Conservation Evidence: Evidence Data

Collected Evidence: Collected Evidence: Retain riparian buffer strips during timber harvest Twelve studies investigated the effectiveness of retaining buffer strips during timber harvest for amphibians. Six 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 on abundance depending on species and buffer width. One found that amphibian abundance was significantly higher with buffers. Eleven studies, including 10 replicated and/or controlled studies in Canada and the USA and one meta-analysis, compared amphibian numbers in forest with riparian buffers retained during harvest to unharvested forest. Six found mixed effects depending on species or volume of existing downed wood. Four found that abundance and species composition were similar to unharvested forest. Two found that numbers of species and abundance were lower than in unharvested forest. Two of four replicated studies (including one randomized, controlled, before-and-after study) in Canada and the USA found that numbers of amphibian species and abundance were greater in wider riparian buffer strips. Two found that there was no difference in abundance in buffers of different widths. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F747https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F747Wed, 17 Jul 2013 13:42:46 +0100Collected Evidence: Collected Evidence: Mechanically remove mid-storey or ground vegetation One randomized, replicated, controlled study in the USA found that numbers of amphibian species, but not abundance, were significantly higher in plots with mechanical understory reduction compared to those without. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F781https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F781Thu, 22 Aug 2013 13:38:07 +0100Collected Evidence: Collected Evidence: Leave coarse woody debris in forests Two replicated, controlled studies in the USA found that there was no significant difference in abundance in clearcuts with woody debris retained or removed for eight of nine amphibian species, but that the overall response (population, physiological and behavioural) 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 decrease amphibian diversity or overall amphibian abundance, but did reduce species richness in one study. 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 in piles of woody debris than in open areas, and was similar in wood piles to unharvested forest. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F843https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F843Fri, 30 Aug 2013 15:15:04 +0100Collected Evidence: Collected Evidence: Harvest groups of trees instead of clearcutting Three studies (including two randomized, replicated, controlled, before-and-after studies) in the USA found that compared to clearcutting, harvesting trees in small groups did not result in higher amphibian or salamander abundance. A meta-analysis of 24 studies in North America found that partial harvest, which included harvesting groups or individual trees, thinning and shelterwood harvesting, resulted in smaller reductions in salamander populations than clearcutting Two studies (including one randomized, replicated, controlled, before-and-after study) in the USA found that compared to no harvesting, harvesting trees in small groups significantly 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 were similar and proportion of eggs per female and juveniles similar or lower in harvested plots that included harvest of groups of trees. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F844https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F844Fri, 30 Aug 2013 15:47:36 +0100Collected Evidence: Collected Evidence: Leave standing deadwood/snags in forests One randomized, replicated, controlled, before-and-after study in the USA found that compared to total clearcutting, leaving dead or wildlife trees did not result in higher abundances of salamanders. Two studies (including one randomized, replicated, controlled, before-and-after study) in the USA found that compared to no harvesting, leaving dead or wildlife trees during clearcutting did not prevent a decrease in salamander abundance or change in species composition. One randomized, replicated, controlled study in the USA found that numbers of amphibian species and abundance were similar with removal or creation of dead trees within forest. 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 plots where dead and wildlife trees were left during clearcutting, depending on species and time since harvest. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F845https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F845Fri, 30 Aug 2013 16:07:51 +0100Collected Evidence: Collected Evidence: Use leave-tree harvesting instead of clearcutting 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. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F846https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F846Fri, 30 Aug 2013 16:21:07 +0100Collected Evidence: Collected Evidence: Use patch retention instead of clearcutting 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. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F847https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F847Fri, 30 Aug 2013 16:30:32 +0100Collected Evidence: Collected Evidence: Use shelterwood harvesting instead of clearcutting Three studies (including two randomized, replicated, controlled, before-and-after studies) in the USA found that compared to clearcutting, shelterwood harvesting resulted in higher, similar or initially higher and then similar salamander abundance. A meta-analysis of 24 studies in North America found that partial harvest, which included shelterwood harvesting with three other types, resulted in smaller reductions in salamander populations than clearcutting Two of three studies (including two randomized, replicated, controlled, before-and-after studies) in the USA found that compared to no harvesting, shelterwood harvesting decreased salamander abundance and changed species composition. One found that shelterwood harvesting did not affect salamander abundance. 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 shelterwood harvested plots, depending on species and time since harvest. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F851https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F851Thu, 05 Sep 2013 14:42:48 +0100Collected Evidence: Collected Evidence: Thin trees within forests Five studies (including four replicated and/or controlled studies) in the USA compared amphibians in thinned to unharvested forest. Two found mixed effects of thinning on abundance, depending on amphibian species and time since harvest. One found that amphibian abundance increased, except for ensatina salamanders. One found a negative overall response (population, physiological and behavioural) of amphibians and one found that thinning did not affect abundance. A meta-analysis of 24 studies in North America found that partial harvest, which included thinning with three other types, decreased salamander populations. One controlled, before-and-after site comparison study in the USA found that high volumes of pre-existing downed wood prevented declines in amphibian populations following thinning. Four studies (including two replicated, controlled studies) in the USA compared amphibians in thinned to clearcut forest. Two found higher amphibian abundance, apart from ensatina salamanders, or a less negative overall response (population, physiological and behavioural) of amphibians in thinned forest. Two found mixed effects on abundance depending on species, life stage and time since harvest. A meta-analysis of 24 studies in North America found that partial harvest, which included thinning with three other types, resulted in smaller reductions in salamander populations than clearcutting. One randomized, replicated, controlled study in the USA found that migrating amphibians used thinned forest a similar amount, or for one species more than unharvested forest and that emigrating salamanders, but not frogs, used it significantly more than clearcuts. One site comparison study in the USA found that thinning decreased the body condition of ensatina salamanders 10 years after harvest. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F852https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F852Thu, 05 Sep 2013 14:53:21 +0100