Collected Evidence: Collected Evidence: Plug/dam canals or trenches: freshwater marshes One study evaluated the effects, on vegetation, of plugging/damming canals or trenches in freshwater marshes. The study was in the USA. VEGETATION COMMUNITY Overall extent (1 study): One replicated, site comparison study of backfilled canals in freshwater marshes in the USA reported that emergent marsh vegetation coverage was greater within the channels of plugged than unplugged canals, after 6–60 months. However, coverage on former spoil areas did not significantly differ between plugged and unplugged canals. VEGETATION ABUNDANCE   VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2991https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2991Mon, 29 Mar 2021 12:08:23 +0100Collected Evidence: Collected Evidence: Plug/dam canals or trenches: brackish/salt marshes Two studies evaluated the effects, on vegetation, of plugging/damming canals or trenches in brackish/salt marshes. Both studies were in the USA. There was overlap in the canals used in the studies. Both studies included some freshwater areas in some analyses, but all results are based predominantly on canals in brackish or saline marshes. VEGETATION COMMUNITY   VEGETATION ABUNDANCE Overall abundance (2 studies): Two replicated, site comparison studies studied emergent vegetation of backfilled canals in the USA. One study reported that plugged canals had greater coverage of emergent marsh vegetation than unplugged canals after 6–60 months. One study found that emergent vegetation coverage on former spoil heaps did not significantly differ alongside plugged and unplugged canals after 6–11 years. The first study also reported that plugged canals were more likely to contain floating/submerged vegetation than unplugged canals. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2992https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2992Mon, 29 Mar 2021 12:08:35 +0100Collected Evidence: Collected Evidence: Plug/dam canals or trenches: freshwater swampsWe found no studies that evaluated the effects, on vegetation, of plugging/damming canals or trenches in freshwater swamps.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F2993https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2993Mon, 29 Mar 2021 12:08:51 +0100Collected Evidence: Collected Evidence: Plug/dam canals or trenches: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of plugging/damming canals or trenches in brackish/saline swamps.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F2994https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2994Mon, 29 Mar 2021 12:09:11 +0100Collected Evidence: Collected Evidence: Provide new technologies to reduce harvesting pressure on vegetationWe found no studies that evaluated the effects, on vegetation or human behaviour, of providing new technologies to reduce harvesting pressure on vegetation in marshes or swamps.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3014https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3014Wed, 31 Mar 2021 14:22:01 +0100Collected Evidence: Collected Evidence: Raise water level to restore degraded freshwater marshes Five studies evaluated the effects, on vegetation, of raising the water level to restore degraded freshwater marshes. There were three studies in the USA and one in each of the Netherlands and Japan. VEGETATION COMMUNITY Overall extent (1 study): One before-and-after study of a floodplain in Japan reported that the area covered by marsh vegetation was higher five years after dechannelizing a river than 10 years before. Community types (1 study): One before-and-after study of a floodplain in Japan reported changes in the area covered by different marsh plant communities over five years after dechannelizing a river compared to 10 years before. Community composition (1 study): One replicated study of dune slacks in the Netherlands reported changes in the overall plant community composition after stopping groundwater extraction (along with other interventions). Overall richness/diversity (2 studies): One replicated, site comparison study of dune slacks in the Netherlands reported that overall plant species richness was greater in restored slacks (groundwater extraction stopped five years previously, along with other interventions) than in mature unmanaged slacks. One replicated, before-and-after study of floodplain marshes in the USA reported that total plant species richness tended to be lower over nine years after raising the water table than before, but that there was no significant difference for diversity. Characteristic plant richness/diversity (1 study): One replicated study of dune slacks in the Netherlands simply quantified the richness of characteristic plant species – typical of dune slacks or nutrient-rich marshes – over five years after stopping groundwater extraction (along with other interventions). VEGETATION ABUNDANCE Overall abundance (3 studies): One replicated, before-and-after study of floodplain marshes in the USA reported that total vegetation cover tended to be lower over nine years after raising the water table than before. One replicated, randomized, paired, controlled, before-and-after study of freshwater marshes in the USA found that damming to raise the water table prevented increases in understory vegetation cover over the following year. One replicated study of dune slacks in the Netherlands simply quantified total vegetation over five years after stopping groundwater extraction (along with other interventions). Cover never exceeded 50%. Herb abundance (1 study): One replicated, randomized, paired, controlled, before-and-after study of freshwater marshes in the USA found that damming to raise the water table had no significant effect on cover of sedges Carex There were similar increases in dammed and undammed marshes over one year. Characteristic plant abundance (1 study): One replicated, before-and-after study of floodplain marshes in the USA reported changes in the cover of wetland- and habitat-characteristic plant species over nine years after raising the water table. Individual species abundance (3 studies): Three studies quantified the effect of this intervention on the abundance of individual plant species. For example, one replicated, before-and-after study in the USA reported that rewetted floodplain marshes became dominated by a non-native wetland shrub, approximately 4–9 years after raising the water table. One replicated study of a freshwater wetland in the USA reported that the effects of reflooding on the density of emergent plant species depended on the species and water level. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3026https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3026Wed, 31 Mar 2021 14:47:11 +0100Collected Evidence: Collected Evidence: Raise water level to restore degraded brackish/salt marshes Two studies evaluated the effects, on vegetation, of raising the water level to restore degraded brackish/salt marshes. One study was in the Netherlands and one was in Tunisia. VEGETATION COMMUNITY Community types (2 study): One before-and-after study of a lakeshore brackish/salt marsh in Tunisia reported an increase in coverage of bulrush-dominated vegetation relative to salt marsh vegetation over three years after modifying a canal to retain water in the marsh. One study of a salt marsh in the Netherlands reported increased coverage of pioneer succulent plant communities, and reduced coverage of short-grass communities, over approximately 10 years following abandonment of the drainage system (along with other interventions). Overall richness/diversity (1 study): One study of a salt marsh in the Netherlands reported that overall plant species richness increased over 14 years after abandoning drainage systems (along with other interventions). VEGETATION ABUNDANCE Individual species abundance (1 study): One study of a salt marsh in the Netherlands reported that some individual plant species became more common over 14 years after abandoning drainage systems (along with other interventions). These included saltbush Atriplex prostrata and seablite Suaeda maritima. Some other species became less common, including creeping bentgrass Agrostis stolonifera and common cordgrass Spartina anglica. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3027https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3027Wed, 31 Mar 2021 14:47:25 +0100Collected Evidence: Collected Evidence: Raise water level to restore degraded brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of raising the water level to restore degraded brackish/saline swamps.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3029https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3029Wed, 31 Mar 2021 14:47:55 +0100Collected Evidence: Collected Evidence: Raise water level to prevent wild firesWe found no studies that evaluated the effects, on marsh/swamp vegetation, of raising the water level to prevent wild fires in or near these habitats.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3079https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3079Fri, 02 Apr 2021 16:56:58 +0100Collected Evidence: Collected Evidence: Put up signs to discourage firesWe found no studies that evaluated the effects, on marsh/swamp vegetation or human behaviour, of putting up signs to discourage fires in or near these habitats.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3081https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3081Fri, 02 Apr 2021 16:59:56 +0100Collected Evidence: Collected Evidence: Put up signs to discourage litteringWe found no studies that evaluated the effects, on vegetation or human behaviour, of putting up signs to discourage littering in/near marshes or swamps.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3165https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3165Tue, 06 Apr 2021 13:16:24 +0100Collected Evidence: Collected Evidence: Raise water level (before/after planting)We found no studies that evaluated the effects, on vegetation, of raising the water level in areas planted with emergent marsh/swamp plants.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3274https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3274Sat, 10 Apr 2021 17:03:59 +0100Collected Evidence: Collected Evidence: Plant non-woody plants into moisture-retaining peat pots: freshwater wetlands One study evaluated the effects of using moisture-retaining peat pots when planting emergent, non-woody vegetation in freshwater wetlands. The study was in the USA. VEGETATION COMMUNITY   VEGETATION ABUNDANCE Individual species abundance (1 study): One replicated, randomized, paired, controlled study in a wetland in the USA found that tussock sedge Carex stricta cover was similar across plots, after two growing seasons, whether sedges were planted into peat pots or into existing wetland soil. VEGETATION STRUCTURE Individual plant size (1 study): One replicated, randomized, paired, controlled study in a wetland in the USA found that the biomass of tussock sedge Carex stricta plants was similar, after two growing seasons, whether they were planted into peat pots or into existing wetland soil. OTHER Survival (1 study): One replicated, randomized, paired, controlled study in a wetland in the USA found that the survival rate of tussock sedge Carex stricta plants was similar, after two growing seasons, whether they were planted into peat pots or into existing wetland soil. Growth (1 study): The same study found that the growth rate of tussock sedge Carex stricta was typically similar, over two growing seasons, when planted into peat pots or into existing wetland soil. However, in a dry area and in a dry year, planting in peat pots did increase the growth rate. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3341https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3341Sun, 11 Apr 2021 16:45:47 +0100Collected Evidence: Collected Evidence: Plant non-woody plants into moisture-retaining peat pots: brackish/saline wetlandsWe found no studies that evaluated the effects of using moisture-retaining peat pots when planting emergent, non-woody vegetation in brackish/saline wetlands.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3342https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3342Sun, 11 Apr 2021 16:46:08 +0100Collected Evidence: Collected Evidence: Plant trees/shrubs into moisture-retaining peat pots: freshwater wetlandsWe found no studies that evaluated the effects of using moisture-retaining peat pots when planting trees/shrubs in freshwater wetlands.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3343https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3343Sun, 11 Apr 2021 16:46:17 +0100Collected Evidence: Collected Evidence: Plant trees/shrubs into moisture-retaining peat pots: brackish/saline wetlandsWe found no studies that evaluated the effects of using moisture-retaining peat pots when planting trees/shrubs in brackish/saline wetlands.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3344https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3344Sun, 11 Apr 2021 16:46:35 +0100Collected Evidence: Collected Evidence: Plant vegetation into heavy containersWe found no studies that evaluated the effects of planting emergent wetland vegetation into heavy containers.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3345https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3345Sun, 11 Apr 2021 16:55:25 +0100Collected Evidence: Collected Evidence: Prune roots of non-woody plants before planting: freshwater wetlandsWe found no studies that evaluated the effects – on emergent, non-woody plants typical of freshwater wetlands – of pruning their roots before planting.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3355https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3355Sun, 11 Apr 2021 17:23:33 +0100Collected Evidence: Collected Evidence: Prune roots of non-woody plants before planting: brackish/saline wetlandsWe found no studies that evaluated the effects – on emergent, non-woody plants typical of brackish/saline wetlands – of pruning their roots before planting.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3356https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3356Sun, 11 Apr 2021 17:23:56 +0100Collected Evidence: Collected Evidence: Prune roots of trees/shrubs before planting: freshwater wetlands Two studies evaluated the effects – on trees/shrubs typical of freshwater wetlands – of pruning their roots before planting. Both studies were in the USA. One study was in a laboratory. VEGETATION COMMUNITY   VEGETATION ABUNDANCE   VEGETATION STRUCTURE   OTHER Survival (2 studies): One replicated, controlled study in created wetlands in the USA reported that root-pruned red maple Acer rubrum seedlings had a higher survival rate than unpruned seedlings, 1–2 years after planting. One replicated, randomized, controlled study in a laboratory in the USA found that root-pruned and unpruned Nuttall oak Quercus nuttallii seedlings had similar survival rates, 108 days after planting. Growth (1 study): One replicated, randomized, controlled study in a laboratory in the USA found that root-pruned and unpruned Nuttall oak Quercus nuttallii seedlings grew in height by a similar amount over the first 108 days after planting. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3357https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3357Sun, 11 Apr 2021 17:24:04 +0100Collected Evidence: Collected Evidence: Prune roots of trees/shrubs before planting: brackish/saline wetlandsWe found no studies that evaluated the effects the effects – on trees/shrubs typical of brackish/saline wetlands – of pruning their roots before planting.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3358https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3358Sun, 11 Apr 2021 17:24:15 +0100Collected Evidence: Collected Evidence: Provide general protection for marshes or swamps Three studies evaluated the overall effects, on vegetation or human behaviour, of providing general protection for marshes or swamps. There was one study in each of Puerto Rico, China and Canada. VEGETATION COMMUNITY Overall extent (3 studies): Two studies in China and Canada reported that the area of wetlands (including habitats other than marshes or swamps) in their study regions declined over 10–29 years, despite general protection of wetlands. However, in China, the decline was slower than in a previous period without protection. One before-and-after study of mangrove forests in Puerto Rico reported that their area increased following legal protection. VEGETATION ABUNDANCE   VEGETATION STRUCTURE Overall structure (1 study): One before-and-after study in China reported degradation in wetland landscape structure over 29 years when wetlands were generally protected. However, the decline was slower than in a previous period when wetlands were not protected. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3385https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3385Mon, 12 Apr 2021 09:30:20 +0100Collected Evidence: Collected Evidence: Raise public awareness about marshes or swampsWe found no studies that evaluated the effects, on vegetation or human behaviour, of interventions to raise public awareness about marshes or swamps.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3389https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3389Mon, 12 Apr 2021 11:52:00 +0100Collected Evidence: Collected Evidence: Provide education/training programmes about marshes or swamps Two studies evaluated the effects, on vegetation or human behaviour, of providing education/training programmes related to marshes or swamps. One study was in Kenya and one was in Vietnam. VEGETATION COMMUNITY   VEGETATION ABUNDANCE   VEGETATION STRUCTURE   OTHER Human behaviour (2 studies): One study in Kenya reported that after a series of seminars and workshops about marsh conservation, two community-based management groups were established by local stakeholders and a grazing fee was introduced. One before-and-after study in Vietnam reported that after local people were trained to make more complex handicrafts from marsh plants (along with helping them to sell those handicrafts in markets), their income increased. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3391https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3391Mon, 12 Apr 2021 11:55:44 +0100Collected Evidence: Collected Evidence: Produce guidance for marsh or swamp conservation One study evaluated the effects, on vegetation or human behaviour, of producing guidance for marsh or swamp conservation. The study was in Sri Lanka. VEGETATION COMMUNITY   VEGETATION ABUNDANCE   VEGETATION STRUCTURE   OTHER Survival (1 study): One study of coastal sites in Sri Lanka found that planted mangrove propagules/seedlings had a higher survival rate in sites where published guidance had been consulted to select appropriate areas for planting, than in sites where guidance was not consulted. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3392https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3392Mon, 12 Apr 2021 12:07:08 +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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