Collected Evidence: Collected Evidence: Raise water level to restore/create freshwater marshes from other land uses Twenty-six studies evaluated the effects, on vegetation, of raising the water level to restore/create freshwater marshes from other land uses or habitat types. Twenty-one studies were in the USA. There was one study in each of Israel, the UK, China, Luxembourg and Canada. Eight studies used sites from a common set of 62 restored prairie potholes in the Midwest USA. Five studies monitored the effects of one river dechannelization project in Florida. VEGETATION COMMUNITY Overall extent (5 studies): One replicated, paired, before-and-after, site comparison study in the USA reported that damming a stream reduced the area of emergent vegetation on the floodplain. Two before-and-after studies of a floodplain in the USA reported that after dechannelizing a river to raise the water level, the area of emergent herbaceous vegetation increased. Two studies in the USA and Luxembourg simply quantified coverage of wetland vegetation 1–6 years after raising the water table (sometimes along with other interventions). Community types (9 studies): Nine studies quantified the effect of this action on specific types of marsh vegetation. For example, one before-and-after study of a floodplain in the USA reported greatly increased coverage of wet prairie plant communities after dechannelizing a river to raise the water table, but only slightly increased coverage of mixed herbaceous/shrubby wetland communities. Five studies in the USA and Luxembourg simply quantified the number, abundance or extent of wetland plant communities present 1–6 years after raising the water table (typically along with other interventions). Community composition (8 studies): Three replicated, site comparison studies (two also paired) in the USA evaluated the effects of rewetting farmed depressions (along with planting cover crops in/around them). One of these studies reported that restored wetlands contained a different overall plant community to natural wetlands after 5–7 years. One study reported that the plant community composition differed more between restored and natural wetlands than amongst restored or natural wetlands. The final study found that restoration increased vegetation quality after ≥10 years, but not to the level of natural wetlands. Two site comparison studies in China and the USA reported that the plant community became more similar to natural wetlands over 6–15 years after raising the water level – in terms of species composition or overall wetness. Three replicated studies in the USA simply quantified the plant community composition for up to three years after rewetting farmland (sometimes along with other interventions). Overall richness/diversity (12 studies): Four replicated, site comparison studies (two also paired) of one set of historically farmed depressions in the USA reported that restored wetlands (rewetted, along with planting cover crops in/around the sites) had lower overall plant species richness than nearby natural wetlands, after 1–7 years. Two before-and-after, site comparison studies of historical wetlands on a floodplain in the USA reported that raising the water level reduced overall plant species richness in the following six years. One site comparison study of lakeshore marshes in China reported that the total plant species richness in former paddy fields with breached weirs was similar to a nearby natural marsh, after 2–15 years. Five studies (two replicated) in the USA and Israel simply quantified overall plant species richness and/or diversity between three months and 19 years after raising the water table (sometimes along with other interventions). Characteristic plant richness/diversity (1 study): One before-and-after, site-comparison study of a floodplain in the USA reported that dechannelizing a river to raise the water level had no clear effect on the richness of wetland-characteristic plant species in the following six years. VEGETATION ABUNDANCE                                                                             Overall abundance (9 studies): Three before-and-after, site-comparison studies of historical wetlands on a floodplain in the USA reported that dechannelizing a river to raise the water level reduced overall vegetation cover in the following 6–9 years. One site comparison study in China reported that vegetation biomass in former paddy fields with breached weirs was similar to a nearby natural marsh, after 2–15 years. In contrast, one replicated, site comparison study in the USA found that vegetation cover in rewetted, formerly farmed depressions (also planted with cover crops) was lower than in nearby natural wetlands, after 5–7 years. Four studies (two replicated) in the USA and the UK simply quantified vegetation abundance between three months and six years after raising the water table (sometimes along with other interventions). Characteristic plant abundance (4 studies): Three before-and-after studies (two also site comparisons) of historical wetlands on a floodplain in the USA reported that dechannelizing a river to raise the water level increased the abundance of habitat- and/or wetland-characteristic plant species in the following 6–9 years. One study in the UK simply quantified the abundance of wet meadow plant species present 3–5 years after rewetting farmland (and introducing grazing). Bryophyte abundance (1 study): One replicated, site comparison study in the USA found that the frequency of bryophytes in (the wettest parts of) marshes rewetted 34 years previously was not significantly different from their frequency in (the wettest parts of) nearby natural marshes. Individual species abundance (11 studies): Eleven studies quantified the effect of this action on the abundance of individual plant species. For example, one replicated, site comparison study of freshwater marshes in the USA reported that Kneiff’s feathermoss Leptodictyum riparium was the most abundant plant species in marshes rewetted 34 years previously and nearby natural marshes. One before-and-after study of historical wetlands on a floodplain in the USA reported that after dechannelizing a river to raise the water level, some plots became dominated by a non-native grass species. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3198https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3198Fri, 09 Apr 2021 07:44:56 +0100Collected Evidence: Collected Evidence: Raise water level to restore/create brackish/salt marshes from other land uses Two studies evaluated the effects, on vegetation, of raising the water level to restore/create brackish/salt marshes from other land uses or habitat types. Both studies were in the same area of Iraq, but used different study sites. VEGETATION COMMUNITY Community types (1 study): One before-and-after study of a slightly brackish marsh in Iraq reported that fewer plant community types were present three years after reflooding than before drainage. Overall richness/diversity (2 studies): Two before-and-after studies of brackish marshes in Iraq reported that fewer plant species were present three years after reflooding than before drainage. One of these studies also reported that individual plant communities typically had lower diversity after reflooding than before drainage. VEGETATION ABUNDANCE Overall abundance (1 study): One before-and-after study of a slightly brackish marsh in Iraq reported that six of seven studied plant communities had lower spring and/or summer biomass three years after reflooding than before drainage. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3199https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3199Fri, 09 Apr 2021 07:45:05 +0100Collected Evidence: Collected Evidence: Raise water level to restore/create freshwater swamps from other land uses Two studies evaluated the effects, on vegetation, of raising the water level to restore/create freshwater swamps from other land uses or habitat types. Both studies monitored the effects of one river dechannelization project in the USA. VEGETATION COMMUNITY Overall extent (1 study): One before-and-after study of a floodplain in the USA reported that after dechannelizing a river to raise the water level, the area of shrubby and forested wetlands increased – reaching greater coverage than before intervention, but also than before degradation. Community types (1 study): The same study broke down overall swamp coverage into specific community types. For example, most of the shrubby wetlands that developed after raising the water level were dominated by a non-native species – which was not present historically. VEGETATION ABUNDANCE                                                                             Overall abundance (1 study): One before-and-after, site comparison study of historical shrubby wetlands on a floodplain in the USA reported that dechannelizing a river to raise the water level reduced overall vegetation cover in the following nine years. Characteristic plant abundance (1 study): The same study reported that after dechannelizing a river to raise the water level, only one of two sites became dominated by wetland-characteristic shrubs. The other site remained dominated by wetland-characteristic herb species. Individual species abundance (1 study): The same study reported that dechannelizing a river to raise the water level slightly increased cover of buttonbush Cephalanthus occidentalis in one of two sites (no data for other site). VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3200https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3200Fri, 09 Apr 2021 07:45:18 +0100Collected Evidence: Collected Evidence: Raise water level to restore/create brackish/saline swamps from other land usesWe found no studies that evaluated the effects, on vegetation, of raising the water level to restore/create brackish/saline swamps from other land uses or habitat types.   ‘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%2F3201https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3201Fri, 09 Apr 2021 07:45:30 +0100Collected Evidence: Collected Evidence: Lower water level to restore/create freshwater marshes from other land uses Two studies evaluated the effects, on vegetation, of lowering the water level to restore/create freshwater marshes from other land uses or habitat types. One study was in the USA and one was in the Netherlands. VEGETATION COMMUNITY Overall extent (1 study): One replicated, before-and-after study of a freshwater wetland in the USA reported that following a drawdown of water levels, emergent vegetation coverage increased in areas that were previously open water. VEGETATION ABUNDANCE Overall abundance (1 study): One before-and-after study at the edge of a freshwater lake in the Netherlands reported that following a drawdown of the lake water level, vegetation cover developed in areas that were previously open water. Cover varied between years and elevations. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3202https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3202Fri, 09 Apr 2021 07:46:42 +0100Collected Evidence: Collected Evidence: Lower water level to restore/create brackish/salt marshes from other land usesWe found no studies that evaluated the effects, on vegetation, of lowering the water level to restore/create brackish/salt marshes from other land uses or habitat types.   ‘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%2F3203https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3203Fri, 09 Apr 2021 07:47:14 +0100Collected Evidence: Collected Evidence: Lower water level to restore/create freshwater swamps from other land usesWe found no studies that evaluated the effects, on vegetation, of lowering the water level to restore/create freshwater swamps from other land uses or habitat types.   ‘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%2F3204https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3204Fri, 09 Apr 2021 07:47:30 +0100Collected Evidence: Collected Evidence: Lower water level to restore/create brackish/saline swamps from other land usesWe found no studies that evaluated the effects, on vegetation, of lowering the water level to restore/create brackish/saline swamps from other land uses or habitat types.   ‘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%2F3205https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3205Fri, 09 Apr 2021 07:47:43 +0100Collected Evidence: Collected Evidence: Facilitate tidal exchange to restore/create freshwater marshes from other land usesWe found no studies that evaluated the effects, on vegetation, of facilitating tidal exchange to restore/create freshwater marshes from other land uses or habitat types.   ‘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%2F3206https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3206Fri, 09 Apr 2021 07:48:40 +0100Collected Evidence: Collected Evidence: Facilitate tidal exchange to restore/create brackish/salt marshes from other land uses Fourteen studies evaluated the effects, on vegetation, of facilitating tidal exchange to restore/create brackish/salt marshes from other land uses or habitat types. Seven studies were in the UK. Five studies were in the USA. There was one study in each of Australia and the Netherlands. There was overlap in the sites used in four of the studies. VEGETATION COMMUNITY Overall extent (3 studies): Three before-and-after studies in Australia, the UK and the Netherlands reported increases in the overall extent of salt marsh vegetation over 3–10 years after restoring tidal exchange. Community types (3 studies): One replicated, paired, site comparison study in the UK reported that restored marshes, developing after 2–13 years of tidal exchange, contained a different type of salt marsh plant community to natural marshes in four of four cases. Two before-and-after studies in the UK and the Netherlands reported increases in the frequency or coverage of salt marsh plant communities after restoring tidal exchange, reaching 93–100% after 9–10 years. Community composition (4 studies): Four site comparison studies (two replicated, one paired) in the UK and the USA reported that after facilitating tidal exchange on freshwater wetlands or farmland, the overall plant community composition remained somewhat different from natural brackish/salt marshes for up to 30 years. Three of the studies reported increasing community similarity to natural marshes over 11–30 years of tidal exchange. Overall richness/diversity (6 studies): Two site comparison studies of brackish/salt marshes in the USA and the UK reported that overall plant species richness was similar in marshes developing after 4–11 years of tidal exchange, and in nearby natural marshes. Two site comparison studies (one replicated) of salt marshes in the UK reported that marshes developing after 1–14 years of tidal exchange (sometimes along with other interventions) had lower plant species richness or diversity than nearby natural marshes. Two before-and-after studies in the UK compared the number of plant/algae species present in salt marshes that developed over 1–9 years after restoring tidal exchange to the number of plant species present before intervention. In one study there were more species after intervention, but in the other study there were fewer. Characteristic plant richness/diversity (2 studies): One replicated, site comparison study of salt marshes in the UK reported that marshes developing after 1–14 years of tidal exchange contained a similar number of salt-tolerant plant species to natural marshes. One before-and-after study in the Netherlands reported that all 23 target brackish/salt marsh species were present in the study site 10 years after restoring regular tidal exchange: more than were present before restoration. VEGETATION ABUNDANCE Overall abundance (6 studies): Two site comparison studies (one replicated) of salt marshes in the UK reported that marshes developing after 1–14 years of tidal exchange (sometimes along with other interventions) had lower overall vegetation cover than nearby natural marshes. One before-and-after study in the UK reported that 99% of salt marsh quadrats were vegetated nine years after restoring tidal exchange, compared to 100% in the freshwater wetland that previously occupied the site and 43% one summer after restoration. Three studies in the USA and the UK simply quantified the overall cover of vegetation present in sites for up to 15 years after facilitating tidal exchange (sometimes along with other interventions). Characteristic plant abundance (1 study): One site comparison study in the USA reported that some plant species diagnostic of natural brackish marshes were absent from a marsh that had developed over >30 years of restored tidal exchange. Individual species abundance (6 studies): Six studies quantified the effect of this action on the abundance of individual plant species. For example, three site comparison studies of salt marshes in the UK reported that cover of saltmarsh grass Puccinellia maritima was similar or lower in marshes developing after 1–14 years of tidal exchange (sometimes along with other interventions) than in nearby natural marshes. In contrast, in these studies, cover of glassworts Salicornia was higher in restored than natural marshes. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3207https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3207Fri, 09 Apr 2021 07:49:08 +0100Collected Evidence: Collected Evidence: Facilitate tidal exchange to restore/create freshwater swamps from other land usesWe found no studies that evaluated the effects, on vegetation, of facilitating tidal exchange to restore/create freshwater swamps from other land uses or habitat types.   ‘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%2F3208https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3208Fri, 09 Apr 2021 07:49:21 +0100Collected Evidence: Collected Evidence: Facilitate tidal exchange to restore/create brackish/saline swamps from other land uses Two studies evaluated the effects, on vegetation, of facilitating tidal exchange to restore/create brackish/saline swamps from other land uses or habitat types. One study was in Australia and one was in Thailand. VEGETATION COMMUNITY                              Overall extent (1 study): One before-and-after study in an estuary in Australia reported that the area of mangrove forest on an island was greater 3–9 years after restoring full tidal exchange than in the years before. Tree/shrub richness/diversity (1 study): One study in a former shrimp pond in Thailand reported the number of mangrove tree species that spontaneously colonized in the six years after restoring full tidal exchange (along with other interventions). VEGETATION ABUNDANCE Individual species abundance (1 study): One study in a former shrimp pond in Thailand reported the number of mangrove trees, by species, that spontaneously colonized in the six years after restoring full tidal exchange (along with other interventions). VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3209https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3209Fri, 09 Apr 2021 07:49:33 +0100Collected Evidence: Collected Evidence: Fill/block ditchesWe found no studies that evaluated the effects of filling/blocking ditches in marshes or swamps on vegetation within the ditches.   ‘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%2F3210https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3210Fri, 09 Apr 2021 08:47:05 +0100Collected Evidence: Collected Evidence: Excavate freshwater pools Seven studies evaluated the effects, on vegetation within pools or surrounding marshes/swamps, of excavating freshwater pools. Five studies were in the USA, one was in Guam and one was in Canada. Two of the studies in the USA were based on the same set of pools. VEGETATION COMMUNITY Relative abundance (2 studies): One replicated, paired, site comparison study in a freshwater marsh in Canada reported that a smaller proportion of individual plants around excavated pools were wetland-characteristic species, compared to the proportion around natural pools. The excavated pools were 1–3 years old. One replicated study in the USA reported that excavated pools became dominated by non-native plant species over eight years. Overall richness/diversity (3 studies): One replicated, paired, site comparison study in a freshwater marsh in Canada found that overall plant species richness and diversity were similar around excavated pools and natural pools, 1–3 years after excavation. Two studies involving freshwater marshes in Guam and the USA simply quantified plant species richness 12–18 months after excavation (along with other interventions). VEGETATION ABUNDANCE Overall abundance (1 study): One replicated, site comparison study in the USA found that excavated and natural pools had similar cover of emergent vegetation, seven years after excavation. The same was true for submerged vegetation. Characteristic plant abundance (2 studies): Two replicated studies in the USA reported the abundance of native pool-characteristic species over 3–8 years after excavating pools. One of the studies was also a site comparison and reported that these species were less abundant in the excavated pools than nearby natural pools. Shrub abundance (2 studies): One replicated, site comparison study in the USA found that excavated and natural pools had similar cover of shrubby vegetation after seven years. One replicated study in the USA simply quantified shrub abundance over five years after excavating pools/potholes (along with other interventions). Algae/phytoplankton abundance (1 study): One replicated, site comparison study in the USA found that excavated and natural pools contained a similar biomass of surface-coating algae and phytoplankton, after seven years. The same was true for phytoplankton after eight years. Individual species abundance (5 studies): Five studies quantified the effect of this action on the abundance of individual plant species. For example, one replicated, site comparison study in the USA found that excavated and natural pools had similar cover of loosestrife Lythrum sp. seven years after excavation, but that excavated pools had greater cover of duckweed Lemna sp., cattails Typha spp. and common reed Phragmites australis. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3211https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3211Fri, 09 Apr 2021 08:47:38 +0100Collected Evidence: Collected Evidence: Excavate brackish/saline poolsWe found no studies that evaluated the effects, on vegetation within pools or surrounding marshes/swamps, of excavating brackish/saline pools.   ‘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%2F3212https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3212Fri, 09 Apr 2021 08:48:33 +0100Collected Evidence: Collected Evidence: Disturb soil/sediment surface: freshwater marshes Two studies evaluated the effects, on vegetation, of disturbing the surface of freshwater marshes. Both studies were in the USA – in the same region but different sites. VEGETATION COMMUNITY Community composition (1 study): One replicated, paired, controlled study in rewetted marshes in the USA found that ploughed plots contained a plant community characteristic of wetter conditions than unploughed plots after one growing season – but not after two. Overall richness/diversity (2 studies): Two replicated, controlled studies in rewetted marshes in the USA found that ploughed plots typically contained more wetland plant species than unploughed plots after one growing season – but not after two. VEGETATION ABUNDANCE Overall abundance (2 studies): Two replicated, controlled studies in rewetted marshes in the USA found that ploughed plots had greater cover of wetland plants than unploughed plots after one growing season – but not after two. Individual species abundance (1 study): One replicated, controlled study in rewetted marshes in the USA found that ploughed plots had much greater cover of cattails Typha than unploughed plots after two growing seasons. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3226https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3226Fri, 09 Apr 2021 14:04:02 +0100Collected Evidence: Collected Evidence: Disturb soil/sediment surface: brackish/salt marshes One study evaluated the effects, on vegetation, of disturbing the surface of brackish/salt marshes. The study was in the USA. VEGETATION COMMUNITY Community composition (1 study): One replicated, paired, site comparison study of brackish/salt marshes in the USA reported that marshes disked every spring for at least six years (and drawn down during spring/autumn) shared only 24–34% of plant species with marshes that were not disked (or drawn down). Overall richness/diversity (1 study): The same study found that overall plant species richness and diversity were similar in managed marshes (disked every spring and drawn down during spring/autumn, for at least six years) and unmanaged marshes (neither disked nor drawn down). VEGETATION ABUNDANCE   VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3227https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3227Fri, 09 Apr 2021 14:04:14 +0100Collected Evidence: Collected Evidence: Disturb soil/sediment surface: freshwater swampsWe found no studies that evaluated the effects, on vegetation, of disturbing the surface of 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%2F3228https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3228Fri, 09 Apr 2021 14:04:26 +0100Collected Evidence: Collected Evidence: Disturb soil/sediment surface: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of disturbing the surface of 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%2F3229https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3229Fri, 09 Apr 2021 14:04:36 +0100Collected Evidence: Collected Evidence: Deposit soil/sediment to form physical structure of freshwater marshes Two studies evaluated the effects, on vegetation, of depositing soil/sediment to form the physical structure of freshwater marshes (without introducing vegetation). One study was in the USA and one was in the Netherlands. VEGETATION COMMUNITY Community types (1 study): One replicated, paired, site comparison study in the Netherlands reported that marshes created by depositing sand at lake margins contained fewer plant community types, after 8–16 years, than mature natural marshes. VEGETATION ABUNDANCE Overall abundance (2 studies): One site comparison study in the USA reported that plant stem density was similar, after 4–10 years, in marshes created by depositing sediment and in natural marshes, but that vegetation cover was lower in the created marshes. One replicated, paired, site comparison study in the Netherlands reported that marshes created by depositing sand at lake margins contained similar vegetation biomass to nearby natural marshes after 8–16 years. VEGETATION STRUCTURE Height (1 study): One site comparison study in the USA reported that a freshwater marsh created by depositing sediment contained vegetation of a similar height to nearby natural marshes after 4–10 years. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3235https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3235Fri, 09 Apr 2021 15:01:56 +0100Collected Evidence: Collected Evidence: Deposit soil/sediment to form physical structure of freshwater swampsWe found no studies that evaluated the effects on vegetation, of depositing soil/sediment to form the physical structure of freshwater swamps (without introducing vegetation).   ‘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%2F3237https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3237Fri, 09 Apr 2021 15:02:24 +0100Collected Evidence: Collected Evidence: Introduce nurse plants: freshwater marshesWe found no studies that evaluated the effects, on naturally colonizing vegetation, of introducing nurse plants to restore or create freshwater marshes.   ‘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%2F3252https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3252Sat, 10 Apr 2021 13:03:49 +0100Collected Evidence: Collected Evidence: Introduce nurse plants: brackish/salt marshesWe found no studies that evaluated the effects, on naturally colonizing vegetation, of introducing nurse plants to restore or create brackish/salt marshes.   ‘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%2F3253https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3253Sat, 10 Apr 2021 13:04:09 +0100Collected Evidence: Collected Evidence: Introduce nurse plants: freshwater swampsWe found no studies that evaluated the effects, on naturally colonizing vegetation, of introducing nurse plants to restore or create 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%2F3254https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3254Sat, 10 Apr 2021 13:04:24 +0100Collected Evidence: Collected Evidence: Introduce nurse plants: brackish/saline swamps One study evaluated the effects, on naturally colonizing vegetation, of introducing nurse plants to restore or create brackish/saline swamps. The study was in India. VEGETATION COMMUNITY   VEGETATION ABUNDANCE   VEGETATION STRUCTURE Height (1 study): One study on an estuarine mudflat in India reported that the average height of mangrove propagules trapped by nurse grasses increased by 21–90% (depending on the species) over the first month after establishment. OTHER Germination/emergence (1 study): One study on an estuarine mudflat in India reported that 60–80% (depending on the species) of mangrove propagules trapped by nurse grasses developed into seedlings. Saltmarsh grasses trapped 1,200–1,372 mangrove propagules/m2/week, approximately 1–2 years after they were planted. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3255https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3255Sat, 10 Apr 2021 13:04:30 +0100
What Works 2021 cover

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.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 21

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust
For a full list of, and information about, our champions:
All Evidence Champions
About our champions, why and how to become one:
Become an Evidence Champion

This website uses Cookies

We use limited Cookies to run the site and to analyse our traffic (none for site vendors). By using this site, you will be providing your consent to our use of Cookies.

Accept & continue