Action: Restore or create savannas
Key messagesRead our guidance on Key messages before continuing
- Two studies evaluated the effects on mammals of restoring or creating savannas. One study was in Senegal and one was in the USA.
COMMUNITY RESPONSE (1 STUDY)
- Richness/diversity (1 study): A replicated, randomized, paired sites, controlled study in the USA found that restoring savannas by removing trees increased small mammal diversity.
POPULATION RESPONSE (2 STUDIES)
- Abundance (2 studies): A study in Senegal found that in a population of dorcas gazelle translocated into a fenced enclosure where vegetation had been restored, births outnumbered deaths. A replicated, randomized, paired sites, controlled study in the USA found that restoring savannas by removing trees did not, in most cases, change small mammal abundance.
BEHAVIOUR (0 STUDIES)
Through under-grazing or burning suppression, savannah vegetation can revert to denser scrubland. Restoring savanna may benefit mammals typically associated with the habitat.
See also: Restore or create grassland.
Supporting evidence from individual studies
A study in 2009–2013 in a savanna site in Katané, Senegal (Abáigar et al. 2016) found that in a population of dorcas gazelle Gazella dorcas neglecta translocated into a fenced enclosure where vegetation had been restored, births outnumbered deaths. It is not clear whether these effects were a direct result of vegetation restoration or translocation into a fenced area. Over four years after release, more births (31) than deaths (4) of dorcas gazelles were recorded. Twenty-three (nine male and 14 female) dorcas gazelles were translocated between two reserves in northern Senegal in March 2009. Vegetation was restored prior to the translocation but no details regarding the restoration are provided. Gazelles were released into a 440-ha fenced enclosure that was enlarged to 640 ha in 2010. The translocated dorcas gazelles shared the enclosure with scimitar-horned oryx Oryx dammah, mhorr gazelle Nanger dama mhorr and red-fronted gazelle Eudorcas rufifrons. The enclosure fence was not impermeable to small-to-medium sized animals, including predators. Dorcas gazelles were ear-tagged and monitored from June 2009 to March 2013.
A replicated, randomized, paired sites, controlled study in 2008–2013 in five areas in a former oak savanna in Michigan, USA (Larsen et al. 2016) found that restoring savannas by removing trees resulted in no change in small mammal abundance in 18 of 21 comparisons, but that small mammal diversity increased. After five years, in 18 of 21 comparisons small mammal abundance did not differ between areas where trees were removed (0.0–4.2 animals/area) and areas where trees were retained (0.0–0.6 animals/area). However, in three of 21 comparisons there were more small mammals (trees removed: 1.8–4.6 animals/area; trees retained: 0.0–1.8 animals/area). Small mammal diversity increased where trees were removed, but it declined where trees were retained (data reported as model results). In June–July 2008, five 3.2-ha blocks, each comprising four 0.8-ha plots, were designated. In each block, trees were removed from three plots and retained in one plot. In July 2010 the entire area was burnt in a prescribed burn. Once a year, in October 2008–July 2013, nine live traps baited with sunflower seeds were placed in each plot. Traps were set at 17:00–20:00 and checked at 6:00–11:00. Captured animals were individually marked to enable identification of re-captures.
- Abáigar T., Cano M., Djigo C.A.T., Gomis J., Sarr T., Youm B., Fernandez-Bellon H. & Ensenyat C. (2016) Social organization and demography of reintroduced Dorcas gazelle (Gazelle dorcas neglecta) in North Ferlo Fauna Reserve, Senegal. Mammalia, 80, 593-600
- Larsen A.L., Jacquot J.J., Keenlance P.W. & Keough H.L. (2016) Effects of an ongoing oak savanna restoration on small mammals in Lower Michigan. Forest Ecology and Management, 367, 120-127