Action: Create tree plantations on agricultural land to provide roosting and foraging habitat for bats
- Three studies evaluated the effects of creating tree plantations on agricultural land to provide roosting and foraging habitat for bats on bat populations. The three studies were in Australia.
COMMUNITY RESPONSE (3 STUDIES)
- Richness/diversity (3 studies): Three replicated, site comparison studies in Australia found no difference in the number of bat species in agricultural areas with and without plantations of native trees.
POPULATION RESPONSE (3 STUDIES)
- Abundance (3 studies): Two of three replicated, site comparison studies in Australia found no difference in bat activity (relative abundance) in agricultural areas with and without plantations of native trees. The other study found higher bat activity in plantations next to remnant native vegetation than in isolated plantations or over grazing land. In all three studies, bat activity was lower in plantations compared to original forest and woodland remnants.
USAGE (0 STUDIES)
Creating tree plantations on agricultural land may replace lost roosting and foraging habitat for bats. For evidence relating to planting single or scattered trees, see ‘Plant in-field trees’. For an intervention relating to planting trees to shade crops as part of agroforestry farming systems, see ‘Retain or plant native trees and shrubs amongst crops (agroforestry)’. For studies that may carry out this intervention alongside other interventions to benefit bats on farmland, see ‘Introduce agri-environment schemes’.
Supporting evidence from individual studies
A replicated, site comparison study in 1999 of four agricultural sites planted with native bluegum Eucalyptus globulus in Western Australia (Hobbs et al 2003) found that tree plantations next to remnant vegetation had higher overall bat activity than isolated plantations or agricultural grazing land, but the number of bat species was similar. More bat passes were recorded in plantations next to remnant vegetation (52 bat passes) than in plantations isolated from remnant vegetation (4 bat passes) or over agricultural grazing land (14 bat passes), although no statistical tests were carried out. Bat activity was highest in remnants of original vegetation (75 bat passes). Similar numbers of bat species (2–4) were recorded in plantations and grazing land. Eight bat species were recorded in total (see original reference for data for individual species). All four sites had farm forestry plantations (4–6 years old), remnants of original native vegetation, and open grazing land. At each of four sites, one location within each of four habitats (plantations next to remnants, isolated plantations, grazing land, and remnant vegetation) was sampled with a bat detector for one full night in October 1999.
A replicated, site comparison study in 2002 of 120 sites in an agricultural area in New South Wales and Victoria, Australia (Law & Chidel 2006) found that sites planted with native Eucalypt spp. trees had similar overall bat activity and a similar number of bat species as treeless grazed paddocks. Bat activity and the number of bat species did not differ significantly between plantations (average 87 bat passes/night, 5–7 species) and treeless grazed paddocks (50 bat passes/night, 5 species). Bat activity was significantly lower in plantations than in remnants of original forest (302 bat passes/night), but the number of bat species was similar (7 species in remnants). Eleven bat species were recorded in total (see original reference for data for individual species). Grazing land with small remnants of forest had been planted with native tree species from the mid-1970s to 1991. Twelve treatments were sampled including different shapes or sizes (narrow, small, medium, large, very large) and ages (<10 or >10 years old) of plantations and remnant forest, and grazed paddocks with and without trees. For each of 12 treatments, 10 points were sampled with bat detectors for one full night in November–December 2002.
A replicated, site comparison study in 2006–2007 at 14 farms in New South Wales, Australia (Law et al 2011) found that tree plantations on agricultural land had similar bat activity and species richness as treeless paddocks, and lower bat activity, species richness and numbers of roosts than remnant native woodlands. Bat activity and the number of bat species recorded was similar between plantations (87 bat passes/night, 6–8 species) and paddocks (40 passes/night, 7 species), but higher in remnant woodland (650 bat passes/night, 10 species), although no statistical tests were carried out. Species composition was also similar in plantations and paddocks but differed in remnant woodland (data reported as results of statistical models). Twenty-eight bat roosts were identified in remnant trees, but none in plantations. Twelve bat species were recorded in total (see original reference for data for individual species). Forty-four sites were surveyed across 14 farms (11 in remnant woodland, 27 in plantations, six in treeless paddocks). Plantations (2–40 ha) consisted of 1–4 Eucalyptus spp. and were 4–5 or 10 years old. Each of 44 sites was surveyed for two consecutive nights/site in September 2006 and February 2007. Ten bats were caught in harp traps and radiotracked in late summer and spring 2008 at three farms.
- Hobbs R., Catling P.C., Wombey J.C., Clayton M., Atkins L. & Reid A. (2003) Faunal use of bluegum (Eucalyptus globulus) plantations in southwestern Australia. Agroforestry Systems, 58, 195-212
- Law B.S. & Chidel M. (2006) Eucalypt plantings on farms: Use by insectivorous bats in south-eastern Australia. Biological Conservation, 133, 236-249
- Law B.S., Chidel M. & Penman T. (2011) Do young eucalypt plantations benefit bats in an intensive agricultural landscape? Wildlife Research, 38, 173-187