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What Works in Conservation 2017

 | 
William J. Sutherland
, 
Lynn V. Dicks
, 
Nancy Ockendon
, 
et al.

1. AMPHIBIAN CONSERVATION

1.5 Threat: Biological resource use

Texte intégral

1.5.1 Hunting and collecting terrestrial animals

Based on the collated evidence, what is the current assessment of the effectiveness of interventions for hunting and collecting terrestrial animals?

Likely to be beneficial

● Reduce impact of amphibian trade

Unknown effectiveness (limited evidence)

● Use legislative regulation to protect wild populations

No evidence found (no assessment)

● Commercially breed amphibians for the pet trade
● Use amphibians sustainably

Likely to be beneficial

Reduce impact of amphibian trade

1One review found that reducing trade through legislation allowed frog populations to recover from over-exploitation. Assessment: likely to be beneficial (effectiveness 76%; certainty 40%; harms 0%).
http://www.conservationevidence.com/​actions/​824

Unknown effectiveness (limited evidence)

Use legislative regulation to protect wild populations

2One review found that legislation to reduce trade resulted in the recovery of frog populations. One study in South Africa found that the number of permits issued for scientific and educational use of amphibians increased from 1987 to 1990. Assessment: unknown effectiveness — limited evidence (effectiveness 60%; certainty 30%; harms 5%).
http://www.conservationevidence.com/​actions/​785

No evidence found (no assessment)

3We have captured no evidence for the following interventions:

  • Commercially breed amphibians for the pet trade

  • Use amphibians sustainably

1.5.2 Logging and wood harvesting

Based on the collated evidence, what is the current assessment of the effectiveness of interventions for logging and wood harvest?

Likely to be beneficial

● Retain riparian buffer strips during timber harvest
● Use shelterwood harvesting instead of clearcutting

Trade-off between benefit and harms

● Leave coarse woody debris in forests

Unknown effectiveness (limited evidence)

● Use leave-tree harvesting instead of clearcutting

Unlikely to be beneficial

● Leave standing deadwood/snags in forests
● Use patch retention harvesting instead of clearcutting

Likely to be ineffective or harmful

● Harvest groups of trees instead of clearcutting
● Thin trees within forests

Likely to be beneficial

Retain riparian buffer strips during timber harvest

4Six replicated and/or controlled studies in Canada and the USA compared amphibian numbers following clearcutting with or without riparian buffer strips. Five found mixed effects and one found that abundance was higher with riparian buffers. Two of four replicated studies, including one randomized, controlled, before-and-after study, in Canada and the USA found that numbers of species and abundance were greater in wider buffer strips. Two found no effect of buffer width. Assessment: likely to be beneficial (effectiveness 50%; certainty 61%; harms 10%).
http://www.conservationevidence.com/​actions/​747

Use shelterwood harvesting instead of clearcutting

5Three studies, including two randomized, replicated, controlled, before-and-after studies, in the USA found that compared to clearcutting, shelterwood harvesting resulted in higher or similar salamander abundance. One meta-analysis of studies in North America found that partial harvest, which included shelterwood harvesting, resulted in smaller reductions in salamander populations than clearcutting. Assessment: likely to be beneficial (effectiveness 40%; certainty 57%; harms 10%).
http://www.conservationevidence.com/​actions/​851

Trade-off between benefit and harms

Leave coarse woody debris in forests

6Two replicated, controlled studies in the USA found that abundance was similar in clearcuts with woody debris retained or removed for eight of nine amphibian species, but that the overall response of amphibians was more negative where woody debris was retained. Two replicated, controlled studies in the USA and Indonesia found that the removal of coarse woody debris from standing forest did not affect amphibian diversity or overall amphibian abundance, but did reduce species richness. One replicated, controlled study in the USA found that migrating amphibians used clearcuts where woody debris was retained more than where it was removed. One replicated, site comparison study in the USA found that within clearcut forest, survival of juvenile amphibians was significantly higher within piles of woody debris than in open areas. Assessment: trade-offs between benefits and harms (effectiveness 40%; certainty 60%; harms 26%).
http://www.conservationevidence.com/​actions/​843

Unknown effectiveness (limited evidence)

Use patch retention harvesting instead of clearcutting

7We 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 move towards retained tree patches, large patches were selected more and moved out of less than small patches. Assessment: unknown effectiveness — limited evidence (effectiveness 20%; certainty 25%; harms 0%).
http://www.conservationevidence.com/​actions/​847

Unlikely to be beneficial

Leave standing deadwood/snags in forests

8One randomized, replicated, controlled, before-and-after study in the USA found that compared to total clearcutting, leaving dead and wildlife trees did not result in higher abundances of salamanders. One randomized, replicated, controlled study in the USA found that numbers of amphibians and species were similar with removal or creation of dead trees within forest. Assessment: unlikely to be beneficial (effectiveness 5%; certainty 58%; harms 2%).
http://www.conservationevidence.com/​actions/​845

Use leave-tree harvesting instead of clearcutting

9Two 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. Assessment: unlikely to be beneficial (effectiveness 10%; certainty 48%; harms 11%).
http://www.conservationevidence.com/​actions/​846

Likely to be ineffective or harmful

Harvest groups of trees instead of clearcutting

10Three studies, including two randomized, replicated, controlled, before and-after studies, in the USA found that harvesting trees in small groups resulted in similar amphibian abundance to clearcutting. One meta-analysis and one randomized, replicated, controlled, before-and-after study in North America and the USA found that harvesting, which included harvesting groups of trees, resulted in smaller reductions in salamander populations than clearcutting. Assessment: likely to be ineffective or harmful (effectiveness 33%; certainty 60%; harms 23%).
http://www.conservationevidence.com/​actions/​844

Thin trees within forests

11Six studies, including five replicated and/or controlled studies, in the USA compared amphibians in thinned to unharvested forest. Three found that thinning had mixed effects and one found no effect on abundance. One found that amphibian abundance increased following thinning but the body condition of ensatina salamanders decreased. One found a negative overall response of amphibians. Four studies, including two replicated, controlled studies, in the USA compared amphibians in thinned to clearcut forest. Two found that thinning had mixed effects on abundance and two found higher amphibian abundance or a less negative overall response of amphibians following thinning. One meta-analysis of studies in North America found that partial harvest, which included thinning, decreased salamander populations, but resulted in smaller reductions than clearcutting. Assessment: likely to be ineffective or harmful (effectiveness 35%; certainty 60%; harms 40%).
http://www.conservationevidence.com/​actions/​852

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