scholarly journals How linear features alter predator movement and the functional response

2012 ◽  
Vol 2 (2) ◽  
pp. 205-216 ◽  
Author(s):  
Hannah W. McKenzie ◽  
Evelyn H. Merrill ◽  
Raymond J. Spiteri ◽  
Mark A. Lewis

In areas of oil and gas exploration, seismic lines have been reported to alter the movement patterns of wolves ( Canis lupus ). We developed a mechanistic first passage time model, based on an anisotropic elliptic partial differential equation, and used this to explore how wolf movement responses to seismic lines influence the encounter rate of the wolves with their prey. The model was parametrized using 5 min GPS location data. These data showed that wolves travelled faster on seismic lines and had a higher probability of staying on a seismic line once they were on it. We simulated wolf movement on a range of seismic line densities and drew implications for the rate of predator–prey interactions as described by the functional response. The functional response exhibited a more than linear increase with respect to prey density (type III) as well as interactions with seismic line density. Encounter rates were significantly higher in landscapes with high seismic line density and were most pronounced at low prey densities. This suggests that prey at low population densities are at higher risk in environments with a high seismic line density unless they learn to avoid them.

Author(s):  
Natalie Packham ◽  
Lutz Schloegl ◽  
Wolfgang M. Schmidt

2021 ◽  
Author(s):  
Megan Schmidt ◽  
Scott J. Davidson ◽  
Maria Strack

Abstract Oil and gas exploration has resulted in over 300,000 km of linear disturbances known as seismic lines, throughout boreal peatlands across Canada. Sites are left with altered hydrologic and topographic conditions that prevent tree re-establishment. Restoration efforts have concentrated on tree recovery through mechanical mounding to re-create microtopography and support planted tree seedlings to block sightlines and deter predator use, but little is known about the impact of seismic line disturbance or restoration on peatland carbon cycling. This study looked at two mounding treatments and compared carbon dioxide and methane fluxes to untreated lines and natural reference areas in the first two years post-restoration. We found no significant differences in net ecosystem CO2 exchange, but untreated seismic lines were slightly more productive than natural reference areas and mounding treatments. Both restoration treatments increased ecosystem respiration, decreased net productivity by 6–21 gCO2m− 2d− 1, and created areas of increased methane emissions, including an increase in the contribution of ebullition, of up to 2000 mgCH4m− 2d− 1. Further research on this site to assess the longer-term impacts of restoration, as well as application on other sites with varied conditions, will help determine if these restoration practices are effective.


2013 ◽  
Vol 13 (12) ◽  
pp. 1871-1889 ◽  
Author(s):  
Natalie Packham ◽  
Lutz Schloegl ◽  
Wolfgang M. Schmidt

2002 ◽  
Vol 10 (1) ◽  
pp. 113-142
Author(s):  
In Joon Kim ◽  
Suk Joon Byun ◽  
Yuen Jung Park

This paper presents a numerical procedure for pricing collateralized bond obligations (CBO) and analyze the impact of default correlations for the prices of collateralized bond obligations. Specifically, we adopt default correlation model of Zhou (2001) and first passage time model of Black and Cox (1976). The model of Black and Cox is used for estimating the value of the firm and the volatility of the firm value which are unobservable variables. We find that the impact of default correlations on the prices of collateralized bond obligations is generally quite large. This can be tested by carrying out Monte-Carlo simulations for firm value processes, assuming first no default correlations and second modeling default correlations between the processes. We also compare the model prices and recently issued CBO market price and find that no default correlation model over prices the issued CBO and default correlation model under prices the issued CBO. These results in this paper emphasize that modeling default correlations is very important in analyzing CBO and a more complicated further analysis is required.


2011 ◽  
Vol 7 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Ruimin Xu ◽  
Paul D McNicholas ◽  
Anthony F Desmond ◽  
Gerarda A Darlington

Author(s):  
Natalie Packham ◽  
Lutz Schloegl ◽  
Wolfgang M. Schmidt

2010 ◽  
Author(s):  
Andre Bonfrer ◽  
George Knox ◽  
J. Eliashberg ◽  
Jeongwen Chiang

Sign in / Sign up

Export Citation Format

Share Document