What size is a biologically relevant landscape?
- 1.6k Downloads
The spatial extent at which landscape structure best predicts population response, called the scale of effect, varies across species. An ability to predict the scale of effect of a landscape using species traits would make landscape study design more efficient and would enable landscape managers to plan at the appropriate scale. We used an individual based simulation model to predict how species traits influence the scale of effect. Specifically, we tested the effects of dispersal distance, reproductive rate, and informed movement behavior on the radius at which percent habitat cover best predicts population abundance in a focal area. Scale of effect for species with random movement behavior was compared to scale of effect for species with three (cumulative) levels of information use during dispersal: habitat based settlement, conspecific density based settlement, and gap-avoidance during movement. Consistent with a common belief among researchers, dispersal distance had a strong, positive influence on scale of effect. A general guideline for empiricists is to expect the radius of a landscape to be 4–9 times the median dispersal distance or 0.3–0.5 times the maximum dispersal distance of a species. Informed dispersal led to greater increases in population size than did increased reproductive rate. Similarly, informed dispersal led to more strongly decreased scales of effect than did reproductive rate. Most notably, gap-avoidance resulted in scales that were 0.2–0.5 times those of non-avoidant species. This is the first study to generate testable hypotheses concerning the mechanisms underlying the scale at which populations respond to the landscape.
KeywordsLandscape context Spatial scale Habitat fragmentation Focal patch Buffer Informed dispersal Habitat selection Edge-mediated dispersal Boundary behavior
We thank Lutz Tischendorf for his modelling suggestions and for his assistance with NetLogo. This work was supported by Natural Sciences and Engineering Research Council of Canada (NSERC) grants to LF. We thank Nathan Jackson and three anonymous reviewers for their helpful suggestions.
- Brennan JM, Bender DJ, Contreras TA, Fahrig L (2002) Focal patch landscape studies for wildlife management: optimizing sampling effort across scales. In: Liu J, Taylor WW (eds) Integrating landscape ecology into natural resource management. Cambridge University Press, CambridgeGoogle Scholar
- Burnham KP, Anderson DR (2002) Model selection and inference: a practical information-theoretic approach. Springer, New YorkGoogle Scholar
- Okubo A (1980) Diffusion and ecological problems: mathematical models. Springer, New YorkGoogle Scholar
- Ritchie ME (2010) Scale, heterogeneity, and the structure and diversity of ecological communities. Princeton University Press, PrincetonGoogle Scholar
- Tischendorf L, Grez A, Zaviezo T, Fahrig L (2005) Mechanisms affecting population density in fragmented habitat. Ecol Soc 10:13Google Scholar
- Tittler R (2008) Source–sink dynamics, dispersal, and landscape effects on North American songbirds. Dissertation, Carleton University, OttawaGoogle Scholar
- Turchin P (1998) Quantitative analysis of movement: measuring and modeling population redistribution in animals and plants. Sinauer Associates, Inc., SunderlandGoogle Scholar
- Wilensky U (1999) Netlogo. http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston