Action: Use leave-tree harvesting instead of clearcutting
Key messagesRead our guidance on Key messages before continuing
- Two studies (including one randomized, replicated, controlled, before-and-after study) in the USA found that compared to clearcutting, leaving a low density of trees during harvest did not result in higher salamander abundance.
- Two studies (including one randomized, replicated, controlled, before-and-after study) in the USA found that compared to no harvesting, leaving a low density of trees during harvest decreased salamander abundance and changed species composition.
- 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 leave-tree harvests, depending on species and time since harvest.
Leave-tree harvest retains a low density of high-quality trees uniformly through the forest stand. Trees can be retained in groups or dispersed and may contain trees with structural characteristics important to wildlife. Compared to clearcutting, this type of management can help maintain forest species.
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 leave-tree harvesting decreased relative abundance of salamanders in a similar way to clearcutting. Captures decreased significantly after both leave-tree harvesting (before: 8; one year after: 4; three years after: 1 amphibian/search) and clearcutting (before: 10; one year after: 7; three years after: 1/search). Abundance did not differ significantly within the unharvested plot (before: 10; one year after: 10; three years after: 8). Treatments on 2 ha plots were: leave-tree (up to 16 trees/ha retained), clearcutting (up to 12 wildlife and dead trees retained) and unharvested. Salamanders were monitored along 15 x 2 m transects with artificial cover objects (50/plot).
A randomized, replicated, controlled, before-and-after study in 1993–1999 of five harvested hardwood forests in Virginia, USA (Knapp et al. 2003) found that leave-tree harvesting did not result in higher salamander abundances than clearcutting (see also Homyack & Haas 2009). Abundance was similar in the leave-tree and clearcut plots (2 vs 1/30 m2 respectively). Abundance was significantly lower than unharvested plots (6/30 m2). Species composition differed before and three years post-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 (leave-tree, shelterwoods and clearcut with wildlife trees or snags left). The proportion of juveniles was similar except for slimy salamander Plethodon glutinosus, which had a significantly lower proportion in harvested plots. There were five sites with 2 ha plots with the following treatments: leave-tree harvest (up to 50 trees/ha retained uniformly; average 28%), 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.
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 leave-tree harvesting did not result in higher salamander abundance compared to clearcutting up to 13 years after harvest. Abundance was similar between treatments (4 vs 2/transect respectively) and significantly lower than unharvested plots (7/transect). Proportions of juveniles and eggs/female were significantly lower in harvested (leave-tree, shelterwoods, group cutting and clearcut with wildlife trees or snags left) 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: leave-tree harvest (25–45 trees/ha retained), 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.
- Harpole D.N. & Haas C.A. (1999) Effects of seven silvicultural treatments on terrestrial salamanders. Forest Ecology and Management, 114, 349-356
- 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
- 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