scholarly journals Testing biodiversity theory using species richness of reef-building corals across a depth gradient

2019 ◽  
Vol 15 (10) ◽  
pp. 20190493 ◽  
Author(s):  
T. Edward Roberts ◽  
Sally A. Keith ◽  
Carsten Rahbek ◽  
Tom C. L. Bridge ◽  
M. Julian Caley ◽  
...  
Keyword(s):  
Species Richness ◽  
Large Scale ◽  
Coral Species ◽  
Environmental Gradients ◽  
Abiotic Factors ◽  
Empirical Support ◽  
Null Model ◽  
Local Scale ◽  
Small Scale ◽  
Energy Availability

Natural environmental gradients encompass systematic variation in abiotic factors that can be exploited to test competing explanations of biodiversity patterns. The species–energy (SE) hypothesis attempts to explain species richness gradients as a function of energy availability. However, limited empirical support for SE is often attributed to idiosyncratic, local-scale processes distorting the underlying SE relationship. Meanwhile, studies are also often confounded by factors such as sampling biases, dispersal boundaries and unclear definitions of energy availability. Here, we used spatially structured observations of 8460 colonies of photo-symbiotic reef-building corals and a null-model to test whether energy can explain observed coral species richness over depth. Species richness was left-skewed, hump-shaped and unrelated to energy availability. While local-scale processes were evident, their influence on species richness was insufficient to reconcile observations with model predictions. Therefore, energy availability, either in isolation or in combination with local deterministic processes, was unable to explain coral species richness across depth. Our results demonstrate that local-scale processes do not necessarily explain deviations in species richness from theoretical models, and that the use of idiosyncratic small-scale factors to explain large-scale ecological patterns requires the utmost caution.

scholarly journals Distinctive patterns and signals at major environmental events and collapse zone boundaries

2021 ◽  
Vol 193 (10) ◽  
Author(s):  
Melinda Pálinkás ◽  
Levente Hufnagel
Keyword(s):  
Climate Change ◽  
Cluster Analysis ◽  
Species Richness ◽  
Relative Abundance ◽  
Large Scale ◽  
Hierarchical Cluster ◽  
Small Scale ◽  
Total Abundance ◽  
First Order ◽  
Environmental Events

AbstractWe studied the patterns of pre-collapse communities, the small-scale and the large-scale signals of collapses, and the environmental events before the collapses using four paleoecological and one modern data series. We applied and evaluated eight indicators in our analysis: the relative abundance of species, hierarchical cluster analysis, principal component analysis, total abundance, species richness, standard deviation (without a rolling window), first-order autoregression, and the relative abundance of the dominant species. We investigated the signals at the probable collapse triggering unusual environmental events and at the collapse zone boundaries, respectively. We also distinguished between pulse and step environmental events to see what signals the indicators give at these two different types of events. Our results show that first-order autoregression is not a good environmental event indicator, but it can forecast or indicate the collapse zones in climate change. The rest of the indicators are more sensitive to the pulse events than to the step events. Step events during climate change might have an essential role in initiating collapses. These events probably push the communities with low resilience beyond a critical threshold, so it is crucial to detect them. Before collapses, the total abundance and the species richness increase, the relative abundance of the species decreases. The hierarchical cluster analysis and the relative abundance of species together designate the collapse zone boundaries. We suggest that small-scale signals should be involved in analyses because they are often earlier than large-scale signals.

scholarly journals Large-scale spatial heterogeneity of macrozooplankton in Lake of Geneva

1999 ◽  
Vol 56 (8) ◽  
pp. 1437-1451 ◽  
Author(s):  
Bernadette Pinel-Alloul ◽  
Catherine Guay ◽  
Nadine Angeli ◽  
Pierre Legendre ◽  
Pierre Dutilleul ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Water Temperature ◽  
Chlorophyll A ◽  
Large Scale ◽  
Abiotic Factors ◽  
Distribution Patterns ◽  
Small Scale ◽  
Lake Basin ◽  
Fish Biomass ◽  
Trophic Groups

Spatial distribution of macrozooplankton was studied during spring in Lake of Geneva to evaluate the influence of abiotic (water temperature and stability, nutrients) and biotic (bacteria, chlorophyll a, fish biomass) factors on macrozooplankton distribution. Mapping and spatial analyses revealed that abiotic factors, as well as crustacean abundances, were structured along a gradient in the great lake basin. Chlorophyll a biomass, bacteria density, cyclopoid abundance, and fish biomass showed more patchy or inshore-offshore distribution patterns. Using canonical analyses, we determined the relative contribution of the spatial and environmental factors to the distribution of macrozooplankton species and of trophic groups based on herbivory and omnivory/carnivory. The distribution of macrozooplankton can be explained by small-scale variations and lake gradients in abiotic and biotic factors, with a dominant contribution of the abiotic factors. Water temperature and stability, as well as ammonium, are the main factors related to macrozooplankton distribution in Lake of Geneva during spring. Chlorophyll a biomass was also related to the distribution of cyclopoids. The canonical models explained 35-72% of the variance in the distribution of total crustaceans, species, and trophic groups. However, 28-65% of the macrozooplankton variance remained unexplained, which may be due to fine-scale variations in other environmental factors.

Arctic snow distribution patterns at the watershed scale

2014 ◽  
Vol 46 (4) ◽  
pp. 507-520 ◽  
Author(s):  
Joel W. Homan ◽  
Douglas L. Kane
Keyword(s):  
Large Scale ◽  
Snow Water Equivalent ◽  
Regional Scale ◽  
Distribution Patterns ◽  
Local Scale ◽  
Small Scale ◽  
Watershed Scale ◽  
Quality Of Data ◽  
Weather Patterns ◽  
Snow Distribution

Watershed-scale hydrologic models require good estimates of spatially distributed snow water equivalent (SWE) at winter's end. Snow on the ground in arctic environments is susceptible to significant wind redistribution, which results in heterogeneous snowpacks. The scarcity and quality of data collected by snow gauges provides a poor indicator of actual snowpack distribution. Snow distribution patterns are similar from year to year because they are largely controlled by the interaction of topography, vegetation, and consistent weather patterns. Consequently, shallow and deep areas of snow tend to be spatially predetermined, resulting in depth (or SWE) differences that may vary as a whole, but not relative to each other. Our aim was to identify snowpack distribution patterns and establish their stability in time and space at a watershed scale. Snow patterns were established by: (1) using numerous field surveys from end-of-winter field campaigns; and (2) differentiating snowpacks that characterize small-scale anomalies (local scale) from snowpacks that represent a large-scale area (regional scale). We concluded that basic snow survey site descriptions could be used to separate survey locations into regional and local-scale representative sites. Removing local-scale influences provides a more accurate representation of the regional snowpack, which will aid in forecasting snowmelt runoff events.

scholarly journals Distribution of aquatic macrophytes along depth gradients in Lajeado Reservoir, Tocantins River, Brazil

2019 ◽  
Vol 31 ◽  
Author(s):  
Ester Vieira Noleto ◽  
Marcus Vinícius Moreira Barbosa ◽  
Fernando Mayer Pelicice
Keyword(s):  
Species Richness ◽  
Aquatic Macrophytes ◽  
Environmental Gradients ◽  
Life Forms ◽  
Individual Species ◽  
Small Scale ◽  
Middle Section ◽  
Tocantins River ◽  
Depth Gradients ◽  
Emergent Species

Abstract Aim The present study investigated the diversity of aquatic macrophytes in the littoral zone of Lajeado Reservoir, Tocantins River. We characterized spatial variations in species richness, composition and abundance along depth gradients. Methods Macrophyte sampling occurred at the end of the dry season (September and October 2014) in four sites of the reservoir. We established transects perpendicular to the shoreline, each 25 m long, divided in 3 sections (plots of 5 x 5 m). Results In total, we recorded 18 taxa of aquatic macrophytes, belonging to nine families and four life forms. Najas microcarpa, Echinodorus tenellus. and Chara sp. were the more frequent and abundant taxa. Considering depth gradients, we recorded 18 taxa in the section closer to the shoreline, 13 in the middle section and 10 in the section more distant to the shoreline. Submerged and emergent species were more frequent and abundant, especially in the section close to the shoreline; epiphytes and free-floating species were rare. Plot species richness (total, emergent and submerged) decreased along the gradient, and a Non-Metric Multidimensional Scaling (NMDS) revealed that the plot close to the shoreline had different composition when compared to adjacent sections. Individual species showed particular behaviors, but most tended to decline in abundance and occurrence along the gradient. Conclusions The present study revealed that small-scale environmental gradients affect the distribution of aquatic plants in Lajeado Reservoir, with greater diversity in habitats close to the shoreline.

scholarly journals Predicted the Cumulative Annual Rainfall in Iraq Using SDSM Modal

2021 ◽  
Vol 32 (2) ◽  
pp. 11
Author(s):  
Ali Mokhles Abdul-Jabbar ◽  
Asraa Khtan Abdulkareem
Keyword(s):  
Large Scale ◽  
Daily Rainfall ◽  
Local Scale ◽  
Annual Rainfall ◽  
Small Scale ◽  
Middle Region ◽  
The West ◽  
The North ◽  
West Region ◽  
The World

Rain is deemed one of the most important climate elements. It must be given special attention for being the basis without which no kind of life in the world can be there. the aim of the study is to use Statistical models Downscaling (SDSM) where it is a universal model used to converting large scale output into a small scale that can be used to study impact at the local scale (Iraq)' to Forecasting cumulative annual rainfall for the next years where there are a few studies used this model in Iraq. Daily rainfall data from the Iraqi Meteorological Organization and Seismology (IMOS) (2007-2016) for the study areas (Baghdad, Karbala, Al-Hay, Mosul, Kirkuk, Khanaqin, Basra, Nasiriya, Diwaniya, and Rutba) is used to estimate the amount of rainfall by using SDSM. The model was used to estimate the rain values and then the results were compared with the actual values, the results were very close to each other. Also, the model used to predict the cumulative annual rainfall from (2017-2021), The result shows that the bigger amount of rainfall in the north region with (3821) mm and the lowest amount in the west region (665) mm, while middle region (1848) mm and south region (1828) mm.

scholarly journals NWP and Radar Extrapolation: Comparisons and Explanation of Errors

2020 ◽  
Vol 148 (12) ◽  
pp. 4783-4798
Author(s):  
James Wilson ◽  
Dan Megenhardt ◽  
James Pinto
Keyword(s):  
Data Assimilation ◽  
Large Scale ◽  
Rainfall Intensity ◽  
Large Fraction ◽  
Precipitation Amount ◽  
Local Scale ◽  
Colorado Front Range ◽  
Small Scale ◽  
Front Range ◽  
Rain Events

AbstractThis paper examines nowcasts of precipitation from the High-Resolution Rapid Refresh (HRRRv2) model from the summer of 2017 along the Colorado Front Range. It was found that model nowcasts (2 h or less) of precipitation amount were less skillful than extrapolation of the KFTG WSR-88-D data at a spatial scale of 120 km. It was also found that local-scale (mesoscale) influences on rainfall intensity and amount have a much greater impact on rainfall intensity than large-scale (synoptic) influences. Thus, large-scale trends are not useful for modifying extrapolation nowcasts on the local scale. Errors in the HRRR nowcasts are attributed to an inability of the model and data assimilation to resolve convergence along outflow boundaries and other terrain-influenced mesogamma-scale flows that contribute to storm formation and evolution. While the HRRRv2 1-h nowcasts were strongly correlated with observed precipitation events, the nowcast precipitation amounts were in error by more than a factor of 2 about 50% of the time, with half of the cases being overestimates and half being underestimates. A large fraction of the HRRRv2 overestimates were associated with stratiform rain events. It is speculated that this was a result of misinterpretation of the radar bright band as more intense precipitation aloft by the data assimilation scheme. A large fraction of the HRRRv2 underestimates occurred when the data assimilation and model were unable to fully resolve the low-level convergence along small-scale, narrow boundaries that led to new storm initiation and/or storm growth.

Small-scale patterns of species richness and floristic composition in relation to microsite variation in herb-rich woodlands

2010 ◽  
Vol 58 (4) ◽  
pp. 271 ◽  
Author(s):  
J. N. Price ◽  
J. W. Morgan
Keyword(s):  
Species Richness ◽  
Abiotic Factors ◽  
Incident Light ◽  
Light Availability ◽  
Eucalyptus Camaldulensis ◽  
Floristic Composition ◽  
Distribution Patterns ◽  
Small Scale ◽  
Character Species ◽  
Weak Support

Non-riverine Eucalyptus camaldulensis (red gum) woodlands with herbaceous understoreys in southern Australia have been recognised as botanically significant due to their high small-scale species richness, but little is known about the factors that underpin these patterns. To examine the influence of local environmental variation (microsites) on small-scale vegetation patterns, we sampled vegetation under trees, away from trees, and in depressions and hummocks in three herb-rich woodlands. Trees influenced both the composition and richness of the ground-layer vegetation, with reductions in species richness found under trees in sites where incident light availability was reduced by >40%. Species composition and richness differed between microsites, indicating that spatial heterogeneity is an important factor affecting species distribution patterns. Patchiness in relation to abiotic factors creates environmentally and compositionally distinct patterns. Indicator species analysis found that all microsites could be distinguished by character species with some evidence for microsite limitation for only a few species, lending weak support for a niche-based model of community assembly for herb-rich woodlands. A more plausible explanation for extremely high small-scale species richness is the lack of dominant species in these low productivity woodlands.

Recolonization dynamics of benthic macroinvertebrates after artificial and natural disturbances in an Australian temporary stream

1991 ◽  
Vol 42 (3) ◽  
pp. 295 ◽  
Author(s):  
SS Brooks ◽  
AJ Boulton
Keyword(s):  
Particle Size ◽  
Species Richness ◽  
Benthic Macroinvertebrates ◽  
Large Scale ◽  
South Australia ◽  
Natural Disturbance ◽  
Small Scale ◽  
Temporary Stream ◽  
Large Scale Disturbance ◽  
Coarse Gravel

The effects of substratum particle size (cobbles, coarse gravel and medium-fine gravel) on recolonization by benthic macroinvertebrates after disturbance was investigated in small plots (0.05 m2) in the Finniss River, an intermittent stream in South Australia. Six weeks after flow resumed, the intermediate particle size (coarse gravel) supported the greatest densities of taxa and individuals. Experimental disturbance reduced species richness by 83% and numbers of individuals by 97%. Rapid recolonizers (e.g. mayfly and stonefly nymphs) showed little substratum specificity and attained predisturbance densities within one day. Slow recolonizers (e.g. chironomid hatchlings) favoured gravel substrata and had not reached predisturbance densities within 4 days. Recolonization of small plots appeared to be by surface movement from neighbouring intact areas. A spate on Day 7 prevented further sampling, destroying all experimental plots, but this permitted a study of macroinvertebrate recolonization following a natural disturbance at a larger spatial scale. The spate reduced species richness by 45% and numbers of individuals by 70%. Vertical migration rather than drift appeared to be the major source of recolonizing fauna. Our data show that results from small-scale experiments can not be extrapolated to large-scale disturbance because the scale of disturbance strongly influences the rate and pathways of recolonization as well as the sources and faunal composition of the recolonists.

scholarly journals The noctilucent cloud (NLC) display during the ECOMA/MASS sounding rocket flights on 3 August 2007: morphology on global to local scales

2009 ◽  
Vol 27 (3) ◽  
pp. 953-965 ◽  
Author(s):  
G. Baumgarten ◽  
J. Fiedler ◽  
K. H. Fricke ◽  
M. Gerding ◽  
M. Hervig ◽  
...  
Keyword(s):  
Large Scale ◽  
Planetary Wave ◽  
Local Scale ◽  
Sounding Rocket ◽  
Small Scale ◽  
Meteor Radar ◽  
Horizontal Temperature Gradient ◽  
Noctilucent Cloud ◽  
Planetary Scale ◽  
Lidar Observations

Abstract. During the ECOMA/MASS rocket campaign large scale NLC/PMC was observed by satellite, lidar and camera from polar to mid latitudes. We examine the observations from different instruments to investigate the morphology of the cloud. Satellite observations show a planetary wave 2 structure. Lidar observations from Kühlungsborn (54° N), Esrange (68° N) and ALOMAR (69° N) show a highly dynamic NLC layer. Under favorable solar illumination the cloud is also observable by ground-based cameras. The cloud was detected by cameras from Trondheim (63° N), Juliusruh (55° N) and Kühlungsborn. We investigate planetary scale morphology and local scale gravity wave structures, important for the interpretation of the small scale rocket soundings. We compare in detail the lidar observations with the NLC structure observed by the camera in Trondheim. The ALOMAR RMR-lidar observed only a faint NLC during the ECOMA launch window, while the camera in Trondheim showed a strong NLC display in the direction of ALOMAR. Using the high resolution camera observations (t~30 s, Δx<5 km) and the wind information from the meteor radar at ALOMAR we investigate the formation and destruction of NLC structures. We observe that the NLC brightness is reduced by a factor of 20–40 within 100 s which can be caused by a temperature about 15 K above the frostpoint temperature. A horizontal temperature gradient of more than 3 K/km is estimated.

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