scholarly journals Priority Effects and Nonhierarchical Competition Shape Species Composition in a Complex Grassland Community

2019 ◽  
Vol 193 (2) ◽  
pp. 213-226 ◽  
Author(s):  
Lawrence H. Uricchio ◽  
S. Caroline Daws ◽  
Erin R. Spear ◽  
Erin A. Mordecai
Keyword(s):  
Species Composition ◽  
Priority Effects ◽  
Grassland Community

scholarly journals Priority effects and non-hierarchical competition shape species composition in a complex grassland community

2018 ◽  
Author(s):  
Lawrence H. Uricchio ◽  
S. Caroline Daws ◽  
Erin R. Spear ◽  
Erin A. Mordecai
Keyword(s):  
Species Composition ◽  
Exotic Species ◽  
Native Species ◽  
Complex Mixture ◽  
Single Species ◽  
Priority Effects ◽  
Complex Species ◽  
Species Dominance ◽  
Grassland Community ◽  
Population Dynamic Model

AbstractNiche and fitness differences control the outcome of competition, but determining their relative importance in invaded communities – which may be far from equilibrium – remains a pressing concern. Moreover, it is unclear whether classic approaches for studying competition, which were developed predominantly for pairs of interacting species, will fully capture dynamics in complex species assemblages. We parameterized a population dynamic model using competition experiments of two native and three exotic species from a grassland community. We found evidence for minimal fitness differences or niche differences between the native species, leading to slow replacement dynamics and priority effects, but large fitness advantages allowed exotics to unconditionally invade natives. Priority effects driven by strong interspecific competition between exotic species drove single-species dominance by one of two exotic species in 80% of model outcomes, while a complex mixture of non-hierarchical competition and coexistence between native and exotic species occurred in the remaining 20%. Fungal infection, a commonly hypothesized coexistence mechanism, had weak fitness effects, and is unlikely to substantially affect coexistence. In contrast to previous work on pairwise outcomes in largely native-dominated communities, our work supports a role for nearly-neutral dynamics and priority effects as drivers of species composition in invaded communities.

Priority effects and desert anuran communities

2005 ◽  
Vol 83 (8) ◽  
pp. 1112-1116 ◽  
Author(s):  
G H Dayton ◽  
L A Fitzgerald
Keyword(s):  
Species Composition ◽  
Laboratory Experiments ◽  
Hatching Success ◽  
Aquatic Ecology ◽  
Priority Effects ◽  
Scaphiopus Couchii ◽  
Ephemeral Pools ◽  
Desert Regions ◽  
Community Assemblages ◽  
Current Paradigm

The roles of priority effects and predation in structuring anuran communities have not been considered important in desert environments characterized by highly ephemeral pools and anuran species that breed synchronously. Predation is one mechanism that can set the stage for priority effects to be important, especially in ephemeral pools where resources are limiting and densities are high. We observed oophagy by Scaphiopus couchii Baird, 1854 on eggs of Bufo speciosus Girard, 1854 in the field and conducted laboratory experiments to test the hypothesis that S. couchii tadpoles would reduce B. speciosus survivorship via predation. Three-day-old S. couchii tadpoles reduced hatching success of B. speciosus eggs by nearly 90%. When S. couchii and B. speciosus eggs were laid the same day, S. couchii tadpoles reduced B. speciosus egg survivorship by 56%. Our results indicate that priority effects and predation may play an important role in influencing species composition of anuran assemblages in desert regions. Our study provides more support for the need to reevaluate the current paradigm in aquatic ecology that suggests predation does not play a role in structuring community assemblages in highly ephemeral pools.

Use of a weighing lysimeter system to assess the effects of trampling on evapotranspiration of montane plant communities

2002 ◽  
Vol 80 (6) ◽  
pp. 675-683 ◽  
Author(s):  
David Scott ◽  
Neil G Bayfield ◽  
Alexander Cernusca ◽  
David A Elston
Keyword(s):  
Species Composition ◽  
Plant Communities ◽  
Water Loss ◽  
Vegetation Structure ◽  
Vascular Plant ◽  
Grassland Community ◽  
Montane Vegetation ◽  
Heath Communities ◽  
Contrasting Structure ◽  
Weighing Lysimeter

The aim was to investigate the impacts of trampling on water loss and partitioning in vegetation with contrasting structure and species composition. A new design of weighing lysimeter was used in glasshouse experiments to compare evapotranspiration from intact and trampled blocks of vegetation. The lysimeter system was able to detect differences between treatments after only a few hours. Evapotranspiration was recorded for six communities, representative of cryptogam - vascular plant communities found in the Cairngorm Mountains of Scotland. Vegetation blocks of Racomitrium and Vaccinium/Hylocomium heath communities had the greatest cumulative evapotranspiration and lichen heath the least over 48 h. Blocks from three of the communities (Agrostis/Festuca grassland, Calluna wet heath, and lichen heath) were used in a trampling experiment with five levels of damage. Trampling progressively destroyed the structure of the vegetation of all communities and increased the rates of water loss from the blocks. The grassland community vegetation was the most resilient. These results help to link the massive changes in vegetation structure resulting from trampling to effects on water loss and microclimate.Key words: weighing lysimeter, evapotranspiration, recreation, trampling, cryptogams, montane vegetation.

scholarly journals The exotic species Senecio inaequidens pays the price for arriving late in temperate European grassland communities

Oecologia ◽  
2019 ◽  
Vol 191 (3) ◽  
pp. 657-671 ◽  
Author(s):  
Benjamin M. Delory ◽  
Emanuela W. A. Weidlich ◽  
Miriam Kunz ◽  
Joshua Neitzel ◽  
Vicky M. Temperton
Keyword(s):  
Exotic Species ◽  
Native Species ◽  
Species Abundance ◽  
Priority Effects ◽  
Native Community ◽  
Grassland Community ◽  
Early Arrival ◽  
Senecio Inaequidens ◽  
A Site ◽  
Timing Of Arrival

Abstract The exotic South African ragwort (Senecio inaequidens DC.) rapidly spread across Central Europe after its introduction, but we still do not know to what extent its timing of arrival in a plant community (i.e. before or after natives) and the composition of the native community being invaded affect (1) its capacity to invade a European grassland, (2) the performance of the native species, and (3) the direction and strength of priority effects. In a greenhouse experiment, we manipulated the timing of arrival of the exotic species (Senecio) and the composition of the native community to test the influence of these factors on the productivity and N content of exotic and native species. We also investigated if the plant species origin (native or exotic) and the native community composition affected the benefit of arriving early and the cost of arriving late in the community. The establishment success of Senecio strongly depended on its timing of arrival in a grassland community. Senecio benefited more from arriving early than did the natives. The presence of legumes in the community did not favour invasion by Senecio. When natives arrived later than Senecio, however, priority effects were weaker when legumes were part of the native community. Our results showed that inhibitory priority effects created by natives can lower the risk of invasion by Senecio. An early arrival of this species at a site with low native species abundance is a scenario that could favour invasion.

Trends in vegetation cover in the grassland community on the Bogong High Plains, Victoria.

1985 ◽  
Vol 7 (2) ◽  
pp. 93 ◽  
Author(s):  
Rees H van ◽  
WA Papst ◽  
K McDougall ◽  
RC Boston
Keyword(s):  
Species Composition ◽  
Plant Species ◽  
Vegetation Cover ◽  
The Other ◽  
Alpine Grassland ◽  
High Plains ◽  
Grassland Community ◽  
Major Species ◽  
A Site ◽  
Free Ranging

Cover and luxuriance of plant species in the alpine grassland community were measured. Four grassland sites were monitored regularly from 1979 to 1984; three are grazed during summer months by free-ranging cattle, the other has not been grazed since 1974. Data are presented for cover of major species at another grazed site monitored since 1947. Three classes of total vegetation cover were defined in relation to the susceptibility of a site toerosion. Results show that there have been no trends in vegetation cover and luxuriance. Species composition and total vegetation cover varied between sites but there were no dis- cernible trends in these characteristics.

scholarly journals The exotic species Senecio inaequidens pays the price for arriving late in temperate European grasslands

2019 ◽  
Author(s):  
Benjamin Delory ◽  
Emanuela W. A. Weidlich ◽  
Miriam Kunz ◽  
Joshua Neitzel ◽  
Vicky Temperton
Keyword(s):  
Exotic Species ◽  
Native Species ◽  
Species Abundance ◽  
Priority Effects ◽  
Distribution Area ◽  
Native Community ◽  
Grassland Community ◽  
Early Arrival ◽  
Senecio Inaequidens ◽  
Timing Of Arrival

The South African ragwort (Senecio inaequidens DC.) is one of the fastest exotic plant invaders in Central Europe but, despite its large distribution area, it is still not commonly found in European grasslands. In order to better understand the mechanisms behind invasion resistance of grassland communities to S. inaequidens, we determined (1) to what extent the timing of arrival of S. inaequidens in the community affected its invasiveness as well as the performance of the native species, and (2) how the direction and strength of priority effects were affected by the composition of the native community being invaded, particularly with regard to the presence of N2-fixing species (legumes). In a greenhouse experiment, we manipulated the timing of arrival of the exotic species in the community and the composition of the native background community to test the influence of these factors on the productivity and N content of exotic and native species. Using a set of interaction indices, we also investigated if the plant species origin (native or exotic) and the native community composition affected the benefit of arriving early and the cost of arriving late (i.e., priority effects) in the community. We showed that both exotic and native species created inhibitory priority effects for late-arriving species. The establishment success of S. inaequidens strongly depended on its timing of arrival in a grassland community. On average, S. inaequidens benefited more from arriving early than the natives. We did not find any evidence to support that the presence of legumes in the background community would favour invasion by S. inaequidens. When natives arrived later than S. inaequidens, however, priority effects were weaker when legumes were present in the native community. Synthesis: we showed that priority effects created by natives can lower the risk of invasion by S. inaequidens and are an important mechanism to explain why this exotic species is not commonly found in European grasslands yet. Our results suggest that an early arrival of this species at a site with low native species abundance (e.g., following a disturbance) is a scenario that could favour invasion by S. inaequidens.

scholarly journals The problem of maintaining large herbivores in small conservation areas: deterioration of the grassveld in the Addo Elephant National Park

Koedoe ◽  
1991 ◽  
Vol 34 (1) ◽  
Author(s):  
P. Novellie ◽  
A.J. Hall-Martin ◽  
D. Joubert
Keyword(s):  
Species Composition ◽  
Relative Abundance ◽  
Vegetation Cover ◽  
National Park ◽  
Dwarf Shrub ◽  
Grass Cover ◽  
Conservation Areas ◽  
Large Herbivores ◽  
Themeda Triandra ◽  
Grassland Community

Changes in vegetation cover and species composition in a grassland community during a six year period are reported. The grass Themeda triandra and the dwarf shrub Helichrysum rosum decreased in abundance, whereas the grass Eragrostis obtusa increased. Comparison of grazed plots with fenced plots revealed large herbivores were responsible for the increase in abundance ofE. obtusa. The abundance of T. triandra was influenced by large herbivores, but rainfall fluctuations apparently also played a role. The decline in relative abundance of/7. rosum was evidently not caused by large herbivores. Grass cover was closely determined by rainfall. A drought-induced decline in forage abundance evidently caused the buffalo population to crash.

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