Resource Patch Density and Larval Aggregation in Mushroom-Breeding Flies

Oikos ◽  
1998 ◽  
Vol 81 (1) ◽  
pp. 187 ◽  
Author(s):  
Stephen B. Heard
Keyword(s):  
Mushroom Breeding ◽  
Patch Density

scholarly journals Assessment of Tuscany Landscape Structure According to the Regional Landscape Plan Partition

2021 ◽  
Vol 13 (10) ◽  
pp. 5424
Author(s):  
Martina Venturi ◽  
Francesco Piras ◽  
Federica Corrieri ◽  
Beatrice Fiore ◽  
Antonio Santoro ◽  
...  
Keyword(s):  
Landscape Structure ◽  
Agricultural Landscapes ◽  
Edge Density ◽  
Regional Government ◽  
Land Uses ◽  
Landscape Mosaic ◽  
Landscape Complexity ◽  
Economic Role ◽  
Patch Density ◽  
Landscape Units

The landscape is considered a strategic asset by the Tuscan regional government, also for its economic role, meaning that a specific Landscape Plan has been developed, dividing the region into 20 Landscape Units and representing the main planning instrument at the regional level. Following the aims of the Landscape Plan and the guidelines of the European Landscape Convention, it is necessary to develop an adequate assessment of the landscape, evaluating the main typologies and their characteristics. The aim of this research is to carry out an assessment of the landscape diversity in Tuscany based on 20 study areas, analyzing land uses and landscape mosaic structures through the application of landscape metrics: number of land uses, mean patch size (MPS), Hill’s diversity number, edge density (ED), patch density (PD), land use diversity (LUD). The results highlight a correlation between the landscape typologies (forest, agricultural, mixed, periurban) and the complexity of the landscape structure, especially in relation to MPS and PD, while the combination of PD and LUD calculated on the basis of a hexagonal grid allows obtaining landscape complexity maps. Despite the phenomena of reforestation and urban sprawl of recent decades, Tuscany still preserves different landscape typologies characterized by a good level of complexity. This is particularly evident in mixed landscapes, while agricultural landscapes have a larger variability because of different historical land organization forms. The methodology applied in this study provided a large amount of data about land uses and the landscape mosaic structure and complexity and proved to be effective in assessing the landscape structure and in creating a database that can represent a baseline for future monitoring.

scholarly journals Coupled local facilitation and global hydrologic inhibition drive landscape geometry in a patterned peatland

2015 ◽  
Vol 12 (1) ◽  
pp. 1247-1277 ◽  
Author(s):  
S. Acharya ◽  
D. A. Kaplan ◽  
S. Casey ◽  
M. J. Cohen ◽  
J. W. Jawitz
Keyword(s):  
Model Performance ◽  
Characteristic Pattern ◽  
Positive Feedbacks ◽  
Self Organized ◽  
Lower Elevation ◽  
Sediment Redistribution ◽  
Anisotropic Soil ◽  
Patch Density ◽  
Density Patch ◽  
Fractal Landscapes

Abstract. Self-organized landscape patterning can arise in response to multiple processes. Discriminating among alternative patterning mechanisms, particularly where experimental manipulations are untenable, requires process-based models. Previous modeling studies have attributed patterning in the Everglades (Florida, USA) to sediment redistribution and anisotropic soil hydraulic properties. In this work, we tested an alternate theory, the self-organizing canal (SOC) hypothesis, by developing a cellular automata model that simulates pattern evolution via local positive feedbacks (i.e., facilitation) coupled with a global negative feedback based on hydrology. The model is forced by global hydroperiod that drives stochastic transitions between two patch types: ridge (higher elevation) and slough (lower elevation). We evaluated model performance using multiple criteria based on six statistical and geostatistical properties observed in reference portions of the Everglades landscape: patch density, patch anisotropy, semivariogram ranges, power-law scaling of ridge areas, perimeter area fractal dimension, and characteristic pattern wavelength. Model results showed strong statistical agreement with reference landscapes, but only when anisotropically acting local facilitation was coupled with hydrologic global feedback, for which several plausible mechanisms exist. Critically, the model correctly generated fractal landscapes that had no characteristic pattern wavelength, supporting the invocation of global rather than scale-specific negative feedbacks.

scholarly journals Quantifying how urban landscape heterogeneity affects land surface temperature: A comparison of discrete and continuous approaches

2021 ◽  
Author(s):  
ehsan Rahimi ◽  
Shahindokht Barghjelveh ◽  
Pinliang Dong
Keyword(s):  
Surface Temperature ◽  
Spatial Patterns ◽  
Land Surface Temperature ◽  
Landscape Metrics ◽  
Land Surface ◽  
Urban Landscape ◽  
Landscape Heterogeneity ◽  
Alternative Measures ◽  
Heterogeneity Effects ◽  
Patch Density

Abstract The present study examines the efficiency of discrete and continuous approaches to measuring urban heterogeneity effects on land surface temperature (LST). In the discrete approach, landscape metrics have been widely applied to quantifying the relationship between land surface temperature and urban spatial patterns and have received acceptable verification from landscape ecologists but some studies have shown their inaccurate results. The objective of the study is to compare landscape metrics and alternative approaches to measuring urban heterogeneity effects on LST. We compared landscape metrics results with nine texture-based measures, and two local spatial autocorrelation indices (local Moran’s I and Gi statistics) applied to NDVI and BAI indices as a proxy of the spatial patterns of Tehran vegetation and built-up classes. The statistical results showed that urban landscape heterogeneity had significant impacts on the LST variations, and there was a compatibility between landscape metrics and alternative measures results. Overall results showed that the less-fragmented, the more complex, larger, and the higher number of patches, the lower LST. The most significant relationship was between patch density (PD) and LST (r= -0.71). Higher values of PD have mostly been interpreted to show higher fragmentation, but other landscape metrics and alternative measures declined this conclusion. Our study demonstrated that PD was not a reliable metric and presented no information about the spatial distribution of landscape elements. This study confirms alternative measures for overcoming landscape metrics shortcomings in estimating the effects of landscape heterogeneity on LST variations and gives land managers and urban planners new insights into the urban design.

scholarly journals INVESTIGATION AND EVALUATION OF SPATIAL PATTERNS IN TABRIZ PARKS USING LANDSCAPE METRICS

2017 ◽  
Vol 10 (2) ◽  
pp. 263-269
Author(s):  
Ali Majnouni Toutakhane ◽  
Mojtaba Mofareh
Keyword(s):  
Spatial Distribution ◽  
Spatial Patterns ◽  
Landscape Metrics ◽  
Shape Index ◽  
Quantitative Information ◽  
Green Spaces ◽  
Quantitative Results ◽  
Patch Density ◽  
Distribution Composition ◽  
Nearest Neighborhood

Nowadays, the green spaces in cities and especially metropolises have adopted a variety of functions. In addition to improving the environmental conditions, they are suitable places for spending free times and mitigating nervous pressures of the machinery life based on their distribution and dispersion in the cities. In this research, in order to study the spatial distribution and composition of the parks and green spaces in Tabriz metropolis, the map of Parks prepared using the digital atlas of Tabriz parks and Arc Map and IDRISI softwares. Then, quantitative information of spatial patterns of Tabriz parks provided using Fragstats software and a selection of landscape metrics including: the area of class, patch density, percentage of landscape, average patch size, average patch area, largest patch index, landscape shape index, average Euclidean distance of the nearest neighborhood and average index of patch shape. Then the spatial distribution, composition, extent and continuity of the parks was evaluated. Overall, only 8.5 percent of the landscape is assigned to the parks, and they are studied in three classes of neighborhood, district and regional parks. Neighborhood parks and green spaces have a better spatial distribution pattern compared to the other classes and the studied metrics showed better results for this class. In contrast, the quantitative results of the metrics calculated for regional parks, showed the most unfavorable spatial status for this class of parks among the three classes studied in Tabriz city.

Effects of vegetation patch density on flow velocity characteristics in an open channel

2018 ◽  
Vol 31 (5) ◽  
pp. 1052-1059 ◽  
Author(s):  
Wen-qi Li ◽  
Dan Wang ◽  
Jun-li Jiao ◽  
Ke-jun Yang
Keyword(s):  
Flow Velocity ◽  
Open Channel ◽  
Vegetation Patch ◽  
Patch Density

An initial assessment of bed destabilization risk past vegetation patches using instrumented particles

2021 ◽  
Author(s):  
Yi Xu ◽  
Valyrakis Manousos ◽  
Panagiotis Michalis
Keyword(s):  
Initial Assessment ◽  
Flow Structures ◽  
Clear Water ◽  
Flow Conditions ◽  
Flow Parameters ◽  
Water Conditions ◽  
The Mean ◽  
Acoustic Doppler Velocimetry ◽  
Patch Density ◽  
Vegetation Patches

<p>Instream vegetation may alter the mean and turbukent flow fields leading to destabilizing riverbed surface, under certain flow conditions. In particular, recent research on instream vegetation hydrodynamics and ecohydrogeomorphology has focused on how energetic flow structures and bulk flow parameters downstream a vegetation may result in riverbed destabilization. This study, demonstrated the application of a 20mm novel instrumented particle in recording entrainment rates downstream simulated vegetation patches of distinct densities, at various distances downstream these. A patch of 6mm acrilic cylinders is used to simulate the emergent vegetation having the same diameter (12cm) and different porosities or densities (void volume equal to 1.25%, 3.15%, 6.25%, 11.25%, and 17.25%). The flow velocity near the instrumented particle is recorded using acoustic Doppler velocimetry (ADV) with appropriate seeding, under clear water conditions. Preliminary results are presented with focus on the effect of vegetation patch density on the flow field and subsequent effects on particle entrainment rates and implications for bed surface destabilisation.</p>

Using Geospatial Techniques to Analyze Landscape Factors Controlling Ionic Composition of Arctic Lakes, Toolik Lake Region, Alaska

2012 ◽  
Vol 3 (3) ◽  
pp. 37-57 ◽  
Author(s):  
Prasad Pathak ◽  
Stephen Whalen
Keyword(s):  
Ionic Composition ◽  
Arctic Lakes ◽  
The Arctic ◽  
Geospatial Techniques ◽  
Arctic Alaska ◽  
Data Regression ◽  
Concentration Of Ions ◽  
Major Nutrients ◽  
Patch Density ◽  
Shape Complexity

The impacts of climate change on landscapes in arctic Alaska are evident in terms of permafrost melting, frequent thermokarst activity, and the occurrence of more broadleaf vegetation. These changes may alter natural biogeochemical cycles of ions along with major nutrients and affect ionic compositions of lakes, as they are connected with the landscapes. However, the nature of the connectivity between lakes and landscapes in this region is not yet explored. The authors propose that geospatial analysis of landscape properties along with observed lake ion concentrations will enable an understanding of the currently existing landscape controls over ion inputs into the lakes. For the watersheds of 41 lakes in the Arctic Foothills region of Alaska, spatial properties of natural vegetation communities expressed in terms of percentage, shape complexity, and patch density metrics were derived using satellite data. Regression analyses were performed for concentration of ions as well as conductivity in lake water where the spatial metrics along with lake physical properties, lake order, and glacial till age categories were used as predicting variables in the regression. Landscape metrics for major land covers i.e., Percentage of Moist Acidic Tundra (MAT) and Moist Non-acidic Tundra (MNT) were the major predicting variables for concentration of several ions.

scholarly journals Environmental heterogeneity decreases reproductive success via effects on foraging behaviour

2019 ◽  
Vol 286 (1904) ◽  
pp. 20190795 ◽  
Author(s):  
Alice M. Trevail ◽  
Jonathan A. Green ◽  
Jonathan Sharples ◽  
Jeff A. Polton ◽  
Peter I. Miller ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Environmental Heterogeneity ◽  
Optimal Foraging Theory ◽  
Gps Tracking ◽  
Heterogeneous Environments ◽  
Rissa Tridactyla ◽  
Distribution Of Resources ◽  
Resource Patches ◽  
Patch Density ◽  
The Cost

Environmental heterogeneity shapes the uneven distribution of resources available to foragers, and is ubiquitous in nature. Optimal foraging theory predicts that an animal's ability to exploit resource patches is key to foraging success. However, the potential fitness costs and benefits of foraging in a heterogeneous environment are difficult to measure empirically. Heterogeneity may provide higher-quality foraging opportunities, or alternatively could increase the cost of resource acquisition because of reduced patch density or increased competition. Here, we study the influence of physical environmental heterogeneity on behaviour and reproductive success of black-legged kittiwakes, Rissa tridactyla . From GPS tracking data at 15 colonies throughout their British and Irish range, we found that environments that were physically more heterogeneous were associated with longer trip duration, more time spent foraging while away from the colony, increased overlap of foraging areas between individuals and lower breeding success. These results suggest that there is greater competition between individuals for finite resources in more heterogeneous environments, which comes at a cost to reproduction. Resource hotspots are often considered beneficial, as individuals can learn to exploit them if sufficiently predictable. However, we demonstrate here that such fitness gains can be countered by greater competition in more heterogeneous environments.

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