Spatial ecology in a changing world

New article: Modelling bird species distribution change in fire prone Mediterranean landscapes.


In this new article published in the journal Ecography, ECO-LAND members lab, in collaboration with Andrew Fall and Marie-Josée Fortin, present the development of new tools to model the distribution changes of species in dynamic  landscapes driven by perturbations such as fire. These developments are framed in the context of the projects BIOPRED, MONTES and SCALES.

The modelling approach links the fire landscape model MEDFIRE and a spatially explicit population model accounting for dispersal constraints and population processes.

Species distribution models (SDMs) have traditionally been founded on the assumption that species distributions are in equilibrium with environmental conditions and that these species–environment relationships can be used to estimate species responses to environmental changes. Insight into the validity of this assumption can be obtained from comparing the performance of correlative species distribution models with more complex hybrid approaches accounting for mismatches between habitat suitability and species occupancy patterns.

Here we compared the ability of correlative SDMs and hybrid models, which can accommodate non-equilibrium situations arising from dispersal constraints, to reproduce the distribution dynamics of the
ortolan bunting Emberiza hortulana in highly dynamic, early successional, fire driven Mediterranean landscapes. Whereas, habitat availability was derived from a correlative statistical SDM, occupancy was modelled using a hybrid approach combining a grid-based, spatially-explicit population model that explicitly included bird dispersal with the correlative model.

We compared species occupancy patterns under the equilibrium assumption and different scenarios of species dispersal capabilities. To evaluate the predictive capability of the different models, we used independent species data collected in areas affected to different degree by fires. In accordance with the view that disturbance leads to a disparity between the suitable habitat and the occupancy patterns of the ortolan bunting, our results indicated that hybrid modelling approaches were superior to correlative models in predicting species spatial dynamics. Furthermore, hybrid models that incorporated short dispersal distances were more likely to reproduce the observed changes in ortolan bunting distribution patterns, suggesting that dispersal plays a key role in limiting the colonization of recently burnt areas.

We conclude that SDMs used in a dynamic context can be significantly improved by using combined hybrid modelling approaches that explicitly account for interactions between key ecological constraints such as dispersal and habitat suitability that drive species response to environmental changes.


Modelització dinàmica de la distribució d’espècies en paisatges afectats pel foc

En aquest nou article publicat a la revista Ecography, membres d’ECO-LAND, en col.laboració amb Andrew Fall i Marie-Josée Fortin, presenten el desenvolupament de noves eines per modelitzar els canvis en la disribució de les espècies en paisatges dinàmics afectats pels grans incendis forestals. Aquests desenvolupaments s’han dut a terme en el marc dels projectes BIOPRED, MONTES and SCALES.

Aquest article és el primer del grup que utilitza el model de dinàmica de paisatge i incendis forestals (MEDFIRE) i enllaça els seus resultats and models poblacionals espacialment explíctis en els que s’inclouen procesos poblacionals i les limitacions que la dispersió imposa a la colonització de nous hàbitats per part de les espècies.

Brotons L, De Cáceres M, Fall A, Fortin MJ (2012) Incorporating species dispersal and landscape dynamics to the modeling of bird species distribution changes in fire prone mediterranean landscapes. Ecography, in press.

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