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Providing evidence to improve practice

Action: Remove/control non-native plants Terrestrial Mammal Conservation

Key messages

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  • Two studies evaluated the effects on mammals of removing or controlling non-native invasive plants. Both studies were in the USA.


  • Richness/diversity (1 study): A replicated study in the USA found that control of introduced saltcedar did not change small mammal species richness.


  • Abundance (1 study): A site comparison study in the USA found that partial removal of velvet mesquite did not increase abundances of six mammal species.


Supporting evidence from individual studies


A site comparison study in 1976–1978 in three desert sites in Arizona, USA (Germano et al. 1983) found that partial removal of velvet mesquite Prosopis juliflora var. velutina did not increase abundances of six mammal species, and complete removal reduced the abundance of two species. The abundance of black-tailed jackrabbits Lepus californicus was higher in the undisturbed (0.37/km) and partially cleared mesquite sites (0.36/km) than in the cleared, mesquite-free, site (0.06/km). The same pattern held for antelope jackrabbit Lepus alleni (0.37 and 0.56 vs 0.09/km). However, abundances were similar in the undisturbed, partially and fully cleared sites for desert mule deer Odocoileus hemionus crooki (0.30, 0.24 and 0.16/km), javelina Dicotyles tajacu (0.24, 0.15 and 0.00/km), coyote Canis latrans (0.05, 0.06 and 0.01/km) and desert cottontail Sylvilagus audubonii (0.04, 0.02 and 0.03/km). Mesquite was cleared from one 300 ha site in 1955 using diesel oil, and partially removed from a second 300 ha site by clearing seven 2.8–30.4 ha patches by chaining in July 1976. At the third 300 ha site, mesquite was left undisturbed. Mammals were counted monthly along four 1,200-m transects between September 1976 and June 1978.


A replicated study in 2001–2012 in three sites in Nevada, USA (Longland 2014) found that control of introduced saltcedar Tamarix ramosissima, did not change small mammal species richness. Ten years after saltcedar control commenced, small mammal species richness (3–6 species) was similar to that when control started (3–7 species). Small mammals were trapped annually in May or June for three consecutive nights between 2001 and 2011–2012 at three sites along waterways. An additional trapping period of three nights was conducted in July or August 2001–2004 at one site, and 2001–2006 at two sites. Each night at each site, 2–4 parallel rows of 25 Sherman® live traps, baited with wild birdseed mix, were set with 10 m between traps and 25–100 m between rows. Saltcedar was controlled by leaf beetles Diorhabda spp. released at the sites in 2001–2002.

Referenced papers

Please cite as:

Littlewood, N.A., Rocha, R., Smith, R.K., Martin, P.A., Lockhart, S.L., Schoonover, R.F., Wilman, E., Bladon, A.J., Sainsbury, K.A., Pimm S. and Sutherland, W.J. (2020) Terrestrial Mammal Conservation: Global Evidence for the Effects of Interventions for terrestrial mammals excluding bats and primates. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.