Remove trees and shrubs to recreate open areas of land
Overall effectiveness category Likely to be beneficial
Number of studies: 2
Background information and definitions
Through fire suppression, some forest areas have spread onto previously open ground or have developed denser understorey vegetation than was the case under natural fire regimes. To reduce fuel loads and restore more open habitats for mammalian herbivores, trees and shrubs may be removed. Specifically, this intervention includes studies where the intention is to recreate open areas on land onto which forest and scrub has spread.
For interventions that remove just limited vegetation layers within forests, or reduce tree density but leave forest cover, see Remove mid-storey vegetation in forest, Remove understorey vegetation in forest and Thin trees to reduce wildfire risk. For interventions looking to benefit mammals through management of longer-established forest, especially where these are carried out through timber harvesting operations, see Biological Resource Use.
Supporting evidence from individual studies
A controlled study in 1995–1997 at a former savanna in Texas, USA (Schnepf et al. 1998) found that where Ashe juniper Juniperus ashei trees were removed, there were higher abundances of three rodent species. Results were not tested for statistical significance. There were more white-ankled mice Peromyscus pectoralis in areas where Ashe juniper were cut (96 mice caught) than in areas where no trees were cut (10 caught). The same pattern was true for white-footed mouse Peromyscus leucopus (cut: 22 mice caught; uncut: 1 mouse) and for hispid cotton rat Sigmidon hispidus (cut: 4 rats caught; uncut: 0 rats). In 1995–1996, Ashe juniper in three areas was cut with a chainsaw. In two further areas, no trees were cut. In all areas, native oak trees Quercus spp. were left uncut. In October 1995–May 1996, once a month, 20 traps baited with oats were laid along a 100-m-long transect in one cut area and similarly in two areas that had not been cut. In October 1996 to March 1997, three to four times each month, three cut areas and two uncut areas were monitored in the same way. Traps were set in the morning and checked at dawn. Animals caught were ear-tagged to enable identification of recaptures.Study and other actions tested
A before-and-after, site comparison study in 1986–1991 of a mixed grassland, shrubland and woodland site in Utah, USA (Smith et al. 1999) found that removing ponderosa pine Pinus ponderosa and mountain mahogany Cercocarpus spp. trees increased use of these areas by Rocky Mountain bighorn sheep Ovis Canadensis. In areas where trees were removed, sheep activity increased by 165%, but in areas where no trees were cut, sheep activity declined by 45%. Across a 353-ha study area, 32% was clearcut, 49% was unmanaged and 18% was burned (results of burning treatment not present here). Sheep use patterns were assessed, before cutting or burning, from June 1986 to September 1988, by observing 25–30 radio-collared sheep daily. After burning and cutting, use was assessed in June–September 1991, by counting sheep, 62 times, from an 11-km transect.Study and other actions tested