Leave standing deadwood/snags in forests

Overall effectiveness category Unlikely to be beneficial
Number of studies: 4
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How is the evidence assessed?

Effectiveness

5%
Certainty

58%
Harms

2%

Calculating overall effectiveness category

Background information and definitions

Snags or standing dead trees and other dead wood can provide shelter for amphibians within forest. Retaining these within clearcut forest may help to maintain amphibian populations.

Studies investigating the effect of leaving coarse woody debris during harvest are discussed in ‘Leave course woody debris in forests’.

Study locations

Key messages

One randomized, replicated, controlled, before-and-after study in the USA found that compared to total clearcutting, leaving dead or wildlife trees did not result in higher abundances of salamanders.
Two studies (including one randomized, replicated, controlled, before-and-after study) in the USA found that compared to no harvesting, leaving dead or wildlife trees during clearcutting did not prevent a decrease in salamander abundance or change in species composition.
One randomized, replicated, controlled study in the USA found that numbers of amphibian species and abundance were similar with removal or creation of dead trees within forest.
One randomized, replicated, controlled, before-and-after study in the USA found that compared to unharvested plots, the proportion of female salamanders carrying eggs, eggs per female or proportion of juveniles were similar or lower in harvested plots that included plots where dead and wildlife trees were left during clearcutting, depending on species and time since harvest.

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

A controlled, before-and-after study in 1994–1997 in a hardwood forest in Virginia, USA (Harpole & Haas 1999) found that retaining up to 12 wildlife and dead trees during a clear-cut did not prevent a decrease in the relative abundance of salamanders. Captures decreased significantly after treatment (before: 10; one year after: 7; three years: 1/search). Abundance did not differ within the unharvested plot (before: 10; one year after: 10; three years: 8). Treatments were on 2 ha plots. Salamanders were monitored along 2 x 15 m transects with artificial cover objects (50/plot).
Study and other actions tested
Referenced paper
Harpole D.N. & Haas C.A. (1999) Effects of seven silvicultural treatments on terrestrial salamanders. Forest Ecology and Management, 114, 349-356.
A randomized, replicated, controlled, before-and-after study in 1993–1999 of four harvested hardwood forests in Virginia, USA (Knapp et al. 2003) found that leaving up to 12 wildlife or dead trees did not result in higher salamander abundances than clearcutting (see also Homyack & Haas 2009). Abundance was similar between treatments (2 vs 1/30 m² respectively). Abundance was significantly lower than unharvested plots (6/30 m²). Species composition differed before and three years after harvest. There was no significant difference in the proportion of females carrying eggs or eggs/female for red-backed salamander Plethodon cinereus (7 eggs) or mountain dusky salamander Desmognathus ochrophaeus (12–13 eggs) in unharvested and harvested treatments (clearcut with wildlife trees/snags, shelterwood and leave-tree harvesting). The proportion of juveniles was similar except for slimy salamander Plethodon glutinosus, which had a significantly lower proportion in harvested plots. There were four sites with 2 ha plots with the following treatments: clearcutting with up to 12 wildlife or dead trees retained (small stems felled and left), clearcutting, other harvested treatments and an unharvested control. Salamanders were monitored on 9–15 transects (2 x 15 m)/plot at night in April-October. One or two years of pre-harvest and 1–4 years of post-harvest data were collected.
Study and other actions tested
Referenced paper
Knapp S.M., Haas C.A., Harpole D.N. & Kirkpatrick R.L. (2003) Initial effects of clearcutting and alternative silvicultural practices on terrestrial salamander abundance. Conservation Biology, 17, 752-762.
A randomized, replicated, controlled study in 1998–2005 of pine stands in South Carolina, USA (Owens et al. 2008) found that amphibian abundance, species richness and diversity did not differ with removal or creation of snags within forest. Abundance, species richness and diversity did not differ significantly between plots with 10-fold increase in snags (1/night; 7; 17 respectively), removal of all snags and downed course woody debris (2; 7; 18) and unmanipulated controls (2; 7; 19). Captures of anurans, salamanders and six individual species did not differ between treatments. Treatments were randomly assigned to 9 ha plots within three forest blocks. The first set of treatments was undertaken in 1996–2001 and the second set in 2002–2005. Five drift-fence arrays with pitfall traps/plot were used for sampling in 1998–2005.
Study and other actions tested
Referenced paper
Owens A.K., Moseley K.R., McCay T.S., Castleberry S.B., Kilgo J.C. & Ford W.M. (2008) Amphibian and reptile community response to coarse woody debris manipulations in upland loblolly pine (Pinus taeda) forests. Forest Ecology and Management, 256, 2078-2083.
In a continuation of a previous study (Knapp et al. 2003), a randomized, replicated, controlled study in 1994–2007 of six hardwood forests in Virginia, USA (Homyack & Haas 2009) found that leaving scattered wildlife or dead trees did not result in higher salamander abundance compared to clearcutting up to 13-years post-harvest. Abundance was similar between treatments (3 vs 2/transect respectively) and significantly lower than unharvested plots (7/transect). Proportions of juveniles and eggs/female were significantly lower in harvested (clearcut with wildlife trees, shelterwoods, leave-tree and group harvesting) compared to unharvested treatments for mountain dusky salamander Desmognathus ochrophaeus and juveniles for red-backed salamander Plethodon cinereus. Proportions of females carrying eggs for slimy salamander Plethodon glutinosus and southern ravine salamanders Plethodon richmondii were similar in harvested and unharvested plots. There were six sites with 2 ha plots randomly assigned to treatments: clearcutting with wildlife trees (<10 stems/ha), complete clearcutting, other harvested treatments and an unharvested control. Treatments were in 1994–1998 and salamanders were monitored at night along nine 2 x 15 m transects/site.
Study and other actions tested
Referenced paper
Homyack J.A. & Haas C.A. (2009) Long-term effects of experimental forest harvesting on abundance and reproductive demography of terrestrial salamanders. Biological Conservation, 142, 110-121.

Please cite as:

Smith, R.K., Meredith, H. & Sutherland, W.J. (2020) Amphibian Conservation. Pages 9-64 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Amphibian Conservation

Related Actions

Actions	Effectiveness	Studies	Category
Leave standing deadwood/snags in forests Action Link	Unlikely to be beneficial	4	Synopsis Link
Leave coarse woody debris in forests Action Link	Trade-off between benefit and harms	7	Synopsis Link
Thin trees within forests Action Link	Likely to be ineffective or harmful	9	Synopsis Link