Effect of propagule source on competitive ability of pasture grasses: spatial dynamics of six grasses in simulated swards

1994 ◽  
Vol 72 (1) ◽  
pp. 111-121 ◽  
Author(s):  
Roy Turkington
Keyword(s):  
Species Interactions ◽  
Competitive Ability ◽  
Community Dynamics ◽  
Spatial Dynamics ◽  
Phleum Pratense ◽  
The Other ◽  
Individual Species ◽  
Bare Ground ◽  
Lateral Expansion ◽  
Pasture Grasses

Simulated swards were constructed to investigate the potential effect of propagule source on competitive ability of pasture grasses, to monitor the spatial dynamics of pasture communities, and to assess the importance of species interactions and disturbances in community structure. The design used six species of grasses, Agrostis alba, Dactylis glomerata, Holcus lanatus, Lolium perenne, Phleum pratense, and Poa compressa, arranged in a mosaic of hexagonal patches with each hexagon being sown with one species of grass or left as bare ground and being surrounded by each of the other species. Three swards were constructed, one using plant material collected from an 11-year-old pasture, one with material from an adjacent 49-year-old pasture, and the third from material grown from seed. After 20 months of interaction across the interfaces between the patches, the swards were destructively harvested above ground and the contents of each hexagon separated into species. Grasses from four different-aged origins, including the three above, were also grown in plots without any neighbours for 16 months. Each species had its own individual behavior: Agrostis and Phleum from the older pastures were the better invaders, Holcus and Poa were the poorest, and Phleum from the oldest community was the most resistant to lateral expansion of the other species. In a number of cases the grasses from the older pastures, but never from the seeded bed, invaded other patches of grass as readily as they expanded into bare ground. The total aboveground community biomass showed a nonsignificant decline with age, and the community as a whole became more open to lateral expansion by individual species. No results were obtained to support the cyclic regeneration hypothesis of Watt; the functional equivalence arguments of Aarssen may be more appropriate in this fine-grained pasture environment. Key words: community dynamics, invasion, pasture, competitive effect and response, disturbance, patches.

CLIPPING FREQUENCY AND FERTILIZER EFFECTS ON PRODUCTIVITY AND LONGEVITY OF FIVE GRASSES

1961 ◽  
Vol 41 (1) ◽  
pp. 97-108 ◽  
Author(s):  
D. H. Heinrichs ◽  
K. W. Clark
Keyword(s):  
Crude Protein ◽  
Competitive Ability ◽  
Forage Yield ◽  
The Other ◽  
Protein Yield ◽  
Agropyron Cristatum ◽  
Cold Climates ◽  
Agropyron Intermedium ◽  
Pasture Grasses

Agropyron cristatum, Agropyron intermedium, Agropyron riparium, Elymus junceus and Stipa viridula were studied in relation to clipping effects on productivity and longevity. All species, except Elymus junceus, produced progressively less as number of clippings increased. Agropyron intermedium yielded the most forage, especially when harvested only once per season, followed closely by Agropyron cristatum. Crude protein yield was less variable under various frequencies of clipping than forage yield, and differences between species were also smaller. Elymus junceus and Agropyron cristatum displayed the strongest competitive ability, especially under frequent clipping and Stipa viridula the lowest. The amount of root produced varied significantly between species. Agropyron cristatum and Elymus junceus produced the most root and Stipa viridula the least. Fertilizer applied in the fourth and fifth crop years increased the yield by 30 to 200 per cent. It was concluded that Agropyron cristatum and Elymus junceus were about equally persistent under frequent clipping and should be more useful long-term pasture grasses than the other three in dry cold climates.

scholarly journals Higher-order effects, continuous species interactions, and trait evolution shape microbial spatial dynamics

2021 ◽  
Vol 119 (1) ◽  
pp. e2020956119
Author(s):  
Anshuman Swain ◽  
Levi Fussell ◽  
William F. Fagan
Keyword(s):  
Microbial Diversity ◽  
Species Interactions ◽  
Community Dynamics ◽  
Spatial Dynamics ◽  
Higher Order ◽  
Formation Time ◽  
Community Formation ◽  
Order Effects ◽  
Disturbance Regimes ◽  
Antagonistic Interactions

The assembly and maintenance of microbial diversity in natural communities, despite the abundance of toxin-based antagonistic interactions, presents major challenges for biological understanding. A common framework for investigating such antagonistic interactions involves cyclic dominance games with pairwise interactions. The incorporation of higher-order interactions in such models permits increased levels of microbial diversity, especially in communities in which antibiotic-producing, sensitive, and resistant strains coexist. However, most such models involve a small number of discrete species, assume a notion of pure cyclic dominance, and focus on low mutation rate regimes, none of which well represent the highly interlinked, quickly evolving, and continuous nature of microbial phenotypic space. Here, we present an alternative vision of spatial dynamics for microbial communities based on antagonistic interactions—one in which a large number of species interact in continuous phenotypic space, are capable of rapid mutation, and engage in both direct and higher-order interactions mediated by production of and resistance to antibiotics. Focusing on toxin production, vulnerability, and inhibition among species, we observe highly divergent patterns of diversity and spatial community dynamics. We find that species interaction constraints (rather than mobility) best predict spatiotemporal disturbance regimes, whereas community formation time, mobility, and mutation size best explain patterns of diversity. We also report an intriguing relationship among community formation time, spatial disturbance regimes, and diversity dynamics. This relationship, which suggests that both higher-order interactions and rapid evolution are critical for the origin and maintenance of microbial diversity, has broad-ranging links to the maintenance of diversity in other systems.

scholarly journals Moving apart together: co-movement of a symbiont community and their ant host, and its importance for community assembly

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
T. Parmentier ◽  
R. Claus ◽  
F. De Laender ◽  
D. Bonte
Keyword(s):  
Community Assembly ◽  
Species Interactions ◽  
Spatial Dynamics ◽  
Joint Movement ◽  
Red Wood Ants ◽  
Ant Nests ◽  
Mobile Species ◽  
Directional Movement ◽  
Wood Ants ◽  
Red Wood Ant

Abstract Background Species interactions may affect spatial dynamics when the movement of one species is determined by the presence of another one. The most direct species-dependence of dispersal is vectored, usually cross-kingdom, movement of immobile parasites, diseases or seeds by mobile animals. Joint movements of species should, however, not be vectored by definition, as even mobile species are predicted to move together when they are tightly connected in symbiont communities. Methods We studied concerted movements in a diverse and heterogeneous community of arthropods (myrmecophiles) associated with red wood ants. We questioned whether joint-movement strategies eventually determine and speed-up community succession. Results We recorded an astonishingly high number of obligate myrmecophiles outside red wood ant nests. They preferentially co-moved with the host ants as the highest densities were found in locations with the highest density of foraging red wood ants, such as along the network of ant trails. These observations suggest that myrmecophiles resort to the host to move away from the nest, and this to a much higher extent than hitherto anticipated. Interestingly, functional groups of symbionts displayed different dispersal kernels, with predatory myrmecophiles moving more frequently and further from the nest than detritivorous myrmecophiles. We discovered that myrmecophile diversity was lower in newly founded nests than in mature red wood ant nests. Most myrmecophiles, however, were able to colonize new nests fast suggesting that the heterogeneity in mobility does not affect community assembly. Conclusions We show that co-movement is not restricted to tight parasitic, or cross-kingdom interactions. Movement in social insect symbiont communities may be heterogeneous and functional group-dependent, but clearly affected by host movement. Ultimately, this co-movement leads to directional movement and allows a fast colonisation of new patches, but not in a predictable way. This study highlights the importance of spatial dynamics of local and regional networks in symbiont metacommunities, of which those of symbionts of social insects are prime examples.

scholarly journals The importance of species interactions in eco-evolutionary community dynamics under climate change

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Anna Åkesson ◽  
Alva Curtsdotter ◽  
Anna Eklöf ◽  
Bo Ebenman ◽  
Jon Norberg ◽  
...  
Keyword(s):  
Climate Change ◽  
Species Interactions ◽  
Community Dynamics ◽  
Evolutionary Dynamics ◽  
Negative Impact ◽  
Trophic Levels ◽  
Temperature Dependent ◽  
Modeling Framework ◽  
Impact Of Climate Change ◽  
The Impact

AbstractEco-evolutionary dynamics are essential in shaping the biological response of communities to ongoing climate change. Here we develop a spatially explicit eco-evolutionary framework which features more detailed species interactions, integrating evolution and dispersal. We include species interactions within and between trophic levels, and additionally, we incorporate the feature that species’ interspecific competition might change due to increasing temperatures and affect the impact of climate change on ecological communities. Our modeling framework captures previously reported ecological responses to climate change, and also reveals two key results. First, interactions between trophic levels as well as temperature-dependent competition within a trophic level mitigate the negative impact of climate change on biodiversity, emphasizing the importance of understanding biotic interactions in shaping climate change impact. Second, our trait-based perspective reveals a strong positive relationship between the within-community variation in preferred temperatures and the capacity to respond to climate change. Temperature-dependent competition consistently results both in higher trait variation and more responsive communities to altered climatic conditions. Our study demonstrates the importance of species interactions in an eco-evolutionary setting, further expanding our knowledge of the interplay between ecological and evolutionary processes.

scholarly journals Introduction: Special issue on species interactions, ecological networks and community dynamics – Untangling the entangled bank using molecular techniques

2019 ◽  
Vol 28 (2) ◽  
pp. 157-164 ◽  
Author(s):  
Tomas Roslin ◽  
Michael Traugott ◽  
Mattias Jonsson ◽  
Graham N. Stone ◽  
Simon Creer ◽  
...  
Keyword(s):  
Species Interactions ◽  
Community Dynamics ◽  
Ecological Networks ◽  
Molecular Techniques ◽  
Special Issue

scholarly journals A Competitive Ratio for Quantifying Competition Between Intercrops

1980 ◽  
Vol 16 (2) ◽  
pp. 117-125 ◽  
Author(s):  
R. W. Willey ◽  
M. R. Rao
Keyword(s):  
Competitive Ratio ◽  
Competitive Ability ◽  
Maximum Yield ◽  
The Other ◽  
Competitive Balance ◽  
Crop Competition

SUMMARYA simple competitive ratio (CR) is proposed as a measure of intercrop competition, to indicate the number of times by which one component crop is more competitive than the other. Intercropping data show that this CR term could be useful in (i) comparing the competitive ability of different crops, (ii) measuring competitive changes within a given combination, (iii) identifying which plant characters are associated with competitive ability, and (iv) determining what competitive balance between components is most likely to give maximum yield advantages.

Species interactions in mixed-community crystalline biofilms on urinary catheters

2007 ◽  
Vol 56 (11) ◽  
pp. 1549-1557 ◽  
Author(s):  
Sarah M. Macleod ◽  
David J. Stickler
Keyword(s):  
Urinary Tract ◽  
Species Interactions ◽  
The Other ◽  
Experimental Investigations ◽  
Crystal Formation ◽  
Urinary Catheters ◽  
E Coli ◽  
Pure Cultures ◽  
Providencia Stuartii

Previous experimental investigations of the crystalline biofilms that colonize and block urinary catheters have focussed on their formation by pure cultures of Proteus mirabilis. In the urine of patients undergoing long-term catheterization, P. mirabilis is commonly found in mixed communities with other urinary tract pathogens. Little is known about the effect that the other species have on the rate at which P. mirabilis encrusts catheters. In the present study, a set of data on the nature of the bacterial communities on 106 catheter biofilms has been analysed and it was found that while species such as Providencia stuartii and Klebsiella pneumoniae were commonly associated with P. mirabilis, when Escherichia coli, Morganella morganii or Enterobacter cloacae were present, P. mirabilis was rarely or never found. The hypothesis that the absence of P. mirabilis from some biofilm communities could be due to its active exclusion by other species has also been examined. Experiments in laboratory models showed that co-infection of P. mirabilis with M. morganii, K. pneumoniae or E. coli had no effect on the ability of P. mirabilis to encrust and block catheters. Co-infection with Ent. cloacae or Pseudomonas aeruginosa, however, significantly increased the time that catheters took to block (P <0.05). The growth of Ent. cloacae, M. morganii, K. pneumoniae or E. coli in the model for 72 h prior to superinfection with P. mirabilis significantly delayed catheter blockage. In the case of Ent. cloacae, for example, the mean time to blockage was extended from 28.7 h to 60.7 h (P ≤0.01). In all cases, however, P. mirabilis was able to generate alkaline urine, colonize the biofilms, induce crystal formation and block the catheters. The results suggest that although there is a degree of antagonism between P. mirabilis and some of the other urinary tract organisms, the effects are temporary and whatever the pre-existing urinary microbiota, infection with P. mirabilis is thus likely to lead to catheter encrustation and blockage.

scholarly journals Species interactions in three Lemnaceae species growing along a gradient of zinc pollution

2021 ◽  
Author(s):  
Lorena Lanthemann ◽  
Sofia van Moorsel
Keyword(s):  
Growth Rates ◽  
Species Interactions ◽  
Metal Removal ◽  
Lemna Minor ◽  
Polluted Water ◽  
Future Research ◽  
Individual Species ◽  
High Tolerance ◽  
Species Mixture ◽  
The Individual

Duckweeds (Lemnaceae) are increasingly studied for their potential for phytoremediation of heavy-metal polluted water bodies. A prerequisite for metal removal, however, is the tolerance of the organism to the pollutant, e.g., the metal zinc (Zn). Duckweeds have been shown to differ in their tolerances to Zn, however, despite them most commonly co-occurring with other species, there is a lack of research concerning the effect of species interactions on Zn tolerance. Here we tested whether the presence of a second species influenced the growth rate of the three duckweed species Lemna minor, Lemna gibba, and Lemna turionifera. We used four different Zn concentrations in a replicated microcosm experiment under sterile conditions, either growing the species in isolation or in a 2-species mixture. The response to Zn differed between species, but all three species showed a high tolerance to Zn, with low levels of Zn even increasing the growth rates. The growth rates of the individual species were influenced by the identity of the competing species, but this was independent of the Zn concentration. Our results suggest that species interactions should be considered in future research with duckweeds and that several duckweed species have high tolerance to metal pollution, making them candidates for phytoremediation efforts.

scholarly journals Differential arthropod responses to warming are altering the structure of Arctic communities

2018 ◽  
Vol 5 (4) ◽  
pp. 171503 ◽  
Author(s):  
Amanda M. Koltz ◽  
Niels M. Schmidt ◽  
Toke T. Høye
Keyword(s):  
Community Composition ◽  
Primary Productivity ◽  
Species Interactions ◽  
Ecosystem Processes ◽  
The Arctic ◽  
Individual Species ◽  
Freeze Thaw ◽  
Compositional Changes ◽  
Arctic Communities

The Arctic is experiencing some of the fastest rates of warming on the planet. Although many studies have documented responses to such warming by individual species, the idiosyncratic nature of these findings has prevented us from extrapolating them to community-level predictions. Here, we leverage the availability of a long-term dataset from Zackenberg, Greenland (593 700 specimens collected between 1996 and 2014), to investigate how climate parameters influence the abundance of different arthropod groups and overall community composition. We find that variation in mean seasonal temperatures, winter duration and winter freeze–thaw events is correlated with taxon-specific and habitat-dependent changes in arthropod abundances. In addition, we find that arthropod communities have exhibited compositional changes consistent with the expected effects of recent shifts towards warmer active seasons and fewer freeze–thaw events in NE Greenland. Changes in community composition are up to five times more extreme in drier than wet habitats, with herbivores and parasitoids generally increasing in abundance, while the opposite is true for surface detritivores. These results suggest that species interactions and food web dynamics are changing in the Arctic, with potential implications for key ecosystem processes such as decomposition, nutrient cycling and primary productivity.

Metacommunities

2019 ◽  
pp. 266-284
Author(s):  
Gary G. Mittelbach ◽  
Brian J. McGill
Keyword(s):  
Species Diversity ◽  
Species Interactions ◽  
Neutral Theory ◽  
Patch Dynamics ◽  
Species Traits ◽  
Local Communities ◽  
The Other ◽  
Species Sorting ◽  
Niche Differences ◽  
Dynamics Of Populations

Just as the dispersal of individuals may link the dynamics of populations in space, the dispersal of species among communities may link local communities into a metacommunity. Four different perspectives characterize how dispersal rates, environmental heterogeneity, and species traits interact to influence diversity in metacommunities. These perspectives are: patch dynamics, species sorting, mass effects, and the neutral perspective. The neutral perspective stands in stark contrast to the other three perspectives in that it assumes that niche differences between species are unimportant and that species are demographically identical in terms of their birth, death, and dispersal rates. Under the neutral perspective, species diversity is maintained by a balance between speciation, extinction, and dispersal. Although neutral theory is incompatible with realistic modes and rates of speciation, it has been enormously influential in focusing our attention on the linkages between species interactions on local scales, and evolutionary and biogeographic processes occurring on large scales.

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