Thin trees by girdling (cutting rings around tree trunks)

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Share Tweet Email

View assessment score

How is the evidence assessed?

Effectiveness

58%
Certainty

13%
Harms

0%

Calculating overall effectiveness category

Background information and definitions

Girdling, i.e. thinning trees by cutting rings around their trunk, is used as a conservation management practice to increase forest structural diversity. This method imitates the natural death of a tree without using chemicals or cutting trees.

Study locations

Key messages

One before-and-after trial in Canada found that thinning trees by girdling (cutting rings around tree trunks) increased understory plant species richness, diversity and cover.

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 before-and-after trial in 1992-2003 in boreal forest in Quebec, Canada (Grandpré et al. 2011) found that thinning trees by girdling increased understory species richness, diversity and cover. The number of species increased following girdling (before: 5-9; after: 7-12/1 m² plot) and remained similar in uncut plots (before: 5-10; after: 6-12). Species diversity increased following girdling (Shannon's index before: 0.8-1.1; after: 1.2-1.7) and remained similar in uncut plots (before: 0.7-1.3; after: 0.8-1.5). Plant cover increased following girdling (before: 80%; after: 100-120%) and remained similar in uncut plots (before: 90-100%; after: 90-120%). In 1992, girdling (cutting >1 cm deep cuts around the trunks of all conifers) and uncut treatments (100 m²) were replicated in three blocks (>625 m²) at each of two sites. Data were collected before (1992) and after treatments (2003) in 5-12 plots (1 m²) in each treatment.
Study and other actions tested
Referenced paper
Grandpré L., Boucher D., Bergeron Y. & Gagnon D. (2011) Effects of small canopy gaps on boreal mixedwood understory vegetation dynamics. Community Ecology, 12, 67-77.

Please cite as:

Agra, H., Schowanek, S., Carmel, Y., Smith, R.K. & Ne’eman, G. (2020) Forest Conservation. Pages 323-366 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:

Forest Conservation

Related Actions

Actions	Effectiveness	Studies	Category
Retain fallen trees Action Link	No evidence found (no assessment)	0	Synopsis Link
Use shelterwood harvesting Action Link	Trade-off between benefit and harms	8	Synopsis Link
Imitate natural disturbances by pushing over trees Action Link	No evidence found (no assessment)	0	Synopsis Link