Use patch retention harvesting instead of clearcutting

Overall effectiveness category Likely to be beneficial
Number of studies: 2
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How is the evidence assessed?

Effectiveness

70%
Certainty

46%
Harms

0%

Calculating overall effectiveness category

Background information and definitions

In forests in which trees are commercially exploited for timber, a system known as patch retention harvesting may be used as an alternative to a total clear-cut. Typically, around 10% of mature and/or immature trees are retained in patches within an otherwise, clear-cut harvest compartment, with ‘prompt reforestation’ subsequent to timber extraction in the other 90%. These retained patches could help maintain characteristic forest species and act as reservoirs for re-colonisation by forest dependant species.

Study locations

Key messages

One before-and-after study of two from the USA found that areas under patch retention harvesting contained more birds of more species than clearcut areas, retaining similar numbers to unharvested areas.
Two studies from the USA found that forest specialist species were found with greater frequency in patch retention plots than other management types. One found that habitat generalists increased on other management types, relative to patch retention areas.

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

In McDonald-Dunn Forest, Oregon, USA, a replicated, controlled study (Chambers et al. 1999) found that patch-group-harvested stands (33% of tree volume removed in 0.2 ha patches) retained an old forest-associated bird composition more similar to that of control (unharvested, old-growth Douglas-fir Pseudotsuga menziesii) stands, compared to two-story (66% of wood removed) and modified clearcut (1.2 trees retained/ha) stands. Of ten abundant forest species in patch group stands, five restricted-range species declined in modified clear-cut and two-story harvested stands, whilst nine mostly habitat generalists species increased in these two treatments. Seven to 11 stands of each treatment were studied, with birds surveyed in the breeding season prior to, and in the two years after, timber harvest (1989-1993).
Study and other actions tested
Referenced paper
Chambers C.L., McComb W.C. & Tappeiner II J.C. (1999) Breeding bird responses to three silvicultural treatments in the Oregon Coast Range. Ecological Applications, 9, 171-185.
A controlled before-and-after study in May-June 1999-2001 in bottomland hardwood forest in South Carolina, USA (Harrison & Kilgo 2004), found that a small increase in species richness in the short-term in an area with patch-retention harvesting and a control area, whilst richness decreased in an area with clearcutting (patch retention area: 21 species in 1999, 15 in 2000, 25 in 2001; clear cut area: 25, nine, five; control area: 18 in 1999 and 30 in 2001). Species lost from the clearcut plot were mostly forest specialists. Estimated bird density in the patch-retention area fell from c.3.5 pairs/ha in 1999 to 17 in 2000, recovering to around 34 in 2001. In the clear-cut area, it fell from 3.3 pairs/ha before harvest to around three in 2000 and 14 in 2001. Densities in the control remained relatively constant (c.3.2 pairs/ha). Estimated bird density in the patch-retention area fell from 3.5 pairs/ha in 1999 to 1.7 in 2000, recovering to around 3.4 in 2001. In the clear-cut area, it fell from 3.3 pairs/ha before harvest to around 0.3 in 2000 and 1.4 in 2001. Densities in the control remained relatively constant (3.2 pairs/ha).
Study and other actions tested
Referenced paper
Harrison C.A. & Kilgo J.C. (2004) Short-term breeding bird response to two harvest practices in a bottomland hardwood forest. The Wilson Bulletin, 116, 314-323.

Please cite as:

Williams, D.R., Child, M.F., Dicks, L.V., Ockendon, N., Pople, R.G., Showler, D.A., Walsh, J.C., zu Ermgassen, E.K.H.J. & Sutherland, W.J. (2020) Bird Conservation. Pages 137-281 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:

Bird Conservation

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