Leave standing deadwood/snags in forests

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

  • One study evaluated the effects on mammals of leaving standing deadwood or snags in forests. This study was in the USA.



  • Abundance (1 study): A replicated, controlled study in the USA found that increasing the quantity of standing deadwood in forests increased the abundance of one of three shrew species, compared to removing deadwood.


About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A replicated, controlled study in 2007–2008 of three stands of loblolly pine Pinus taeda in South Carolina, USA (Davis et al. 2010) found that increasing the amount of forest standing deadwood increased the abundance of one of three shrew species compared to removing dead wood but not compared to in unmanipulated plots. More southeastern shrews Sorex longirostris were caught in plots with increased standing deadwood quantities (0.046 shrews/m of drift fence) than in plots cleared of fallen debris (0.013). Neither treatment differed significantly from the quantity in unmanipulated plots (0.026). There were no significant differences between treatments for southern short-tailed shrew Blarina carolinensis (standing deadwood: 0.069 shrews/m of drift fence; debris cleared: 0.051; unmanipulated: 0.058) or North American least shrew Cryptotis parva (standing deadwood: 0.004 shrews/m of drift fence; debris cleared: 0.014; unmanipulated: 0.015). Three plots, each 9.3 ha, were located in each of three loblolly pine stands, planted in 1950–1953. In each stand, standing deadwood quantities were increased tenfold in one plot in 2001, by ringbarking and injecting herbicide into trees, in another plot woody debris ≥10 cm across and ≥60-cm long was removed annually from 1996 and one plot was unmanipulated. Shrews were sampled across plots for 14 days, on seven occasions, from January 2007 to August 2008. Shrews were caught in 19-l plastic buckets, connected by drift fencing.

    Study and other actions tested
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.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

Terrestrial Mammal Conservation

This Action forms part of the Action Synopsis:

Terrestrial Mammal Conservation
Terrestrial Mammal Conservation

Terrestrial Mammal Conservation - Published 2020

Terrestrial Mammal Conservation

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