Action: Use selective or reduced impact logging instead of conventional logging
Key messagesRead our guidance on Key messages before continuing
- Four studies evaluated the effects of using selective or reduced impact logging instead of conventional logging on bat populations. Two studies were in the Neotropics, one study was in Italy, and one in Germany.
COMMUNITY RESPONSE (1 STUDY)
- Community composition (1 study): One replicated, controlled, site comparison study in Trinidad found that the composition of bat species differed between selectively logged and conventionally logged forest.
- Richness/diversity (1 study): One replicated, site comparison study in Germany found similar bat diversity in selectively logged and conventionally logged forest.
POPULATION RESPONSE (3 STUDIES)
- Abundance (3 studies): One replicated, site comparison study in Germany found similar overall bat activity (relative abundance) in selectively logged and conventionally logged forest. A review of 41 studies in the Neotropics found that reduced impact logging had a smaller effect on bat abundance than conventional logging. One replicated, site comparison study in Italy found greater bat activity at two of three sites that used selective logging techniques to open up the forest canopy rather than leaving the canopy intact.
BEHAVIOUR (0 STUDIES)
Selective logging is the removal of selected trees within a forest based on criteria such as diameter, height or species. Remaining trees are left in the stand, as opposed to clearcutting where all trees are felled.
Reduced impact logging is a sustainable harvesting and management method that aims to minimize ecological disturbance. It involves selective logging as well as other practices such as directional tree felling, stream buffer zones, constructing roads, trails and landings to minimum widths, and methods to extract timber with minimal damage. One study on reduced impact logging has been included but the effects of selective logging cannot be separated from the other interventions used.
Supporting evidence from individual studies
A replicated, controlled, site comparison study in 2001–2002 of six tropical forest sites in Victoria-Mayaro Forest Reserve, Trinidad (Clarke et al. 2005) found that the composition of bat species differed between selectively logged forest, continuously logged forest and undisturbed forest. Fewer fruit-eating and gleaning animal-eating bat species were captured in selectively logged forest (fruit-eating: 352 bats of nine species; animal-eating: 25 bats of seven species) than in continuously logged forest (fruit-eating: 958 bats of 13 species; animal-eating: 52 bats of eight species). In undisturbed forest, fewer fruit-eating bats (282 bats of 10 species) and more animal-eating bats (71 bats of nine species) were captured than in either type of logged forest. In total, 38 bat species were captured (see original paper for data for individual species). Two sites were surveyed in each of three forest types: selectively logged forest (4–8 selected trees/ha felled in blocks of 150–300 ha), continuously logged forest (trees continuously felled creating an open canopy with fruit plants growing below) and undisturbed forest. At each of six sites, bats were captured at five sampling points using mist nets and harp traps for 6 h from sunset on two nights in 2001–2002.
A review in 2014 of 41 logging studies in the Neotropics (Bicknell et al. 2014) found that reduced impact logging had a smaller effect on bat abundance than conventional logging, even when conventional logging used similar harvesting intensities as reduced impact logging (≤30 m3/ha). The average effect sizes were lower for reduced impact logging than for conventional logging (data reported as statistical model results). Effect sizes were calculated from a meta-analysis of all available studies (n = 41) and included multiple species-level comparisons for each logging method (reduced impact logging: 88 comparisons, all conventional logging: 139 comparisons; conventional logging with harvesting intensity ≤30 m3/ha; 84 comparisons). All 41 studies used selective logging alongside other interventions typical of reduced-impact logging such as directional felling, winching of logs and careful planning of logging roads.
A replicated, site comparison study in 2014 in three mixed forest sites across Italy (Cistrone et al. 2015) found that ‘innovative’ selective logging resulted in greater bat activity than ‘traditional’ selective logging at two of three sites. Two sites had greater bat activity in ‘innovatively’ logged forest than ‘traditionally’ logged and unlogged forest (data reported as statistical model results). One site had similar bat activity in ‘innovatively’ and ‘traditionally’ logged forest but lower bat activity in unlogged forest (data reported as statistical model results). Nine bat species were recorded in total (see original paper for data for individual species). In the ‘innovatively’ logged forest, trees were selectively retained (40–80 trees/ha) according to their shape, dominance, position and quality, and adjacent trees were cut to create openings. In the ‘traditionally’ logged forest, understorey trees were selectively thinned every 20–30 years and the canopy left intact. Unlogged forest had not been logged for >20 years. At each of three sites, three plots (3–6 ha) were surveyed for each of three treatments (‘innovatively’ logged, ‘traditionally’ logged, unlogged). Each plot was surveyed three times in June–September 2014 for two consecutive nights. Bat detectors recorded bat activity for 8 h from 30 minutes before sunset.
A replicated, site comparison study in 2009–2010 of 43 forest sites in central Germany (Schall et al. 2018) found that selectively logged sites had similar overall bat activity and diversity to conventionally logged sites and unmanaged forest. There was no significant difference in overall bat activity (data reported as statistical model results) and bat diversity (data reported as diversity indices) between selectively logged sites, conventionally logged sites and unmanaged forest. Surveys were carried out in 13 selectively logged sites (uneven-aged forest with large diameter overstorey trees harvested every five years), 17 conventionally logged sites (even-aged forest stands of 4–8 ha harvested in rotation) and 13 forest sites unmanaged for 20–70 years. All sites were European beech Fagus sylvatica forest. Bats were monitored in 2009 and 2010 (details of methods not reported).
- Clarke F.M., Pio D.V. & Racey P.A. (2005) A comparison of logging systems and bat diversity in the Neotropics. Conservation Biology, 19, 1194-1204
- Bicknell J.E., Struebig M.J., Edwards D.P. & Davies Z.G. (2014) Improved timber harvest techniques maintain biodiversity in tropical forests. Conservation Biology, 19, R1119-R1120
- Cistrone L., Altea T., Matteucci G., Posillico M., De Cinti B. & Russo D. (2015) The effect of thinning on bat activity in Italian high forests: the LIFE+ "ManFor C.BD." experience. Hystrix, the Italian Journal of Mammalogy, 26, 125-131
- Schall P., Gossner M.M., Heinrichs S., Fischer M., Boch S., Prati D., Jung K., Baumgartner K., Blaser S., Böhm S., Buscot F., Daniel R., Goldmann K., Kaiser K., Kahl T., Lange M., Müller J., Overmann J., Renner S.C., Schulze E.-D., Sikorski J., Tschapka M., Türke M., Weisser W.W., Wemheuer B., Wubet T. & Ammer C. (2018) The impact of even-aged and uneven-aged forest management on regional biodiversity of multiple taxa in European beech forests. Journal of Applied Ecology, 55, 267-278