Thesis subject

Impacts of roads and other infrastructure on biodiversity

Biodiversity is increasingly threatened by rapid infrastructure expansion and its associated ecological effects.

Infrastructure, such as roads, alter ecological conditions, cut through natural habitats, and consequently reduce populations of many wildlife species. The ecological impacts of infrastructure extend into the adjacent landscape (e.g., 'infrastructure-effect zone' ). The zone ranges from few hundred meters up to 50 km. As a result local species abundance decline in the proximity of infrastructure and increase with distance from the infrastructure until levelling off at a certain threshold distance. This decrease in population density varies by taxonomic group, with mammals being affected over larger distances than birds. Benítez-López et al (2010) identified the infrastructure-effect zones for bird and mammal populations using a meta-analytical approach of 49 studies and 90 datasets, including 201 bird species and 33 mammal species. These relationships have been used in a number of scientific publications, however, their full applicability in biodiversity assessments is limited by (a) geographical bias (88% studies coming from Europe and North America), b) taxonomic bias (only birds and mammals), (c) lack of differentiation between infrastructure types and habitat types, and (d) a lack of understanding of infrastructure-mediated effects on different functional groups. Therefore, an update of the wildlife abundance responses to proximity of infrastructure is needed.
Special attention should be given to broaden the geographical scope by including studies performed in Asia, Asian-Pacific, Africa, and South America. Some of these regions face expansion of transport and energy infrastructure driven by escalating demand for minerals, fossil fuels, timber and agricultural products. The addition of new species' data sets to the data used in Benitez-Lopez et al., would allow improving response functions as well as revealing the differences among habitat types (temperate forests, tropical forests, agricultural lands…), infrastructure types (highways, secondary roads, pipelines, wind parks), and functional groups.
Possible subtopics, all using systematic reviews and meta-analysis include (but are not restricted to):

- Update distance decay functions for mammals and birds using a species-specific approach (instead of a composite biodiversity indicator).

- Determine abundance-distance relationships for other taxa (reptiles, amphibians, invertebrates, plants).

- Determine specific distance decay functions for different types of habitat (agricultural lands, grasslands, temperate forests, tropical forests, arid and semi-arid lands...).

- Determine specific distance decay functions for different types of infrastructure

Benítez-López, A., Alkemade, R. & Verweij, P. A. The impacts of roads and other infrastructure on mammal and bird populations: a meta-analysis. (2010). Biological Conservation 143, 1307-1316