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 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.

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.

scholarly journals Priority Treatment Leaves Grassland Restoration Vulnerable to Invasion

Diversity ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 71 ◽  
Author(s):  
Katharine L. Stuble ◽  
Truman P. Young
Keyword(s):  
Native Species ◽  
Priority Effects ◽  
Native Grasses ◽  
Target Species ◽  
California Grasslands ◽  
Early Arrival ◽  
Regional Species Pool ◽  
Conservation Concern ◽  
Indirect Impacts ◽  
One Year

Priority effects can be used to promote target species during restoration. Early planting can provide an advantage over later-arriving species, increasing abundance of these early-arrivers in restored communities. However, we have limited knowledge of the indirect impacts of priority effects in restoration. In particular, we do not understand how priority effects impact non-target species. Of particular conservation concern is how these priority effects influence establishment by non-native species. We use a field-based mesocosm experiment to explore the impacts of priority effects on both target and non-target species in California grasslands. Specifically, we seeded native grasses and forbs, manipulating order of arrival by planting them at the same time, planting forbs one year before grasses, planting grasses one year before forbs, or planting each functional group alone. While our study plots were tilled and weeded for the first year, the regional species pool was heavily invaded. We found that, while early-arrival of native grasses did not promote establishment of non-native species, giving priority to native forbs ultimately left our restoration mesocosms vulnerable to invasion by non-native species. This suggests that, in some cases, establishment of non-native species may be an unintended consequence of using priority treatments as a restoration tool.

scholarly journals Native Plant Recovery following Three Years of Common Reed (Phragmites australis) Control

2018 ◽  
Vol 11 (4) ◽  
pp. 175-180 ◽  
Author(s):  
Christopher L. Zimmerman ◽  
Rebecca R. Shirer ◽  
Jeffrey D. Corbin
Keyword(s):  
Phragmites Australis ◽  
Native Species ◽  
Plant Cover ◽  
Management Strategies ◽  
Species Abundance ◽  
Common Reed ◽  
Exotic Plant ◽  
Native Plant ◽  
Native Community ◽  
Native Plant Community

AbstractProjects that aim to control invasive species often assume that a reduction of the target species will increase native species abundance. However, reports of the responses of native species following exotic species control are relatively rare. We assessed the recovery of the native community in five tidal wetland locations in which we attempted to eradicate the invasive common reed [Phragmites australis (Cav.) Trin. ex Steud.]. We tested whether 3 yr of treatment were able to eradicate Phragmites and promote recovery of the native plant community. After 3 yr of treatment, Phragmites density declined sharply in all treated stands, though it was not eradicated in any of them. Native plant cover increased significantly in treated areas, and community composition, particularly in smaller stands, converged toward that of uninvaded habitat. Thus, even within the relatively short timescale of the treatments and monitoring, significant progress was made toward achieving the goals of controlling Phragmites infestations and promoting native biodiversity. There was a trend toward greater promise for success in smaller stands than larger stands, as has been observed in other studies. A greater emphasis on monitoring whole-community responses to exotic plant control, across a range of conditions, would enhance our ability to plan and design successful management strategies.

scholarly journals Alien Species vs. Native Species: From Community Ecology to Eco-Evolutionary Dynamics

2019 ◽  
Author(s):  
Andersonn Silveira Prestes
Keyword(s):  
Alien Species ◽  
Exotic Species ◽  
Native Species ◽  
Evolutionary Dynamics ◽  
Evolutionary Processes ◽  
Native Communities ◽  
Individualized Approach ◽  
History Of ◽  
Relationship Of ◽  
The Relationship

The establishment and spread of exotic species is a contemporary major concern. Alien species may become invasive in their new habitat, leading to both/either environmental and/or economic impacts. I briefly reviewed the literature in the last decade about the relationship of exotic species and native communities. I identified that professionals usually approach the subject in two main points of view: (1) researchers tend to point out the impacts of alien species on entire communities, evaluating if the relationship is positive, negative or neutral; (2) they focus on the eco-evolutionary processes involved in the introductions, the dynamics of invasion, and individual study cases. When evaluating the response of introductions to entire communities, evidence seems to be ambiguous and may support positive, negative or neutral relationship, especially depending on the scale approached. The unique eco-evolutionary pathways of each introduction may be a great shortcoming in the searching for generalities. On the other hand, advances have been made in understanding the dynamics of invasion on different lineages through a more selective/individualized approach. I suggest that the dynamics of invasion might be studied through a perspective in which different eco-evolutionary processes, levels of organization (from gene to entire communities), the history of the organism(s) and time are taken into account. Individual cases might be compared in attempt to understand how the relationship exotic and native works and in the search for generalities.

scholarly journals Abundance of ants (Hymenoptera: Formicidae) and the functional groups in two different habitats

2020 ◽  
Vol 21 (5) ◽  
Author(s):  
Ananto Triyogo ◽  
Budiadi ◽  
Siti Muslimah Widyastuti ◽  
Sena Adi Subrata ◽  
Suwito Susetyo Budi
Keyword(s):  
Functional Groups ◽  
Native Species ◽  
Diversity Index ◽  
Species Abundance ◽  
Land Development ◽  
Invasive Ants ◽  
Ant Communities ◽  
Anoplolepis Gracilipes ◽  
Research Education ◽  
June July

Abstract. Triyogo A, Budiadi, Widyastuti SM, Subrata SA, Budi SS. 2020. Abundance of ants (Hymenoptera: Formicidae) and the functional groups in two different habitats. Biodiversitas 21: 2079-2087. Land development often affects the quantity and diversity of ants (Hymenoptera: Formicidae). The aim of this study, therefore, was to determine and compare the ant species abundance and the functional groups between two different habitats, representing land development, including pioneer and agroforestry. This research involved a survey of the ants at the Forest Research Education (FRE) of Wanagama I Yogyakarta, and data were accumulated over a period of five months (April, May, June, July, and August). In addition, pit-fall trap and direct collection methods were used, involving the placement of 54 pit-fall traps at two habitats, and the ant specimens were retrieved after a two day period. The results show the total individual abundance of 2,310 and 2,067, on agroforestry and pioneer, respectively. Furthermore, the species richness and diversity index was higher in agroforestry (7; 2.01), compared with pioneer (6; 1.49), where the three dominant species include, Anoplolepis gracilipes, Solenopsis sp., Odontoponera denticulata; and Anoplolepis gracilipes, Odontoponera denticulata, Camponotus sp., respectively. Conversely, the highest amount of invasive ants (Solenopsis sp.) was observed in agroforestry, which negatively impacted on the presence of native species (Odontoponera denticulata). In addition, PCA analysis showed the development of three ant groups on each habitat, hence agroforestry made more real differences in the aspect of species abundance, and none in terms of richness. Therefore, notable differences were observed in the ant communities between both habitats, and agroforestry was indicated as a disturbed area, based on the increment in tramp and invasive ants, alongside low abundance of native and functional groups.

scholarly journals Intrinsic Prey Preference and Selection of the Giant Gartersnake: A Threatened Predator in a Nonnative Prey-Dominated Community

2020 ◽  
Vol 11 (1) ◽  
pp. 164-173
Author(s):  
Julia S.M. Ersan ◽  
Brian J. Halstead ◽  
Erica L. Wildy ◽  
Michael L. Casazza ◽  
Glenn D. Wylie
Keyword(s):  
Exotic Species ◽  
Native Species ◽  
Prey Selection ◽  
Central Valley ◽  
Prey Preference ◽  
Live Prey ◽  
Species Of Conservation Concern ◽  
Conservation Concern ◽  
Behavioral Trials ◽  
Selection Of

Abstract The introduction of exotic species into an environment can introduce great change in the trophic dynamics of native species. This is of even greater concern if the native species is of conservation concern. The giant gartersnake, Thamnophis gigas, an endemic predator of the Central Valley of California and a species of conservation concern at the state and federal levels, has declined as a result of conversion of its once vast wetland habitat to agriculture. Another anthropogenic factor contributing to this snake's changing ecology is the introduction of nonnative prey into the species' habitats. These introductions have resulted in a prey community that is almost completely composed of exotic species and have potential for considerable effects. In order to assess prey preference and selection we performed three sets of behavioral trials on naïve neonates. We examined 1) neonate prey preference in response to olfactory cues of prepared prey extracts, 2) neonate consumption of different live prey items presented simultaneously; and 3) terrestrial feeding behavior and/or latency to successful attack. Results from the olfactory study suggest that native Sierran treefrogs, Pseudacris sierra, are preferred by neonates. Results from consumption trials suggest that neonates are more likely to select frog species than fish species. This is the first study that we are aware of that examines prey selection of this threatened species and serves to inform its conservation and management.

scholarly journals Decline in New Zealand's freshwater fish fauna: Effect of land use

2020 ◽  
Author(s):  
Michael Joy ◽  
KJ Foote ◽  
P McNie ◽  
M Piria
Keyword(s):  
New Zealand ◽  
Land Cover ◽  
Freshwater Fish ◽  
Native Species ◽  
Species Abundance ◽  
Fish Fauna ◽  
Fish Distribution ◽  
Individual Species ◽  
Freshwater Fish Fauna ◽  
Over Time

© 2019 CSIRO. The number of New Zealand's freshwater fish listed as threatened has increased since 1992 when the first New Zealand threat classification system list was compiled. In this study, temporal and land cover-related trends were analysed for data on freshwater fish distribution, comprising more than 20 000 records for the 47 years from January 1970 to January 2017 from the New Zealand Freshwater Fish Database. The analysis included individual species abundance and distribution trends, as well as an index of fish community integrity, namely the Index of Biotic Integrity (IBI). Of the 25 fish species that met the requirements for analysis to determine changes in the proportion of sites they occupied over time, 76% had negative trends (indicating declining occurrence). Of the 20 native species analysed for the proportion of sites occupied over time, 75% had negative trends; 65% of these were significant declines and more species were in decline at pasture sites than natural cover sites. The average IBI score also declined over the time period and, when analysed separately, the major land cover types revealed that the IBI declined at pasture catchment sites but not at sites with natural vegetation catchments.

scholarly journals Preliminary Study of the Influence of Conductivity and Calcium Concentrations on the Density and Species Richness of Native and Invasive Gastropods in Grand Teton National Park, Wyoming

2013 ◽  
Vol 36 ◽  
pp. 46-49
Author(s):  
Michele Larson ◽  
Gary Beauvais
Keyword(s):  
Invasive Species ◽  
Native Species ◽  
Native Community ◽  
Ecological Processes ◽  
Freshwater Gastropods ◽  
Carbon And Nitrogen ◽  
Nitrogen Levels ◽  
Freshwater Habitats ◽  
Primary Producer ◽  
Preliminary Study

Freshwater gastropods are a diverse taxa that inhabit a wide variety of freshwater habitats (Lydeard et al. 2004, Strong et al. 2008). Freshwater gastropods often form narrow endemic ranges (Strong et al. 2008) with many species restricted to a single drainage or an isolated spring (Brown et al. 2008). In North America, over 60% of freshwater snails are listed as imperiled or presumed extinct (Lysne et al. 2008). The main factors for the reduction in snail biodiversity are habitat loss, water pollution, and the introduction of invasive species (Strong et al. 2008). Invasive species can dramatically alter the native community by reducing biodiversity and changing ecological processes (Alonso and Castro-Diez 2008). The effects of invasive species on aquatic ecosystems are often permanent and lead to reductions in biodiversity due to predation and competition with native species (Alonso and Castro-Diez 2008, Lysne et al. 2008, Strayer 1999). Invasive gastropods impact native ecosystems by altering carbon and nitrogen levels (Hall et al. 2003, Arango et al. 2009), consuming large amounts of primary producer biomass (Hall et al. 2003, Riley et al. 2008, Strayer 2010), and changing native macroinvertebrate community composition (Kerans et al. 2005, Riley et al. 2008, Cross et al. 2010, Brenneis et al. 2011).

Effect of indaziflam on native species in natural areas and rangeland

2019 ◽  
Vol 12 (1) ◽  
pp. 60-67 ◽  
Author(s):  
Shannon L. Clark ◽  
Derek J. Sebastian ◽  
Scott J. Nissen ◽  
James R. Sebastian
Keyword(s):  
Species Richness ◽  
Weed Management ◽  
Native Species ◽  
Species Abundance ◽  
Unintended Consequences ◽  
Ecological Impacts ◽  
Limited Information ◽  
Perennial Species ◽  
Temporary Reduction ◽  
Species Richness And Abundance

AbstractMinimizing the negative ecological impacts of exotic plant invasions is one goal of land management. Using selective herbicides is one strategy to achieve this goal; however, the unintended consequences of this strategy are not always fully understood. The recently introduced herbicide indaziflam has a mode of action not previously used in non-crop weed management. Thus, there is limited information about the impacts of this active ingredient when applied alone or in combination with other non-crop herbicides. The objective of this research was to evaluate native species tolerance to indaziflam and imazapic applied alone and with other broadleaf herbicides. Replicated field plots were established at two locations in Colorado with a diverse mix of native forbs and grasses. Species richness and abundance were compared between the nontreated control plots and plots where indaziflam and imazapic were applied alone and in combination with picloram and aminocyclopyrachlor. Species richness and abundance did not decrease when indaziflam or imazapic were applied alone; however, species abundance was reduced by treatments containing picloram and aminocyclopyrachlor. Species richness was only impacted at one site 1 yr after treatment (YAT) by these broadleaf herbicides. Decreases in abundance were mainly due to reductions in forbs that resulted in a corresponding increase in grass cover. Our data suggest that indaziflam will control downy brome (Bromus tectorumL.) for multiple years without reduction in perennial species richness or abundance. IfB. tectorumis present with perennial broadleaf weeds requiring the addition of herbicides like picloram or aminocyclopyrachlor, forb abundance could be reduced, and in some cases there could be a temporary reduction in perennial species richness.

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