Collected Evidence: Collected Evidence: Cut/mow herbaceous plants to maintain or restore disturbance: freshwater marshes Twenty studies evaluated the effects, on vegetation, of cutting/mowing to maintain or restore disturbance in freshwater marshes. There were four studies in Belgium, three of which took place in one wetland area so probably shared some experimental plots. There were two studies in each of the UK, the USA and Estonia. There was one study in each of seven other European countries, Japan, Mexico and Brazil. In 15 of the studies vegetation was measured at least six months after the last cut. VEGETATION COMMUNITY Community composition (6 studies): Four replicated, paired, controlled studies (two also randomized and before-and-after) of freshwater marshes and wet meadows in Belgium, Switzerland, Mexico and Estonia reported that the overall plant community composition differed between cut and uncut sites after 1–5 years, or typically diverged in cut and uncut areas over 3–10 years. One before-and-after study in a freshwater marsh in Belgium reported that the overall plant community composition changed over seven years after resuming annual mowing. One replicated, paired, controlled, before-and-after study in wet grasslands in Germany reported that over 20 years, mowing increased the average moisture preference of the vegetation. Overall richness/diversity (11 studies): Seven studies (including two replicated, paired, controlled) in freshwater marshes in Belgium, the UK, Mexico and Estonia reported that cut marshes had higher plant species richness than uncut marshes. Two of these studies reported the same result for diversity. One before-and-after study in a freshwater marsh in Belgium reported that plant species richness increased over seven years after resuming annual mowing. Three replicated, paired, controlled studies in reedbeds in the UK and wet meadows in Germany and Estonia reported that cutting typically had no clear or significant effect on plant species richness, after 3–5 months or over 5–20 years. The two studies in the UK and Estonia found the same result for diversity. Characteristic plant richness/diversity (1 study): One replicated, paired, controlled, before-and-after study in a temporary marsh in France reported that two years of annual autumn cutting increased the number of habitat-characteristic plant species present. VEGETATION ABUNDANCE Overall abundance (3 studies): Two replicated, controlled studies (one also randomized, paired, before-and-after) in freshwater marshes in the USA found that cutting had no significant effect on overall vegetation cover over 72 days or three years. One replicated, paired, controlled study in wet grasslands in Belgium reported that plots mown annually for two years contained less above-ground biomass, just before mowing, than unmown plots. Herb abundance (1 study): One replicated, paired, controlled, before-and-after study in wet grasslands in Germany reported that mowing increased sedge cover over 20 years, but had no clear effect on cover of rushes, forbs, ferns, grasses and legumes. Tree/shrub abundance (1 study): One replicated, randomized, paired, controlled, before-and-after study in a wet prairie in the USA found that cutting had no significant effect on woody plant cover: there were similar increases, over three years, in cut and uncut plots. Bryophyte abundance (1 study): One replicated study in a freshwater marsh in Belgium reported that total moss cover increased over five years after resuming annual mowing. Individual species abundance (15 studies): Fifteen studies quantified the effect of this action on the abundance of individual plant species. For example, five studies (including one replicated, randomized, paired, controlled) in freshwater marshes in Belgium, the UK and the Czech Republic reported that common reed Phragmites australis was more abundant in cut than uncut areas. Two studies (one site comparison, one before-and-after) in fresh/brackish marshes in Belgium and Denmark reported that cutting reduced common reed cover or density. The two studies in Belgium reported that cutting had no clear effect on common reed frequency. Four studies (including one replicated, randomized, paired, before-and-after) in freshwater marshes in the Netherlands, Switzerland, Japan and Italy found that the effect of cutting on common reed abundance depended on factors such as the year, plant community type, cutting season, cutting intensity and time since mowing. VEGETATION STRUCTURE Overall structure (1 study): One replicated, randomized, paired, controlled study in wet meadows in Switzerland reported that mown plots experienced a shift in vegetation cover towards lower vegetation layers, over 3–4 years, compared to a shift to upper layers in unmown plots. Visual obstruction (1 study): One replicated, controlled study in a freshwater marsh in Belgium reported that summer-cut plots had lower horizontal vegetation cover than uncut plots (or winter-cut plots) over six years after resuming annual mowing. Height (6 studies): Three replicated, controlled studies (one also randomized and paired) in freshwater marshes in Belgium, the UK and the USA reported that cut marshes had shorter vegetation than uncut marshes. This was true for vegetation overall, vegetation other than common reed Phragmites australis, and for common reed cut in winter or spring (but not summer). Two replicated, paired, controlled, before-and-after studies in a marsh in Mexico and wet grasslands in Germany reported that cutting/mowing had no significant or clear effect on vegetation height, after 12 months or over 20 years. One site comparison study in the Czech Republic found that common reed was taller, when measured in the summer, in a winter-mown reedbed than in an unmown reedbed. Diameter/perimeter/area (5 studies): Two studies (one site comparison, one before-and-after) in fresh/brackish marshes in Belgium and Denmark reported that cutting, or time since last cutting, had no significant or clear effect on the stem diameter of common reed Phragmites australis. Two studies (including one replicated, randomized, paired, controlled) of reedbeds in the UK and the Czech Republic found that cut areas contained thicker reed stems than uncut areas, after one growing season. One replicated, randomized, paired, controlled, before-and-after study in wet meadows in Switzerland found that the effect of cutting on common reed shoot diameter depended on the plant community type and season of mowing. Basal area (1 study): One site comparison study in a fresh/brackish marsh in Denmark found that the basal area of common reed Phragmites australis stems was smaller in a reedbed cut two years previously than in a reedbed cut seven years previously. Only “tall” stems were sampled. OTHER Survival (1 study): One replicated, randomized, paired, controlled study in a wet prairie in the USA found that mowing had no significant effect on woody plant survival over the following year. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3044https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3044Thu, 01 Apr 2021 15:18:37 +0100Collected Evidence: Collected Evidence: Cut/mow herbaceous plants to maintain or restore disturbance: brackish/salt marshes Six studies evaluated the effects, on vegetation, of cutting/mowing to maintain or restore disturbance in brackish/salt marshes. Two studies were in France. There was one study in each of the USA, Denmark, South Africa and Estonia. VEGETATION COMMUNITY Community composition (1 study): One replicated, randomized, controlled, before-and-after study in brackish wet grasslands in Estonia found that annual cutting affected overall plant community composition, with significant differences between cut and uncut plots after four years. Overall richness/diversity (3 studies): Two replicated, site comparison studies in France found that cut and uncut reedbeds had similar overall plant species richness. One replicated, randomized, controlled, before-and-after study in brackish wet grasslands in Estonia found that cut and uncut plots typically had similar plant species richness and diversity over four years. VEGETATION ABUNDANCE Overall abundance (1 study): One replicated, site comparison study in France found that cut and uncut reedbeds had similar cover of plants other than common reed Phragmites australis. Individual species abundance (5 studies): Five studies quantified the effect of this action on the abundance of individual plant species. For example, two replicated, randomized, controlled, before-and-after studies in brackish marshes or grasslands in South Africa and Estonia found that cutting had mixed effects on the abundance of common reed Phragmites australis after 1–4 years, depending on the water level of the plots. One site comparison study in Denmark found that a fresh/brackish reedbed cut two years previously contained fewer “tall” common reed stems than a reedbed cut seven years previously. Two replicated, site comparison studies in France found that cut reedbeds contained a similar number (and, in one study, biomass) of live reed stems than uncut reedbeds, but far fewer dead stems. VEGETATION STRUCTURE Height (4 studies): Two controlled studies (one also replicated, randomized, before-and-after) in brackish marshes in the USA and South Africa reported that rushes or reeds were shorter in cut plots than in uncut plots, for up to one year after cutting. Two replicated, site comparison studies in France found that live reed stems were a similar height in cut and uncut reedbeds. Diameter/perimeter/area (3 studies): Two site comparison studies (one replicated) in fresh/brackish reedbeds in Denmark and France found that common reed Phragmites australis stems were a similar diameter in cut and uncut reedbeds. One replicated, randomized, controlled, before-and-after study in a brackish marsh in South Africa found that cutting reduced the diameter of common reed stems present one year later. Basal area (1 study): One site comparison study in a fresh/brackish marsh in Denmark found that the basal area of common reed Phragmites australis stems was smaller in a reedbed cut two years previously than in a reedbed cut seven years previously. Only “tall” stems were sampled. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3045https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3045Thu, 01 Apr 2021 15:21:23 +0100Collected Evidence: Collected Evidence: Cut large trees/shrubs to maintain or restore disturbance: freshwater marshes Four studies evaluated the effects, on vegetation, of cutting large trees/shrubs to maintain or restore disturbance in freshwater marshes. Three studies were in the USA. One was in Germany. VEGETATION COMMUNITY Community types (1 study): One study of a riparian wet meadow in Germany reported changes in the area of plant community types over four years after cutting trees/shrubs (along with grazing). Community composition (1 study): One replicated, randomized, controlled, before-and-after study aiming to restore freshwater marshes in the USA found that cutting trees (along with other interventions) significantly affected the overall plant community composition over the following five years. Overall richness/diversity (1 study): One study of a riparian wet meadow in Germany reported that plant species richness increased over four years after cutting trees/shrubs (along with grazing). VEGETATION ABUNDANCE Overall abundance (2 studies): Of two replicated, randomized, paired, controlled, before-and-after studies in the USA, one found that cutting and removing woody plants from a degraded wet prairie had no significant effect on overall vegetation cover three years later. The other study was in wet patches of a pine forest and found that understory vegetation cover increased more, over one year, where trees were thinned than where they were not thinned. 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 cutting trees (along with other interventions), 16 were obligate wetland taxa. Herb abundance (1 study): One replicated, randomized, paired, controlled, before-and-after study in wet patches of a pine forest in the USA found that cover of sedges Carex increased more, over one year, where trees were thinned than where they were not thinned. Tree/shrub abundance (2 studies): One replicated, randomized, paired, controlled, before-and-after study of a wet prairie in the USA found that woody plant cover declined, over three years, in plots where trees/shrubs were cut – but increased in plots where trees/shrubs were not cut. One study of a riparian wet meadow in Germany simply reported that some trees/shrubs regrew over four years after cutting trees/shrubs (along with grazing). Individual species abundance (1 study): One study quantified the effect of this action on the abundance of individual plant species. The replicated, randomized, paired, controlled, before-and-after study of a wet prairie in the USA found, for example, that cutting trees and shrubs had no significant effect on cover of the dominant herbaceous plant, tussock grass Deschampsia cespitosa, three years later. VEGETATION STRUCTURE Height (1 study): One site comparison study of a riparian wet meadow in Germany reported that an area in which trees/shrubs were cut back (along with reinstating cattle grazing) contained shorter vegetation than an adjacent unmanaged area. OTHER Survival (2 studies): One replicated, randomized, paired, controlled study in a wet prairie in the USA found that cutting woody plants did not significantly affect their survival in the following year. One study of a riparian wet meadow in Germany simply 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%2Fwww.conservationevidence.com%2Factions%2F3046https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3046Thu, 01 Apr 2021 19:06:56 +0100Collected Evidence: Collected Evidence: Cut large trees/shrubs to maintain or restore disturbance: brackish/salt marshesWe found no studies that evaluated the effects, on vegetation, of cutting large trees/shrubs 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%2Fwww.conservationevidence.com%2Factions%2F3047https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3047Thu, 01 Apr 2021 19:10:37 +0100Collected Evidence: Collected Evidence: Cut large trees/shrubs to maintain or restore disturbance: freshwater swamps One study evaluated the effects, on vegetation, of cutting large trees/shrubs 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 cutting woody vegetation (and applying herbicide) 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 cutting woody vegetation (and applying herbicide) 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 cutting woody vegetation (and applying herbicide) reduced canopy cover – to similar levels as in high-quality swamps after one year. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3048https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3048Thu, 01 Apr 2021 19:10:54 +0100Collected Evidence: Collected Evidence: Cut large trees/shrubs to maintain or restore disturbance: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of cutting large trees/shrubs 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%2Fwww.conservationevidence.com%2Factions%2F3049https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3049Thu, 01 Apr 2021 19:11:08 +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%2Fwww.conservationevidence.com%2Factions%2F3050https%3A%2F%2Fwww.conservationevidence.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%2Fwww.conservationevidence.com%2Factions%2F3051https%3A%2F%2Fwww.conservationevidence.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%2Fwww.conservationevidence.com%2Factions%2F3052https%3A%2F%2Fwww.conservationevidence.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%2Fwww.conservationevidence.com%2Factions%2F3053https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3053Thu, 01 Apr 2021 19:58:30 +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%2Fwww.conservationevidence.com%2Factions%2F3054https%3A%2F%2Fwww.conservationevidence.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%2Fwww.conservationevidence.com%2Factions%2F3055https%3A%2F%2Fwww.conservationevidence.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%2Fwww.conservationevidence.com%2Factions%2F3056https%3A%2F%2Fwww.conservationevidence.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%2Fwww.conservationevidence.com%2Factions%2F3057https%3A%2F%2Fwww.conservationevidence.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%2Fwww.conservationevidence.com%2Factions%2F3058https%3A%2F%2Fwww.conservationevidence.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%2Fwww.conservationevidence.com%2Factions%2F3059https%3A%2F%2Fwww.conservationevidence.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%2Fwww.conservationevidence.com%2Factions%2F3060https%3A%2F%2Fwww.conservationevidence.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%2Fwww.conservationevidence.com%2Factions%2F3061https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3061Fri, 02 Apr 2021 12:14:18 +0100Collected Evidence: Collected Evidence: Remove plant litter: freshwater marshes One study evaluated the effects, on vegetation, of removing plant litter from freshwater marshes. The study was in the USA. VEGETATION COMMUNITY Community composition (1 study): One replicated, paired, controlled study in rewetted marshes in the USA found that plots cleared of plant litter contained a plant community characteristic of wetter conditions than uncleared plots after one growing season – but not after two. Overall richness/diversity (1 study): The same study found that plots cleared of plant litter contained a similar number of wetland plant species to uncleared plots, after 1–2 growing seasons. VEGETATION ABUNDANCE                                                          Overall abundance (1 study): One replicated, paired, controlled study in rewetted marshes in the USA found that plots cleared of plant litter had greater cover of wetland plants than uncleared plots after one growing season – but not after two. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3062https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3062Fri, 02 Apr 2021 12:40:27 +0100Collected Evidence: Collected Evidence: Remove plant litter: brackish/salt marshesWe found no studies that evaluated the effects, on vegetation, of removing plant litter from brackish/salt marshes.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3063https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3063Fri, 02 Apr 2021 13:01:21 +0100Collected Evidence: Collected Evidence: Remove plant litter: freshwater swampsWe found no studies that evaluated the effects, on vegetation, of removing plant litter from freshwater swamps.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3064https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3064Fri, 02 Apr 2021 13:01:38 +0100Collected Evidence: Collected Evidence: Remove plant litter: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of removing plant litter from brackish/saline swamps.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3065https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3065Fri, 02 Apr 2021 13:01:57 +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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