How Important Are Resistance, Dispersal Ability, Population Density and Mortality in Temporally Dynamic Simulations of Population Connectivity? A Case Study of Tigers in Southeast Asia

Eric Ash,Żaneta Kaszta,Tim Redford,David W Macdonald,Samuel A Cushman

doi:10.3390/land9110415

Eric Ash, Żaneta Kaszta + Show 3 more

Open Access

https://doi.org/10.3390/land9110415

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Abstract

Development of landscape connectivity and spatial population models is challenging, given the uncertainty of parameters and the sensitivity of models to factors and their interactions over time. Using spatially and temporally explicit simulations, we evaluate the sensitivity of population distribution, abundance and connectivity of tigers in Southeast Asia to variations of resistance surface, dispersal ability, population density and mortality. Utilizing a temporally dynamic cumulative resistant kernel approach, we tested (1) effects and interactions of parameters on predicted population size, distribution and connectivity, and (2) displacement and divergence in scenarios across timesteps. We evaluated the effect of varying levels of factors on simulated population, cumulative resistance kernel extent, and kernel sum across nine timesteps, producing 24,300 simulations. We demonstrate that predicted population, range shifts, and landscape connectivity are highly sensitive to parameter values with significant interactions and relative strength of effects varying by timestep. Dispersal ability, mortality risk and their interaction dominated predictions. Further, population density had intermediate effects, landscape resistance had relatively low impacts, and mitigation of linear barriers (highways) via lowered resistance had little relative effect. Results are relevant to regional, long-term tiger population management, providing insight into potential population growth and range expansion across a landscape of global conservation priority.

Highlights

Population dynamics are the result of the interplay between birth, death, immigration and emigration
For the purposes of evaluating dispersal from the source population in Dong Phayayen-Khao Yai forest complex (DPKY), we summarized the frequency of simulations in which source points were generated in Khao Yai National Park (KYNP) in the western section of DPKY, Cambodia, and Laos
While similar dominant effects of dispersal ability on connectivity predictions were previously reported by several studies (e.g., [9,10,20]), less attention has been directed to the effect of spatially differential mortality risk on population size and connectivity [11,12,15]

Summary

Introduction

Population dynamics are the result of the interplay between birth, death, immigration and emigration. Explicit population models typically have adopted a metapopulation framework [3]. In which a network of populations interact through dispersal. In many cases, populations are better characterized as gradient systems of differential density, mortality, dispersal and other factors across heterogeneous landscapes [4]. Land 2020, 9, 415 through space and time in response to spatially varying habitat quality gradients, patterns of mortality risk, and how landscape features drive movement and dispersal. Accounting for temporally dynamic interactions among spatially explicit patterns of habitat quality, mortality rates and dispersal is a deeply challenging task [5,6]

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Conclusion