scholarly journals Responses of community structure and diversity to nitrogen deposition and rainfall addition in contrasting steppes are ecosystem-dependent and dwarfed by year-to-year community dynamics

2019 ◽  
Vol 124 (3) ◽  
pp. 461-469 ◽  
Author(s):  
Xuejun Yang ◽  
Zhenying Huang ◽  
Ming Dong ◽  
Xuehua Ye ◽  
Guofang Liu ◽  
...  
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
Global Change ◽  
Nitrogen Deposition ◽  
Community Composition ◽  
Community Dynamics ◽  
Environmental Variability ◽  
The Other ◽  
Desert Steppe ◽  
Typical Steppe

Abstract Background and Aims Long-term studies to disentangle the multiple, simultaneous effects of global change on community dynamics are a high research priority to forecast future distribution of diversity. Seldom are such multiple effects of global change studied across different ecosystems. Methods Here we manipulated nitrogen deposition and rainfall at levels realistic for future environmental scenarios in three contrasting steppe types in Mongolia and followed community dynamics for 7 years. Key Results Redundancy analyses showed that community composition varied significantly among years. Rainfall and nitrogen manipulations did have some significant effects, but these effects were dependent on the type of response and varied between ecosystems. Community compositions of desert and meadow steppes, but not that of typical steppe, responded significantly to rainfall addition. Only community composition of meadow steppe responded significantly to nitrogen deposition. Species richness in desert steppe responded significantly to rainfall addition, but the other two steppes did not. Typical steppe showed significant negative response of species richness to nitrogen deposition, but the other two steppes did not. There were significant interactions between year and nitrogen deposition in desert steppe and between year and rainfall addition in typical steppe, suggesting that the effect of the treatments depends on the particular year considered. Conclusions Our multi-year experiment thus suggests that responses of community structure and diversity to global change drivers are ecosystem-dependent and that their responses to experimental treatments are dwarfed by the year-to-year community dynamics. Therefore, our results point to the importance of taking annual environmental variability into account for understanding and predicting the specific responses of different ecosystems to multiple global change drivers.

Community Ecology of Stream Fishes: Concepts, Approaches, and Techniques

2010 ◽  
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
Community Ecology ◽  
Community Dynamics ◽  
Spatial Scales ◽  
River Mouth ◽  
Extrinsic Factors ◽  
Local Species Richness ◽  
Community Convergence ◽  
Local Filters

<em>Abstract</em>.—Community ecology increasingly seeks to integrate the influences of regional and historical processes with species interactions within local habitats. This broadened perspective is largely based on comparative approaches that employ “natural experiments” to identify factors shaping community structure. Because coastal rivers are separated from one another by insurmountable barriers (oceans or land), freshwater fishes are particularly well suited for comparative analyses of factors that influence fish community organization. In this chapter, we review how this comparative approach shed light on large-scale biodiversity gradients, community saturation, community convergence, density compensation, and the role of intrinsic and extrinsic factors in community dynamics. The main factors (e.g., river mouth discharge and history) empirically related to species richness of a river are well identified, and metacommunity ecology provides a fruitful conceptual framework for understanding how regional (river) species richness translates into local species richness. Much work remains to identify factors explaining differences among whole river basin assemblages with regard to ecological traits (e.g., trophic status and life history) composition and to assess whether trait-related environmental and biotic local filters act similarly over large spatial scales. One important conclusion that can be drawn from the studies reviewed here is that history cannot be neglected whatever the scale of investigation (global, river, or site). A second conclusion is that historical effects are not strong enough to blur the occurrence of qualitatively repeatable patterns of community structure over large spatial scale, which is encouraging because it suggests development of general predictive models of community structure is an attainable goal.

Effects of Grazer Community Composition and Fish on Algal Dynamics

1992 ◽  
Vol 49 (9) ◽  
pp. 1908-1915 ◽  
Author(s):  
Andrew M. Turner ◽  
Gary G. Mittelbach
Keyword(s):  
Community Structure ◽  
Factorial Design ◽  
Chlorophyll A ◽  
Community Composition ◽  
Standing Crop ◽  
Zooplankton Community ◽  
The Other ◽  
Light Extinction ◽  
Phytoplankton Abundance ◽  
Zooplankton Community Structure

We examined the effects of grazer community composition and fish on phytoplankton abundance by manipulating zooplankton community structure and the intensity of planktivory in a factorial experiment. Enclosures (1700-L bags) were treated with fish (present/absent) and two grazer communities (one a large-bodied community dominated by Daphnia and the other a small-bodied community dominated by Ceriodaphnia) in a 2 × 2 factorial design. We sampled zooplankton and algae every 4–8 d during the 5-wk experiment. Algal biovolume, chlorophyll a, total particulates, and light extinction were all significantly higher in the presence of fish. Further, the effect of fish on algal standing crop did not depend on which grazer assemblage was initially present. Fish enhanced algal standing crop to the same degree in both Daphnia and Ceriodaphnia treatments. We discuss these results in light of patterns reported in the literature, and the nature of size-structured interactions among fish, zooplankton, and algae.

scholarly journals Community composition and species richness of parasitoids infesting Yponomeuta species in the Netherlands

2004 ◽  
Vol 73 (4) ◽  
pp. 255-261 ◽  
Author(s):  
Daniel F.R. Cleary
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
The Netherlands ◽  
Community Composition ◽  
Host Species ◽  
Community Similarity ◽  
Parasitoid Species ◽  
Temporal And Spatial Variation ◽  
Significant Difference ◽  
Temporal And Spatial

Parasitoid assemblages infesting Yponomeuta species in the Netherlands were investigated. Parasitoid species richness and community composition were related to host species, habitat, temporal and spatial variation. Both community structure and species richness did not differ among habitats. There was no significant difference in species richness between years (1994 and 1995) but there was a significant difference in community composition. Community composition and species richness both differed among host species, although this latter result was solely due to the host species Y. evonymellus. There was no significant relationship between community similarity and distance. These results indicate that the parasitoids of the moth genus Yponomeuta in the Netherlands appear to form a spatially stable, but temporally variable community. Most of the variation in community structure was, however, related to the host species. The marked difference in parasitoid species richness and community composition of Y. evonymellus when compared to the other species warrants further study.

scholarly journals Changes in community composition determine recovery trajectories from multiple agricultural stressors in freshwater ecosystems

2020 ◽  
Author(s):  
Francesco Polazzo ◽  
Talles Bruno Oliveira dos Anjos ◽  
Alba Arenas-Sánchez ◽  
Susana Romo ◽  
Marco Vighi ◽  
...  
Keyword(s):  
Species Richness ◽  
Community Composition ◽  
Community Dynamics ◽  
Pesticide Exposure ◽  
Population Level ◽  
Experimental Period ◽  
Freshwater Ecosystems ◽  
Nutrient Loads ◽  
Protection Measures ◽  
Pesticide Mixtures

AbstractPesticides have been identified worldwide as a threat for aquatic biodiversity due to their widespread use in agriculture and their capacity to reach freshwater ecosystems. Very little is known about the consequences of pesticide mixtures targeting different organism groups on community dynamics. Especially, how horizontal changes within one trophic level are propagated vertically across the food web has been rarely investigated. To get insight on the effects of pesticide mixtures on community dynamics, we performed a mesocosm experiment manipulating three common agricultural stressors: chlorpyrifos (an insecticide), diuron (an herbicide) and nutrients. The results of this study show that all stressors had significant effects on community composition, species richness and abundance. However, recovery trajectories and ecosystem functioning effects largely depended on the type of stressor as well as on post-disturbance trophic and non-trophic interactions. Effects of pesticides were generally recovered by the end of the experimental period when considering abundance, whereas community composition further departed from control systems. High nutrient loads led to a shift in community composition characterized by high taxa dominance and lower species richness, which in turn contributed to increased total organism abundance and reduced recovery times to pesticide exposure. We found interactions between the tested stressors to be significant only few times at the community level, while interactions were more common at the population level. Our findings indicate that management of freshwater ecosystems should consider pre-disturbance community composition and long-term changes in interactions across different organism groups to set effective protection measures.

scholarly journals Variation in the helminth community structure in bank voles (Clethrionomys glareolus) from three comparable localities in the Mazury Lake District region of Poland

Parasitology ◽  
2001 ◽  
Vol 123 (4) ◽  
pp. 401-414 ◽  
Author(s):  
J. M. BEHNKE ◽  
C. J. BARNARD ◽  
A. BAJER ◽  
D. BRAY ◽  
J. DINMORE ◽  
...  
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
Habitat Quality ◽  
The Other ◽  
Clethrionomys Glareolus ◽  
Helminth Parasite ◽  
Component Community ◽  
Parasite Communities ◽  
Host Sex ◽  
Index Of Diversity

We tested the null hypothesis that populations of hosts trapped in isolated neighbouring locations showing comparable habitat quality, should support similar helminth parasite communities. The study was undertaken in a 2-week period in late summer in NE Poland in a single year, thereby eliminating seasonal and between-year variation in parasite burdens. A total of 139 Clethrionomys glareolus (bank vole) were sampled from 3 forest sites of similar habitat quality. Total species richness was 11 (6 nematodes and 5 cestodes) with 85·6% of the voles carrying at least 1 species and an overall mean species richness of 1·4. At the component community level, the fewest species of helminths were recorded from site 2 (n = 6, compared with 9 at each of the other sites), but site 3 had the lowest Berger-Parker Dominance Index and the highest Simpson's Index of Diversity. At the infracommunity level, site 3 had the highest mean no. of helminth species/vole, the highest mean Brillouin's Index of Diversity but the lowest mean no. of helminths/vole. Voles from sites 1 and 3 differed in the nematodes that were most common (site 1, Heligmosomum mixtum – 95%; site 3, Heligmosomoides glareoli – 79·3%). At site 2 no species exceeded 50% but prevalence of Syphacia petrusewiczi was higher than at the other sites. The prevalence of cestodes was too low to test reliably (12·9%), but the highest prevalence of adult cestodes was recorded at site 1 (22·5% compared with 4·9 and 1·7% for sites 2 and 3 respectively). Host sex did not influence infection, but mean species richness increased with age. The different sites were responsible for most of the variation in our data, and the intrinsic factors (sex and age) were less important in shaping the component community structure of helminths. We conclude that even locations in relative close proximity to one another (13–25 km), selected on the basis of similar habitat quality, have rodent populations that differ in their helminth parasite communities, although for reasons other than the factors quantified in the present study.

scholarly journals Bacterial Community Structure of Acid-Impacted Lakes: What Controls Diversity?

2008 ◽  
Vol 74 (6) ◽  
pp. 1856-1868 ◽  
Author(s):  
Sascha F. Percent ◽  
Marc E. Frischer ◽  
Paul A. Vescio ◽  
Ellen B. Duffy ◽  
Vincenzo Milano ◽  
...  
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
Community Composition ◽  
The United States ◽  
Trophic Levels ◽  
Community Diversity ◽  
Rrna Gene ◽  
Clone Libraries ◽  
Bacterioplankton Community ◽  
Bacterioplankton Communities

ABSTRACT Although it is recognized that acidification of freshwater systems results in decreased overall species richness of plants and animals, little is known about the response of aquatic microbial communities to acidification. In this study we examined bacterioplankton community diversity and structure in 18 lakes located in the Adirondack Park (in the state of New York in the United States) that were affected to various degrees by acidic deposition and assessed correlations with 31 physical and chemical parameters. The pH of these lakes ranged from 4.9 to 7.8. These studies were conducted as a component of the Adirondack Effects Assessment Program supported by the U.S. Environmental Protection Agency. Thirty-one independent 16S rRNA gene libraries consisting of 2,135 clones were constructed from epilimnion and hypolimnion water samples. Bacterioplankton community composition was determined by sequencing and amplified ribosomal DNA restriction analysis of the clone libraries. Nineteen bacterial classes representing 95 subclasses were observed, but clone libraries were dominated by representatives of the Actinobacteria and Betaproteobacteria classes. Although the diversity and richness of bacterioplankton communities were positively correlated with pH, the overall community composition assessed by principal component analysis was not. The strongest correlations were observed between bacterioplankton communities and lake depth, hydraulic retention time, dissolved inorganic carbon, and nonlabile monomeric aluminum concentrations. While there was not an overall correlation between bacterioplankton community structure and pH, several bacterial classes, including the Alphaproteobacteria, were directly correlated with acidity. These results indicate that unlike more identifiable correlations between acidity and species richness for higher trophic levels, controls on bacterioplankton community structure are likely more complex, involving both direct and indirect processes.

Zooplankton Communities and Water Chemistry of Sudbury Area Lakes: Changes Related to pH Recovery

1994 ◽  
Vol 51 (1) ◽  
pp. 151-160 ◽  
Author(s):  
Andrea Locke ◽  
W. Gary Sprules ◽  
W. Keller ◽  
J. Roger Pitblado
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
Community Composition ◽  
Temporal Trends ◽  
Community Change ◽  
Crustacean Zooplankton ◽  
Chemical Recovery ◽  
Acidic Ph ◽  
Zooplankton Community Structure ◽  
Acid Lakes

Temporal trends in pH, alkalinity, and crustacean zooplankton species richness and community composition were studied in 80 Sudbury area lakes sampled in 1971–76, 1981, and 1988–90. Alkalinity and pH have increased in recent years, but many of the study lakes remain quite acidic (modal pH 4.5–4.9). Species richness has also increased, on average, by 1.9 species/lake but is still low in many acid lakes relative to that in circumneutral lakes. Community composition differed among lakes of pH <5.0, 5.0–5.9, and ≥6.0, with some overlap between these groups because zooplankton recovery has lagged behind chemical recovery. Trajectories of community change in recovering acid lakes varied substantially in the early stages of recovery from highly acidic (pH <5.0) to moderately acidic pH (5.0–5.9). In contrast, trajectories in lakes recovered to pH ≥6.0 converged toward the community structure more typical of circumneutral lakes in the 1970's. This suggests that given sufficient time, zooplankton community structure of recovering lakes may approach that of circumneutral lakes.

Short-term logging and burning impacts on species richness, abundance and community structure of birds in open eucalypt forest in Western Australia

2003 ◽  
Vol 30 (4) ◽  
pp. 321 ◽  
Author(s):  
Ian Abbott ◽  
Amanda Mellican ◽  
Michael D. Craig ◽  
Matthew Williams ◽  
Graeme Liddelow ◽  
...  
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
Western Australia ◽  
Bird Species ◽  
The Other ◽  
Short Term ◽  
Eucalyptus Marginata ◽  
External Reference ◽  
One Year ◽  
The Impact

In 1985 new silvicultural prescriptions for managing jarrah (Eucalyptus marginata) forest in south-west Western Australia came into operation. The most extreme logging treatment (gap release) involved removal of most of the overstorey from patches no larger than 10 ha, followed by a regeneration fire. In the other logging treatment (shelterwood), less wood was removed from a larger area, also followed by a fire. This study examined the impact of these disturbances on the avifauna by monitoring species richness and abundance of birds one year before logging, one year before burning, and for five years after burning. Although 68 bird species were recorded during the seven years of the study, 29 of these were detected fewer than 15 times. Of the other 39 bird species recorded, only two (Gerygone fusca and Acanthiza apicalis) showed a statistically significant treatment effect over time on their abundance. The abundance of G. fusca initially declined in the disturbed treatments and by Year 7 of the study (5 years post-fire) in the gap-release treatment had not recovered its original abundance. A. apicalis increased its abundance in both shelterwood and gap-release treatments. By Year 7, both species in the logged treatments had abundances similar to those in the unlogged treatments. Total abundance of all species varied little across treatments. Species richness was highest by Year 7 in the shelterwood and lowest in the gap-release treatment. In some years community structure varied more at the external-reference sites (not recently logged or burnt) than at the gap-release sites. In particular, there was little overlap in community structure in the external-reference treatment between the first and final years, whereas the pre-logging and final year in the gap-release treatment showed a high degree of overlap. These differences are suggestive of overriding short-term annual variation in broad-scale factors rather than local factors. Yearly variation in rainfall and temperature was documented; during low rainfall periods, populations of foliage arthropods may have been reduced.

scholarly journals Insect pollinator's community structure in different habitats of Shivapuri--Nagarjun National Park, Nepal

2021 ◽  
Author(s):  
Urmila Dyola ◽  
Chitra Baniya ◽  
Pushpa Acharya ◽  
Pradip Subedi ◽  
Anjeela Pandey ◽  
...  
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
Community Composition ◽  
Environmental Variables ◽  
National Park ◽  
Strong Positive Correlation ◽  
Pollinator Species ◽  
Lower Elevation ◽  
Insect Pollinators ◽  
Important Means

Insect pollinators are important means for a stable ecosystem. The habitat types play a crucial role in the community composition, abundance, diversity, and species richness of the pollinators. The present study in Shivapuri–Nagarjun National Park explored the species richness and abundances of insect pollinators in four different habitats and different environmental variables in determining the community composition of the pollinators. Data were collected from 1500 m–2700 m using pan traps and hand sweeping methods. Non–metric multidimensional scaling (NMDS) and redundancy analysis (RDA) were conducted to show the association between insect pollinators and environmental variables. The results firmly demonstrated that species richness and abundances were higher in open trails compared to other habitats. The distribution of the pollinator species was more uniform in the open trail followed by the grassland. Similarly, a strong positive correlation between flower resources and pollinator’s abundance was found. In conclusion, the open trail harbor rich insect pollinators in lower elevation. The community structure of the pollinators was strongly influenced by the presence of flowers in the trails.

scholarly journals Global change effects on plant communities are magnified by time and the number of global change factors imposed

2019 ◽  
Vol 116 (36) ◽  
pp. 17867-17873 ◽  
Author(s):  
Kimberly J. Komatsu ◽  
Meghan L. Avolio ◽  
Nathan P. Lemoine ◽  
Forest Isbell ◽  
Emily Grman ◽  
...  
Keyword(s):  
Community Structure ◽  
Global Change ◽  
Community Composition ◽  
Plant Community ◽  
Plant Communities ◽  
Human Activities ◽  
Global Changes ◽  
Herbaceous Plant ◽  
Community Responses ◽  
Similar Frequency

Global change drivers (GCDs) are expected to alter community structure and consequently, the services that ecosystems provide. Yet, few experimental investigations have examined effects of GCDs on plant community structure across multiple ecosystem types, and those that do exist present conflicting patterns. In an unprecedented global synthesis of over 100 experiments that manipulated factors linked to GCDs, we show that herbaceous plant community responses depend on experimental manipulation length and number of factors manipulated. We found that plant communities are fairly resistant to experimentally manipulated GCDs in the short term (<10 y). In contrast, long-term (≥10 y) experiments show increasing community divergence of treatments from control conditions. Surprisingly, these community responses occurred with similar frequency across the GCD types manipulated in our database. However, community responses were more common when 3 or more GCDs were simultaneously manipulated, suggesting the emergence of additive or synergistic effects of multiple drivers, particularly over long time periods. In half of the cases, GCD manipulations caused a difference in community composition without a corresponding species richness difference, indicating that species reordering or replacement is an important mechanism of community responses to GCDs and should be given greater consideration when examining consequences of GCDs for the biodiversity–ecosystem function relationship. Human activities are currently driving unparalleled global changes worldwide. Our analyses provide the most comprehensive evidence to date that these human activities may have widespread impacts on plant community composition globally, which will increase in frequency over time and be greater in areas where communities face multiple GCDs simultaneously.

Sign in / Sign up

Export Citation Format

Share Document