Conservation Evidence: Evidence Data

Collected Evidence: Collected Evidence: Reduce intensity of livestock grazing: freshwater marshes Three studies evaluated the effects, on vegetation, of reducing livestock grazing intensity in freshwater marshes (without stopping grazing entirely). Two studies were in the USA and the other was in Ireland. In all three studies, livestock were cattle. VEGETATION COMMUNITY Community composition (1 study): One site comparison study in Ireland found that lightly and heavily grazed wet meadows contained a similar overall mix of plant species. Relative abundance (1 study): One replicated, randomized, paired, controlled study in the USA found that seasonally and continuously grazed ephemeral pools had similar cover of grasses relative to forbs. Overall richness/diversity (1 study): One site comparison study in Ireland found that lightly and heavily grazed wet meadows had similar overall plant species richness. Native plant richness/diversity (1 study): One replicated, randomized, paired, controlled study in the USA found that seasonally and continuously grazed ephemeral pools experienced similar changes in native plant species richness over three years. VEGETATION ABUNDANCE Overall abundance (1 study): One site comparison study in Ireland reported that lightly and heavily grazed wet meadows had similar overall vegetation cover. Herb abundance (1 study): One replicated, randomized, paired, controlled, before-and-after study in the USA found that lightly and moderately grazed springs/creeks had similar herb cover. Individual species abundance (1 study): One study quantified the effect of this action on the abundance of individual plant species. The site comparison study in Ireland reported, for example, that lightly grazed wet meadows had greater cover of black sedge Carex nigra, and lower cover of creeping bent Agrostis stolonifera, than more heavily grazed wet meadows. VEGETATION STRUCTURE Height (1 study): One site comparison study in Ireland found that lightly grazed wet meadows contained taller vegetation than heavily grazed wet meadows. Vegetation was measured in the summer, during the grazing season. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2970https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2970Thu, 25 Mar 2021 14:15:51 +0000Collected Evidence: Collected Evidence: Reduce intensity of livestock grazing: brackish/salt marshes Nine studies evaluated the effects, on vegetation, of reducing livestock grazing intensity in brackish/salt marshes (without stopping grazing entirely). Five studies were in Germany. Four studies were in the Netherlands. Livestock were cattle, sheep or horses. There was overlap in the sites used in two of the German studies and three of the Dutch studies. VEGETATION COMMUNITY Overall extent (1 study): One controlled study of a salt marsh in Germany reported that the total vegetated area was slightly larger in plots grazed at a lower intensity, for eight years, than plots grazed at a higher intensity. Community types (4 studies): Two controlled studies of salt marshes in Germany and the Netherlands reported similar coverage, or similar change in coverage, of plant community types under different grazing intensities. Two studies of brackish and salt marshes in the Netherlands and Germany reported that reducing grazing intensity (along with other interventions) affected coverage of plant community types. In one study, the precise effect varied with environmental conditions. Community composition (1 study): One replicated, randomized, paired, before-and-after study on a salt marsh in the Netherlands found that plots grazed under different grazing intensities experienced a similar turnover of plant species over six years, and had a similar overall plant community composition after six years. Overall richness/diversity (5 studies): Three replicated, paired, controlled studies on salt marshes in Germany and the Netherlands found that plots grazed at lower intensities never had greater plant species richness, after 1–22 years, than plots grazed at higher intensities. One controlled study on a salt marsh in Germany found that paddocks grazed at low intensity had greater plant species richness, after 16–18 years, than paddocks grazed at higher intensities. Two studies of salt marshes in the Netherlands found that plant species richness increased over 6–14 years of reduced grazing intensity (sometimes along with other interventions). VEGETATION ABUNDANCE Overall abundance (1 study): One controlled study on a salt marsh in Germany reported that overall vegetation cover was greater in lightly and moderately grazed paddocks than in a heavily grazed paddock – with the highest cover of all in the moderately grazed paddock. Individual species abundance (6 studies): Six studies quantified the effect of this action on the abundance of individual plant species. For example, three studies (including two controlled) on salt marshes in Germany and the Netherlands reported that plots under different grazing intensities supported a similar abundance (frequency or cover) of saltmarsh grass Puccinellia maritima – but with a tendency for greater abundance under lower intensities. VEGETATION STRUCTURE Height (6 studies): Six controlled studies (three also replicated and paired) in salt marshes in Germany and the Netherlands reported that vegetation was taller on average (or contained taller vegetation patches) in areas that had been grazed at lower intensities. However, in one of the studies, this was only true for canopy height: understory grasses were a similar height under all grazing intensities. One of the replicated, paired, controlled studies found that, after two summers, variation in vegetation height between patches was similar under all grazing intensities. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2971https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2971Thu, 25 Mar 2021 14:16:01 +0000Collected Evidence: Collected Evidence: Reduce intensity of livestock grazing: freshwater swampsWe found no studies that evaluated the effects, on vegetation, of reducing livestock grazing intensity in freshwater swamps (without stopping grazing entirely). ‘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%2F2972https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2972Thu, 25 Mar 2021 14:16:10 +0000Collected Evidence: Collected Evidence: Reduce intensity of livestock grazing: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of reducing livestock grazing intensity in brackish/saline swamps (without stopping grazing entirely). ‘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%2F2973https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2973Thu, 25 Mar 2021 14:16:22 +0000Collected Evidence: Collected Evidence: Reduce frequency of vegetation harvest: freshwater marshes Three studies evaluated the effects, on vegetation, of reducing the frequency of harvest in freshwater marshes (or harvesting at different frequencies). There was one study in each of the USA, Belgium and Italy. VEGETATION COMMUNITY Overall richness/diversity (1 study): One replicated, paired, controlled, before-and-after study in wet grasslands in Belgium reported that overall plant species richness was similar in plots harvested once or twice/year. VEGETATION ABUNDANCE Overall abundance (1 study): One replicated, paired, controlled, before-and-after study in wet grasslands in Belgium reported that the effect of harvesting twice/year (in July and October) on total above-ground biomass was intermediate between the effects of harvesting once/year in July or October. Individual species abundance (3 studies): All three studies quantified the effect of this action on the abundance of individual plant species. For example, one replicated, paired, controlled study in freshwater marshes in the USA reported that cattail Typha biomass was greater, nine months after the last harvest, in plots harvested every six weeks than in plots harvested every three weeks. One paired, controlled, before-and-after study in reedbeds in Italy found that the common reed Phragmites australis biomass was similar in plots harvested once or twice/year, when measured at least five months after the last harvest. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2997https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2997Wed, 31 Mar 2021 13:15:36 +0100Collected Evidence: Collected Evidence: Reduce frequency of vegetation harvest: brackish/salt marshesWe found no studies that evaluated the effects, on vegetation, of reducing the frequency of harvest in brackish/salt marshes (or harvesting at different frequencies). ‘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%2F2998https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2998Wed, 31 Mar 2021 13:16:12 +0100Collected Evidence: Collected Evidence: Reduce frequency of vegetation harvest: freshwater swampsWe found no studies that evaluated the effects, on vegetation, of reducing the frequency of harvest in freshwater swamps (or harvesting at different frequencies). ‘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%2F2999https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2999Wed, 31 Mar 2021 13:16:35 +0100Collected Evidence: Collected Evidence: Reduce frequency of vegetation harvest: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of reducing the frequency of harvest in brackish/saline swamps (or harvesting at different frequencies). ‘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%2F3000https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3000Wed, 31 Mar 2021 13:16:57 +0100Collected Evidence: Collected Evidence: Reduce intensity of vegetation harvest: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of reducing the intensity of harvest in brackish/saline swamps (or harvesting at different intensities). ‘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%2F3004https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3004Wed, 31 Mar 2021 13:27:31 +0100Collected Evidence: Collected Evidence: Reduce frequency of hunting/collecting animalsWe found no studies that evaluated the effects, on vegetation, of reducing the frequency of hunting/collecting animals 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%2F3015https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3015Wed, 31 Mar 2021 14:23:23 +0100Collected Evidence: Collected Evidence: Reduce intensity of hunting/collecting animalsWe found no studies that evaluated the effects, on vegetation, of reducing the intensity of hunting/collecting animals 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%2F3016https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3016Wed, 31 Mar 2021 14:24:32 +0100Collected Evidence: Collected Evidence: Raise water level to restore degraded freshwater swampsWe found no studies that evaluated the effects, on vegetation, of raising the water level to restore degraded 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%2F3028https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3028Wed, 31 Mar 2021 14:47:37 +0100Collected Evidence: Collected Evidence: Reduce frequency of cutting/mowing: freshwater marshes Four studies evaluated the effects, on vegetation, of reducing the frequency of cutting/mowing in freshwater marshes (or cutting/mowing them at different frequencies). There was one study in each of USA, the Netherlands, Belgium and Italy. VEGETATION COMMUNITY Community composition (1 study): One replicated, randomized, paired, controlled study of farmland ditches in the Netherlands found that marshy areas cut once, twice or three times/year had a similar overall plant community composition, when surveyed in July. Overall richness/diversity (2 studies): Two replicated, paired, controlled studies in farmland ditches in the Netherlands and wet grasslands in Belgium reported that overall plant species richness was similar in plots cut once or twice/year (and three times/year in the Netherlands). VEGETATION ABUNDANCE Overall abundance (1 study): One replicated, paired, controlled, before-and-after study in wet grasslands in Belgium reported that the effect of cutting twice/year (in July and October) on total above-ground biomass was intermediate between the effects of cutting once/year in July or October. Individual species abundance (4 studies): All four studies quantified the effect of this action on the abundance of individual plant species. For example, one replicated, paired, controlled study in freshwater marshes in the USA reported that cattail Typha spp. biomass was greater, nine months after the last cut, in plots cut every six weeks than in plots cut every three weeks. One paired, controlled, before-and-after study in reedbeds in Italy found that common reed Phragmites australis biomass was similar in plots mown once or twice/year, when measured at least five months after the last cut. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3066https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3066Fri, 02 Apr 2021 13:14:38 +0100Collected Evidence: Collected Evidence: Reduce frequency of cutting/mowing: brackish/salt marshesWe found no studies that evaluated the effects, on vegetation, of reducing the frequency of cutting/mowing in brackish/salt marshes (or cutting/mowing them at different frequencies). ‘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%2F3067https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3067Fri, 02 Apr 2021 13:17:06 +0100Collected Evidence: Collected Evidence: Reduce intensity of cutting/mowingWe found no studies that evaluated the effects, on vegetation, of reducing the intensity of cutting/mowing in marshes or swamps (or cutting/mowing them at different intensities). ‘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%2F3068https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3068Fri, 02 Apr 2021 13:29:11 +0100Collected Evidence: Collected Evidence: Reduce frequency of prescribed burningWe found no studies that evaluated the effects, on vegetation, of reducing the frequency of prescribed burning in marshes or swamps (or burning them at different frequencies). ‘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%2F3072https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3072Fri, 02 Apr 2021 14:40:50 +0100Collected Evidence: Collected Evidence: Reduce intensity of prescribed burningWe found no studies that evaluated the effects, on vegetation, of reducing the intensity of prescribed burning in marshes or swamps (or burning them at different intensities). ‘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%2F3073https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3073Fri, 02 Apr 2021 14:44:31 +0100Collected Evidence: Collected Evidence: Reduce fertilizer or herbicide use: freshwater marshes One study evaluated the effects, on vegetation in freshwater marshes, of reducing the amount of fertilizer or herbicide used in the marshes or adjacent areas. The study was in Brazil. VEGETATION COMMUNITY Community composition (1 study): One replicated, site comparison study of rice fields in Brazil found that the overall plant community composition (excluding rice) was similar in organically farmed fields and conventionally farmed fields, but different from the community in nearby natural marshes. Overall richness/diversity (1 study): The same study found that organically farmed rice fields contained a similar average richness and diversity of wetland plants (at any single point in time) to conventionally farmed rice fields, although more species were recorded in the organic fields over the year of the study. Organically farmed rice fields had lower wetland plant richness and diversity than nearby natural marshes. VEGETATION ABUNDANCE Overall abundance (1 study): One replicated, site comparison study of rice fields in Brazil found that organically farmed fields contained more wetland plant biomass than conventionally farmed fields over the year of the study, but less wetland plant biomass than nearby natural marshes. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3152https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3152Mon, 05 Apr 2021 15:48:02 +0100Collected Evidence: Collected Evidence: Reduce fertilizer or herbicide use: brackish/salt marshesWe found no studies that evaluated the effects, on vegetation in brackish/salt marshes, of reducing the amount of fertilizer or herbicide used in the marshes or adjacent areas. ‘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%2F3153https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3153Mon, 05 Apr 2021 15:48:23 +0100Collected Evidence: Collected Evidence: Reduce fertilizer or herbicide use: freshwater swampsWe found no studies that evaluated the effects, on vegetation in freshwater swamps, of reducing the amount of fertilizer or herbicide used in the swamps or adjacent areas. ‘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%2F3154https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3154Mon, 05 Apr 2021 15:48:47 +0100Collected Evidence: Collected Evidence: Reduce fertilizer or herbicide use: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation in brackish/saline swamps, of reducing the amount of fertilizer or herbicide used in the swamps or adjacent areas. ‘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%2F3155https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3155Mon, 05 Apr 2021 15:48:59 +0100Collected 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 +0100