Action: Use patch retention instead of clearcutting
Key messagesRead our guidance on Key messages before continuing
- We found no evidence for the effect of retaining patches of trees rather than clearcutting on amphibian populations.
- One replicated study in Canada found that although released red-legged frogs did not show significant movement towards retained tree patches, large patches were selected more and moved out of less than small patches.
Patch retention harvesting may be used as an alternative to a total clearcutting in commercial forests exploited for timber. Typically, around 10% of trees are retained in patches within a clearcut area. These retained patches can help maintain characteristic forest species and act as reservoirs for recolonization by forest dependent species.
Supporting evidence from individual studies
A replicated study in 2000–2001 of red-legged frogs Rana aurora in harvested coniferous forest on Vancouver Island, Canada (Chan-McLeod & Moy 2007) found that although frogs did not show significant movement towards retained patches of trees within the harvested area, large patches of trees were selected more and moved out of less than small patches. Overall, 55% of frogs left patches of trees within 72 hours of being released. However, frogs were less likely to leave with increasing patch size and stream density. Frogs did not tend to move towards patches unless released within 20 m. However, when given a choice, frogs moved towards large patches (0.8 ha) significantly more and small patches (0.3 ha) significantly less than expected. Forest blocks had been harvested two years previously with 5–30% of trees retained. Ten radio-collared frogs were released at the centre of 20 tree patches or at individual trees (canopy areas 1–3 ha) and monitored for 72 hours. Another 10 frogs were released at each of four randomly located tree patches and four other random locations and were monitored for six days. Seven frogs were released from each of four points equal distances from three different size patches (0.3–0.8 ha). Ten frogs were released at five distances (5–80 m) from two patches.