Richness and Composition of Oasis Bird Communities: Spatial Issues and Species–Area Relationships

Abstract We used data on breeding bird communities of the oases of southern Tunisia to investigate variation in species richness and composition among local communities in relation to spatial configuration of the oasis system and to assess significance of the relationship between oasis size and local richness. Oases could be grouped into three regional systems, namely littoral, saharan, and mountainous oases. We found that at the scale of the entire oasis system, species richness and species composition exhibited significant spatial autocorrelation. That result was consistent with our prediction that the particular spatial organization of oases may have led to regional differences in availability of potential colonizers and that higher species exchange within oasis zones than among oasis zones may have played an important role in shaping local communities. With regard to the species–area relationship, we thus found that a model accounting for spatial covariance was more parsimonious than a standard regression model not incorporating information on the spatial location of oases. Overall, oasis size was a good predictor of species richness, but results were sensitive to spatial scale at which the relationship was examined. Aside from oceanic islands and forest patches, oases may constitute interesting systems to study how regional processes affect local diversity.

Download Full-text

The influence of forest-forming tree species on diversity and spatial distribution of algae in forest litter

Folia Oecologica ◽

10.2478/foecol-2018-0008 ◽

2018 ◽

Vol 45 (2) ◽

pp. 72-81 ◽

Cited By ~ 2

Author(s):

Yevhen Maltsev ◽

Irina Maltseva

Keyword(s):

Species Richness ◽

Leaf Litter ◽

Green Algae ◽

Tree Species ◽

Spatial Organization ◽

Forest Litter ◽

Equal Distribution ◽

Blue Green Algae ◽

Different Types ◽

The Relationship

Abstract The forest litter plays a significant role in forest ecosystems. The composition of the litter biota comprises micro- and mesofauna, and a great diversity of microorganisms, including unrecognized algae (eukaryotic representatives and Cyanoprokaryota). The aim of this work was to study the diversity of algae in the different types of forest litters and to clarify the relationship between the algae composition and the forest-forming tree species. Our results show that the pine forest litter is the most appropriate habitat for the development of green and yellow-green algae and that this litter type limits the variety of blue-green ones. The admixture of deciduous leaf litter to pine litter caused an increase in the species richness of blue-green algae and diatoms. The algae were unevenly distributed across the sub-horizons of pine litter. The highest species richness of algae was identified in the enzymatic sub-horizon of litter. The peculiarity of the composition of leaf litter algae was a significant variety of green, yellow-green and blue-green algae. The spatial organization of algae communities in the leaf litter was characterized by equal distribution of algae species in the litter-subhorizons.

Download Full-text

Organizing Locally, Competing Globally: The Kibbutz Factory as Home and Work

Environment and Planning A Economy and Space ◽

10.1068/a290063 ◽

1997 ◽

Vol 29 (1) ◽

pp. 63-75

Author(s):

A Lichtenstein

Keyword(s):

Economic Development ◽

Spatial Structure ◽

Spatial Organization ◽

Spatial Configuration ◽

Local Communities ◽

Social Structures ◽

Positive Role ◽

The Social ◽

Organization Of Production

In this paper I examine one aspect of the organization of industrial production in the kibbutz that could advance our understanding of equitable economic development in local communities: the spatial unification of home and work within the kibbutz. This feature highlights the positive role of the spatial organization of production in preserving the social structure of the kibbutz. Specifically, the distinct spatial structure of the kibbutz facilitates the articulation of the kibbutz's ideological values and thereby provides an appropriate framework to contain the advancement both of the social and of the technical divisions of labor. I contend that the social and economic attributes of the kibbutz are embedded in a spatial configuration that unites work and home. The factory is part of the kibbutz home. In other words, there is both a spatial and a social unification of home and work. An understanding of the performance of kibbutz industry, and its commitment to the community, cannot be appreciated without recognizing the contributions both of the spatial and of the social structures.

Download Full-text

Patterns of biological diversity

Community Ecology ◽

10.1093/oso/9780198835851.003.0002 ◽

2019 ◽

pp. 11-37

Author(s):

Gary G. Mittelbach ◽

Brian J. McGill

Keyword(s):

Species Richness ◽

Species Interactions ◽

Biological Diversity ◽

Spatial Scales ◽

Species Numbers ◽

Diversity Gradient ◽

Species Abundances ◽

Species Area ◽

Species Area Relationship ◽

The Relationship

This chapter examines how biodiversity, the variety of life, is distributed across the globe and within local communities. It begins by considering some of the challenges associated with assessing biological diversity at different spatial scales. Then, three of the best-studied patterns in species richness are examined in detail—the species–area relationship, the distribution of species abundances, and the relationship between productivity and species richness. The chapter concludes with a detailed exploration of the most dramatic of Earth’s biodiversity patterns—the latitudinal diversity gradient. The above patterns constitute much of what community ecology seeks to explain about nature. Their study provides a foundation from which to explore mechanisms of species interactions, and to understand the processes that drive variation in species numbers and their distribution.

Download Full-text

The spatial configuration of biotic interactions shapes coexistence-area relationships in an annual plant community

Nature Communications ◽

10.1038/s41467-021-26487-2 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

David García-Callejas ◽

Ignasi Bartomeus ◽

Oscar Godoy

Keyword(s):

Species Richness ◽

Spatial Heterogeneity ◽

Species Interactions ◽

Spatial Configuration ◽

Spatial Scales ◽

Single Species ◽

Small Population ◽

Collective Effects ◽

Species Dominance ◽

Species Area

AbstractThe increase of species richness with area is a universal phenomenon on Earth. However, this observation contrasts with our poor understanding of how these species-area relationships (SARs) emerge from the collective effects of area, spatial heterogeneity, and local interactions. By combining a structuralist approach with five years of empirical observations in a highly-diverse Mediterranean grassland, we show that spatial heterogeneity plays a little role in the accumulation of species richness with area in our system. Instead, as we increase the sampled area more species combinations are realized, and they coexist mainly due to direct pairwise interactions rather than by changes in single-species dominance or by indirect interactions. We also identify a small set of transient species with small population sizes that are consistently found across spatial scales. These findings empirically support the importance of the architecture of species interactions together with stochastic events for driving coexistence- and species-area relationships.

Download Full-text

Functional evenness of bird communities varies along the elevational gradient in Europe: Conservation implications

10.32942/osf.io/sx9n8 ◽

2019 ◽

Author(s):

Federico Morelli ◽

Yanina

Keyword(s):

Species Richness ◽

Elevation Gradient ◽

Bird Species ◽

Elevational Gradient ◽

Negative Association ◽

Bird Communities ◽

Breeding Bird ◽

Bird Species Richness ◽

Large Spatial Scale ◽

Functional Evenness

ContextThe negative association between elevation and species richness is a well-recognized pattern in macro-ecology. ObjectivesThe aim of this study was to investigate changes in functional evenness of breeding bird communities along an elevation gradient in Europe. MethodsUsing the bird data from the EBCC Atlas of European Breeding Birds we estimated an index of functional evenness which can be assumed as a measure of the potential resilience of communities.ResultsOur findings confirm the existence of a negative association between elevation and bird species richness in all European eco regions. However, we also explored a novel aspect of this relationship, important for conservation: Our findings provide evidence at large spatial scale of a negative association between the functional evenness (potential community resilience) and elevation, independent of the eco region. We also found that the Natura2000 protected areas covers the territory most in need of protection, those characterized by bird communities with low potential resilience, in hilly and mountainous areas.ConclusionsThese results draw attention to European areas occupied by bird communities characterized by a potential lower capacity to respond to strong ecological changes, and, therefore, potentially more exposed to risks for conservation.

Download Full-text

Seasonal changes in the relationship between species richness and community biomass in grassland under grazing and exclosure, Horqin Sandy Land, northern China

Sciences in Cold and Arid Regions ◽

10.3724/sp.j.1226.2013.00177 ◽

2013 ◽

Vol 5 (2) ◽

pp. 177 ◽

Cited By ~ 2

Author(s):

Zuo XiaoAn ◽

Zhao XueYong ◽

Zhang TongHui ◽

Wang ShaoKun ◽

Luo YaYong ◽

...

Keyword(s):

Species Richness ◽

Seasonal Changes ◽

Northern China ◽

Horqin Sandy Land ◽

Sandy Land ◽

Community Biomass ◽

The Relationship

Download Full-text

Relationships between resource availability and elevation vary between metrics creating gradients of nutritional complexity

Oecologia ◽

10.1007/s00442-020-04824-4 ◽

2021 ◽

Vol 195 (1) ◽

pp. 213-223

Author(s):

Mark A. Lee ◽

Grace Burger ◽

Emma R. Green ◽

Pepijn W. Kooij

Keyword(s):

Species Richness ◽

Plant Species ◽

Resource Availability ◽

Plant Biomass ◽

Plant Species Richness ◽

Mineral Contents ◽

Nutritive Values ◽

Animal Community ◽

Nutritional Chemistry ◽

The Relationship

AbstractPlant and animal community composition changes at higher elevations on mountains. Plant and animal species richness generally declines with elevation, but the shape of the relationship differs between taxa. There are several proposed mechanisms, including the productivity hypotheses; that declines in available plant biomass confers fewer resources to consumers, thus supporting fewer species. We investigated resource availability as we ascended three aspects of Helvellyn mountain, UK, measuring several plant nutritive metrics, plant species richness and biomass. We observed a linear decline in plant species richness as we ascended the mountain but there was a unimodal relationship between plant biomass and elevation. Generally, the highest biomass values at mid-elevations were associated with the lowest nutritive values, except mineral contents which declined with elevation. Intra-specific and inter-specific increases in nutritive values nearer the top and bottom of the mountain indicated that physiological, phenological and compositional mechanisms may have played a role. The shape of the relationship between resource availability and elevation was different depending on the metric. Many consumers actively select or avoid plants based on their nutritive values and the abundances of consumer taxa vary in their relationships with elevation. Consideration of multiple nutritive metrics and of the nutritional requirements of the consumer may provide a greater understanding of changes to plant and animal communities at higher elevations. We propose a novel hypothesis for explaining elevational diversity gradients, which warrants further study; the ‘nutritional complexity hypothesis’, where consumer species coexist due to greater variation in the nutritional chemistry of plants.

Download Full-text

EPCO-31. EPIGENOMIC INTRATUMORAL HETEROGENEITY OF GLIOBLASTOMA IN THREE-DIMENSIONAL SPACE

Neuro-Oncology ◽

10.1093/neuonc/noaa215.310 ◽

2020 ◽

Vol 22 (Supplement_2) ◽

pp. ii76-ii76

Author(s):

Radhika Mathur ◽

Sriranga Iyyanki ◽

Stephanie Hilz ◽

Chibo Hong ◽

Joanna Phillips ◽

...

Keyword(s):

Spatial Organization ◽

Dimensional Space ◽

Three Dimensional ◽

Spatial Location ◽

Therapy Resistance ◽

Regulatory Elements ◽

Chromatin Accessibility ◽

Intratumoral Heterogeneity ◽

Tumor Evolution ◽

Open Chromatin

Abstract Treatment failure in glioblastoma is often attributed to intratumoral heterogeneity (ITH), which fosters tumor evolution and generation of therapy-resistant clones. While ITH in glioblastoma has been well-characterized at the genomic and transcriptomic levels, the extent of ITH at the epigenomic level and its biological and clinical significance are not well understood. In collaboration with neurosurgeons, neuropathologists, and biomedical imaging experts, we have established a novel topographical approach towards characterizing epigenomic ITH in three-dimensional (3-D) space. We utilize pre-operative MRI scans to define tumor volume and then utilize 3-D surgical neuro-navigation to intra-operatively acquire 10+ samples representing maximal anatomical diversity. The precise spatial location of each sample is mapped by 3-D coordinates, enabling tumors to be visualized in 360-degrees and providing unprecedented insight into their spatial organization and patterning. For each sample, we conduct assay for transposase-accessible chromatin using sequencing (ATAC-Seq), which provides information on the genomic locations of open chromatin, DNA-binding proteins, and individual nucleosomes at nucleotide resolution. We additionally conduct whole-exome sequencing and RNA sequencing for each spatially mapped sample. Integrative analysis of these datasets reveals distinct patterns of chromatin accessibility within glioblastoma tumors, as well as their associations with genetically defined clonal expansions. Our analysis further reveals how differences in chromatin accessibility within tumors reflect underlying transcription factor activity at gene regulatory elements, including both promoters and enhancers, and drive expression of particular gene expression sets, including neuronal and immune programs. Collectively, this work provides the most comprehensive characterization of epigenomic ITH to date, establishing its importance for driving tumor evolution and therapy resistance in glioblastoma. As a resource for further investigation, we have provided our datasets on an interactive data sharing platform – The 3D Glioma Atlas – that enables 360-degree visualization of both genomic and epigenomic ITH.

Download Full-text

Can clearcuts increase bird species richness in managed forests?

Journal of Forest Science ◽

10.17221/787-jfs ◽

2008 ◽

Vol 54 (No. 4) ◽

pp. 189-193

Author(s):

M. Żmihorski

Keyword(s):

Species Richness ◽

Bird Species ◽

Bird Communities ◽

Cumulative Number ◽

Managed Forests ◽

Managed Forest ◽

Bird Species Richness ◽

Forest Interior ◽

Transect Counts ◽

The Difference

Clearcuts are one of the results of forest management. The aim of this study was to assess the effect of clearcuts on bird communities in a managed forest in Western Poland. I applied the method of point transect counts. 20 points were located near clearcuts (less than 100 m from the nearest clearcut) and 25 points in the forest interior. In total, 36 bird species were recorded. On average, I found 9.20 bird species at points located near clearcuts and 6.72 species at points situated in the forest interior, and the difference was significant. The cumulative number of bird species for a given number of sampling points in the vicinity of clearcuts was higher than in the forest interior. The obtained results indicate that in managed, even-aged forests the generation of clearcuts can lead to an increase in local bird species richness.

Download Full-text