Collected Evidence: Collected Evidence: Encourage leaf litter development in new planting We found no evidence for the effect of encouraging leaf litter development in new planting on forests. 'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.    Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1204https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1204Thu, 19 May 2016 13:32:14 +0100Collected Evidence: Collected Evidence: Use wire fences within grazing areas to exclude livestock from specific forest sections Four of eight studies (including two replicated, randomized, controlled studies) in Argentina, Australia, Belgium, Israel, New Zealand, Spain, West Africa and the USA found that excluding livestock using wire fences increased biomass , species richness, density and cover of understory plants. The other four studies found mixed effects or no effect of livestock exclusion on understory plants. Three of four studies (including one replicated, randomized, controlled study) in Mexico, Kenya, Israel and Panama found that excluding livestock using wire fences increased the size and density of regenerating trees and the number of regenerating trees. One study found livestock exclusion decreased tree density but not tree size.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1205https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1205Thu, 19 May 2016 13:44:09 +0100Collected Evidence: Collected Evidence: Prevent livestock grazing in forests Two of three studies (including one replicated, controlled study) in Brazil, UK and Costa Rica found that preventing livestock grazing increased survival, species richness and diversity of understory plants. One study found mixed effects. One site comparison study in Israel found that preventing cattle grazing increased the density of oak seedlings and saplings.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1206https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1206Thu, 19 May 2016 14:09:33 +0100Collected Evidence: Collected Evidence: Reduce the intensity of livestock grazing in forests One replicated study in the UK found that reducing grazing intensity increased the number of tree saplings. One replicated, randomized, controlled study in Greece found that reducing grazing intensity increased understory biomass.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1207https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1207Thu, 19 May 2016 14:24:40 +0100Collected Evidence: Collected Evidence: Shorten livestock grazing period or control grazing season in forests One replicated, controlled study in Spain found that shortening the livestock grazing period increased the abundance and size of regenerating oak trees. One paired-sites study in Australia found no effect of shortening the livestock grazing period on native plant species richness. One replicated study in the UK found that the number of tree seedlings was higher following summer compared to winter grazing.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1208https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1208Thu, 19 May 2016 14:33:45 +0100Collected Evidence: Collected Evidence: Thin trees within forests: effects on mature trees Eleven of 12 studies (including two replicated, randomized, controlled studies) in Brazil, Canada, and the USA found that thinning trees in forests decreased the density and cover of trees. One study found no effect of thinning on tree density. Five of six studies (including one replicated, controlled, before-and-after study) in Australia, Sweden and the USA found that thinning trees in forests increased tree size. One found mixed effects of thinning on tree size. One replicated, controlled study in the USA found that thinning trees in forests decreased tree species richness and diversity. One replicated, site comparison study in the USA found that thinning reduced the number of conifers killed by beetles. Two replicated, controlled studies in the USA found no effect of thinning on bark-beetle caused tree mortality. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1209https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1209Thu, 19 May 2016 15:02:55 +0100Collected Evidence: Collected Evidence: Thin trees within forests: effects on young trees Six of twelve studies (including two replicated, randomized, controlled studies) in Japan and the USA found that thinning trees in forests increased the density of young trees. One study found that thinning decreased the density of young trees. Five found no effect or mixed effects on the density of young trees. One replicated, controlled study in the USA found no effect of thinning on the density of oak acorns. One controlled study in Peru found that thinning increased the growth rate of young trees. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1210https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1210Thu, 19 May 2016 15:49:33 +0100Collected Evidence: Collected Evidence: Thin trees within forests: effects on understory plants Seventeen of 25 studies (including four replicated, randomized, controlled studies) in Argentina, Brazil, Canada, Japan, Spain and the USA found that thinning trees in forests increased the density and cover of understory plants. Seven studies found no effect or mixed effects. One study found a decrease in the abundance of herbaceous species. Thirteen of 19 studies (including 10 replicated, randomized, controlled studies) in Argentina, Canada, Sweden, the USA and West Africa found that thinning trees in forests increased species richness and diversity of understory plants. Seven studies found no effect. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1211https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1211Fri, 20 May 2016 08:24:54 +0100Collected Evidence: Collected Evidence: Thin trees within forests: effects on non-vascular plants Four studies (including one replicated, randomized, controlled study) in Canada, Finland, and Sweden examined the effects of thinning trees in forests on non-vascular plants. Three found it decreased epiphytic plant abundance and species richness. Three found mixed effects depending on thinning method and species.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1212https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1212Fri, 20 May 2016 13:24:45 +0100Collected Evidence: Collected Evidence: Remove woody debris after timber harvest One of six studies (including two replicated, randomized, controlled studies) in the USA and France found that woody debris removal increased understory vegetation cover. Three studies found no effect or mixed effects on cover. Four of the studies found no effect or mixed effects on understory vegetation species richness and diversity and two found no effect of woody debris removal on coverand species diversity of trees. Six studies (including two replicated, randomized, controlled studies) in Canada, Ethiopia, Spain and the USA examined the effect of woody debris removal on young trees. One study found that debris removal increased young tree density, another study found that it decreased young tree density, and three studies found mixed effects or no effect on young tree density. One found no effect of woody-debris removal on young tree survival.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1213https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1213Fri, 20 May 2016 13:32:58 +0100Collected Evidence: Collected Evidence: Use shelterwood harvest instead of clearcutting Three replicated, controlled studies in Sweden and the USA found that shelterwood harvesting resulted in higher plant diversity, lower grass cover and higher density of tree species compared with clearcutting.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1214https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1214Fri, 20 May 2016 13:48:37 +0100Collected Evidence: Collected Evidence: Use partial retention harvesting instead of clearcutting Three studies (including one replicated, randomized, controlled study) in Canada found that using partial retention harvesting instead of clearcutting decreased the density of young trees.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1215https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1215Fri, 20 May 2016 13:59:21 +0100Collected Evidence: Collected Evidence: Use summer instead of winter harvesting One replicated study in the USA found no effect of logging season on plant species richness and diversity.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1216https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1216Fri, 20 May 2016 14:06:18 +0100Collected Evidence: Collected Evidence: Use prescribed fire: effects on mature trees Four of eight studies (including two replicated, randomized, controlled studies) from the USA found that prescribed fire decreased tree cover, density and diversity. One study found it increased tree cover and three found no effect or mixed effects of prescribed fire on cover and density of trees. Seven studies from the USA (including one replicated, randomized, controlled study) found that prescribed fire increased tree mortality. One of three studies from the USA (including one replicated, controlled study) found that prescribed fire increased tree size while two found no effect of prescribed fire on tree size.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1217https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1217Fri, 20 May 2016 14:09:36 +0100Collected Evidence: Collected Evidence: Use herbicides to remove understory vegetation to reduce wildfires We found no evidence for the effects of using herbicides to remove understory vegetation to reduce wildfiress. 'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.    Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1218https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1218Fri, 20 May 2016 14:40:39 +0100Collected Evidence: Collected Evidence: Mechanically remove understory vegetation to reduce wildfires We found no evidence for the effects of mechanically removing understory vegetation to reduce wildfires. 'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.    Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1219https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1219Fri, 20 May 2016 14:42:38 +0100Collected Evidence: Collected Evidence: Use prescribed fire: effects on young trees Five of 15 studies (including four replicated, randomized, controlled studies) from Canada, France and the USA found that prescribed fire increased the density and biomass of young trees. Two studies found that fire decreased new tree density. Eight found no effect or mixed effects depending on the tree species, location and fire frequency. Two of the above studies found mixed effects of prescribed fire on species diversity of young trees depending on the location. Two replicated, controlled studies from the USA found mixed effects of prescribed fire on the survival of young trees.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1220https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1220Fri, 20 May 2016 14:45:40 +0100Collected Evidence: Collected Evidence: Use prescribed fire: effect on understory plants Eight of 22 studies (including seven replicated, randomized, controlled studies) from the USA, Australia and Canada found that prescribed fire increased the cover, density and biomass of understory plants. Six of the studies found it decreased plant cover. Eight found no effect or mixed effects on cover and density of understory plants. Fourteen of 24 studies (including ten replicated, randomized, controlled studies) from the USA, Australia, France and West Africa found that prescribed fire increased species richness and diversity of understory plants. One study found that it decreased species richness.  Nine found no effect or mixed effects on species richness and diversity of understory plants.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1221https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1221Mon, 23 May 2016 08:21:42 +0100Collected Evidence: Collected Evidence: Use clearcutting to increase understory diversity Eight of 12 studies (including three replicated, randomized, controlled studies) in Belgium, Brazil, Canada, China, Germany, Israel, spain and the USA found that clearcutting increased the cover and species richness of understory plants. Two found it decreased the density and species richness, and two found no effect or mixed effects. Three of six studies (including five replicated, randomized, controlled studies) in Brazil, Canada and Spain found that clearcutting increased the density and species richness of young trees. One found it decreased new tree density and two found no effect or mixed effects depending on the tree species. Three of nine studies (including four replicated, randomized, controlled studies) in Australia, Brazil4, Canada, Japan and the USA found that clearcutting decreased density, species richness and diversity of mature trees. One study found it increased trees species richness .Six studies found no effect or mixed effects on tree density, size and species richness and diversity.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1222https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1222Mon, 23 May 2016 08:58:48 +0100Collected Evidence: Collected Evidence: Use shelterwood harvesting Six of seven studies (including five replicated, controlled studies) in Australia, Iran, Nepal and the USA found that shelterwood harvesting increased abundance, species richness and diversity of understory plants, as well as the growth and survival rate of young trees. One study found shelterwood harvesting decreased plant species richness and abundance. One study found no effect of shelterwood harvest on tree abundance. One replicated, controlled study in Canada found no effect of shelterwood harvest on red oak acorn production.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1223https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1223Mon, 23 May 2016 09:34:29 +0100Collected Evidence: Collected Evidence: Use group-selection harvesting Four of eight studies (including one replicated, controlled study) in Australia, Canada, Costa Rica and the USA found that group-selection harvesting increased cover and diversity of understory plants and the density of young trees. Two studies found it decreased understory species richness2 and biomass.Two studies found no effect on understory species richness and diversity and two found no effect of group-selection harvest on tree density and growth-rate.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1224https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1224Mon, 23 May 2016 09:45:25 +0100Collected Evidence: Collected Evidence: Use herbicides to thin trees One replicated, controlled study in Canada found no effect of using herbicide to thin pine trees on total plant species richness.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1225https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1225Mon, 23 May 2016 10:33:00 +0100Collected Evidence: Collected Evidence: Thin trees by girdling (cutting rings around tree trunks) 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.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1226https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1226Mon, 23 May 2016 10:34:52 +0100Collected Evidence: Collected Evidence: Use thinning followed by prescribed fire Three of six studies (including one replicated, randomized, controlled study) in the USA found that thinning followed by prescribed burning increased cover and abundance1 of understory plants as well as the density of deciduous trees. One study found that thinning then burning decreased trees density and species richness.  Three studies found no effect or mixed effects of thinning followed by burning on tree growth rate and density of young trees. One replicated, controlled study Australia found no effect of thinning followed by burning on the genetic diversity of black ash.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1227https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1227Mon, 23 May 2016 10:38:49 +0100Collected Evidence: Collected Evidence: Mechanically/manually remove invasive plants One replicated, controlled study in Hawaii found that removal of invasive grass species increased understory plant biomass. One replicated, controlled study in the USA found no effect of invasive shrub removal on understory plant diversity. One replicated, controlled study in Ghana found that removal of invasive weed species increased tree seedling height. One replicated, controlled study in Hawaii found no effect of invasive plant removal on growth rate of native species. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1228https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1228Mon, 23 May 2016 10:45:49 +0100
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What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

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