Changes in mesopredator-community structure in response to urbanization

2004 ◽  
Vol 82 (11) ◽  
pp. 1804-1817 ◽  
Author(s):  
Suzanne Prange ◽  
Stanley D Gehrt

Common raccoons (Procyon lotor (L., 1758)), Virginia opossums (Didelphis virginiana Kerr, 1792), and striped skunks (Mephitis mephitis (Schreber, 1776)) are common urban inhabitants, yet their relative demographic response to urbanization is unknown. Urbanization often affects community structure, and understanding these effects is essential in rapidly changing landscapes. We examined mesopredator-community structure in small and large patches of natural habitat surrounded by urban, suburban, or rural matrices. We created generalized logit models using road-survey and livetrapping data to examine effects of surrounding land use on proportions of opossums and skunks relative to raccoons, while accounting for effects of season and year and their interactions. For large sites, the land use × season model was chosen for both data sets, and occurrence of opossums and skunks relative to raccoons was higher at the rural site (P < 0.001 for all tests). For small sites, the land-use model best fit the road-survey data, with a higher occurrence of skunks relative to raccoons at the rural site (χ2 = 21.06, df = 1, P < 0.001). However, the season model best fit the trapping data for small sites. Our data indicated that raccoons exhibited a greater demographic response to urbanization, suggesting that they exploit anthropogenic resources more efficiently. Although numerous reasons exist for disparity in anthropogenic-resource use, differences in intraspecific tolerance and the role of learning in foraging behaviors were best supported by our observations.

Insects ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 306
Author(s):  
Vinicio Carrión-Paladines ◽  
Andreas Fries ◽  
Andrés Muñoz ◽  
Eddy Castillo ◽  
Roberto García-Ruiz ◽  
...  

This study evaluated the effects of land-use change (L-UCH) on dung beetle community structure (Scarabaeinae) in a disturbed dry ecosystem in southern Ecuador. Five different L-UCH classes were analyzed by capturing the dung beetle species at each site using 120 pitfall traps in total. To determine dung beetle abundance and diversity at each L-UCH, a general linear model (GLM) and a redundancy analysis (RDA) were applied, which correlated environmental and edaphic conditions to the community structure. Furthermore, changes in dung-producing vertebrate fauna were examined, which varied significantly between the different L-UCH classes due to the specific anthropogenic use or level of ecosystem disturbance. The results indicated that soil organic matter, pH, potassium, and phosphorus (RDA: component 1), as well as temperature and altitude (RDA: component 2) significantly affect the abundance of beetles (GLM: p value < 0.001), besides the food availability (dung). The highest abundance and diversity (Simpson’s index > 0.4, Shannon-Wiener index > 1.10) was found in highly disturbed sites, where soils were generally more compacted, but with a greater food supply due to the introduced farm animals. At highly disturbed sites, the species Canthon balteatus, Dichotomius problematicus, and Onthphagus confuses were found specifically, which makes them useful as bio-indicators for disturbed dry forest ecosystems in southern Ecuador.


2021 ◽  
Vol 10 (3) ◽  
pp. 149
Author(s):  
Nuno Pinto ◽  
António P. Antunes ◽  
Josep Roca

Cellular automata (CA) models have been used in urban studies for dealing with land use change. Transport and accessibility are arguably the main drivers of urban change and have a direct influence on land use. Land use and transport interaction models deal with the complexity of this relationship using many different approaches. CA models incorporate these drivers, but usually consider transport (and accessibility) variables as exogenous. Our paper presents a CA model where transport variables are endogenous to the model and are calibrated along with the land use variables to capture the interdependent complexity of these phenomena. The model uses irregular cells and a variable neighborhood to simulate land use change, taking into account the effect of the road network. Calibration is performed through a particle swarm algorithm. We present an application of the model to a comparison of scenarios for the construction of a ring road in the city of Coimbra, Portugal. The results show the ability of the CA model to capture the influence of change of the transport network (and thus in accessibility) in the land use dynamics.


2016 ◽  
Vol 8 (3) ◽  
pp. 94 ◽  
Author(s):  
Mouhamadou A.M.T. Bald ◽  
Babacar M. Ndiaye

Our paper deals with the Transportation Network and Land Use (TNLU) problem.  It consists in finding, simultaneously, the best location of urban area activities, as well as of the road network design that may minimize the moving cost in the network, and the network costs. We propose a new mixed integer programming formulation of the problem, and a new heuristic method for the resolution of TNLU. Then, we give a methodology to find locations or relocations of some Dakar region amenities (home, shop, work and leisure places), that may reduce travel time or travel distance. The proposed methodology mixes multi-agent simulation with combinatorial optimization techniques; that is individual agent strategies versus global optimization using Geographical Information System. Numerical results which show the effectiveness of the method,  and simulations based on the scenario of Dakar city are given.


2019 ◽  
Vol 77 ◽  
pp. 1-18
Author(s):  
Julien Carlier ◽  
James Moran

Across Europe, Greenways upcycle disused railway infrastructure into non-motorised public infrastructure, often with limited consideration to potential ecological synergies. Pre-development, disused transport corridors become relatively undisturbed and potentially host diverse semi-natural habitats. The study objectives were 1) to produce a highly detailed and accurate dataset using remote sensing with rapid assessment techniques for ground truthing and 2) subsequently examine habitat diversity existing along a proposed Greenway. A 7000 ha study corridor was based on a disused railway proposed as a transfrontier Greenway connecting the Republic of Ireland and the United Kingdom. The study applied a rapid-assessment virtual validation techniquealongside remote sensing and accuracy assessment. Inter-relationship between seminatural habitat diversity and land-use intensification was examined. Remote sensing accuracies of 89% and 99% for a real and linear habitat classification were obtained. Degrees of land-use intensification were observed throughout the corridor, highlighting the importance of maintaining and enhancing remaining semi-natural habitat that exists along the proposed Greenway route. Through understanding the landscape matrix composition and semi-natural habitat diversity, European Greenwayscan achieve multi-functionality for ecosystem conservation, forming integral components of Green Infrastructure.


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