Internal fragmentation: the effects of roads, highways and powerline clearings on movements and mortality of rainforest vertebrates

Goosem, Miriam (1997) Internal fragmentation: the effects of roads, highways and powerline clearings on movements and mortality of rainforest vertebrates. In: Laurance, William F., and Bierregaard, Richard O., (eds.) Tropical Forest Remnants: ecology, management, and conservation of fragmented communities. University of Chicago Press, Chicago, IL, USA, pp. 241-255.

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General Implications:

1. Linear environmental discontinuities such as roads and powerlines may fragment rainforest wildlife populations. Arboreal species and those of the rainforest understory and ground layer are most likely to be affected.

2. The mobility and behavioural characteristics of species, particularly those relating to open-space avoidance, largely determine the magnitude of the linear barrier effect. In contrast, species that do not avoid open space may be prone to road mortality or predation along roads.

3. As the width of the linear clearing increases, road-crossing attempts by many rainforest species rapidly decline. Eventually, clearings are likely to form a complete or almost complete barrier, apart from rare stochastic crossings.

4. In clearings wide enough to support grassy swaths, the presence of a distinctive grassland faunal community may compound structural and microclimatic differences to result in almost complete exclusion of rainforest species.

5. To mitigate fragmentation effects of rainforest roads and highways, the widths should be minimised, particularly near streams and gullies, where many species attempt to cross.

6. Canopy connectivity above a road should be maintained wherever possible to provide potential crossing points for arboreal species. In addition, the presence of some canopy cover produces a microclimate on the road surface that is somewhat similar to that of the adjacent rainforest, and provides some cover for understory species attempting to cross.

7. Underpasses and culverts form crossing routes for a number of rainforest mammals and other vertebrates. A range of sizes and designs of culverts may increase their utility as faunal crossing routes.

8. Allowing rainforest regrowth to develop along powerline clearings clearly helps to mitigate the barrier effects of these clearings for small mammals.

9. The effects of new powerlines can be reduced by clearing only tower footprints, and subsequently maintaining the powerline by helicopter. Alternatively, strips of forest can be retained in gullies along the powerline route.

10. When planning for new roads and powerlines, resource managers should strive to avoid critical habitats for rare or threatened species as well as areas of high biological diversity and abundance.

Item ID: 35245
Item Type: Book Chapter (Research - B1)
ISBN: 978-0-226-46899-0
Keywords: fragmentation; roads; highways; powerline clearings; habitat loss and alteration; edge effects; disturbance; invasions; linear barrier effect; road mortality
Funders: Wet Tropics Management Authority, Queensland Electricity Commission
Date Deposited: 13 Oct 2014 01:16
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050205 Environmental Management @ 25%
05 ENVIRONMENTAL SCIENCES > 0501 Ecological Applications > 050104 Landscape Ecology @ 25%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050211 Wildlife and Habitat Management @ 50%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960505 Ecosystem Assessment and Management of Forest and Woodlands Environments @ 50%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 25%
96 ENVIRONMENT > 9613 Remnant Vegetation and Protected Conservation Areas > 961306 Remnant Vegetation and Protected Conservation Areas in Forest and Woodlands Environments @ 25%
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