Collected Evidence: Collected Evidence: Use low-impact methods to harvest vegetation: freshwater marshesWe found no studies that evaluated the effects, on vegetation, of using supposedly low-impact methods to harvest vegetation in 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%2Fconservationevidencejournal.com%2Factions%2F3009https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3009Wed, 31 Mar 2021 14:09:59 +0100Collected Evidence: Collected Evidence: Use low-impact methods to harvest vegetation: brackish/salt marshesWe found no studies that evaluated the effects, on vegetation of using supposedly low-impact methods to harvest vegetation in 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%2Fconservationevidencejournal.com%2Factions%2F3010https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3010Wed, 31 Mar 2021 14:10:09 +0100Collected Evidence: Collected Evidence: Use low-impact methods to harvest vegetation: freshwater swamps One study evaluated the effects, on vegetation, of using supposedly low-impact methods to harvest vegetation in freshwater swamps. The study was in the USA. VEGETATION COMMUNITY Overall richness/diversity (1 study): One controlled study in a freshwater swamp in the USA reported that after seven years, a plot where logs had been extracted by helicopter only contained fewer plant species than a plot where logs had been extracted by helicopter and ground vehicles. VEGETATION ABUNDANCE Overall abundance (1 study): One controlled study in a freshwater swamp in the USA reported that after seven years, a plot where logs had been extracted by helicopter only contained less overall plant biomass than a plot where logs had been extracted by helicopter and ground vehicles. This was also true for the overstory and ground layers separately. However, overstory tree density did not significantly differ between helicopter-extracted and vehicle-extracted plots. Individual species abundance (1 study): The same study found that the abundance of some individual plant species – particularly swamp ash Fraxinus caroliniana and water tupelo Nyssa aquatica – significantly differed between helicopter-extracted and vehicle-extracted plots. VEGETATION STRUCTURE Height (1 study): One controlled study in a freshwater swamp in the USA found that after seven years, the average height of the overstory was similar in a plot where logs had been extracted by helicopter only and a plot where logs had been extracted by helicopter and ground vehicles. Diameter, perimeter, area (1 study): The same study found that after seven years, the average stem diameter of overstory trees was similar in helicopter-extracted and vehicle-extracted plots. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3011https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3011Wed, 31 Mar 2021 14:10:30 +0100Collected Evidence: Collected Evidence: Use low-impact methods to harvest vegetation: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of using supposedly low-impact methods to harvest vegetation 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%2Fconservationevidencejournal.com%2Factions%2F3012https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3012Wed, 31 Mar 2021 14:10:48 +0100Collected Evidence: Collected Evidence: Use low-impact methods to hunt/collect animalsWe found no studies that evaluated the effects, on vegetation, of using supposedly low-impact methods to hunt/collect 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%2Fconservationevidencejournal.com%2Factions%2F3017https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3017Wed, 31 Mar 2021 14:25:33 +0100Collected Evidence: Collected Evidence: Use grazing to maintain or restore disturbance: freshwater marshes Five studies evaluated the effects, on vegetation, of using grazing to maintain or restore disturbance in freshwater marshes. Two studies were in the UK. There was one study in each of the Netherlands, Germany and the USA. VEGETATION COMMUNITY Community types (2 studies): One study of a riparian wet meadow in Germany reported changes in the area of plant community types over four years of grazing (after cutting trees/shrubs). One replicated, before-and-after study of dune slacks in the UK reported that the plant community type within plots remained stable over 16 years of grazing. Community composition (3 studies): Two replicated, randomized, paired, controlled, studies in freshwater marshes/wet meadows in the UK and the USA reported that the overall plant community composition was similar in grazed and ungrazed plots after 2–9 years. One replicated study of dune slacks in the Netherlands simply reported changes in the overall plant community composition after resuming grazing (along with other interventions). Overall richness/diversity (4 studies): Two studies (one replicated, before-and-after) in wetlands in Germany and the UK reported that after resuming grazing (and cutting trees/shrubs in one study), there were increases in total plant species richness and/or diversity. One replicated, randomized, paired, controlled, before-and-after study in the UK reported that grazing had no significant effect on overall plant species richness in wet grassland and flush vegetation: there were similar declines over nine years in grazed and ungrazed plots. One replicated study of dune slacks in the Netherlands simply quantified total plant species richness over three years after resuming grazing (along with other interventions). Characteristic plant richness/diversity (2 studies): One replicated, before-and-after study in dune slacks in the UK reported that after resuming grazing, the number of dune-slack indicator species increased. 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 three years after resuming grazing (along with other interventions). VEGETATION ABUNDANCE Overall abundance (2 studies): One replicated, randomized, paired, controlled, before-and-after study in freshwater marshes/wet meadows in the USA found that grazing typically had no significant effect on overall vegetation biomass after 1–2 years. One replicated study of dune slacks in the Netherlands simply quantified total vegetation cover over three years after resuming grazing (along with other interventions). Cover never exceeded 50%. Herb abundance (1 study): One replicated, randomized, paired, controlled, before-and-after study in the UK reported that grazing had no significant effect on the cover of forbs or grass-like plants in wet grassland and flush vegetation: there were similar declines over nine years in grazed and ungrazed plots. Tree/shrub abundance (1 study): One study of a riparian wet meadow in Germany reported that some trees/shrubs regrew over four years of grazing (after cutting trees/shrubs). Bryophyte abundance (1 study): One replicated, randomized, paired, controlled, before-and-after study in the UK reported that grazing had no significant effect on bryophyte cover in wet grassland and flush vegetation: there were similar changes over nine years in grazed and ungrazed plots. Individual species abundance (1 study): One replicated study of dune slacks in the Netherlands simply quantified the cover of individual species present over three years after resuming grazing (along with other interventions). Only two species had >1% cover in any slack. VEGETATION STRUCTURE Height (2 studies): One site comparison study of a riparian wet meadow in Germany reported that an area grazed by cattle (after cutting trees/shrubs) contained shorter vegetation than an adjacent unmanaged area. One replicated, randomized, paired, controlled study in wet grassland and flush vegetation in the UK found that the maximum vegetation height was typically similar, over four years, in plots grazed by cattle and plots from which cattle were excluded. OTHER Survival (1 study): One study of a riparian wet meadow in Germany reported that 20% of black alder Alder glutinosa trees were still alive after being cut back and grazed for four years. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3050https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3050Thu, 01 Apr 2021 19:34:04 +0100Collected Evidence: Collected Evidence: Use grazing to maintain or restore disturbance: brackish/salt marshes Four studies evaluated the effects, on vegetation, of using grazing to maintain or restore disturbance in brackish/salt marshes. The studies were in the UK, Denmark, France and the USA. VEGETATION COMMUNITY Community composition (1 study): One replicated, paired, controlled, before-and-after study of brackish marshes in France reported that the overall plant community composition diverged, over five years, in plots where grazing was maintained and plots where grazing ceased. The precise effect depended on the flooding regime. Overall richness/diversity (2 studies): One controlled study on a salt marsh in Denmark reported that an area where grazing was maintained had identical plant species richness, after six years, to an area where grazing had ceased. One replicated, paired, controlled, before-and-after study of brackish marshes in France reported that the effect of continued grazing on plant species richness depended on the flooding regime. VEGETATION ABUNDANCE Overall abundance (3 studies): Two controlled studies on salt marshes in the UK and Denmark reported that areas where grazing was maintained contained less vegetation overall, after 2–6 years, than areas where grazing ceased. This was measured in terms of biomass or cover. One replicated, randomized, paired, controlled, before-and-after study in alkali marshes in the USA found that grazing had no significant effect on total vegetation biomass after 1–2 years. Individual species abundance (3 studies): Three studies quantified the effect of this action on the abundance of individual plant species. For example, one replicated, paired, controlled, before-and-after study of brackish marshes in France reported that continued grazing strongly limited colonization by common reed Phragmites australis over five years. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3051https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3051Thu, 01 Apr 2021 19:35:04 +0100Collected Evidence: Collected Evidence: Use grazing to maintain or restore disturbance: freshwater swampsWe found no studies that evaluated the effects, on vegetation, of using grazing to maintain or restore disturbance 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%2Fconservationevidencejournal.com%2Factions%2F3052https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3052Thu, 01 Apr 2021 19:57:56 +0100Collected Evidence: Collected Evidence: Use prescribed fire to maintain or restore disturbance: freshwater marshes Fifteen studies evaluated the effects, on vegetation, of using prescribed fire to maintain or restore disturbance in freshwater marshes. Ten studies were in the USA. Two studies, based on one experimental set-up, were in the Netherlands. There was one study in each of the UK, Romania and South Africa. VEGETATION COMMUNITY Community composition (4 studies): Of four replicated, controlled studies (three also before-and-after) in freshwater wetlands in the USA, two found that burning (sometimes along with other interventions) significantly affected the overall plant community composition in the following 2–5 years. The other two studies found that burning had no clear or significant effect on the overall plant community composition over the following two years. One of these studies also found that the plant community in burned marshes was less similar to pristine local marshes than the plant community in unburned marshes, after two years. Overall richness/diversity (8 studies): Four replicated, paired, controlled studies in freshwater marshes/wet meadows in the UK and the USA found that burning had no significant effect on overall plant species richness and/or diversity over 1–2 growing seasons. However, three replicated, paired, controlled studies in the UK and the USA reported that burning increased plant species richness or diversity after 1–3 growing seasons. Two replicated studies (including one paired, site comparison) in the USA and South Africa reported that burning reduced plant species richness or diversity after 1–3 growing seasons. However, the study in the USA also reported that burning increased richness after 4–8 growing seasons. VEGETATION ABUNDANCE Overall abundance (5 studies): Four studies (including two randomized, paired, controlled, before-and-after) in freshwater marshes/wet meadows in the USA found that prescribed burning had no significant effect on overall vegetation abundance (biomass or cover) after 1–3 growing seasons. One replicated, randomized, paired, controlled study in a freshwater marsh in the USA reported that burned plots contained less vegetation biomass, one year after the latest burn, than unburned plots. Characteristic plant abundance (1 study): One replicated, randomized, controlled, before-and-after study of overgrown freshwater marshes in the USA reported that of 26 plant taxa that became more frequent after burning (along with other interventions), 16 were obligate wetland taxa. Herb abundance (1 study): One replicated, paired, site comparison study of sedge meadows in the USA found that burned meadows typically contained similar cover of herbaceous plant groups (grasses, sedges/rushes and forbs) to unburned meadows, after 1–8 growing seasons. Tree/shrub abundance (2 studies): One replicated, randomized, paired, controlled, before-and-after study in a degraded, shrubby wet prairie the USA found that over three years, burning reduced woody plant cover. One replicated, before-and-after study of freshwater marshes within a forest plantation in South Africa reported that burning never increased overall tree density five months later, although the precise effect apparently depended on site wetness. Algae/phytoplankton abundance (1 study): One controlled study in a freshwater marsh in the USA found that burned plots contained a greater abundance (cover and biomass) of surface-encrusting algae, over the following 72 days, than unburned plots. Individual species abundance (9 studies): Nine studies quantified the effect of this action on the abundance of individual plant species. The nine studies (including eight controlled or site comparison) in the Netherlands, the UK, the USA, Romania and South Africa reported mixed effects of burning on dominant herbaceous species, depending on the species, metric, site conditions and/or time after burning. VEGETATION STRUCTURE Height (5 studies): Four studies (including one replicated, randomized, paired, controlled) – in reedbeds in the UK and Romania, a marsh in the USA and freshwater marshes within a forest plantation in South Africa – found that burned plots contained shorter vegetation than unburned plots in the subsequent growing season. One study in a marsh in the USA reported that over the 50 days after prescribed burning, the average height of sawgrass Cladium jamaicense increased. Diameter/perimeter/area (3 studies): Two replicated, paired, controlled studies in reedbeds in the Netherlands and the UK found that common reed Phragmites australis stems were typically thicker in spring-burned plots than unburned plots, in the subsequent growing season. However, one site comparison study of reedbeds in Romania found that common reed stems were thinner in winter-burned plots than unburned plots, in the following spring. OTHER            Survival (1 study): One replicated, randomized, paired, controlled, before-and-after study in a degraded, shrubby wet prairie the USA found that woody plants had a lower survival rate, after one year, in burned plots than in unburned plots. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3054https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3054Fri, 02 Apr 2021 08:55:35 +0100Collected Evidence: Collected Evidence: Use prescribed fire to maintain or restore disturbance: brackish/salt marshes Ten studies evaluated the effects, on vegetation, of using prescribed fire to maintain or restore disturbance in brackish/salt marshes. Seven studies were in the USA. Two studies were in Argentina but based on the same experimental set-up. One study was in Guadeloupe. VEGETATION COMMUNITY Community composition (1 study): One replicated, paired, controlled study in a salt marsh in Argentina reported that burned plots had a different overall plant community composition to unburned plots, five months after burning. The same was true in one of two comparisons 17 months after burning. Overall richness/diversity (5 studies): Three studies (including one replicated, paired, controlled) in brackish marshes in the USA and Guadeloupe reported that burning had no significant effect on overall plant species richness, measured approximately 10 weeks to 2 years after the latest burn. In one of the studies, the effects of burning and legal protection were not separated. One replicated, randomized, paired, controlled, before-and-after study in brackish marshes in the USA reported that burning typically had no significant effect on changes in plant species richness over two years. One replicated, paired, controlled study in a salt marsh in Argentina reported that burned plots had greater overall plant species richness and diversity than unburned plots, 5–17 months after burning. Characteristic plant richness/diversity (1 study): One study of a coastal marsh in the USA reported that over three years after restoration – involving a prescribed burn along with restoration of tidal exchange – the number of salt-tolerant plant species increased, whilst the number of freshwater plant species decreased. VEGETATION ABUNDANCE Overall abundance (5 studies): Three replicated studies (one also randomized, paired, controlled) in brackish marshes in the USA found that overall vegetation biomass was lower in burned than unburned plots, 10 weeks or 1 year after the latest burn. One replicated, randomized, paired, controlled, before-and-after study in alkali marshes in the USA found that a single prescribed burn had no significant effect on overall vegetation biomass: there was a similar change over two years in burned and unburned plots. One replicated, paired, controlled study in a salt marsh in Argentina found that the effect of a single prescribed burn on the frequency of seedlings depended on the time since burning, but that seedlings were more frequent in burned than unburned plots after 9–12 months. Characteristic plant abundance (1 study): One study of a coastal marsh in the USA found that over three years after restoration – involving a prescribed burn along with restoration of tidal exchange – the cover of salt-tolerant plant species increased, whilst the cover of freshwater plant species decreased. Individual species abundance (7 studies): Seven studies quantified the effect of this action on the abundance of individual plant species. For example, five studies quantified the effects of prescribed burning on the abundance of dominant cordgrasses Spartina sp. in brackish and salt marshes in the USA and Argentina. Two replicated, paired, controlled studies found that cordgrass abundance (biomass or cover) was lower in burned than unburned plots, between 10 weeks and 17 months after the latest burn. However, one replicated, paired, site comparison study found that burning typically had no significant effect on cordgrass biomass or density after 2–8 months. One replicated, before-and-after study found that cordgrass biomass was lower, but cover greater, one year after burning than before. One study reported mixed effects on cordgrass cover across two marshes. VEGETATION STRUCTURE Height (2 studies): Two studies (one controlled, one site comparison) in brackish marshes in the USA and Guadeloupe reported that the height of dominant grass-like plants was lower in burned than unburned areas for up to 1–2 years after the latest burn. The study in the USA reported recovery, to a slightly greater height than in unburned areas, after three years. The study in Guadeloupe also reported that the tallest trees in burned marshes were shorter than the tallest trees in unburned marshes. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3055https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3055Fri, 02 Apr 2021 08:57:38 +0100Collected Evidence: Collected Evidence: Use prescribed fire to maintain or restore disturbance: freshwater swamps Two studies evaluated the effects, on vegetation, of using prescribed fire to maintain or restore disturbance in freshwater swamps. Both studies were in the USA. VEGETATION COMMUNITY Tree/shrub richness/diversity (1 study): One replicated, site comparison study in the USA found that shrub-dominated wetlands burned every three years contained fewer species of mature tree than unburned wetlands, but a similar number of shrub and sapling species. VEGETATION ABUNDANCE Overall abundance (1 study): One replicated, site comparison study of bottomland swamps in the USA found that swamps burned every 2–3 years had a similar overall density of midstory and understory vegetation to unburned swamps. Herb abundance (2 studies): One replicated, site comparison study of shrub-dominated wetlands in the USA found that wetlands burned every three years had greater cover of grasses than unburned wetlands, but statistically similar cover of forbs and ferns. Another replicated, site comparison study of bottomland swamps in the USA found that swamps burned every 2–3 years had a similar density of understory grasses to unburned swamps. Tree/shrub abundance (2 studies): One replicated, site comparison study of shrub-dominated wetlands in the USA found that wetlands burned every three years had greater cover of shrubs than unburned wetlands. Another replicated, site comparison study of bottomland swamps in the USA found that swamps burned every 2–3 years had a similar density of shrubs, vines and other woody plants to unburned swamps. VEGETATION STRUCTURE Height (2 studies): One replicated, site comparison study of bottomland swamps in the USA found that swamps burned every 2–3 years had a shorter tree canopy than unburned swamps – but a similar-height midstory and understory. Another replicated, site comparison study of shrub-dominated wetlands in the USA found that the tree canopy was a similar height in wetlands burned every three years and unburned wetlands. Basal area (1 study): One replicated, site comparison study of bottomland swamps in the USA found that swamps burned every 2–3 years had a similar basal area of trees to unburned swamps. Canopy cover (1 study): One replicated, site comparison study of shrub-dominated wetlands in the USA found that wetlands burned every three years had less canopy cover than unburned wetlands. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3056https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3056Fri, 02 Apr 2021 08:57:49 +0100Collected Evidence: Collected Evidence: Use prescribed fire to maintain or restore disturbance: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of using prescribed fire to maintain or restore disturbance 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%2Fconservationevidencejournal.com%2Factions%2F3057https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3057Fri, 02 Apr 2021 08:58:02 +0100Collected Evidence: Collected Evidence: Use herbicide to maintain or restore disturbance: freshwater marshes One study evaluated the effects, on vegetation, of using herbicide to maintain or restore disturbance in freshwater marshes. The study was in the USA. VEGETATION COMMUNITY Community composition (1 study): One replicated, randomized, controlled, before-and-after study aiming to restore freshwater marshes in the USA found that applying herbicide to trees (along with other interventions) significantly affected the overall plant community composition over the following five years. VEGETATION ABUNDANCE Characteristic plant abundance (1 study): One replicated, randomized, controlled, before-and-after study aiming to restore freshwater marshes in the USA reported that of the 26 plant taxa that became more frequent after applying herbicide to trees (along with other interventions), 16 were obligate wetland taxa. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3058https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3058Fri, 02 Apr 2021 12:13:44 +0100Collected Evidence: Collected Evidence: Use herbicide to maintain or restore disturbance: brackish/salt marshesWe found no studies that evaluated the effects, on vegetation, of using herbicide to maintain or restore disturbance in 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%2Fconservationevidencejournal.com%2Factions%2F3059https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3059Fri, 02 Apr 2021 12:13:54 +0100Collected Evidence: Collected Evidence: Use herbicide to maintain or restore disturbance: freshwater swamps One study evaluated the effects, on vegetation, of using herbicide to maintain or restore disturbance in freshwater swamps. The study was in the USA. VEGETATION COMMUNITY   VEGETATION ABUNDANCE Herb abundance (1 study): One replicated, randomized, controlled, before-and-after, site comparison study of freshwater swamps in the USA found that applying herbicide to woody vegetation (after cutting it) had no significant effect on herbaceous ground cover one year later: there were similar changes in treated and untreated swamps. VEGETATION STRUCTURE Basal area (1 study): One replicated, randomized, controlled, before-and-after, site comparison study of freshwater swamps in the USA found that applying herbicide to woody vegetation (after cutting it) had no significant effect on the basal area of woody vegetation one year later: there were similar changes in treated and untreated swamps. Canopy cover (1 study): The same study found that applying herbicide to woody vegetation (after cutting it) reduced canopy cover – to similar levels as in high-quality swamps after one year. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3060https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3060Fri, 02 Apr 2021 12:14:06 +0100Collected Evidence: Collected Evidence: Use herbicide to maintain or restore disturbance: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of using herbicide to maintain or restore disturbance 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%2Fconservationevidencejournal.com%2Factions%2F3061https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3061Fri, 02 Apr 2021 12:14:18 +0100Collected Evidence: Collected Evidence: Use prescribed fire to control problematic plants: freshwater marshes Four studies evaluated the effects, on vegetation, of using prescribed fire to control problematic plants in freshwater marshes. Two studies were in the USA. There was one study in each of Australia and Costa Rica. VEGETATION COMMUNITY Overall extent (1 study): One controlled, before-and-after study in a freshwater marsh in Costa Rica reported that burning (and physically damaging) cattail stands reduced the area of live vegetation present 5–22 months later. Overall richness/diversity (2 studies): One controlled study in a freshwater marsh in Costa Rica found that plots in which cattail stands were managed (burned and physically damaged) had greater overall plant species richness than unmanaged plots, 11–22 months after intervention. One replicated, randomized, controlled study in a marsh in the USA found that the effect of prescribed burning on plant species richness in the following autumn depended on the season of burning. VEGETATION ABUNDANCE Overall abundance (2 studies): One controlled, before-and-after study in a freshwater marsh in Costa Rica reported that burning (and physically damaging) cattail stands reduced live vegetation cover 5–22 months later. One replicated, randomized, controlled study in a marsh in the USA found that the effect of prescribed burning on overall vegetation cover in the following autumn depended on the season of burning. Herb abundance (1 study): One study of a floodplain marsh in Australia simply reported grass/sedge cover for up to four years after burning mimosa-invaded vegetation (along with other interventions). Native/non-target abundance (2 studies): One replicated, randomized, paired, controlled study in canarygrass-invaded wet meadows in the USA found that prescribed burning had no significant effect on the biomass of plants other than the invasive species, 2–3 growing seasons later. One study of a floodplain marsh in Australia simply reported non-target vegetation cover for up to four years after burning mimosa-invaded vegetation (along with other interventions). Individual species abundance (1 study): One study quantified the effect of this action on the abundance of individual plant species, other than the species being controlled. The replicated, randomized, controlled study in a marsh in the USA found that the effect of prescribed burning on the cover of dominant species in the following autumn depended on the season of burning. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3116https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3116Sun, 04 Apr 2021 16:05:02 +0100Collected Evidence: Collected Evidence: Use prescribed fire to control problematic plants: brackish/salt marshes Four studies evaluated the effects, on vegetation, of using prescribed fire to control problematic plants in brackish/salt marshes. All four studies were in the USA. Two studies were based on the same experimental set-up. VEGETATION COMMUNITY Overall richness/diversity (4 studies): Two replicated, randomized, paired, controlled studies in brackish and salt marshes in the USA reported that burned and unburned plots had similar plant species richness over the following 1–3 years. Two studies in saltgrass- or reed-dominated marshes in the USA reported that burned areas had greater plant species richness than unburned areas, after approximately 1–3 years. In one of the studies, burned areas had also been sprayed with herbicide for nine years – and contained more plant species than a nearby natural marsh. VEGETATION ABUNDANCE Overall abundance (3 studies): Three replicated, randomized, paired, controlled studies in brackish and salt marshes in the USA evaluated the effect of prescribed burning on vegetation cover. One study found that autumn-burned plots had lower overall vegetation cover than unburned plots after 11 months, but one found that winter-burned plots had similar overall vegetation cover to unburned plots after one year. Two of the studies reported that winter-burned plots had less standing dead vegetation cover than unburned plots in the following summer or winter. Individual species abundance (4 studies): All four studies quantified the effect of this action on the abundance of individual plant species, other than a species being controlled. For example, three replicated, randomized, paired, controlled studies in brackish and salt marshes in the USA reported mixed effects of burning on cover of saltgrass Distichlis spicata: higher in burned than unburned plots in the following summer, lower in burned than unburned plots in the following winter, or mixed effects amongst marsh types. Two replicated, randomized, paired, controlled studies in brackish and salt marshes in the USA reported that burning did not reduce cover of saltmeadow cordgrass Spartina patens, compared to cover in unburned plots, over the following 1–3 years. One site comparison study of brackish marshes in the USA reported that a marsh that had been burned for three years (and sprayed with herbicide for nine) contained more smooth cordgrass Spartina alterniflora than an unburned and unsprayed marsh, and a similar amount of smooth cordgrass to a nearby natural marsh. VEGETATION STRUCTURE Visual obstruction (1 study): One replicated, randomized, paired, controlled study in brackish and salt marshes in the USA found that the visual obstruction caused by vegetation (combination of height and horizontal cover) was similar in burned and unburned plots, after 11 months. Height (1 study): One site comparison study of brackish marshes in the USA found that in a marsh burned for two years (and sprayed with herbicide for nine), the dominant plant species (smooth cordgrass Spartina alterniflora) grew to a similar height as in a nearby natural marsh. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3117https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3117Sun, 04 Apr 2021 16:05:16 +0100Collected Evidence: Collected Evidence: Use prescribed fire to control problematic plants: freshwater swamps One study evaluated the effects, on vegetation, of using prescribed fire to control problematic plants in freshwater swamps. The study was in the USA. VEGETATION COMMUNITY Overall richness/diversity (1 study): One replicated, randomized, controlled study aiming to restore a swamp in the USA found that burning canarygrass-invaded vegetation after spraying it with herbicide increased overall plant diversity, two growing seasons later, compared to spraying alone. However, burning had no significant effect on plant species richness. Native/non-target richness/diversity (1 study): The same study found that burning canarygrass-invaded vegetation after spraying it with herbicide had no significant effect on native plant species richness, two growing seasons later, compared to spraying alone. VEGETATION ABUNDANCE Tree/shrub abundance (1 study): One replicated, randomized, controlled study aiming to restore a swamp in the USA found that burning canarygrass-invaded vegetation after spraying it with herbicide had no significant effect on the density of non-planted tree seedlings, two growing seasons later, compared to spraying alone. Individual species abundance (1 study): The same study reported that burning canarygrass-invaded vegetation after spraying it with herbicide affected the abundance of some individual plant species two growing seasons later. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3118https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3118Sun, 04 Apr 2021 16:05:25 +0100Collected Evidence: Collected Evidence: Use prescribed fire to control problematic plants: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of using prescribed fire to control problematic plants 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%2Fconservationevidencejournal.com%2Factions%2F3119https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3119Sun, 04 Apr 2021 16:05:37 +0100Collected Evidence: Collected Evidence: Use herbicide to control problematic plants: freshwater marshes Seventeen studies evaluated the effects, on vegetation, of using herbicide to control problematic plants in freshwater marshes. Twelve studies were in the USA. Two studies were in Australia. There was one study in each of Canada, Mexico and the UK. There was overlap in the sites used in two studies. Two pairs of studies in Australia and the USA used the same general study area, but different plots or experimental set-ups. VEGETATION COMMUNITY Overall extent (3 studies): Two replicated, randomized, controlled, before-and-after studies in the USA found that marshes sprayed with herbicide had lower live vegetation coverage but greater dead vegetation coverage than unsprayed marshes, after 1–2 years. Overall vegetation coverage was lower in sprayed than unsprayed marshes in one study, but similar in sprayed and unsprayed marshes in the other. One study of a dune slack in the UK simply reported an increase in overall vegetation coverage between one and two years after clearing scrub (by cutting and applying herbicide). Overall richness/diversity (6 studies): Three studies (including one replicated, randomized, paired, controlled) in ephemeral marshes/wet meadows in the USA reported that spraying invaded vegetation with herbicide (sometimes along with other interventions) typically increased total plant species richness 1–5 growing seasons later. Two replicated, randomized, paired, controlled studies (one also before-and-after) in freshwater marshes/wet meadows in the USA and Mexico found that plots treated with herbicide (sometimes along with other interventions) had similar overall plant species richness and diversity to untreated plots, after 4–8 months or three years. One study of a dune slack in the UK simply reported a small increase in total plant richness between one and two years after clearing scrub (by cutting and applying herbicide). Characteristic plant richness/diversity (3 studies): Two before-and-after studies of floodplain marshes in the USA reported that cover of wet-prairie indicator species was higher 1–4 years after applying herbicide than before. However, one of these studies reported that the total cover of non-invasive, wetland-characteristic herbs was similar or lower 2–3 years after applying herbicide than before. One study of a dune slack in the UK simply reported an increase the number of slack-characteristic plant species present between one and two years after clearing scrub (by cutting and applying herbicide). Native/non-target richness/diversity (3 studies): One controlled, before-and-after study in a reed-dominated freshwater marsh in the USA found that applying herbicide (along with cutting/mowing) increased non-reed species richness three years later. One replicated, controlled, before-and-after study in cattail-invaded marshes in the USA reported that marshes sprayed with herbicide contained no living native plants one year later: fewer than were present before spraying and in unsprayed marshes. One study of a dune slack in the UK simply reported an increase in native plant richness between one and two years after clearing scrub (by cutting and applying herbicide). VEGETATION ABUNDANCE Overall abundance (4 studies): Three replicated studies (two also randomized, paired, controlled) in freshwater marshes/wet meadows in the USA and Mexico found that applying herbicide (sometimes along with other interventions) had no clear or significant effect on overall vegetation abundance four months to three years later. Cover and density were similar to untreated plots and/or pre-treatment levels. One replicated, randomized, paired, controlled study in the USA found that wet meadows sprayed with herbicide contained less total vegetation biomass than unsprayed marshes, 2–3 growing seasons later. Native/non-target abundance (7 studies): Four studies (including one replicated, randomized, paired, controlled, before-and-after) in marshes/wet meadows in the USA and Australia found that spraying invaded plots with herbicide (sometimes along with other interventions) did not reduce – and often increased – the abundance of native or non-target vegetation 1–3 growing seasons later. One replicated, controlled, before-and-after study in cattail-invaded marshes in the USA reported that marshes sprayed with herbicide contained no living native plants one year later: density and biomass were lower than before spraying and in unsprayed marshes. One replicated, randomized, paired, controlled study in an alligatorweed-invaded marsh in the USA found that spraying vegetation with herbicide had no significant effect on native plant biomass after 1–2 growing seasons. One study of a floodplain marsh in Australia simply reported non-target vegetation cover for up to four years after treating mimosa-invaded vegetation with herbicide (along with other interventions). Herb abundance (4 studies): Two replicated, randomized, paired, controlled studies in wet meadows in the USA found that treating a problematic plant species with herbicide (sometimes along with physical removal) had no significant effect on cover of forbs, grass-like plants or sedges after 2–3 growing seasons. One replicated, randomized, paired, controlled study in a loosestrife-invaded marsh in Canada found that the density of sedges and grasses was not lower in herbicide-sprayed plots, than in unsprayed plots, after 2–3 years. The precise effect depended on dose of herbicide used. One study of a floodplain marsh in Australia simply reported grass/sedge cover for up to four years after treating mimosa-invaded vegetation with herbicide (along with other interventions). Algae/phytoplankton abundance (1 study): One replicated, randomized, controlled study in a reed-invaded marsh in the USA reported that free-growing filamentous algae were more common in plots sprayed with herbicide than unsprayed plots, approximately one year later. However, spraying with herbicide had no significant effect on the density or biomass of biofilm algae. Individual species abundance (3 studies): Three studies quantified the effect of this action on the abundance of individual plant species, other than the species being controlled. For example, one replicated, randomized, paired, controlled study in a grass-invaded marsh in Mexico found that five of five monitored native species had similar cover in herbicide-sprayed and unsprayed plots after 4–8 months. Two of the studies do not distinguish between the effects of applying herbicide and other interventions. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3120https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3120Sun, 04 Apr 2021 17:19:04 +0100Collected Evidence: Collected Evidence: Use herbicide to control problematic plants: brackish/salt marshes Seven studies evaluated the effects, on vegetation, of using herbicide to control problematic plants in brackish/salt marshes. Six studies were in the USA. One study was in South Africa. Two studies shared part of the same experimental set-up. VEGETATION COMMUNITY Relative abundance (1 study): One site comparison study of brackish marshes in the USA found that a marsh sprayed with herbicide for nine years (and burned for three) and a nearby natural marsh supported a similar relative abundance of the dominant plant species, smooth cordgrass Spartina alterniflora. Overall richness/diversity (1 study): One site comparison study of brackish marshes in the USA reported that a marsh sprayed with herbicide for nine years (and burned for three) contained more plant species than an unburned and unsprayed marsh – but also more plant species than a nearby natural marsh. Native/non-target richness/diversity (2 studies): One replicated, randomized, paired, controlled, before-and-after study in a pepperweed-invaded marsh in the USA found that applying herbicide did not increase the richness of non-pepperweed species over two years after intervention. The precise effect depended on the herbicide used. One study of an intertidal area in the USA simply counted the number of native salt marsh plant species that colonized after treating smooth cordgrass Spartina alterniflora stands with herbicide. VEGETATION ABUNDANCE Native/non-target abundance (5 studies): Three replicated, randomized, paired, controlled, before-and-after studies in pepperweed-invaded marshes in the USA found that applying herbicide typically did not increase cover of non-pepperweed vegetation, in the two years following intervention. The precise effect depended on the herbicide used. Two studies on the coasts of South Africa and the USA simply quantified the abundance of native salt marsh vegetation that colonized after treating smooth cordgrass Spartina alterniflora stands with herbicide. Individual species abundance (4 studies): Four studies quantified the effect of this action on the abundance of individual plant species, other than the species being controlled. For example, one site comparison study of brackish marshes in the USA reported that a marsh sprayed with herbicide for nine years (and burned for three) contained more smooth cordgrass Spartina alterniflora than an unburned and unsprayed marsh, and a similar amount of smooth cordgrass to a nearby natural marsh. One replicated, paired, controlled, before-and-after study in a pepperweed-invaded marsh in the USA reported that applying herbicide typically reduced cover of dominant native species over two years. The precise effect depended on the herbicide used. VEGETATION STRUCTURE Height (1 study): One site comparison study of brackish marshes in the USA found that in a marsh sprayed with herbicide for nine years (and burned for three), the dominant plant species (smooth cordgrass Spartina alterniflora) grew to a similar height as in a nearby natural marsh. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3121https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3121Sun, 04 Apr 2021 17:19:16 +0100Collected Evidence: Collected Evidence: Use herbicide to control problematic plants: freshwater swamps Four studies evaluated the effects, on vegetation, of using herbicide to control problematic plants in freshwater swamps. All four studies were in the USA. VEGETATION COMMUNITY Overall richness/diversity (2 studies): One replicated, randomized, paired, controlled study aiming to restore canarygrass-invaded swamps in the USA found that plots sprayed with herbicide typically had greater plant species richness and diversity than unsprayed plots, after 1–2 growing seasons. One replicated, randomized, controlled study in a petunia-invaded floodplain swamp in the USA found that plots sprayed with herbicide had similar overall plant species richness to unsprayed plots over 15 months after spraying. Native/non-target richness/diversity (3 studies): Three replicated, controlled studies (also paired and/or randomized) in invaded freshwater swamps in the USA found that applying herbicide typically had no significant effect on native plant species richness, over 3–24 months after spraying. VEGETATION ABUNDANCE Tree/shrub abundance (2 studies): Two replicated, controlled studies in the USA evaluated the effects, on tree/shrub abundance, of managing canarygrass-invaded vegetation by applying herbicide. One study found that plots sprayed with herbicide contained more non-planted tree seedlings than unsprayed plots, after 1–2 growing seasons. The other study found that managed plots (cut, disked and sprayed with herbicide) contained more non-planted tree seedlings than unmanaged plots, after 1–3 years. Native/non-target abundance (2 studies): Two replicated, controlled studies in swamps in the USA reported that spraying invaded vegetation with herbicide (sometimes along with other interventions) typically had no clear or significant effect on native/non-target vegetation cover 1–3 years later. Cover was typically similar to unmanaged plots or before intervention. Individual species abundance (1 study): One replicated, randomized, paired, controlled study aiming to restore a canarygrass-invaded swamp in the USA reported that spraying the vegetation with herbicide affected the abundance of some individual plant species – other than the target problematic species – two growing seasons later. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3122https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3122Sun, 04 Apr 2021 17:19:27 +0100Collected Evidence: Collected Evidence: Use herbicide to control problematic plants: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of using herbicide to control problematic plants 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%2Fconservationevidencejournal.com%2Factions%2F3123https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3123Sun, 04 Apr 2021 17:19:48 +0100Collected Evidence: Collected Evidence: Use marketing strategies to increase the value of marshes or swamps One study evaluated the effects, on vegetation or human behaviour, of using marketing strategies to increase the value of marshes or swamps. The study was in Vietnam. VEGETATION COMMUNITY   VEGETATION ABUNDANCE   VEGETATION STRUCTURE   OTHER Human behaviour (1 study): One before-and-after study in Vietnam reported that helping local people to sell handicrafts made from marsh plants in tourist markets (along with training to improve the quality of those products) increased their income. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3393https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3393Mon, 12 Apr 2021 12:09:17 +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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