposition through sampling at five bog sites, 3–6 times per growing season from 2009 to 2016. During this 8-year period, oil sands N emissions steadily increased, while S emissions steadily decreased. We examined the following: (1) whether each species showed changes in tissue chemistry with increasing distance from the Syncrude and Suncor upgrader stacks (the two largest point sources of N and S emissions); (2) whether tissue chemistry changed over the 8 year period in ways that were consistent with increasing N and decreasing S emissions from oil sands facilities; and (3) whether tissue chemistry was correlated with growing season wet deposition of NH4+-N, NO3−-N, or SO42−-S. Based on these criteria, the best biomonitors of a changing N deposition regime were Evernia mesomorpha, Sphagnum fuscum, and Vaccinium oxycoccos. The best biomonitors of a changing S deposition regime were Evernia mesomorpha, Cladonia mitis, Sphagnum fuscum, Sphagnum capillifolium, Vaccinium oxycoccos, and Picea mariana. Changing N and S deposition regimes in the oil sands region appear to be influencing N and S cycling in what once were pristine ombrotrophic bogs, to the extent that these bogs may effectively monitor future spatial and temporal patterns of deposition.

scholarly journals Root and Shoot Response to Nickel in Hyperaccumulator and Non-Hyperaccumulator Species

Plants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 508
Author(s):  
Stefano Rosatto ◽  
Mauro Mariotti ◽  
Sara Romeo ◽  
Enrica Roccotiello
Keyword(s):  
Plant Development ◽  
Root Surface ◽  
Metal Stress ◽  
Physiological Conditions ◽  
Thlaspi Arvense ◽  
Noccaea Caerulescens ◽  
Spiked Soil ◽  
Ecophysiological Response ◽  
Fluorescence Of Chlorophyll A ◽  
Root Surfaces

The soil–root interface is the micro-ecosystem where roots uptake metals. However, less than 10% of hyperaccumulators’ rhizosphere has been examined. The present study evaluated the root and shoot response to nickel in hyperaccumulator and non-hyperaccumulator species, through the analysis of root surface and biomass and the ecophysiological response of the related aboveground biomass. Ni-hyperaccumulators Alyssoides utriculata (L.) Medik. and Noccaea caerulescens (J. Presl and C. Presl) F.K. Mey. and non-hyperaccumulators Alyssum montanum L. and Thlaspi arvense L. were grown in pot on Ni-spiked soil (0–1000 mg Ni kg−1, total). Development of root surfaces was analysed with ImageJ; fresh and dry root biomass was determined. Photosynthetic efficiency was performed by analysing the fluorescence of chlorophyll a to estimate the plants’ physiological conditions at the end of the treatment. Hyperaccumulators did not show a Ni-dependent decrease in root surfaces and biomass (except Ni 1000 mg kg−1 for N. caerulescens). The non-hyperaccumulator A. montanum suffers metal stress which threatens plant development, while the excluder T. arvense exhibits a positive ecophysiological response to Ni. The analysis of the root system, as a component of the rhizosphere, help to clarify the response to soil nickel and plant development under metal stress for bioremediation purposes.

ROOT-SURFACE MYCOFLORA OF SOYBEAN IN RELATION TO SOIL TEMPERATURE AND MOISTURE IN A FIELD ENVIRONMENT

1972 ◽  
Vol 52 (2) ◽  
pp. 199-208 ◽  
Author(s):  
K. C. IVARSON ◽  
A. R. MACK
Keyword(s):  
Soil Temperature ◽  
Relative Frequency ◽  
Incubation Temperature ◽  
Growing Season ◽  
Root Surface ◽  
Growing Seasons ◽  
Field Environment ◽  
Abundant Genus ◽  
Field Plots ◽  
Soil Temperature And Moisture

Studies were made on the root-surface fungi of soybean grown in field plots where various soil temperature and moisture environments had been maintained for five previous growing seasons. Washed-root segments were incubated on agar plates at temperatures corresponding to those of the field plots. Fusarium was the most abundant genus appearing on the plates. Species of Mucor, Trichoderma, Alternaria, Mortierella, Aspergillus, Corynespora, Rhizoctonia, Penicillium, Gliocladium, and sterile forms appeared fairly frequently. Statistical analysis of the data revealed that changes in soil and incubation temperature markedly affected the relative frequency of 12 genera, and age of plant significantly affected nine genera. Soil moisture influenced the frequency of only one genus. High soil and incubation temperature (28 C) encouraged greater root populations of Rhizoctonia early in the season, Trichoderma and Aspergillus throughout the growing season, and Fusarium late in the season. Low soil temperature conditions (12 C) favored growth of Pythium, Mortierella, Mucor, Alternaria, Cladosporium, throughout the growing season, and Corynespora and Cylindrocarpon, primarily during mid-season. Late in the season Gliocladium preferred the intermediate temperature of 20 C.

scholarly journals The commonness of rarity: Global and future distribution of rarity across land plants

2019 ◽  
Author(s):  
Brian Joseph Enquist ◽  
Xiao Feng ◽  
Bradley Boyle ◽  
Brian Maitner ◽  
Erica A. Newman ◽  
...  
Keyword(s):  
Plant Species ◽  
Rare Species ◽  
Large Fraction ◽  
Neutral Theory ◽  
Species Abundance ◽  
Land Plant ◽  
Observation Data ◽  
Heavy Tailed Distributions ◽  
Species Abundance Distributions ◽  
Heavy Tailed

A key feature of life’s diversity is that some species are common but many more are rare. Nonetheless, at global scales, we do not know what fraction of biodiversity consists of rare species. Here, we present the largest compilation of global plant species observation data in order to quantify the fraction of Earth’s extant land plant biodiversity that is common versus rare. Tests of different hypotheses for the origin of species commonness and rarity indicates that sampling biases and prominent models such as niche theory and neutral theory cannot account for the observed prevalence of rare species. Instead, the distribution of commonness is best approximated by heavy-tailed distributions like the Pareto or Poisson-lognormal distributions. As a result, a large fraction, ~36.5% of an estimated ~435k total plant species, are exceedingly rare. We also show that rare species tend to cluster in a small number of ‘hotspots’ mainly characterized by being in tropical and subtropical mountains and areas that have experienced greater climate stability. Our results indicate that (i) non-neutral processes, likely associated with reduced risk of extinction, have maintained a large fraction of Earth’s plant species but that (ii) climate change and human impact appear to now and will disproportionately impact rare species. Together, these results point to a large fraction of Earth’s plant species are faced with increased chances of extinction. Our results indicate that global species abundance distributions have important implications for conservation planning in this era of rapid global change.

scholarly journals Self–organized instability in complex ecosystems

2002 ◽  
Vol 357 (1421) ◽  
pp. 667-681 ◽  
Author(s):  
Ricard V. Solé ◽  
David Alonso ◽  
Alan McKane
Keyword(s):  
Rare Species ◽  
Scaling Law ◽  
Species Abundance ◽  
Field Studies ◽  
Species Number ◽  
Neotropical Forests ◽  
Species Abundances ◽  
Long Tails ◽  
Critical Boundary ◽  
Species Area

Why are some ecosystems so rich, yet contain so many rare species? High species diversity, together with rarity, is a general trend in neotropical forests and coral reefs. However, the origin of such diversity and the consequences of food web complexity in both species abundances and temporal fluctuations are not well understood. Several regularities are observed in complex, multispecies ecosystems that suggest that these ecologies might be organized close to points of instability. We explore, in greater depth, a recent stochastic model of population dynamics that is shown to reproduce: (i) the scaling law linking species number and connectivity; (ii) the observed distributions of species abundance reported from field studies (showing long tails and thus a predominance of rare species); (iii) the complex fluctuations displayed by natural communities (including chaotic dynamics); and (iv) the species–area relations displayed by rainforest plots. It is conjectured that the conflict between the natural tendency towards higher diversity due to immigration, and the ecosystem level constraints derived from an increasing number of links, leaves the system poised at a critical boundary separating stable from unstable communities, where large fluctuations are expected to occur. We suggest that the patterns displayed by species–rich communities, including rarity, would result from such a spontaneous tendency towards instability.

scholarly journals The commonness of rarity: Global and future distribution of rarity across land plants

2019 ◽  
Vol 5 (11) ◽  
pp. eaaz0414 ◽  
Author(s):  
Brian J. Enquist ◽  
Xiao Feng ◽  
Brad Boyle ◽  
Brian Maitner ◽  
Erica A. Newman ◽  
...  
Keyword(s):  
Plant Species ◽  
Conservation Planning ◽  
Rare Species ◽  
Extinction Risk ◽  
Large Fraction ◽  
Neutral Theory ◽  
Species Abundance ◽  
Risk Assessments ◽  
Human Land Use ◽  
Species Abundance Distributions

A key feature of life’s diversity is that some species are common but many more are rare. Nonetheless, at global scales, we do not know what fraction of biodiversity consists of rare species. Here, we present the largest compilation of global plant diversity to quantify the fraction of Earth’s plant biodiversity that are rare. A large fraction, ~36.5% of Earth’s ~435,000 plant species, are exceedingly rare. Sampling biases and prominent models, such as neutral theory and the k-niche model, cannot account for the observed prevalence of rarity. Our results indicate that (i) climatically more stable regions have harbored rare species and hence a large fraction of Earth’s plant species via reduced extinction risk but that (ii) climate change and human land use are now disproportionately impacting rare species. Estimates of global species abundance distributions have important implications for risk assessments and conservation planning in this era of rapid global change.

scholarly journals Ocean currents promote rare species diversity in protists

2020 ◽  
Vol 6 (29) ◽  
pp. eaaz9037
Author(s):  
Paula Villa Martín ◽  
Aleš Buček ◽  
Thomas Bourguignon ◽  
Simone Pigolotti
Keyword(s):  
Species Diversity ◽  
Power Law ◽  
Rare Species ◽  
Species Abundance ◽  
Ecological Factors ◽  
Abundant Species ◽  
Chaotic Advection ◽  
Power Law Decay ◽  
Aquatic Microbes ◽  
Oceanic Currents

Oceans host communities of plankton composed of relatively few abundant species and many rare species. The number of rare protist species in these communities, as estimated in metagenomic studies, decays as a steep power law of their abundance. The ecological factors at the origin of this pattern remain elusive. We propose that chaotic advection by oceanic currents affects biodiversity patterns of rare species. To test this hypothesis, we introduce a spatially explicit coalescence model that reconstructs the species diversity of a sample of water. Our model predicts, in the presence of chaotic advection, a steeper power law decay of the species abundance distribution and a steeper increase of the number of observed species with sample size. A comparison of metagenomic studies of planktonic protist communities in oceans and in lakes quantitatively confirms our prediction. Our results support that oceanic currents positively affect the diversity of rare aquatic microbes.

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