Collected 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 grazing to maintain or restore disturbance: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of using grazing 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%2F3053https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3053Thu, 01 Apr 2021 19:58:30 +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: 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 cutting/mowing to control problematic herbaceous plants: freshwater marshes Eight studies evaluated the effects, on vegetation, of cutting/mowing problematic herbaceous plants or small shrubs in freshwater marshes. Six studies were in the USA, one was in Mexico and one was in Canada. VEGETATION COMMUNITY Community composition (1 study): One replicated, randomized, paired, controlled, before-and-after study in a cattail-dominated marsh in the USA found that cutting altered the overall plant community composition over the following two years. Relative abundance (1 study): One replicated, randomized, paired, controlled study in a grass-invaded marsh in Mexico found that cut and uncut plots supported a similar relative abundance of six common plant species after 4–8 months. Overall richness/diversity (4 studies): Two replicated, randomized, paired, controlled studies in invaded marshes/wet meadows in the USA found that cut plots typically had greater overall plant species richness and/or diversity than uncut plots, after 1–3 growing seasons. One of the studies carried out other interventions along with cutting. Two replicated, controlled studies in freshwater marshes in the USA and Mexico found that cut and uncut plots had similar overall plant richness and/or diversity, after 1–2 growing seasons. Native/non-target richness/diversity (2 studies): One controlled, before-and-after study in a reed-dominated freshwater marsh in the USA found that cutting/mowing (along with applying herbicide) increased non-reed species richness three years later. One replicated, controlled, before-and-after study in cattail-invaded marshes in the USA found that mown and unmown marshes had similar native plant species richness after 1–12 months VEGETATION ABUNDANCE Overall abundance (3 studies): Two replicated, controlled studies in freshwater marshes in the USA and Mexico found that cut and uncut plots contained a similar amount of vegetation after 1–2 growing seasons. This was true for cover of wetland plants and density of all plants. One replicated, randomized, paired, controlled, before-and-after study in iris-invaded lakeshore marshes in Canada reported that cutting reduced overall vegetation cover, one year later, in a permanently flooded marsh but had no clear effect on cover in an intermittently flooded marsh. Herb abundance (1 study): One replicated, randomized, paired, controlled study in a cattail-invaded wet meadow in the USA found that plots in which cattail was cut four times over two growing seasons developed greater cover of sedges Carex than uncut plots, but that cutting cattail only twice had no significant effect on sedge cover. Native/non-target abundance (3 studies): Two controlled studies (one also replicated, randomized, paired; one also before-and-after) in reed- or canarygrass-dominated wetlands in the USA found that cut plots typically contained more native or non-target vegetation than uncut plots, after 1–3 growing seasons. Both studies carried out other interventions along with cutting. One replicated, controlled, before-and-after study in cattail-invaded marshes in the USA found that mown and unmown marshes supported a similar native vegetation density after 1–12 months, and similar native vegetation biomass after 12 months. Individual species abundance (2 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 cut and uncut plots after 4–8 months. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3104https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3104Sun, 04 Apr 2021 09:58:57 +0100Collected Evidence: Collected Evidence: Use cutting/mowing to control problematic herbaceous plants: brackish/salt marshes One study evaluated the effects, on vegetation, of cutting/mowing problematic herbaceous plants or small shrubs in brackish/salt marshes. The study was in the USA. VEGETATION COMMUNITY Overall richness/diversity (1 study): One replicated, randomized, paired, controlled study in a saltgrass-dominated marsh in the USA found that mown and unmown plots had similar overall plant species richness after one year. VEGETATION ABUNDANCE Overall abundance (1 study): One replicated, randomized, paired, controlled study in a saltgrass-dominated marsh in the USA found that mown and unmown plots had similar overall vegetation cover after one year. Individual species abundance (1 study): The same study found that six dominant herb species, other than the species being controlled, had similar cover in mown and unmown plots after one year. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3105https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3105Sun, 04 Apr 2021 09:59:17 +0100Collected Evidence: Collected Evidence: Use cutting/mowing to control problematic herbaceous plants: freshwater swamps Two studies evaluated the effects, on vegetation, of cutting/mowing problematic herbaceous plants or small shrubs in freshwater swamps. Both studies were in the USA. VEGETATION COMMUNITY Overall richness/diversity (1 study): One replicated, controlled study aiming to restore a swamp in the USA found that mowing canarygrass-invaded vegetation before spraying it with herbicide had no significant effect on overall plant richness or diversity, two growing seasons later, compared to spraying alone. Native/non-target richness/diversity (1 study): The same study found that mowing canarygrass-invaded vegetation before 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 (2 studies): Two replicated, controlled studies in the USA evaluated the effects, on tree/shrub abundance, of managing canarygrass-invaded vegetation by cutting. One study found that mowing canarygrass-invaded vegetation before spraying it with herbicide had no significant effect on the density of non-planted tree seedlings, two growing seasons later, compared to spraying alone. 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 (1 study): One replicated, controlled study aiming to restore a swamp in the USA found that plots in which canarygrass-invaded vegetation was managed (by cutting, along with disking and applying herbicide) contained at least as much non-canarygrass herb cover, after 1–3 years, to plots in which vegetation was not managed. Individual species abundance (1 study): One replicated, controlled study aiming to restore a swamp in the USA reported that mowing canarygrass-invaded vegetation before spraying it with herbicide affected the abundance of some individual plant species two growing seasons later. VEGETATION STRUCTURE  Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3106https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3106Sun, 04 Apr 2021 09:59:35 +0100Collected Evidence: Collected Evidence: Use cutting/mowing to control problematic herbaceous plants: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of cutting/mowing problematic herbaceous plants or small shrubs 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%2F3107https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3107Sun, 04 Apr 2021 10:00:38 +0100Collected Evidence: Collected Evidence: Use cutting to control problematic large trees/shrubs: freshwater marshes Two studies evaluated the effects, on vegetation, of cutting down problematic large trees/shrubs in freshwater marshes. One study was in the UK and one was in the USA. VEGETATION COMMUNITY Overall extent (1 study): One study of a dune slack in the UK reported an increase in total vegetation coverage between one and two years after clearing scrub (by cutting and applying herbicide). Overall richness/diversity (1 study): The same study 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 (1 study): The same study reported an increase in 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 (1 study): The same study reported an increase in native plant richness between one and two years after clearing scrub (by cutting and applying herbicide). VEGETATION ABUNDANCE 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 site comparison study in the USA found that tussock sedge Carex stricta was less dense in a wet meadow restored by removing trees (along with other interventions, including planting sedges) than in nearby natural meadows, after 11–14 years. VEGETATION STRUCTURE Height (1 study): One site comparison study in the USA reported that sedge tussocks were shorter in a wet meadow restored by removing trees (along with other interventions, including planting sedges) than in nearby natural meadows, after 11–14 years. Diameter/perimeter/area (1 study): The same study reported that sedge tussocks had a smaller perimeter in a wet meadow restored by removing trees (along with other interventions, including planting sedges) than in nearby natural meadows, after 11–14 years. Basal area (1 study): The same study reported that the basal area of sedge tussocks was smaller in a wet meadow restored by removing trees (along with other interventions, including planting sedges) than in nearby natural meadows, after 11–14 years. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3108https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3108Sun, 04 Apr 2021 14:31:56 +0100Collected Evidence: Collected Evidence: Use cutting to control problematic large trees/shrubs: freshwater swampsWe found no studies that evaluated the effects, on vegetation, of cutting down problematic large trees/shrubs 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%2F3110https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3110Sun, 04 Apr 2021 14:32:24 +0100Collected Evidence: Collected Evidence: Use grazing to control problematic plants: freshwater marshes Three studies evaluated the effects, on vegetation, of using grazing to control problematic plants in freshwater marshes. Two studies were in the USA. One study was in Costa Rica. VEGETATION COMMUNITY Community composition (1 study): One replicated, randomized, paired, controlled study in Costa Rica found that amongst plots where cattail-dominated vegetation had been crushed, grazing had no significant effect on the overall plant community composition over 15 months. Relative abundance (1 study): One replicated, paired, controlled, before-and-after study in a canarygrass-invaded marsh in the USA found that grazing had no significant effect on the relative abundance of the invader: over two years, it declined similarly in grazed and ungrazed plots. Overall richness/diversity (3 studies): Of three replicated, paired, controlled studies in invaded marshes/wet meadows in the USA and Costa Rica, two found that grazing typically had no significant effect on plant species richness and/or diversity over approximately two years. The other study found that grazed areas had higher plant species richness than ungrazed areas after two months. VEGETATION ABUNDANCE Overall abundance (1 study): One replicated, paired, controlled, before-and-after study in a canarygrass-invaded marsh in the USA found that grazing had no significant effect on total vegetation cover at the ground surface, over two years. Native/non-target abundance (1 study): One replicated, paired, controlled, before-and-after study in an invaded wet meadow in the USA found that two months of grazing increased cover of non-invasive grass-like plants. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3112https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3112Sun, 04 Apr 2021 15:42:11 +0100Collected Evidence: Collected Evidence: Use grazing to control problematic plants: brackish/salt marshesWe found no studies that evaluated the effects, on vegetation, of using grazing to control problematic plants 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%2F3113https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3113Sun, 04 Apr 2021 15:42:40 +0100Collected Evidence: Collected Evidence: Use grazing to control problematic plants: freshwater swampsWe found no studies that evaluated the effects, on vegetation, of using grazing to control problematic plants 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%2F3114https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3114Sun, 04 Apr 2021 15:47:05 +0100Collected Evidence: Collected Evidence: Use grazing to control problematic plants: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of using grazing 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%2F3115https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3115Sun, 04 Apr 2021 15:47:21 +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 fences or barriers to protect freshwater wetlands planted with non-woody plants Four studies evaluated the effects, on vegetation, of using fences or barriers to protect freshwater wetlands planted with emergent, non-woody plants. There was one study in each of Canada, the Netherlands, Israel and the USA. VEGETATION COMMUNITY Community composition (1 study): One replicated, site comparison study in the USA found that amongst planted/sown lakeshores, those protected with fences or wave breaks contained different wetland plant communities, after 1–6 years, than those without fences or wave breaks. VEGETATION ABUNDANCE Individual species abundance (1 study): One replicated, controlled study at the edge of a freshwater lake in the Netherlands found that amongst plots planted with lakeshore bulrush Scirpus lacustris, those from which wildfowl had been excluded contained a greater density and biomass of lakeshore bulrush, after 1–2 years, than those that remained open to wildfowl. VEGETATION STRUCTURE   OTHER Survival (2 studies): Two replicated, paired, controlled studies in freshwater wetlands in Canada and Israel reported that protecting emergent herbs, with silt screens or herbivore fencing, increased survival rates over 12–18 months after planting. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3328https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3328Sun, 11 Apr 2021 13:14:37 +0100Collected Evidence: Collected Evidence: Use fences or barriers to protect brackish/saline wetlands planted with non-woody plantsWe found no studies that evaluated the effects, on vegetation, of using fences or barriers to protect brackish/saline wetlands planted with emergent, non-woody plants.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3329https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3329Sun, 11 Apr 2021 13:14:53 +0100Collected Evidence: Collected Evidence: Use fences or barriers to protect freshwater wetlands planted with trees/shrubs Five studies evaluated the effects, on vegetation, of using fences or barriers to protect freshwater wetlands planted with trees/shrubs. Four studies were in the USA and one was in Australia. VEGETATION COMMUNITY   VEGETATION ABUNDANCE Tree/shrub abundance (1 study): One replicated, paired, controlled study in a floodplain swamp clearing in the USA found that amongst plots sown with tree seeds, fencing to exclude deer had no significant effect on total tree seedling density after three years. VEGETATION STRUCTURE Height (2 studies): One replicated, paired, controlled study in a floodplain swamp clearing in the USA found that amongst plots sown with tree seeds, those also fenced to exclude deer contained taller tree seedlings, after three years, than those left unfenced. One replicated, paired, controlled study in created freshwater wetlands in the USA found that the average height of white cedar Thuja occidentalis saplings typically increased by a similar amount, between two and five years after planting, in plots fenced to exclude deer and plots left unfenced. OTHER Survival (3 studies): One replicated, paired, controlled study in floodplain swamps in Australia reported that planted swamp gum Eucalyptus camphora seedlings had a much higher survival rate, over one year, in plots fenced to exclude mammals than in open plots. Two replicated, paired, controlled studies in freshwater wetlands in the USA reported that exclusion fencing sometimes increased survival of planted tree seedlings but sometimes had no clear or significant effect. This depended on factors such as the season of planting, seedling elevation, and site. Growth (1 study): One replicated, randomized, controlled study in a nutria-invaded wetland in the USA found that planted baldcypress Taxodium distichum seedlings grew more, over one growing season, when protected than when left unprotected. Plastic guards increased height and diameter growth rates. Sticky, insect-repellent oil increased the growth rate for height, but not diameter. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3330https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3330Sun, 11 Apr 2021 13:15:05 +0100Collected Evidence: Collected Evidence: Use fences or barriers to protect planted brackish/saline wetlands planted with trees/shrubs One study evaluated the effects, on vegetation, of using fences or barriers to protect brackish/saline wetlands planted with trees/shrubs. The study was in the USA. VEGETATION COMMUNITY   VEGETATION ABUNDANCE   VEGETATION STRUCTURE Height (1 study): One replicated, paired, controlled study in exposed coastal sites in the USA found that red mangrove Rhizophora mangle propagules planted within full-length plastic shelters had grown taller than propagules planted without shelter in three of four comparisons, made 22–129 days after planting. OTHER Survival (1 study): One replicated, paired, controlled study in exposed coastal sites in the USA reported that full-length plastic shelters increased the survival rate of planted red mangrove Rhizophora mangle propagules over 4–8 months, but that full-length bamboo shelters and below-ground plastic shelters had no clear effect on survival. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3331https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3331Sun, 11 Apr 2021 13:15:17 +0100Collected Evidence: Collected Evidence: Use flotation devices to support planted vegetationWe found no studies that evaluated the effects of using flotation devices to support emergent vegetation planted in wetlands.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3340https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3340Sun, 11 Apr 2021 16:45:23 +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.

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