Aurora Torres, Jochen A. G. Jaeger, and Juan Carlos Alonso

ECOLOGY

Significance

Nature is increasingly threatened by rapid infrastructure expansion. For the first time, to our knowledge, we quantify the high pervasiveness of transportation infrastructure in all European countries. Unfortunately, spatial definition of the areas ecologically affected by infrastructure at large scales is complicated. Thus, we present a method for assessing the spatial extent of the impacts on birds and mammals at regional and national scales. As an illustration, its application to Spain shows that most of the country is affected, predicting moderate and severe declines for birds and mammals, respectively. The lack of areas that could be used as controls implies that scientists may no longer be able to measure the magnitude of road effects on wide-ranging mammals in most of Europe.

Abstract

Habitat loss and deterioration represent the main threats to wildlife species, and are closely linked to the expansion of roads and human settlements. Unfortunately, large-scale effects of these structures remain generally overlooked. Here, we analyzed the European transportation infrastructure network and found that 50% of the continent is within 1.5 km of transportation infrastructure. We present a method for assessing the impacts from infrastructure on wildlife, based on functional response curves describing density reductions in birds and mammals (e.g., road-effect zones), and apply it to Spain as a case study. The imprint of infrastructure extends over most of the country (55.5% in the case of birds and 97.9% for mammals), with moderate declines predicted for birds (22.6% of individuals) and severe declines predicted for mammals (46.6%). Despite certain limitations, we suggest the approach proposed is widely applicable to the evaluation of effects of planned infrastructure developments under multiple scenarios, and propose an internationally coordinated strategy to update and improve it in the future.

See: http://www.pnas.org/content/113/30/8472.full

PNAS July 26, vol.113; no.30: 8472–8477

Fig. 4.

Level of exposure to human infrastructure varies throughout a species’ distribution, which we illustrate by considering the distributions of six emblematic species of the Mediterranean fauna. The bars (Left, y axis) indicate the proportions of each species’ distribution found within each 500-m distance band to transport infrastructure (x axis), whereas the blue dots (Right, y axis) indicate the prevalence for each band (i.e., the ratio between the number of cells in which the species was present divided by the total number of cells available at such distances in peninsular Spain).