scholarly journals Urbanization and species-energy relationships

2018 ◽  
Author(s):  
Lucas M. Leveau
Keyword(s):  
Species Richness ◽  
Primary Productivity ◽  
Positive Relationship ◽  
Environmental Heterogeneity ◽  
Negative Relationship ◽  
Habitat Diversity ◽  
Bird Abundance ◽  
Bird Richness ◽  
Urban Rural ◽  
Energy Relationships

AbstractSpecies-energy relationships (SER) have been used scarcely to predict responses of biodiversity to changes in land use. In this work, two hypothesis of the SER were tested on bird communities along urbanization gradients: the increasing population size (IPS) and the niche position (NP) hypotheses. The IPS hypothesis states that sites with more primary productivity have more individuals, decreasing the probability of extinction and increasing species richness. The HPN predicts that sites with greater primary productivity and environmental heterogeneity allow the availability of a greater variety of resources and the presence of specialist species, thus increasing species richness. The hypothesis of habitat heterogeneity was evaluated by which more complex habitats provide more variety of resources and greater species richness. Birds were counted along three urban-rural gradients in the Pampean region of Argentina during the breeding season. The productive energy was measured from the NDVI and the environmental heterogeneity through the Shannon-Wiener diversity index, calculated with the percentage coverage of different substrates. Bird richness and habitat diversity were higher at intermediate levels of urbanization, while primary productivity had a negative relationship with urbanization. Although there was a positive relationship between bird richness and abundance, there was no positive relationship between bird abundance and primary productivity. Bird richness showed a positive relationship with habitat diversity and primary productivity; although path analysis revealed that the habitat diversity increased bird richness through an increase of bird abundance. The NP hypothesis was the most consistent to predict the bird richness along urban-rural gradients.

scholarly journals More individuals but fewer species: testing the ‘more individuals hypothesis’ in a diverse tropical fauna

2010 ◽  
Vol 6 (4) ◽  
pp. 490-493 ◽  
Author(s):  
Terrence P. McGlynn ◽  
Michael D. Weiser ◽  
Robert R. Dunn
Keyword(s):  
Species Richness ◽  
Primary Productivity ◽  
Large Scale ◽  
Positive Relationship ◽  
Tropical Rainforest ◽  
Net Primary Productivity ◽  
Resource Abundance ◽  
Monotonic Increase ◽  
Ant Diversity ◽  
Unimodal Relationship

A positive relationship between species richness and productivity is often observed in nature, but the causes remain contentious. One mechanism, the ‘more individuals hypothesis’ (MIH), predicts richness increases monotonically with density, as a function of resource flux. To test the MIH, we manipulated resource abundance in a community of tropical rainforest litter ants and measured richness and density responses. A unimodal relationship between richness and density most closely fitted the control and disturbance (resource removal) treatments in contrast to expectations of the MIH. Resource addition resulted in a monotonic increase in richness relative to density, a shift from the pattern in the control. In the disturbance treatment, richness was greater than in the control, opposite to expectations of the MIH. While large-scale correlations between ant diversity and net primary productivity or temperature are reconcilable with the MIH, key elements of the hypothesis are not supported.

scholarly journals Evaluating the correlation between area, environmental heterogeneity, and species richness using terrestrial isopods (Oniscidea) from the Pontine Islands (West Mediterranean)

2021 ◽  
Author(s):  
Gabriele Gentile ◽  
Roberto Argano ◽  
Stefano Taiti
Keyword(s):  
Species Richness ◽  
Environmental Heterogeneity ◽  
Geographic Distance ◽  
Habitat Diversity ◽  
Tyrrhenian Sea ◽  
Island Species ◽  
Random Placement ◽  
Species Area ◽  
Pontine Islands ◽  
Volcanic Islands

AbstractArea and environmental heterogeneity influence species richness in islands. Whether area or environmental heterogeneity is more relevant in determining species richness is a central issue in island biogeography. Several models have been proposed, addressing the issue, and they can be reconducted to three main hypotheses developed to explain the species-area relationship: (1) the area-per se hypothesis (known also as the extinction-colonisation equilibrium), (2) the random placement (passive sampling), and the (3) environmental heterogeneity (habitat diversity). In this paper, considering also the possible influence of geographic distance on island species richness, we explore the correlation between area, environmental heterogeneity, and species richness by using faunistic data of Oniscidea inhabiting the Pontine Islands, a group of five small volcanic islands and several islets in the Tyrrhenian Sea, located about 60 km from the Italian mainland. We found that the colonisation of large Pontine Islands may occur via processes independent of geographic distance which could instead be an important factor at a much smaller scale. Such processes may be driven by a combination of anthropogenic influences and natural events. Even in very small-size island systems, environmental heterogeneity mostly contributes to species richness. Environmental heterogeneity could influence the taxocenosis structure and, ultimately, the number of species of Oniscidea via direct and indirect effects, these last mediated by area which may or may not have a direct effect on species richness.

scholarly journals Calling for a new strategy to measure environmental (habitat) diversity in Island Biogeography: a case study of Mediterranean tenebrionids (Coleoptera: Tenebrionidae)

2015 ◽  
Vol 47 (1) ◽  
pp. 1 ◽  
Author(s):  
Simone Fattorini ◽  
Leonardo Dapporto ◽  
Giovanni Strona ◽  
Paulo A.V. Borges
Keyword(s):  
Species Richness ◽  
Land Cover ◽  
Island Biogeography ◽  
Environmental Heterogeneity ◽  
Habitat Diversity ◽  
Central Mediterranean ◽  
Environmental Diversity ◽  
New Strategy ◽  
Per Se

Many recent researches in island biogeography attempted to disentangle the effects of area <em>per se</em> and “habitat diversity” on species richness. However, the expression “habitat diversity” in this context should be avoided, because habitats can be only recognized by referring to the resources needed by a particular species. What is really measured in such researches is some form of “environmental heterogeneity”. Although habitat heterogeneity can be measured in various ways, most researches in island biogeography simply used the number of biotopes (typically classified as land cover categories). However, not all biotopes have the same surface. On the basis of the area occupied by each land cover category, it is possible to calculate indices of environmental diversity, evenness and dominance, as commonly done in community ecology research. These indices can be used to investigate the role of environmental diversity in determining species richness. We used the tenebrionid beetles inhabiting twenty-five small islands around Sicily (Central Mediterranean) to illustrate these concepts. We found that both area per se and environmental heterogeneity contributed to determine species richness. Moreover, we found that the relationship between species richness and environmental homogeneity followed a power function model. This indicates that environmental homogenization may determine a rapid, non linear decline in species richness.

scholarly journals Plant Diversity Along the Urban–Rural Gradient and Its Relationship with Urbanization Degree in Shanghai, China

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 171 ◽  
Author(s):  
Meng Wang ◽  
Junxiang Li ◽  
Shengjian Kuang ◽  
Yujuan He ◽  
Guojian Chen ◽  
...  
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Plant Diversity ◽  
Urban Areas ◽  
Vascular Plant ◽  
Regional Scale ◽  
Negative Relationship ◽  
Native Plant ◽  
Urban Rural ◽  
The Relationship

Urbanization is one of the major causes for plant diversity loss at the local and regional scale. However, how plant species distribute along the urban–rural gradient and what the relationship between urbanization degree and plant diversity is, is not very clear. In this paper, 134 sample sites along two 18 km width transects that run across the urban center of Shanghai were investigated. We quantified the spatial patterns of plant diversity along the urban–rural gradient and measured the relationship between plant diversity and urbanization degree, which was calculated using a land use land cover map derived from high spatial resolution aerial photos. We recorded 526 vascular plant species in 134 plots, 57.8% of which are exotic plant species. Six spatial distribution patterns of species richness were identified for different plant taxa along the rural to urban gradient. The native plant species richness showed no significant relationship to urbanization degree. The richness of the all plants, woody plants and perennial herbs presented significant positive relationship with urbanization degree, while the richness of annual herbs, Shannon-Wiener diversity and Heip evenness all exhibited a negative relationship to urbanization degree. Urbanization could significantly influence plant diversity in Shanghai. Our findings can provide insights to understand the mechanism of urbanization effects on plant diversity, as well as plant diversity conservation in urban areas.

scholarly journals Community Structure of Road Associated Avifauna along theUrban Gradient in Mintal, Davao City, Southern Philippines

2020 ◽  
Vol 11 (3) ◽  
pp. 771-780
Author(s):  
Christian Yancy A. Yurong ◽  
Aileen Grace D. Delima ◽  
Leo Manuel B. Estaña ◽  
Lief Erikson D. Gamalo ◽  
Marion John Michael M. Achondo
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
Positive Relationship ◽  
Negative Relationship ◽  
Urban Landscapes ◽  
Avian Diversity ◽  
Avian Community ◽  
Urbanization Gradient ◽  
Disturbed Areas ◽  
Traffic Rate

The community structure of avifauna along the urbanization gradient in Mintal, Davao Citywas surveyed and analyzed. A total of 4,210 individuals from 34 species belonging to 23 fam-ilies were recorded. Seven species are Philippine endemics and five are introduced species.Correlation and regression analysis showed a positive relationship between increasing vegeta-tion cover with species richness and a negative relationship with abundance. Oppositely, in-creasing urbanization (increase built-up cover, pedestrian and traffic rate) were observed tohave positive relationship to abundance but negative relationship to species richness. Thus, the avian community in the urbanization gradient of Mintal, Davao City follows the general ac-cepted trend that in heavily disturbed areas, species richness is at its lowest while total birdabundance is at its peak. This study also suggests the importance of green spaces with lessertraffic rate in urban landscapes that could support higher avian diversity which includes Philip-pine endemic species.

scholarly journals ¿Qué factores determinan la distribución altitudinal de los peces de ríos tropicales andinos?

2016 ◽  
Vol 64 (1) ◽  
pp. 157 ◽  
Author(s):  
Evans De La Barra ◽  
José Zubieta ◽  
Gastón Aguilera ◽  
Mabel Maldonado ◽  
Marc Pouilly ◽  
...  
Keyword(s):  
Species Richness ◽  
Fish Species ◽  
Altitudinal Gradient ◽  
Species Turnover ◽  
Negative Relationship ◽  
Habitat Diversity ◽  
Limiting Factor ◽  
Energy Availability ◽  
Ecological Processes ◽  
Maximum Slope

Altitudinal gradients represent an appropriate system to assess whether there is a relationship between richness patterns, environmental variables, and the ecological processes that determine the species type and number inhabiting a given area. In mountain streams freshwater fishes, the most prevalent relationship is a monotonic decrease in species richness with elevation. The objective of this study was to evaluate four hypotheses that can explain the negative relationship between local fish species richness and altitude, 1) the hypothesis of decreasing energy availability, 2) the hypothesis of increasing climate severity, 3) the hypothesis of habitat diversity, and 4) the hypothesis of isolation by physical severity of the environment. Fish and macro-invertebrates were collected following standard methods from 83 sites (between 200-4 000 meters) of two river basins in the Bolivian Amazon. The first hypothesis was tested by analyzing relationships between the density of macro-invertebrates, the richness of invertivorous fish species and altitude; while the second and third hypotheses were assessed by a multiple regression analysis (GLM) between fish species richness and several local and regional factors. Besides, assemblage dissimilarity between sites along the altitudinal gradient was analyzed using βsim and βness indices. Fish richness decreases linearly with increasing altitude. The density of macro-invertebrates tends to increase at higher altitudes, contrary to invertivorous fish species richness, suggesting that energy availability is not a limiting factor for fish species colonization. The GLM explained 86 % of the variation in fish species richness, with a significant contribution of water temperature, maximum slope in the river mainstem, and stream width. There is a higher species turnover (βsim) between sites at low elevation. Inversely, βness shows higher values in the upper parts, corresponding to change in assemblages mainly due to species loss. Taken together, these results suggest that climatic and physical severities create strong barriers to colonization, further explaining the decrease in fish richness along the altitudinal gradient.

scholarly journals The function-dominance correlation drives the direction and strength of biodiversity-ecosystem functioning relationships

2021 ◽  
Author(s):  
Michael Crawford ◽  
Kathryn Barry ◽  
Adam Clark ◽  
Caroline Farrior ◽  
Jessica Hines ◽  
...  
Keyword(s):  
Species Richness ◽  
Community Composition ◽  
Ecosystem Functioning ◽  
Positive Relationship ◽  
Negative Relationship ◽  
Positive Function ◽  
Primary Determinant ◽  
Local Species ◽  
Biodiversity Change ◽  
The Relationship

Community composition is a primary determinant of how biodiversity change influences ecosystem functioning and, therefore, the relationship between biodiversity and ecosystem functioning (BEF). We examine the consequences of community composition across six structurally realistic plant community models. We find that a positive correlation between species’ functioning in monoculture vs. their dominance in mixture with regards to a specific function (the “function-dominance correlation”) generates a positive relationship between realized diversity and ecosystem functioning across species richness treatments. However, because realised diversity declines when few species dominate, a positive function-dominance correlation generates a negative relationship between realized diversity and ecosystem functioning within species richness treatments. Removing seed inflow strengthens the link between the function-dominance correlation and BEF relationships across species richness treatments but weakens it within them. These results suggest that changes in species’ identities in a local species pool may more strongly affect ecosystem functioning than changes in species richness.

Organization-Based Self-Esteem Affects Employees' Exchange Relationship Perceptions and Extrarole Behavior

2016 ◽  
Vol 44 (3) ◽  
pp. 509-517 ◽  
Author(s):  
Yanhan Zhu
Keyword(s):  
Social Exchange ◽  
Positive Relationship ◽  
Mainland China ◽  
Negative Relationship ◽  
Self Esteem ◽  
Moderating Effect ◽  
Exchange Relationship ◽  
Significant Positive Relationship ◽  
Significant Negative Relationship ◽  
Practical Implications

The 2 types of exchange relationship perceptions—social exchange relationship perceptions (SERPs) and economic exchange relationship perceptions (EERPs)—constitute the primary concept for understanding individual behavior in the workplace. Using a sample of 581 employees from Mainland China, I explored the effects of SERPs and EERPs on employee extrarole behavior (ERB), as well as the moderating effect of organization-based self-esteem (OBSE) on the relationships between SERPs and ERB, and between EERPs and ERB. The results revealed a significant positive relationship between SERPs and ERB, a significant negative relationship between EERPs and ERB, and a significant moderating effect for OBSE. Theoretical and practical implications of these findings are discussed.

Community characteristics of forest understory birds along an elevational gradient in the Horn of Africa: A multi-year baseline

The Condor ◽  
2021 ◽  
Author(s):  
Kyle D Kittelberger ◽  
Montague H C Neate-Clegg ◽  
Evan R Buechley ◽  
Çağan Hakkı Şekercioğlu
Keyword(s):  
Species Richness ◽  
Species Turnover ◽  
Survival Rates ◽  
Elevational Gradient ◽  
Forest Understory ◽  
Bird Abundance ◽  
Tropical Mountains ◽  
Demographic Rates ◽  
Understory Birds ◽  
Over Time

Abstract Tropical mountains are global hotspots for birdlife. However, there is a dearth of baseline avifaunal data along elevational gradients, particularly in Africa, limiting our ability to observe and assess changes over time in tropical montane avian communities. In this study, we undertook a multi-year assessment of understory birds along a 1,750 m elevational gradient (1,430–3,186 m) in an Afrotropical moist evergreen montane forest within Ethiopia’s Bale Mountains. Analyzing 6 years of systematic bird-banding data from 5 sites, we describe the patterns of species richness, abundance, community composition, and demographic rates over space and time. We found bimodal patterns in observed and estimated species richness across the elevational gradient (peaking at 1,430 and 2,388 m), although no sites reached asymptotic species richness throughout the study. Species turnover was high across the gradient, though forested sites at mid-elevations resembled each other in species composition. We found significant variation across sites in bird abundance in some of the dietary and habitat guilds. However, we did not find any significant trends in species richness or guild abundances over time. For the majority of analyzed species, capture rates did not change over time and there were no changes in species’ mean elevations. Population growth rates, recruitment rates, and apparent survival rates averaged 1.02, 0.52, and 0.51 respectively, and there were no elevational patterns in demographic rates. This study establishes a multi-year baseline for Afrotropical birds along an elevational gradient in an under-studied international biodiversity hotspot. These data will be critical in assessing the long-term responses of tropical montane birdlife to climate change and habitat degradation.

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