scholarly journals STATUS OF THE INVASION OF A POACEAE SPECIES IN TROPICAL SEMIARID RESERVOIRS

2017 ◽  
Vol 35 (0) ◽  
Author(s):  
R.M.A. ALVES ◽  
M.B. ALBUQUERQUE ◽  
L.G. BARBOSA
Keyword(s):  
Spatial Distribution ◽  
Native Species ◽  
Spatial Scales ◽  
Regional Scale ◽  
Statistical Computing ◽  
Relevant Factor ◽  
R Program ◽  
R Project ◽  
Environmental Instability ◽  
Biotic Acceptance

ABSTRACT The species of the Urochloa genus, exotic and infesting in Brazilian waters, are known to be invasive and dominant, occupying from humid, shallow areas, and irrigation canals to margins of deep reservoirs. This paper hypothesis that less depth reservoirs have higher infestation rate and higher biomass of U. arrecta. The objectives were to measure the percentage of occurrence of exotic macrophyte U. arrecta in 40 ecosystems from the Mamanguape basin (Paraíba, Brazil) and determine the infestation of the species in two reservoirs. The acquired data were geo-referenced with the ArcGIS software (v. 9.3). A covariance analysis was performed using the R program (The R project is Statistical Computing). The results showed large spatial distribution of the species, indicating that reservoirs may act as steppingstones in the landscape, in a regional scale. The hypothesis of biotic acceptance is seen as a relevant factor in explaining the presence of the species with low percentage of occurrence in 37 out of the 40 sampled ecosystems, being observed only in areas prone to the colonization of native and naturalized macrophytes, in banks and points of lower declivity, in both spatial scales studied. Thus, factors such as environmental instability (promoted by intermittent or prolonged desiccation of the habitat), shadowing and declivity of the reservoirs synergistically acted on exotic and native species.

scholarly journals High-Resolution Spatial Distribution of Bird Movements Estimated from a Weather Radar Network

2020 ◽  
Vol 12 (4) ◽  
pp. 635 ◽  
Author(s):  
Bart Kranstauber ◽  
Willem Bouten ◽  
Hidde Leijnse ◽  
Berend-Christiaan Wijers ◽  
Liesbeth Verlinden ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Spatial Scales ◽  
Regional Scale ◽  
Habitat Associations ◽  
Fine Scale ◽  
Migration Patterns ◽  
Spatial Image ◽  
Weather Radars ◽  
Spatial Coverage ◽  
Radar Imagery

Weather radars provide detailed information on aerial movements of organisms. However, interpreting fine-scale radar imagery remains challenging because of changes in aerial sampling altitude with distance from the radar. Fine-scale radar imagery has primarily been used to assess mass exodus at sunset to study stopover habitat associations. Here, we present a method that enables a more intuitive integration of information across elevation scans projected in a two-dimensional spatial image of fine-scale radar reflectivity. We applied this method on nights of intense bird migration to demonstrate how the spatial distribution of migrants can be explored at finer spatial scales and across multiple radars during the higher flying en-route phase of migration. The resulting reflectivity maps enable explorative analysis of factors influencing their regional and fine-scale distribution. We illustrate the method’s application by generating time-series of composites of up to 20 radars, achieving a nearly complete spatial coverage of a large part of Northwest Europe. These visualizations are highly useful in interpreting regional-scale migration patterns and provide detailed information on bird movements in the landscape and aerial environment.

scholarly journals Setting the Flow Accumulation Threshold Based on Environmental and Morphologic Features to Extract River Networks from Digital Elevation Models

2021 ◽  
Vol 10 (3) ◽  
pp. 186
Author(s):  
HuiHui Zhang ◽  
Hugo A. Loáiciga ◽  
LuWei Feng ◽  
Jing He ◽  
QingYun Du
Keyword(s):  
Spatial Scales ◽  
Digital Elevation Models ◽  
Regional Scale ◽  
Drainage Density ◽  
River Network ◽  
Landscape Patterns ◽  
Estimation Methods ◽  
River Networks ◽  
Flow Accumulation ◽  
Digital Elevation

Determining the flow accumulation threshold (FAT) is a key task in the extraction of river networks from digital elevation models (DEMs). Several methods have been developed to extract river networks from Digital Elevation Models. However, few studies have considered the geomorphologic complexity in the FAT estimation and river network extraction. Recent studies estimated influencing factors’ impacts on the river length or drainage density without considering anthropogenic impacts and landscape patterns. This study contributes two FAT estimation methods. The first method explores the statistical association between FAT and 47 tentative explanatory factors. Specifically, multi-source data, including meteorologic, vegetation, anthropogenic, landscape, lithology, and topologic characteristics are incorporated into a drainage density-FAT model in basins with complex topographic and environmental characteristics. Non-negative matrix factorization (NMF) was employed to evaluate the factors’ predictive performance. The second method exploits fractal geometry theory to estimate the FAT at the regional scale, that is, in basins whose large areal extent precludes the use of basin-wide representative regression predictors. This paper’s methodology is applied to data acquired for Hubei and Qinghai Provinces, China, from 2001 through 2018 and systematically tested with visual and statistical criteria. Our results reveal key local features useful for river network extraction within the context of complex geomorphologic characteristics at relatively small spatial scales and establish the importance of properly choosing explanatory geomorphologic characteristics in river network extraction. The multifractal method exhibits more accurate extracting results than the box-counting method at the regional scale.

Managing Alien Plants for Biodiversity Outcomes—the Need for Triage

2010 ◽  
Vol 3 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Paul O. Downey ◽  
Moira C. Williams ◽  
Leonie K. Whiffen ◽  
Bruce A. Auld ◽  
Mark A. Hamilton ◽  
...  
Keyword(s):  
Biodiversity Conservation ◽  
Native Species ◽  
Regional Scale ◽  
Management Strategies ◽  
Alien Plants ◽  
Plant Management ◽  
Policy Reforms ◽  
Management Decisions ◽  
Alien Plant ◽  
Triage System

AbstractRecognition that alien plants pose a significant threat to biodiversity has not always translated into effective management strategies, policy reforms, and systems to establish priorities. Thus, many alien plant management decisions for the protection of biodiversity occur with limited knowledge of what needs to be protected (other than biodiversity in a generalized sense) or the urgency of actions. To rectify this, we have developed a triage system that enables alien plant management decisions to be made based on (1) the urgency of control relative to the degree of threat posed to biodiversity, compared with (2) the likelihood of achieving a successful conservation outcome as a result of alien plant control. This triage system is underpinned by a two-step approach, which identifies the biodiversity at risk and assesses sites to determine priorities for control. This triage system was initially developed to manage the threat posed by bitou bush to native species in New South Wales (NSW), Australia. It has subsequently been improved with the national assessment of lantana in Australia, and the adaptation from a single to multiple alien plant species approach on a regional scale. This triage system identifies nine levels of priority for alien plant management aimed at biodiversity conservation, ranging from immediate, targeted action to limited or no action. The development of this approach has enabled long-term management priorities to be set for widespread alien plants that are unlikely to be eradicated. It also enables control to occur in a coordinated manner for biodiversity conservation at a landscape scale, rather than as a series of individual unconnected short-term actions.

scholarly journals Large but decreasing effect of ozone on the European carbon sink

2018 ◽  
Vol 15 (13) ◽  
pp. 4245-4269 ◽  
Author(s):  
Rebecca J. Oliver ◽  
Lina M. Mercado ◽  
Stephen Sitch ◽  
David Simpson ◽  
Belinda E. Medlyn ◽  
...  
Keyword(s):  
Carbon Storage ◽  
Primary Productivity ◽  
Carbon Sink ◽  
Spatial Scales ◽  
Stomatal Closure ◽  
Regional Scale ◽  
Surface Model ◽  
Background Concentrations ◽  
Tropospheric O3 ◽  
The Impact

Abstract. The capacity of the terrestrial biosphere to sequester carbon and mitigate climate change is governed by the ability of vegetation to remove emissions of CO2 through photosynthesis. Tropospheric O3, a globally abundant and potent greenhouse gas, is, however, known to damage plants, causing reductions in primary productivity. Despite emission control policies across Europe, background concentrations of tropospheric O3 have risen significantly over the last decades due to hemispheric-scale increases in O3 and its precursors. Therefore, plants are exposed to increasing background concentrations, at levels currently causing chronic damage. Studying the impact of O3 on European vegetation at the regional scale is important for gaining greater understanding of the impact of O3 on the land carbon sink at large spatial scales. In this work we take a regional approach and update the JULES land surface model using new measurements specifically for European vegetation. Given the importance of stomatal conductance in determining the flux of O3 into plants, we implement an alternative stomatal closure parameterisation and account for diurnal variations in O3 concentration in our simulations. We conduct our analysis specifically for the European region to quantify the impact of the interactive effects of tropospheric O3 and CO2 on gross primary productivity (GPP) and land carbon storage across Europe. A factorial set of model experiments showed that tropospheric O3 can suppress terrestrial carbon uptake across Europe over the period 1901 to 2050. By 2050, simulated GPP was reduced by 4 to 9 % due to plant O3 damage and land carbon storage was reduced by 3 to 7 %. The combined physiological effects of elevated future CO2 (acting to reduce stomatal opening) and reductions in O3 concentrations resulted in reduced O3 damage in the future. This alleviation of O3 damage by CO2-induced stomatal closure was around 1 to 2 % for both land carbon and GPP, depending on plant sensitivity to O3. Reduced land carbon storage resulted from diminished soil carbon stocks consistent with the reduction in GPP. Regional variations are identified with larger impacts shown for temperate Europe (GPP reduced by 10 to 20 %) compared to boreal regions (GPP reduced by 2 to 8 %). These results highlight that O3 damage needs to be considered when predicting GPP and land carbon, and that the effects of O3 on plant physiology need to be considered in regional land carbon cycle assessments.

scholarly journals Are Distribution Patterns Correlated with Plant Traits?

2021 ◽  
Author(s):  
◽  
Benjamin Magana-Rodriguez
Keyword(s):  
Life History ◽  
Leaf Area ◽  
Spatial Patterns ◽  
Life History Traits ◽  
Multiple Scales ◽  
Spatial Scales ◽  
Regional Scale ◽  
Distribution Patterns ◽  
Spatial Arrangement ◽  
Scaling Relationship

<p>The current crisis in loss of biodiversity requires rapid action. Knowledge of species' distribution patterns across scales is of high importance in determining their current status. However, species display many different distribution patterns on multiple scales. A positive relationship between regional (broad-scale) distribution and local abundance (fine-scale) of species is almost a constant pattern in macroecology. Nevertheless interspecific relationships typically contain much scatter. For example, species that possess high local abundance and narrow ranges, or species that are widespread, but locally rare. One way to describe these spatial features of distribution patterns is by analysing the scaling properties of occupancy (e.g., aggregation) in combination with knowledge of the processes that are generating the specific spatial pattern (e.g., reproduction, dispersal, and colonisation). The main goal of my research was to investigate if distribution patterns correlate with plant life-history traits across multiple scales. First, I compared the performance of five empirical models for their ability to describe the scaling relationship of occupancy in two datasets from Molesworth Station, New Zealand. Secondly, I analysed the association between spatial patterns and life history traits at two spatial scales in an assemblage of 46 grassland species in Molesworth Station. The spatial arrangement was quantified using the parameter k from the Negative Binomial Distribution (NBD). Finally, I investigated the same association between spatial patterns and life-history traits across local, regional and national scales, focusing in one of the most diverse families of plant species in New Zealand, the Veronica sect. Hebe (Plantaginaceae). The spatial arrangement was investigated using the mass fractal dimension. Cross-species correlations and phylogenetically independent contrasts were used to investigate the relationships between plant life-history traits and spatial patterns on both data bases. There was no superior occupancy-area model overall for describing the scaling relationship, however the results showed that a variety of occupancy-area models can be fit to different data sets at diverse spatial scales using nonlinear regression. Additionally, here I showed that it is possible to deduce and extrapolate information on occupancy at fine scales from coarse-scale data. For the 46 plantassemblage in Molesworth Station, Specific leaf area (SLA) exhibits a positive association with aggregation in cross-species analysis, while leaf area showed a negative association, and dispersule mass a positive correlation with degree of aggregation in phylogenetic contrast analysis at a local-scale (20 × 20 m resolution). Plant height was the only life-history trait that was associated with degree of aggregation at a regional-scale (100 × 60 mresolution). For the Veronica sect. Hebe dataset, leaf area showed a positive correlation with aggregation while specific leaf area showed a negative correlation with aggregation at a fine local-scale (2.5-60 m resolution). Inflorescence length, breeding system and leaf area showed a negative correlation with degree of aggregation at a regional-scale (2.5-20 km resolution). Height was positively associated with aggregation at national-scale (20-100 km resolution). Although life-history traits showed low predictive ability in explaining aggregation throughout this thesis, there was a general pattern about which processes and traits were important at different scales. At local scales traits related to dispersal and completion such as SLA , leaf area, dispersule mass and the presence of structures in seeds for dispersal, were important; while at regional scales traits related to reproduction such as breeding system, inflorescence length and traits related to dispersal (seed mass) were significant. At national scales only plant height was important in predicting aggregation. Here, it was illustrated how the parameters of these scaling models capture an important aspect of spatial pattern that can be related to other macroecological relationships and the life-history traits of species. This study shows that when several scales of analysis are considered, we can improve our understanding about the factors that are related to species' distribution patterns.</p>

scholarly journals Consistent predictors of microbial community composition across scales in grasslands reveal low context-dependency

2021 ◽  
Author(s):  
Dajana Radujković ◽  
Sara Vicca ◽  
Margaretha van Rooyen ◽  
Peter Wilfahrt ◽  
Leslie Brown ◽  
...  
Keyword(s):  
Microbial Community ◽  
Community Composition ◽  
Spatial Scales ◽  
Regional Scale ◽  
Microbial Community Composition ◽  
Soil Microbial Communities ◽  
Plant Productivity ◽  
Context Dependency ◽  
Fungal Community Composition ◽  
Soil Microbial

Environmental circumstances shaping soil microbial communities have been studied extensively, but due to disparate study designs it has been difficult to resolve whether a globally consistent set of predictors exists, or context-dependency prevails. Here, we used a network of 18 grassland sites (11 sampled across regional plant productivity gradients) to examine i) if the same abiotic or biotic factors predict both large- and regional-scale patterns in bacterial and fungal community composition, and ii) if microbial community composition differs consistently with regional plant productivity (low vs high) across different sites. We found that there is high congruence between predictors of microbial community composition across spatial scales; bacteria were predominantly associated with soil properties and fungi with plant community composition. Moreover, there was a microbial community signal that clearly distinguished high and low productivity soils that was shared across worldwide distributed grasslands suggesting that microbial assemblages vary predictably depending on grassland productivity.

scholarly journals Regional climate and local-scale biotic acceptance explain native–exotic richness relationships in Australian annual plant communities

2018 ◽  
Vol 285 (1886) ◽  
pp. 20181328 ◽  
Author(s):  
Isaac. R. Towers ◽  
John. M. Dwyer
Keyword(s):  
Exotic Species ◽  
Structural Equation ◽  
Spatial Scales ◽  
Regional Climate ◽  
Soil Surface ◽  
Equation Model ◽  
Annual Plant ◽  
Regional Temperature ◽  
Neighbourhood Scale ◽  
Biotic Acceptance

Native and exotic species richness is expected to be negatively related at small spatial scales where individuals interact, and positive at larger spatial scales as a greater variety of habitats are sampled. However, a range of native–exotic richness relationships (NERRs) have been reported, including positive at small scales and negative at larger scales. We present a hierarchical metacommunity framework to explain how contrasting NERRs may emerge across scales and study systems, and then apply this framework to NERRs in an invaded winter annual plant system in southwest Western Australia. We analysed NERRs at increasing spatial scales from neighbourhoods (0.09 m 2 ) to communities (225 m 2 ) to metacommunities (greater than 10 ha) within a multilevel structural equation model. In contrast to many previous studies, native and exotic richness were positively related at the neighbourhood scale and were not significantly associated at larger scales. Heterogeneity in soil surface properties was weakly, but positively, associated with native and exotic richness at the community scale. Metacommunity exotic richness increased strongly with regional temperature and moisture availability, but relationships for native richness were negative and much weaker. Thus, we show that neutral NERRs can emerge at larger scales owing to differential climatic filtering of native and exotic species pools.

New Analog Experiment for Convergent Regime an example of planet Mercury

2021 ◽  
Author(s):  
Sinan Özeren ◽  
A. M. Celal Şengör ◽  
Dursun Acar ◽  
M. Nazmi Postacıoğlu ◽  
Christian Klimczak ◽  
...  
Keyword(s):  
Coherent Structures ◽  
Spatial Scales ◽  
Regional Scale ◽  
Homogeneous Case ◽  
Thrust Faulting ◽  
Slip Planes ◽  
Series Of Experiments ◽  
Analog Experiment ◽  
Stress Patterns ◽  
Cohesive Material

&lt;div&gt; &lt;div&gt; &lt;div&gt; &lt;div&gt; &lt;div&gt; &lt;div&gt; &lt;div&gt; &lt;div&gt; &lt;p&gt;We conduct a series of experiments to understand the nature of thrust faulting as a result of global thermal contraction in planetary bodies such as Mercury. The spatial scales and patterns of faulting due to contraction are still not very well understood. However, the problem is complicated even for the homogeneous case where the crustal thickness and material properties do not vary spatially. Previous research showed that the thrust faulting patterns are non-random and are arranged in long systems. This is probably due to the regional-scale stress patterns interacting with each other, leading to the creation of coherent structures. We first conduct 1-Axis experiments where we simulate the contraction of the substratum using an elastic ribbon. On top of this we place the material for which the friction, cohesion and thickness can be controlled for each experiment. The shared interface between the frictional-cohesive material and the shortening elastic substratum dictates undulations and finally the generation of slip planes in the upper layer. We discuss the spatial distribution of these patterns spatially. We then speculate the interaction of such patterns on a 2D plane.&lt;/p&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt; &lt;div&gt;&amp;#160;&lt;/div&gt; &lt;/div&gt;&lt;div&gt; &lt;div&gt;&amp;#160;&lt;/div&gt; &lt;/div&gt;

scholarly journals Demographic and Comorbidities Data Description of Population in Mexico with SARS-CoV-2 Infected Patients(COVID19): An Online Tool Analysis

2020 ◽  
Vol 17 (14) ◽  
pp. 5173
Author(s):  
Carlos E. Galván-Tejada ◽  
Laura A. Zanella-Calzada ◽  
Karen E. Villagrana-Bañuelos ◽  
Arturo Moreno-Báez ◽  
Huizilopoztli Luna-García ◽  
...  
Keyword(s):  
Demographic Data ◽  
Statistical Computing ◽  
Online Tool ◽  
Data Description ◽  
Graphic Information ◽  
R Project ◽  
Visualization Tools ◽  
Health Organization ◽  
National Governments ◽  
Web Platform

The Word Health Organization (WHO) declared in March 2020 that we are facing a pandemic designated as COVID-19, which is the acronym of coronavirus disease 2019, caused by a new virus know as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In Mexico, the first cases of COVID-19, was reported by the Secretary of Health on 28 February 2020. More than sixteen thousand cases and more than fifteen thousand deaths have been reported in Mexico, and it continues to rise; therefore, this article proposes two online visualization tools (a web platform) that allow the analysis of demographic data and comorbidities of the Mexican population. The objective of these tools is to provide graphic information, fast and updated, based on dataset obtained directly from National Governments Health Secretary (Secretaría de Salud, SSA) which is daily refreshed with the information related to SARS-CoV-2. To allow a dynamical update and friendly interface, and approach with R-project, a well-known Open Source language and environment for statistical computing and Shiny package, were implemented. The dataset is loaded automatically from the latest version released by the federal government of Mexico. Users can choose to study particular groups determined by gender, entity, type of result (positive, negative, pending outcome) and comorbidity. The image results are plots that can be instantly interpreted and supported by the text summary. This tool, in addition to being a consultation for the general public, is useful in Public Health to facilitate the visualization of the data, allowing its timely interpretation due to the changing nature of COVID-19, it can even be used for decision-making by leaders, for the benefit of the health of the community.

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