Collected Evidence: Collected Evidence: Abandon cropland: allow freshwater marshes or swamps to recover without active intervention Four studies evaluated the effects, on vegetation, of abandoning cropland with the expectation that freshwater marshes or swamps would recover spontaneously. There was one study in each of Spain, South Korea, China and Japan. The studies involved former rice fields, soybean fields or pastures. VEGETATION COMMUNITY Community composition (2 studies): Two site comparison studies in South Korea and Japan reported that the overall plant community composition in abandoned cropland became more like natural swamps and/or marshes over time. Overall richness/diversity (2 studies): One site comparison study on a floodplain in Japan found that pastures abandoned for 5–25 years contained a higher richness of vascular, wetland plant species than pastures that remained in use. One study in South Korea simply reported the number of plant species in abandoned rice paddies increased over time. Characteristic plant richness/diversity (1 study): One site comparison study on a floodplain in Japan found that pastures abandoned for 5–25 years typically contained more marsh-indicator and swamp-indicator species than pastures that remained in use. VEGETATION ABUNDANCE Overall abundance (2 studies): One site comparison study in China found that vegetation biomass in abandoned soybean fields was lower than in natural wet meadows after three years, similar to natural wet meadows after six years, and higher than in natural wet meadows after 12 years. One study in Spain simply quantified the peak biomass and density of vegetation in rice fields abandoned for up to six years. Biomass, but not density, increased with time since abandonment. VEGETATION STRUCTURE Height (1 study): One site comparison study in China found that soybean fields abandoned for 3–12 years contained vegetation of a similar height to natural wet meadows. Diameter/perimeter/area (1 study): One site comparison study in South Korea reported that rice fields abandoned for 10 years contained thinner-stemmed Japanese alder Alnus japonica than mature alder forests. Collected Evidencehttps%3A%2F%2Fconservationevidence.com%2Factions%2F2952https%3A%2F%2Fconservationevidence.com%2Factions%2F2952Mon, 22 Mar 2021 13:41:02 +0000Collected Evidence: Collected Evidence: Abandon cropland: allow brackish/saline marshes or swamps to recover without active interventionWe found no studies that evaluated the effects, on vegetation, of abandoning cropland with the expectation that brackish/saline marshes or swamps would recover spontaneously.   ‘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%2Fconservationevidence.com%2Factions%2F2953https%3A%2F%2Fconservationevidence.com%2Factions%2F2953Mon, 22 Mar 2021 13:41:20 +0000Collected Evidence: Collected Evidence: Abandon plantations: allow marshes or swamps to recover without active interventionWe found no studies that evaluated the effects, on vegetation, of abandoning plantations with the expectation that marshes or swamps would recover spontaneously.   ‘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%2Fconservationevidence.com%2Factions%2F2956https%3A%2F%2Fconservationevidence.com%2Factions%2F2956Thu, 25 Mar 2021 13:56:05 +0000Collected Evidence: Collected Evidence: Abandon aquaculture facilities: allow freshwater marshes or swamps to recover without active interventionWe found no studies that evaluated the effects, on vegetation, of abandoning aquaculture facilities with the expectation that freshwater marshes or swamps would recover spontaneously.   ‘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%2Fconservationevidence.com%2Factions%2F2982https%3A%2F%2Fconservationevidence.com%2Factions%2F2982Thu, 25 Mar 2021 15:27:38 +0000Collected Evidence: Collected Evidence: Abandon aquaculture facilities: allow brackish/saline marshes or swamps to recover without active intervention One study evaluated the effects, on vegetation, of abandoning aquaculture facilities with the expectation that brackish/saline marshes or swamps would recover spontaneously. The study was in Costa Rica. VEGETATION COMMUNITY Community composition (1 study): One site comparison study in Costa Rica reported that after 14 years, an abandoned shrimp pond contained the same four tree species as a nearby natural mangrove forest. VEGETATION ABUNDANCE Tree/shrub abundance (1 study): One site comparison study in Costa Rica reported that after 14 years, an abandoned shrimp pond contained a greater density of trees than a nearby natural mangrove forest. VEGETATION STRUCTURE Height (1 study): One site comparison study in Costa Rica reported that after 14 years, an abandoned shrimp pond had a shorter tree canopy than a nearby natural mangrove forest. Basal area (1 study): The same study reported that the basal area of trees was smaller in an abandoned shrimp pond, after 14 years, than in a nearby natural mangrove forest. Collected Evidencehttps%3A%2F%2Fconservationevidence.com%2Factions%2F2983https%3A%2F%2Fconservationevidence.com%2Factions%2F2983Thu, 25 Mar 2021 15:27:56 +0000Collected Evidence: Collected Evidence: Abandon mined land: allow freshwater marshes or swamps to recover without active interventionWe found no studies that evaluated the effects on vegetation, of abandoning formerly mined land with the expectation that freshwater marshes or swamps would recover spontaneously.   ‘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%2Fconservationevidence.com%2Factions%2F2984https%3A%2F%2Fconservationevidence.com%2Factions%2F2984Thu, 25 Mar 2021 20:17:56 +0000Collected Evidence: Collected Evidence: Abandon mined land: allow brackish/saline marshes or swamps to recover without active intervention One study evaluated the effects, on vegetation, of abandoning formerly mined land with the expectation that brackish/saline marshes or swamps would recover spontaneously. The study was in France. VEGETATION COMMUNITY Community types (1 study): One replicated study in France simply classified the plant community types that developed on abandoned salt pans. Areas flooded for at least part of the year developed salt marsh plant communities, with the exact community composition depending on the duration of flooding and soil salinity. VEGETATION ABUNDANCE   VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fconservationevidence.com%2Factions%2F2985https%3A%2F%2Fconservationevidence.com%2Factions%2F2985Thu, 25 Mar 2021 20:18:12 +0000Collected Evidence: Collected Evidence: Actively manage water level: freshwater marshes Ten studies evaluated the effects, on vegetation, of active water level management in freshwater marshes. Eight studies were in the USA. One study was in Cameroon and one study was in the Netherlands. VEGETATION COMMUNITY Community composition (1 study): One before-and-after study in the USA found that directly pumping water into drained marshes and wet meadows generated plant communities characteristic of wetter conditions. This change was reversed in some plots when the pump output was moved further away from the focal wetlands. Relative abundance (2 studies): One replicated, randomized, controlled study of freshwater marshes in the USA reported that irrigated and non-irrigated marshes supported a similar relative abundance of the most common plant species. One before-and-after study on a floodplain in Cameroon found that the relative abundance of some key plant species changed over four years after restoring wet-season flooding. There was also an increase in the cover of perennial relative to annual herbs. Overall richness/diversity (4 studies): One before-and-after study of a marsh/swamp in the USA found that overall plant diversity was higher in the autumn following a managed flood/drawdown than in the autumn before. Two before-and-after studies of marshes and wet meadows in the USA reported that plant species richness and/or diversity declined over 5–6 years of water level management (fluctuation or water addition). One study in the USA simply reported the number of plant species that colonized a floodplain, over three weeks after lowering the river level. VEGETATION ABUNDANCE Overall abundance (3 studies): One study of riparian moist/wet meadows in the USA reported that vascular plant biomass increased in two of three meadow types, over the second year of artificially augmented streamflow. Meanwhile, vascular plant cover declined in two of three meadow types. Two studies in the Netherlands and the USA simply quantified overall vegetation abundance after 1–9 growing seasons of active water level management (sometimes along with other interventions). Characteristic plant abundance (2 studies): Two before-and-after studies of marshes and wet meadows in the USA reported increases in abundance of some individual wetland- or habitat-characteristic species over 5–6 years of water level management (fluctuation or water addition). Moss abundance (1 study): One study of riparian moist/wet meadows in the USA reported that moss cover did not significantly change in two of three meadow types, over the second year of artificially augmented streamflow. It declined in the other meadow type. Individual species abundance (7 studies): Seven studies quantified the effect of this action on the abundance of individual plant species. For example, one before-and-after study of a marsh/swamp in the USA reported mixed effects of a managed flood/drawdown on species cover, including increased cover of Pacific willow Salix lucida and reduced cover of reed canarygrass Phalaris arundinacea. One controlled study of freshwater marshes in the USA found that irrigated marshes developed a greater biomass of pink smartweed Polygonum pensylvanicum, after one growing season, than marshes that were left dry. VEGETATION STRUCTURE Vegetation height (1 study): One replicated, randomized, controlled study of freshwater marshes in the USA reported that four common plant species were taller in irrigated than non-irrigated marshes. Collected Evidencehttps%3A%2F%2Fconservationevidence.com%2Factions%2F3038https%3A%2F%2Fconservationevidence.com%2Factions%2F3038Thu, 01 Apr 2021 10:02:54 +0100Collected Evidence: Collected Evidence: Actively manage water level: brackish/salt marshes Ten studies evaluated the effects, on vegetation, of active water level management in brackish/salt marshes. Six studies were in the USA. There was overlap in the sites used in two of these studies. Two studies were in Canada and based on the same experimental set-up. One study was in France and one was in Tunisia. VEGETATION COMMUNITY Community types (1 study): One before-and-after study of a lakeshore brackish/salt marsh in Tunisia reported an increase in coverage of bulrush-dominated vegetation over nine years of freshwater releases into the lake (to increase its level and restore winter flooding of the marsh). Community composition (3 studies): One replicated, paired, controlled, before-and-after study of brackish marshes in France reported that artificially flooded marshes developed different plant communities, over five years, to fields with unmanaged flooding. One before-and-after, site comparison study of brackish/salt marshes in the USA reported that the overall plant community composition changed more, over four years, in a marsh directly irrigated with treated wastewater than in downstream marshes. One replicated, paired, site comparison study of brackish/salt marshes in the USA reported that that marshes in which water levels were drawn down each spring/autumn (along with disking soils) shared only 24–34% of plant species with marshes that were not drawn down (or disked). Overall richness/diversity (5 studies): Two replicated, site comparison studies of brackish/salt marshes in the USA found that marshes in which water levels were managed (sometimes along with other interventions) had similar plant species richness and/or diversity to marshes without water level management. One replicated, site comparison study of brackish and salt marshes in the USA reported that marshes in which water levels were managed had similar or higher plant species richness, in winter, than marshes without water level management. One before-and-after, site comparison study of brackish/salt marshes in the USA reported that plant species richness increased, over four years, in marshes directly irrigated with treated wastewater – but only to similar levels as in downstream marshes. One replicated, paired, controlled, before-and-after study of brackish marshes in France reported that the effects of artificial flooding on plant species richness depended on whether the marshes were grazed. VEGETATION ABUNDANCE Overall abundance (2 studies): Two replicated, site comparison studies of brackish and salt marshes in the USA reported that marshes in which water levels were managed typically had similar overall vegetation cover to marshes without water level management. One of the studies also reported that cover of standing dead vegetation was higher in the managed marshes than in the unmanaged marshes. Individual species abundance (6 studies): Six studies quantified the effect of this action on the abundance of individual plant species. For example, four replicated, site comparison studies of brackish and salt marshes in the USA reported mixed effects of water level management on the abundance of saltmeadow cordgrass Spartina patens. One replicated, paired, controlled, before-and-after study of brackish marshes in France reported that the effects of artificial flooding on the cover of individual plant species depended on the flooding (and grazing) regime. VEGETATION STRUCTURE   OTHER Germination/emergence (2 studies): Two replicated studies of brackish marshes in Canada reported that seedlings of wetland plants germinated in the spring/summer following drawdowns, after a period of deep flooding. Collected Evidencehttps%3A%2F%2Fconservationevidence.com%2Factions%2F3039https%3A%2F%2Fconservationevidence.com%2Factions%2F3039Thu, 01 Apr 2021 10:03:10 +0100Collected Evidence: Collected Evidence: Actively manage water level: freshwater swamps Two studies evaluated the effects, on vegetation, of active water level management in freshwater swamps. Both studies were in the USA. VEGETATION COMMUNITY Overall richness/diversity (1 study): One before-and-after study of a swamp/marsh in the USA found that overall plant diversity was higher in the autumn following a managed flood/drawdown than in the autumn before. VEGETATION ABUNDANCE Tree/shrub abundance (1 study): One site comparison study of floodplain swamps in the USA found that an artificial flood had no significant effect on tree seedling density in a low and very wet swamp, but increased tree seedling density in a drier swamp higher on the floodplain. Individual species abundance (1 study): One before-and-after study of a swamp/marsh in the USA reported mixed responses of individual plant species’ cover to active water level management. However, the study found that cover of the dominant woody species, Pacific willow Salix lucida, was higher in the autumn following a managed flood/drawdown than in the autumn before. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fconservationevidence.com%2Factions%2F3040https%3A%2F%2Fconservationevidence.com%2Factions%2F3040Thu, 01 Apr 2021 10:03:39 +0100Collected Evidence: Collected Evidence: Actively manage water level: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of active water level management 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%2Fconservationevidence.com%2Factions%2F3041https%3A%2F%2Fconservationevidence.com%2Factions%2F3041Thu, 01 Apr 2021 10:03:56 +0100Collected Evidence: Collected Evidence: Add clean water to reduce pollutionWe found no studies that evaluated the effects, on vegetation in marshes or swamps, of diverting clean water into them to reduce pollution.   ‘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%2Fconservationevidence.com%2Factions%2F3150https%3A%2F%2Fconservationevidence.com%2Factions%2F3150Mon, 05 Apr 2021 15:46:25 +0100Collected Evidence: Collected Evidence: Add below-ground organic matter: freshwater marshesWe found no studies that evaluated the effects, on vegetation, of adding below-ground organic matter to restore or create freshwater marshes.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fconservationevidence.com%2Factions%2F3243https%3A%2F%2Fconservationevidence.com%2Factions%2F3243Sat, 10 Apr 2021 12:32:54 +0100Collected Evidence: Collected Evidence: Add below-ground organic matter: brackish/salt marshes One study evaluated the effects, on vegetation, of adding below-ground organic matter to restore or create brackish/salt marshes. The study was in the USA. VEGETATION COMMUNITY   VEGETATION ABUNDANCE Individual species abundance (1 study): One replicated, randomized, controlled, before-and-after study in a salt marsh in the USA found that plots amended with alginate contained a greater density of smooth cordgrass Spartina alterniflora than unamended plots after 6–52 weeks. However, amended and unamended plots contained similar smooth cordgrass biomass when it was sampled after 52 weeks. VEGETATION STRUCTURE Height (1 study): One replicated, randomized, controlled, before-and-after study in a salt marsh in the USA found that amending plots with alginate had no significant effect on smooth cordgrass height in the first 16 weeks after intervention, but that amended plots contained taller smooth cordgrass than unamended plots after 28–52 weeks. Collected Evidencehttps%3A%2F%2Fconservationevidence.com%2Factions%2F3244https%3A%2F%2Fconservationevidence.com%2Factions%2F3244Sat, 10 Apr 2021 12:33:05 +0100Collected Evidence: Collected Evidence: Add below-ground organic matter: freshwater swampsWe found no studies that evaluated the effects, on vegetation, of adding below-ground organic matter to restore or create freshwater swamps.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fconservationevidence.com%2Factions%2F3245https%3A%2F%2Fconservationevidence.com%2Factions%2F3245Sat, 10 Apr 2021 12:33:22 +0100Collected Evidence: Collected Evidence: Add below-ground organic matter: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of adding below-ground organic matter to restore or create 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%2Fconservationevidence.com%2Factions%2F3246https%3A%2F%2Fconservationevidence.com%2Factions%2F3246Sat, 10 Apr 2021 12:33:31 +0100Collected Evidence: Collected Evidence: Add cover other than mulchWe found no studies that evaluated the effects, on vegetation, of using cover other than mulch to restore/create 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%2Fconservationevidence.com%2Factions%2F3251https%3A%2F%2Fconservationevidence.com%2Factions%2F3251Sat, 10 Apr 2021 13:03:16 +0100Collected Evidence: Collected Evidence: Actively manage water level before/after planting non-woody plants: freshwater wetlands Three studies evaluated the effects, on vegetation, of actively managing water levels in freshwater wetlands planted with emergent, non-woody plants. All three studies were in the USA. Two studies used the same experimental wet basins but planted different species. VEGETATION COMMUNITY Overall richness/diversity (1 study): One study in a freshwater marsh in the USA found that amongst plots amended with wetland soil, those flooded for longer contained fewer emergent plant species over the rest of the growing season following drawdown. Characteristic plant richness/diversity (1 study): The same study found that amongst plots amended with wetland soil, those flooded for longer contained fewer wetland-characteristic plant species over the rest of the growing season following drawdown. VEGETATION ABUNDANCE  Overall abundance (1 study): One study in a freshwater marsh in the USA found that amongst plots amended with wetland soil, those flooded for longer developed more submerged vegetation biomass before drawdown, but developed less emergent vegetation (biomass and stem density) over the rest of the growing season after drawdown. Individual species abundance (2 studies): Two studies quantified the effect of this action on the abundance of individual plant species. For example, one controlled, before-and-after study in wet basins in the USA found that the effect of mimicking a natural (falling) water regime on lake sedge Carex lacustris biomass and density, in the three years after planting, depended on the year and various environmental factors (e.g. planting density, elevation and weeding of competitors). VEGETATION STRUCTURE Height (2 studies): Two controlled studies in wet basins in the USA examined the effect of mimicking a natural (falling) water regime, compared to a stable or rising regime, on the height of sedges over three years after planting. One of the studies found no significant effect on the height of tussock sedge Carex stricta in three of three years. The other study found that the effect on the height of lake sedge Carex lacustris varied within and between years. OTHER Survival (2 studies): Two controlled studies in wet basins in the USA examined the effect of mimicking a natural (falling) water regime, compared to a stable or rising regime, on the survival of sedges Carex over three years after planting. The precise effect depended on the year and/or plot elevation. In the first year, sedge survival was typically lower under the falling regime. Collected Evidencehttps%3A%2F%2Fconservationevidence.com%2Factions%2F3281https%3A%2F%2Fconservationevidence.com%2Factions%2F3281Sat, 10 Apr 2021 17:15:30 +0100Collected Evidence: Collected Evidence: Actively manage water level before/after planting non-woody plants: brackish/saline wetlandsWe found no studies that evaluated the effects, on vegetation, of actively managing water levels in 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%2Fconservationevidence.com%2Factions%2F3282https%3A%2F%2Fconservationevidence.com%2Factions%2F3282Sat, 10 Apr 2021 17:15:48 +0100Collected Evidence: Collected Evidence: Actively manage water level before/after planting trees/shrubs: freshwater wetlandsWe found no studies that evaluated the effects, on vegetation, of actively managing water levels in freshwater wetlands planted with trees/shrubs.   ‘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%2Fconservationevidence.com%2Factions%2F3283https%3A%2F%2Fconservationevidence.com%2Factions%2F3283Sat, 10 Apr 2021 17:15:55 +0100Collected Evidence: Collected Evidence: Actively manage water level before/after planting trees/shrubs: brackish/saline wetlandsWe found no studies that evaluated the effects, on vegetation, of actively managing water levels in brackish/saline wetlands planted with trees/shrubs.   ‘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%2Fconservationevidence.com%2Factions%2F3284https%3A%2F%2Fconservationevidence.com%2Factions%2F3284Sat, 10 Apr 2021 17:16:15 +0100Collected Evidence: Collected Evidence: Add below-ground organic matter before/after planting non-woody plants: freshwater wetlands Seven studies evaluated the effects, on vegetation, of adding below-ground organic matter to freshwater wetlands planted with emergent, non-woody plants. All seven studies were in the USA. Two of the studies were in a greenhouse. VEGETATION COMMUNITY Overall richness/diversity (1 study): One replicated study of marshes alongside a stream in the USA found that adding compost before planting wetland herbs typically reduced overall plant species richness over the following three growing seasons. Richness was negatively related to the amount of soil organic matter in plots. VEGETATION ABUNDANCE Overall abundance (1 study): One replicated study of marshes alongside a stream in the USA found that adding compost before planting wetland herbs had no significant effect on total vegetation biomass after three growing seasons. Biomass was not significantly related to the amount of soil organic matter in plots. Characteristic plant abundance (1 study): One replicated, randomized, paired, controlled, before-and-after study in an experimental wet basin in the USA found that adding sawdust to plots before sowing a mixture of target sedge meadow species had no significant effect on the density of target species overall or target grass-like species. Adding sawdust sometimes affected the density of target forbs, depending on the presence/diversity of a nurse crop. Individual species abundance (2 studies): Two replicated, randomized, paired, controlled studies in wetlands in the USA quantified the effect of this action on the abundance of individual plant species. One study found that incorporating woodchips into soil mounds before planting tussock sedge Carex stricta reduced total tussock sedge cover after two growing seasons. The other study reported varying effects of sawdust addition on the abundance of individual plant species, depending on factors such as the species and presence/diversity of a nurse crop. VEGETATION STRUCTURE Individual plant size (4 studies): Three replicated, controlled studies (one also paired) in the USA found that mixing compost into the substrate before planting tussock sedge Carex stricta seedlings typically increased the biomass and/or number of shoots they developed over 2–3 months. However, in one of the studies, compost typically had no significant effect on top of other soil amendments. One replicated, randomized, paired, controlled study in a wetland in the USA found that incorporating woodchips into soil mounds had no significant effect on the biomass of planted tussock sedge Carex stricta, over two growing seasons. OTHER Germination/emergence (1 study): One replicated, randomized, paired, controlled study in an experimental wet basin in the USA found that seeds of mixed sedge meadow species had a similar germination rate, over 16 weeks after sowing, in plots with or without added sawdust. Survival (2 studies): One replicated, randomized, controlled study in an excavated wetland in the USA found that planted lurid sedge Carex lurida tubers had a higher survival rate, after one year, in plots that had been amended with leaf litter than in unamended plots. One replicated, randomized, paired, controlled study in a wetland in the USA found that incorporating woodchips into soil mounds increased survival of planted tussock sedge Carex stricta in a drier area, but reduced its survival in a wetter area. Growth (1 study): One replicated, randomized, paired, controlled study in a wetland in the USA found that incorporating woodchips into soil mounds had no significant effect on the growth rate of planted tussock sedge Carex stricta, over two growing seasons. Collected Evidencehttps%3A%2F%2Fconservationevidence.com%2Factions%2F3308https%3A%2F%2Fconservationevidence.com%2Factions%2F3308Sun, 11 Apr 2021 09:50:48 +0100Collected Evidence: Collected Evidence: Add below-ground organic matter before/after planting non-woody plants: brackish/saline wetlands Six studies evaluated the effects, on vegetation, of adding below-ground organic matter to brackish/saline wetlands planted with emergent, non-woody plants. Five studies were in the USA and one was in China. Two studies were in the same marsh, but used different experimental set-ups. VEGETATION COMMUNITY   VEGETATION ABUNDANCE Individual species abundance (5 studies): Three replicated, randomized, controlled studies in the USA found that adding organic matter before/after planting cordgrasses Spartina spp. typically had no significant effect on cordgrass abundance (biomass and/or density) after 1–2 growing seasons. One replicated, paired, controlled study in an estuary in the USA found that mixing kelp compost into the sediment before planting California cordgrass Spartina foliosa increased its density, three growing seasons later. One replicated, controlled, before-and-after study in an estuary in China found that mixing reed debris into the sediment before sowing seablite Suaeda salsa increased its biomass, but not its density, five months later. VEGETATION STRUCTURE Individual plant size (1 study): One replicated, randomized, paired, controlled study in an estuary in the USA found that tilling compost into plots before planting salt marsh vegetation typically increased the overall size of plants surviving after 1–2 growing seasons. Size was reported as a combination of height and lateral spread. Height (5 studies): Four replicated, controlled studies in the USA and China found that adding organic matter before/after introducing salt marsh plants (cordgrasses Spartina spp. or seablite Suaeda salsa) had no significant effect on their height after 1–2 growing seasons. One replicated, paired, controlled study in an estuary in the USA found that mixing kelp compost into the sediment before planting California cordgrass Spartina foliosa increased its height, three growing seasons later. OTHER Survival (1 study): One replicated, randomized, paired, controlled study in an estuary in the USA found that plots amended with kelp compost supported a higher survival rate of planted salt marsh vegetation over 1–2 growing seasons, with a similar but typically insignificant trend for survival rates of individual species. Growth (1 study): One replicated, randomized, controlled study in a greenhouse in the USA found that adding alginate after planting cordgrasses had no significant effect on the average number of shoots per plant, nine weeks later. Collected Evidencehttps%3A%2F%2Fconservationevidence.com%2Factions%2F3309https%3A%2F%2Fconservationevidence.com%2Factions%2F3309Sun, 11 Apr 2021 09:50:58 +0100Collected Evidence: Collected Evidence: Add below-ground organic matter before/after planting trees/shrubs: freshwater wetlands One study evaluated the effects, on vegetation, of adding below-ground organic matter to freshwater wetlands planted with trees/shrubs. The study was in the USA. VEGETATION COMMUNITY Community composition (1 study): One replicated, randomized, paired, controlled study in a created wetland in the USA found that amongst plots planted with tree seedlings, those amended with large amounts compost contained a plant community characteristic of drier conditions, three years later, than the community in unamended plots. The lowest compost dose had no significant effect on this outcome. Overall richness/diversity (1 study): The same study found that amongst plots planted with tree seedlings, those amended with a large amount of compost had lower plant species richness and diversity, three years later, than unamended plots. Lower compost doses had no significant effect on either outcome. VEGETATION ABUNDANCE Overall abundance (1 study): One replicated, randomized, paired, controlled study in a created wetland in the USA found that amongst plots planted with tree seedlings, those amended with compost supported a similar overall vegetation biomass, three years later, to unamended plots. VEGETATION STRUCTURE Individual plant size (1 study): One replicated, randomized, paired, controlled study in a created wetland in the USA found that birch Betula saplings were larger, three years after planting seedlings, in plots amended with large amounts of compost than in unamended plots. Collected Evidencehttps%3A%2F%2Fconservationevidence.com%2Factions%2F3310https%3A%2F%2Fconservationevidence.com%2Factions%2F3310Sun, 11 Apr 2021 09:51:11 +0100Collected Evidence: Collected Evidence: Add below-ground organic matter before/after planting trees/shrubs: brackish/saline wetlands One study evaluated the effects, on vegetation, of adding below-ground organic matter to brackish/saline wetlands planted with trees/shrubs. The study was in Brazil. VEGETATION COMMUNITY   VEGETATION ABUNDANCE   VEGETATION STRUCTURE   OTHER Survival (1 study): One replicated, randomized, controlled study in a coastal swamp in Brazil reported that adding manure to plots planted with tree seedlings had mixed effects on their survival over three years, depending on the species of tree and dose of manure. Growth (1 study): The same study reported that adding manure to plots planted with tree seedlings had mixed effects on their growth over three years, depending on the species of tree and dose of manure. Collected Evidencehttps%3A%2F%2Fconservationevidence.com%2Factions%2F3311https%3A%2F%2Fconservationevidence.com%2Factions%2F3311Sun, 11 Apr 2021 09:51:23 +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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