Conservation Evidence: Evidence Data

Collected Evidence: Collected Evidence: Exclude or remove livestock from degraded peatlands Ten studies evaluated the effects on peatland vegetation of excluding or removing livestock from degraded peatlands. Seven studies were in bogs, two in fens and one in an unspecified peatland. Three studies were based on the same experimental set-up in the UK. Plant community composition (2 studies): Of two replicated, paired, controlled studies in bogs in the UK, one found that excluding sheep had no effect on the development of the plant community. The other found no effect in wetter areas of the bog, but that in drier areas excluding sheep favoured dry moorland plants. Herb cover (9 studies): Seven studies (including six replicated, paired, controlled) in bogs in the UK and Australia and fens in the USA found that excluding or removing livestock typically had no effect on cover of key herb groups. Five of five studies found that excluding livestock typically had no effect on cottongrass cover. Two of two studies reported no effect on sedge cover. However, one before-and-after study in a poor fen in Spain reported that rush cover increased after cattle were excluded (along with other interventions). One site comparison study in Chile found that excluding livestock (along with other interventions) increased overall herb cover, but one replicated, paired, controlled study in bogs in Australia found that excluding livestock had no effect on overall herb cover. Moss cover (6 studies): Five replicated, paired, controlled studies in bogs in the UK and Australia found that excluding livestock typically had no effect on Sphagnum moss cover. Responses sometimes varied between species and sites. Three of the studies in the UK also found no effect on cover of other mosses. One before-and-after study in a poor fen in Spain reported that Sphagnum moss appeared after excluding cattle (and rewetting). Tree/shrub cover (8 studies): Four replicated, paired, controlled studies in bogs in the UK and Australia found that excluding livestock had no effect on shrub cover (specifically heather or a heathland community). One replicated, paired, controlled study in a bog in the UK found that excluding sheep had no effect on heather cover in wetter areas, but increased heather cover in drier areas. Three studies (including two site comparisons) in bogs in the UK, fens in the USA and a peatland in Chile found that excluding or removing livestock increased shrub cover. Vegetation structure (1 study): One replicated, paired, controlled study in a bog in the UK found that excluding sheep increased total vegetation, shrub and bryophyte biomass but had no effect on biomass of grass-like herbs. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1734https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1734Mon, 27 Nov 2017 21:21:00 +0000Collected Evidence: Collected Evidence: Exclude wild herbivores using physical barriers One study evaluated the effects on peatland vegetation of physically excluding wild herbivores. The study was in a fen meadow. Vegetation cover (1 study): One replicated, paired, controlled study in a fen meadow in Poland reported that the effect of boar- and deer exclusion on vascular plant and moss cover depended on other treatments applied to plots. Vegetation structure (1 study): The same study reported that the effect of boar- and deer exclusion on total vegetation biomass depended on other treatments applied to plots. Overall plant richness/diversity (1 study): The same study reported that the effect of boar- and deer exclusion on plant species richness depended on other treatments applied to plots. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1860https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1860Mon, 11 Dec 2017 15:07:26 +0000Collected Evidence: Collected Evidence: Extract aggregates from a vessel that is moving rather than static One study examined the effects of dredging from a vessel that is moving rather than static on subtidal benthic invertebrate populations. The study was in the English Channel (UK). COMMUNITY RESPONSE (1 STUDY) Overall species richness/diversity (1 study): One site comparison study in the English Channel found that a site where aggregate extraction was undertaken using a moving trailer suction hopper dredger had similar invertebrate species richness and lower diversity compared to a site where extraction occurred using a static suction hopper dredger. POPULATION RESPONSE (1 STUDY) Overall abundance (1 study): One site comparison study in the English Channel found that a site where aggregate extraction was undertaken using a moving trailer suction hopper dredger had higher abundance of invertebrates compared to a site where extraction occurred using a static suction hopper dredger. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2071https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2071Mon, 21 Oct 2019 14:17:57 +0100Collected Evidence: Collected Evidence: Exclude or limit number of visitors to reserves or protected areas Five studies evaluated the effects on mammals of excluding or limiting the number of visitors to reserves or protected areas. Three studies were in the USA, one was in Ecuador and one was in Thailand. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (2 STUDIES) Abundance (1 study): A site comparison study in Ecuador found that a road with restricted access had a higher population of medium-sized and large mammals compared to a road with unrestricted access. Survival (1 study): A before-and-after study in the USA found that temporarily restricting visitor access resulted in fewer bears being killed to protect humans. BEHAVIOUR (3 STUDIES) Use (3 studies): Three studies (one a before-and-after study), in the USA and Thailand, found that restricting human access to protected areas resulted in increased use of these areas by grizzly bears and leopards. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2330https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2330Thu, 21 May 2020 10:43:02 +0100Collected Evidence: Collected Evidence: Exclude wild mammals using ditches, moats, walls or other barricades to reduce human-wildlife conflict Two studies evaluated the effects of excluding wild mammals using ditches, moats, walls or other barricades to reduce human-wildlife conflict. One study was in Cameroon and Benin and one was in Cameroon. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (2 STUDIES) Human-wildlife conflict (2 studies): Two studies (including one before-and-after study and one site comparison), in Cameroon and Benin and in Cameroon, found that fewer livestock were predated when they were kept in enclosures, especially when these were reinforced. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2420https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2420Mon, 01 Jun 2020 13:39:43 +0100Collected Evidence: Collected Evidence: Exclude or remove livestock from historically grazed freshwater marshes Ten studies evaluated the effects, on vegetation, of excluding or removing livestock from historically grazed freshwater marshes. Seven studies were in the USA, two were in Morocco and one was in Australia. In all 10 studies the focal livestock included cattle (mixed with sheep in the two studies in Morocco). Two studies in the USA were based on the same experimental set-up, and the two studies in Morocco shared some study sites. VEGETATION COMMUNITY Community composition (4 studies): Two site comparison studies in Morocco and the USA reported that marshes/pools fenced to exclude livestock for 3–30 years contained a different overall plant community to grazed sites. In the USA, the precise effect depended on the time since exclusion. Two replicated, randomized, paired, controlled studies in marshes in Australia and the USA found that fencing to exclude cattle typically had no significant effect on the overall plant community composition after 1–14 years. One of the studies also found that the plant community in fenced and grazed marshes was of similar quality, relative to pristine local marshes. Relative abundance (3 studies): Of three replicated, randomized, paired, controlled studies that reported data on the relative abundance of plant groups, two studies (based on one experimental set-up) in the USA found that ephemeral pools fenced to exclude cattle for 1–10 years had similar or greater cover of grasses relative to forbs than pools that remained grazed. The other study, also in the USA, found that the relative abundance of forbs, grass-like plants and shrubs was similar in marshes fenced to exclude cattle for 1–3 years and marshes that remained grazed. Overall richness/diversity (6 studies): Four replicated studies (two also randomized, paired, controlled) in the USA, Morocco and Australia found that marshes/pools fenced to exclude cattle, for 1–30 years, typically had similar overall plant species richness to sites that remained grazed. One of the studies found that the same was true for overall plant diversity. One replicated, site comparison study of ephemeral pools in Morocco found that pools fenced to exclude livestock for >30 years had similar (in a dry year) or greater (in a wet year) plant species richness compared to pools that remained grazed. One site comparison study in the USA found that marshes fenced to exclude cattle for 3–13 years contained fewer plant species than grazed marshes, and had similar or lower plant diversity. Characteristic plant richness/diversity (1 study): One site comparison study of ephemeral pools in Morocco found that pools fenced to exclude livestock for >30 years contained a similar number of wetland-characteristic plant species to pools that remained grazed. Native/non-target richness/diversity (3 studies): Of three replicated, randomized, paired, controlled studies that reported data on native plant species richness, two studies (based on one experimental set-up) in the USA found that fencing ephemeral pools to exclude cattle for 1–10 years typically reduced native plant species richness. The other study, also in the USA, found that native plant species richness was similar in marshes fenced to exclude cattle for 1–3 years and marshes that remained grazed. VEGETATION ABUNDANCE Overall abundance (3 studies): Two replicated, site comparison studies in the USA and Morocco found that ponds/pools fenced to exclude cattle for >10 years contained more vegetation than sites that remained grazed. This was measured in terms of emergent cover around pond margins or peak above-ground biomass in ephemeral pools. One replicated, randomized, paired, controlled study in Australia found that marshes fenced to exclude cattle for ≤4 years contained similar above-ground vegetation biomass to marshes that remained grazed. Characteristic plant abundance (1 study): One site comparison study of ephemeral pools in Morocco found that the overall abundance of wetland-characteristic plant species was greater in pools fenced to exclude livestock for >30 years than in pools that remained grazed. Herb abundance (1 study): One replicated, randomized, paired, controlled, before-and-after study in the USA found that fencing pastures to exclude cattle typically increased herb cover in wetlands along creeks, but had no significant effect on herb cover within spring wetlands. Individual species abundance (2 studies): Two replicated, randomized, paired, controlled studies in freshwater marshes in Australia and the USA quantified the effect of this action on the abundance of individual plant species (see original papers for data). VEGETATION STRUCTURE Visual obstruction (1 study): One replicated, site comparison study in the USA found that ponds fenced to exclude cattle for >10 years had greater horizontal vegetation cover, around their margins, than ponds that remained grazed. Height (2 studies): Two replicated studies (one also randomized, paired, controlled, before-and-after) in the USA found that fencing ponds to exclude cattle, for 1–3 or >10 years, increased the height of vegetation around their margins. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2966https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2966Thu, 25 Mar 2021 14:14:57 +0000Collected Evidence: Collected Evidence: Exclude or remove livestock from historically grazed brackish/salt marshes Fifteen studies evaluated the effects, on vegetation, of excluding or removing livestock from historically grazed brackish/salt marshes. There were five studies in Germany. There were two studies in the UK, Denmark and the Netherlands. There was one study in each of the USA, Sweden, France and Argentina. Livestock were sheep, cattle, sheep and cattle, cattle and horses, or unspecified. There was overlap in the sites used in two studies. Two other studies took place in one marsh, but with different experimental set-ups. VEGETATION COMMUNITY Overall extent (1 study): One controlled study of a salt marsh in Germany reported that in a plot fenced to exclude cattle for eight years, the total vegetated area was greater than in a plot that remained grazed. Community types (1 study): One site comparison study of brackish and salt marshes in Germany reported that reducing (or stopping) grazing affected the nature of transitions between vegetation types over time, but that the precise effect varied with environmental conditions. Community composition (5 studies): Three paired studies (two also replicated and controlled) in brackish/salt marshes in France, Argentina and the Netherlands reported that the effect of excluding livestock for 5–30 years on the overall plant community composition depended on plot elevation/flooding regime. In one of these studies, the effect of livestock exclusion was not separated from the effect of general legal protection. Two studies in one salt marsh in Denmark reported that excluding livestock had little effect on the identity of plant species in the community after six years. Overall richness/diversity (6 studies): Two studies (one controlled, one before-and-after) in one salt marsh in Denmark reported that excluding sheep and cattle for 6–7 years had no effect on overall plant species richness. One replicated, paired, controlled study in a salt marsh in the Netherlands reported that plots fenced to exclude cattle for seven years had lower plant species richness than areas that remained grazed. Two controlled studies (one also replicated and paired) in salt marshes in Germany found that the effect of removing sheep on overall plant species richness depended on the scale of measurement and the grazing intensity used for comparison – with inconsistent results across these studies even for similar scales and intensities. One paired, site comparison study of salt marshes in Argentina found that the effect of excluding cattle (along with legal protection) increased plant species richness at lower elevations, but did not significantly affect plant diversity at any elevation. VEGETATION ABUNDANCE Overall abundance (4 studies): Three studies (two controlled, one before-and-after) in salt marshes in the UK and Denmark reported that excluding livestock for 2–6 years maintained or increased overall vegetation abundance (although in one study, only by a small amount). One controlled study in a salt marsh in Germany found that a paddock left ungrazed for 16–18 years had greater overall vegetation cover than lightly or heavily grazed paddocks, but lower cover than a moderately grazed paddock. Individual species abundance (11 studies): Eleven studies quantified the effect of this action on the abundance of individual plant species. For example, five studies (four controlled, one before-and-after) on salt marshes in the UK, Denmark, Germany and the Netherlands reported that excluding livestock for 2–8 years reduced (or prevented increases in) cover of saltmarsh grass Puccinellia maritima. However, two controlled studies (one also replicated and paired) on salt marshes in Denmark and Sweden reported greater saltmarsh grass cover in areas fenced to exclude livestock for 1–6 years than in areas that remained grazed. Four studies (three controlled, one before-and-after) on salt marshes in Denmark and Germany reported that excluding or removing livestock for 4–16 years increased cover of sea purslane Halimione portulacoides. VEGETATION STRUCTURE Height (5 studies): Five controlled studies (two also replicated and paired) in salt marshes in Sweden and Germany, and brackish wet grassland in the UK, found that ungrazed plots (livestock excluded or removed) contained taller vegetation than plots that remained grazed. Vegetation was surveyed after one month, 1–8 years or 16–22 years. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2967https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2967Thu, 25 Mar 2021 14:15:09 +0000Collected Evidence: Collected Evidence: Exclude or remove livestock from historically grazed freshwater swampsWe found no studies that evaluated the effects, on vegetation, of excluding or removing livestock from historically grazed 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%2F2968https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2968Thu, 25 Mar 2021 14:15:24 +0000Collected Evidence: Collected Evidence: Exclude or remove livestock from historically grazed brackish/saline swamps One study evaluated the effects, on vegetation, of excluding or removing livestock from historically grazed brackish/saline swamps. The study was in South Africa and the focal livestock were cattle. VEGETATION COMMUNITY VEGETATION ABUNDANCE Individual species abundance (1 study): One replicated, paired, controlled study in South Africa reported that more grey mangrove Avicennia marina seedlings appeared in plots fenced to exclude cattle for two years, than in plots left open to cattle. VEGETATION STRUCTURE Height (1 study): One replicated, paired, controlled study in South Africa reported that mangrove trees fenced off from cattle were taller, after two years, than trees accessible to cattle. OTHER Growth (1 study): One replicated, paired, controlled study in South Africa found that mangrove trees fenced off from cattle grew more over two years – in height, diameter and crown volume –than trees accessible to cattle. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2969https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2969Thu, 25 Mar 2021 14:15:41 +0000Collected Evidence: Collected Evidence: Facilitate tidal exchange to restore degraded freshwater marshesWe found no studies that evaluated the effects, on vegetation, of facilitating tidal exchange to restore degraded 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%2Fwww.conservationevidence.com%2Factions%2F3034https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3034Wed, 31 Mar 2021 19:33:44 +0100Collected Evidence: Collected Evidence: Facilitate tidal exchange to restore degraded brackish/salt marshes Seven studies evaluated the effects, on vegetation, of facilitating tidal exchange to restore degraded brackish/salt marshes. Six studies were in the USA. One study included sites in both the USA and Canada. VEGETATION COMMUNITY Overall extent (1 study): One before-and-after study in the USA reported that over 10 years after improving tidal exchange in a degraded marsh, the area of salt marsh vegetation increased – but not quite to historical, pre-degradation levels. Community types (1 study): One before-and-after study in the USA reported that 3–10 years after improving tidal exchange in a degraded marsh, the area of salt marsh community types differed from historical, pre-degradation levels. Community composition (3 studies): Three before-and-after studies in the USA found that in the four years after improving tidal exchange in degraded brackish/salt marshes, the overall plant community composition significantly differed to that present before intervention. However, in one of the studies this was only true in one of two marshes (the most degraded before intervention). One of the studies also reported that the overall plant community composition became more similar to adjacent natural brackish/salt marshes over two growing seasons after intervention. Overall richness/diversity (1 study): One replicated, before-and-after, site comparison study in the USA/Canada found that overall plant species richness was similar in ≥3-year-old tidally restored salt marshes and nearby natural salt marshes. However, there was also no significant difference between degraded marshes (before tidal restoration) and the natural marshes. Characteristic plant richness/diversity (1 study): One study of a coastal marsh in the USA reported that over three years after restoring tidal exchange (along with a prescribed burn), the number of salt-tolerant plant species increased, whilst the number of freshwater plant species decreased. VEGETATION ABUNDANCE Overall abundance (1 study): One replicated, site comparison study of salt marshes in the USA found that tidally restored areas had a lower overall plant stem density, after 13–54 years, than natural salt marshes. Characteristic plant abundance (2 studies): Two before-and-after studies of coastal marshes in North America reported that within three years of restoring tidal exchange (sometimes along with other interventions), total cover of fresh/brackish plant species decreased. In one study the total cover of salt-tolerant plant species increased, but in the other study it did not. One of the studies also found that tidally restored marshes had lower cover of salt-tolerant plants than nearby natural marshes. Individual species abundance (5 studies): Five studies quantified the effect of this action on the abundance of individual plant species. All five studies were in brackish/salt marshes in the USA. Three before-and-after studies reported increases in cover or frequency of smooth cordgrass Spartina alterniflora in the four years after improving tidal exchange. One replicated, site comparison study found that smooth cordgrass cover was lower in tidally restored areas than in natural salt marshes, 13–54 years after tidal restoration. Two before-and-after studies reported no clear change in frequency or cover of saltmeadow cordgrass Spartina patens in the four years after improving tidal exchange, but one before-and-after study reported an increase in saltmeadow cordgrass cover over two growing seasons after improving tidal exchange. Four studies reported declines in cover or frequency of less salt-tolerant species such as common reed Phragmites australis and cattails Typha spp. in the four years after improving tidal exchange (sometimes along with other interventions). One replicated, site comparison study found that common reed cover was similarly low (<1%) in tidally restored areas and natural salt marshes, 13–54 years after tidal restoration. VEGETATION STRUCTURE Vegetation height (3 studies): Two before-and-after studies of brackish/salt marshes in the USA found that common reed was shorter 1–4 years after improving tidal exchange than before. One replicated, site comparison study in the USA found that the maximum vegetation height was similar in tidally restored salt marshes and natural salt marshes, 13–54 years after tidal restoration. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3035https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3035Wed, 31 Mar 2021 19:34:00 +0100Collected Evidence: Collected Evidence: Facilitate tidal exchange to restore degraded freshwater swampsWe found no studies that evaluated the effects, on vegetation, of facilitating tidal exchange to restore degraded freshwater swamps. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3036https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3036Wed, 31 Mar 2021 19:34:19 +0100Collected Evidence: Collected Evidence: Facilitate tidal exchange to restore degraded brackish/saline swamps Four studies evaluated the effects, on vegetation, of facilitating tidal exchange to restore degraded brackish/saline swamps. Three studies were in Mexico and one was in India. VEGETATION COMMUNITY Overall extent (2 studies): Two before-and-after studies on the coasts of India and Mexico reported that the area of mangrove forest in each site was greater 5–6 years after restoring tidal exchange (sometimes along with planting mangrove seedlings) than in the years before. Community composition (1 study): One before-and-after study of a mangrove forest in Mexico reported that the tree community composition was identical before and five years after restoring tidal exchange: the same three tree species were present at both times. Community types (1 study): One before-and-after study of a mangrove forest in Mexico reported that the relative coverage of stands dominated by each of three tree species was similar before and five years after restoring tidal exchange. Tree/shrub richness/diversity (2 studies): One site comparison study in Mexico reported that a tidally restored mangrove forest contained a similar number of tree species to nearby natural mangroves, after 10–11 years. One before-and-after study in Mexico reported identical tree species richness in a mangrove forest before and five years after restoring tidal exchange. VEGETATION ABUNDANCE Tree/shrub abundance (2 studies): Two site comparison studies in Mexico reported that tidally restored mangrove forests contained a lower density of trees or seedlings than nearby natural mangroves. Individual species abundance (1 study): One site comparison study in Mexico compared the abundance of three mangrove tree species in a tidally restored area and nearby natural forests (see original paper for data). VEGETATION STRUCTURE Height (2 studies): One site comparison study in Mexico reported that trees in a tidally restored mangrove forest were a similar height to trees in nearby natural mangroves, after 10–11 years. Another replicated, site comparison study in Mexico reported that seedlings in a tidally restored mangrove forest were taller than seedlings in a nearby natural mangrove. Diameter (1 study): One site comparison study in Mexico reported that trees in a tidally restored mangrove forest had a similar diameter to trees in nearby natural mangroves, after 10–11 years. Basal area (1 study): One site comparison study in Mexico reported that trees in a tidally restored mangrove forest had a smaller basal area than trees in natural mangroves, after 10–11 years. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3037https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3037Wed, 31 Mar 2021 19:34:43 +0100Collected Evidence: Collected Evidence: Exclude wild vertebrates: freshwater marshes Twelve studies evaluated the effects, on vegetation, of physically excluding wild vertebrates from freshwater marshes. Six studies were in the USA. Three studies were in the Netherlands, two were in Australia and one was in Canada. The problematic vertebrates were birds in five studies, mammals in four studies, fish in one study, and mixed taxa in two studies. Two studies were conducted in the same area, but with different experimental set-ups. VEGETATION COMMUNITY Overall extent (1 study): One before-and-after study in a freshwater marsh in Canada found that after two years of excluding common carp Cyprinus carpio, the area of emergent vegetation was similar to the area expected based on the water level and historical data (when carp were present). Community composition (1 study): One replicated, randomized, paired, controlled study in freshwater marshes in Australia found that areas fenced to exclude wild mammals typically had a similar overall plant community composition to open areas, over 14 years. Overall richness/diversity (4 studies): Three replicated, randomized, paired, controlled studies in freshwater marshes in the USA and Australia reported that fencing to exclude wild mammals had no clear or significant effect on total plant species richness. One replicated, paired, controlled study in freshwater marshes in the Netherlands found that fenced plots had higher emergent plant species richness than open plots, but similar diversity. VEGETATION ABUNDANCE Overall abundance (7 studies): Seven replicated, controlled studies (three also randomized and paired) involving freshwater marshes in the USA, the Netherlands and Australia found that areas fenced to exclude wild vertebrates contained at least as much vegetation as open areas – and typically more. This was true for biomass (fenced > open in six of six studies), cover (fenced > open in two of two studies) and stem density (fenced similar to open in one of one studies). Vegetation was monitored over the winter immediately after fencing, or after 1–4 growing seasons. Individual species abundance (8 studies): Eight studies quantified the effect of this action on the abundance of individual plant species. For example, seven replicated, controlled studies (four also paired, two also randomized) in freshwater marshes in the USA, the Netherlands and Australia found that dominant plant species had similar or greater abundance in areas fenced to exclude wild vertebrates, after 1–3 growing seasons, than in areas open to wild vertebrates. The dominant species included switchgrass Panicum virgatum, cordgrasses Spartina spp. and wild rice Zizania aquatica. VEGETATION STRUCTURE Height (1 study): One replicated, paired, controlled study in freshwater marshes in the USA found that plots fenced to exclude Canada geese Branta canadensis contained taller wild rice Zizania aquatica than open plots in two of three comparisons. In the other comparison, after two years of goose control, fenced and open plots contained wild rice of a similar height. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3132https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3132Mon, 05 Apr 2021 12:15:49 +0100Collected Evidence: Collected Evidence: Exclude wild vertebrates: brackish/salt marshes Seven studies evaluated the effects, on vegetation, of physically excluding wild vertebrates from brackish/salt marshes. Five studies were in the USA. The other studies were in France and Sweden. In five studies, the problematic vertebrates were mammals. In the other two studies, they were birds. Two of the studies were conducted in the same area, but with different experimental set-ups. VEGETATION COMMUNITY Overall richness/diversity (3 studies): Two replicated, paired, controlled studies in brackish marshes in the USA found that fencing to exclude nutria Myocastor coypus had no significant effect on total plant species richness: fenced and open plots contained a similar number of plant species after 1–2 growing seasons. One replicated, randomized, paired, controlled, before-and-after study in brackish marshes in the USA reported that excluding mammals typically had no significant effect on changes in plant species richness over two years. VEGETATION ABUNDANCE Overall abundance (5 studies): Five replicated, paired, controlled studies involving brackish marshes in France and the USA found that fencing to exclude medium-large vertebrates maintained or increased overall vegetation abundance. Vegetation cover or biomass were compared between fenced and open plots, after 1–2 growing seasons or over the winter after fencing. Individual species abundance (6 studies): Six studies quantified the effect of this action on the abundance of individual plant species. The six replicated, controlled studies in brackish and salt marshes in France, Sweden and the USA reported that fencing to exclude medium-large mammals typically maintained or increased the abundance of the dominant herb species over 1–4 growing seasons. Four of the studies found that fenced and open plots contained a similar abundance (biomass, cover or density) of cordgrasses Spartina spp. Three of the studies found that bulrushes Schoenoplectus spp./Scirpus spp. were more abundant in fenced than open plots. However, one study reported no clear difference in bulrush abundance between treatments and one study reported mixed effects depending on moisture levels and which mammals were excluded. VEGETATION STRUCTURE Height (3 studies): One replicated, paired, controlled study in a brackish marsh in France found that overall vegetation height increased over two years in plots fenced to exclude medium-large mammals, compared to a decline in plots left open. Two replicated, controlled studies in brackish and salt marshes in Sweden and the USA found that vertebrate exclusion did not reduce (i.e. maintained or increased) the height of dominant herb species over 2–4 growing seasons. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3133https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3133Mon, 05 Apr 2021 12:16:03 +0100Collected Evidence: Collected Evidence: Exclude wild vertebrates: freshwater swampsWe found no studies that evaluated the effects, on vegetation, of physically excluding wild vertebrates 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%2F3134https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3134Mon, 05 Apr 2021 12:16:26 +0100Collected Evidence: Collected Evidence: Exclude wild vertebrates: brackish/saline swampsWe found no studies that evaluated the effects, on vegetation, of physically excluding wild vertebrates 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%2F3135https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3135Mon, 05 Apr 2021 12:16:39 +0100Collected Evidence: Collected Evidence: Exclude wild invertebrates using physical barriersWe found no studies that evaluated the effects, on vegetation, of physically excluding wild invertebrates from marshes or swamps. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3140https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3140Mon, 05 Apr 2021 14:24:23 +0100Collected Evidence: Collected Evidence: Facilitate tidal exchange to restore/create brackish/salt marshes from other land uses Fourteen studies evaluated the effects, on vegetation, of facilitating tidal exchange to restore/create brackish/salt marshes from other land uses or habitat types. Seven studies were in the UK. Five studies were in the USA. There was one study in each of Australia and the Netherlands. There was overlap in the sites used in four of the studies. VEGETATION COMMUNITY Overall extent (3 studies): Three before-and-after studies in Australia, the UK and the Netherlands reported increases in the overall extent of salt marsh vegetation over 3–10 years after restoring tidal exchange. Community types (3 studies): One replicated, paired, site comparison study in the UK reported that restored marshes, developing after 2–13 years of tidal exchange, contained a different type of salt marsh plant community to natural marshes in four of four cases. Two before-and-after studies in the UK and the Netherlands reported increases in the frequency or coverage of salt marsh plant communities after restoring tidal exchange, reaching 93–100% after 9–10 years. Community composition (4 studies): Four site comparison studies (two replicated, one paired) in the UK and the USA reported that after facilitating tidal exchange on freshwater wetlands or farmland, the overall plant community composition remained somewhat different from natural brackish/salt marshes for up to 30 years. Three of the studies reported increasing community similarity to natural marshes over 11–30 years of tidal exchange. Overall richness/diversity (6 studies): Two site comparison studies of brackish/salt marshes in the USA and the UK reported that overall plant species richness was similar in marshes developing after 4–11 years of tidal exchange, and in nearby natural marshes. Two site comparison studies (one replicated) of salt marshes in the UK reported that marshes developing after 1–14 years of tidal exchange (sometimes along with other interventions) had lower plant species richness or diversity than nearby natural marshes. Two before-and-after studies in the UK compared the number of plant/algae species present in salt marshes that developed over 1–9 years after restoring tidal exchange to the number of plant species present before intervention. In one study there were more species after intervention, but in the other study there were fewer. Characteristic plant richness/diversity (2 studies): One replicated, site comparison study of salt marshes in the UK reported that marshes developing after 1–14 years of tidal exchange contained a similar number of salt-tolerant plant species to natural marshes. One before-and-after study in the Netherlands reported that all 23 target brackish/salt marsh species were present in the study site 10 years after restoring regular tidal exchange: more than were present before restoration. VEGETATION ABUNDANCE Overall abundance (6 studies): Two site comparison studies (one replicated) of salt marshes in the UK reported that marshes developing after 1–14 years of tidal exchange (sometimes along with other interventions) had lower overall vegetation cover than nearby natural marshes. One before-and-after study in the UK reported that 99% of salt marsh quadrats were vegetated nine years after restoring tidal exchange, compared to 100% in the freshwater wetland that previously occupied the site and 43% one summer after restoration. Three studies in the USA and the UK simply quantified the overall cover of vegetation present in sites for up to 15 years after facilitating tidal exchange (sometimes along with other interventions). Characteristic plant abundance (1 study): One site comparison study in the USA reported that some plant species diagnostic of natural brackish marshes were absent from a marsh that had developed over >30 years of restored tidal exchange. Individual species abundance (6 studies): Six studies quantified the effect of this action on the abundance of individual plant species. For example, three site comparison studies of salt marshes in the UK reported that cover of saltmarsh grass Puccinellia maritima was similar or lower in marshes developing after 1–14 years of tidal exchange (sometimes along with other interventions) than in nearby natural marshes. In contrast, in these studies, cover of glassworts Salicornia was higher in restored than natural marshes. VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3207https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3207Fri, 09 Apr 2021 07:49:08 +0100Collected Evidence: Collected Evidence: Facilitate tidal exchange to restore/create brackish/saline swamps from other land uses Two studies evaluated the effects, on vegetation, of facilitating tidal exchange to restore/create brackish/saline swamps from other land uses or habitat types. One study was in Australia and one was in Thailand. VEGETATION COMMUNITY Overall extent (1 study): One before-and-after study in an estuary in Australia reported that the area of mangrove forest on an island was greater 3–9 years after restoring full tidal exchange than in the years before. Tree/shrub richness/diversity (1 study): One study in a former shrimp pond in Thailand reported the number of mangrove tree species that spontaneously colonized in the six years after restoring full tidal exchange (along with other interventions). VEGETATION ABUNDANCE Individual species abundance (1 study): One study in a former shrimp pond in Thailand reported the number of mangrove trees, by species, that spontaneously colonized in the six years after restoring full tidal exchange (along with other interventions). VEGETATION STRUCTURECollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3209https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3209Fri, 09 Apr 2021 07:49:33 +0100Collected Evidence: Collected Evidence: Facilitate tidal exchange before/after planting non-woody plants: freshwater wetlandsWe found no studies that evaluated the effects, on vegetation, of facilitating tidal exchange in freshwater 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%2Fwww.conservationevidence.com%2Factions%2F3276https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3276Sat, 10 Apr 2021 17:07:18 +0100Collected Evidence: Collected Evidence: Facilitate tidal exchange before/after planting non-woody plants: brackish/saline wetlands Two studies evaluated the effects, on vegetation, of facilitating tidal exchange in brackish/saline wetlands planted with emergent, non-woody plants. Both studies were in the same estuarine site in the USA. VEGETATION COMMUNITY VEGETATION ABUNDANCE VEGETATION STRUCTURE Height (1 study): One replicated, controlled study in a salt marsh in the USA found that planted California cordgrass Spartina foliosa reached a similar height, after three growing seasons, in areas with an excavated tidal creek and areas without a tidal creek. Individual plant size (1 study): One replicated, controlled study in a salt marsh in the USA found that planted salt marsh herbs reached a similar overall size, after 1–2 growing seasons, in areas with an excavated tidal creek and areas without a tidal creek. OTHER Survival (2 studies): Two replicated, controlled studies in a salt marsh in the USA found that planted salt marsh herbs typically had similar survival rates, after 1–2 growing seasons, in areas with an excavated tidal creek and areas without a tidal creek. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3277https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3277Sat, 10 Apr 2021 17:07:28 +0100Collected Evidence: Collected Evidence: Facilitate tidal exchange before/after planting trees/shrubs: freshwater wetlandsWe found no studies that evaluated the effects, on vegetation, of facilitating tidal exchange 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%2Fwww.conservationevidence.com%2Factions%2F3278https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3278Sat, 10 Apr 2021 17:07:37 +0100Collected Evidence: Collected Evidence: Facilitate tidal exchange before/after planting trees/shrubs: brackish/saline wetlandsWe found no studies that evaluated the effects, on vegetation, of facilitating tidal exchange 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%2Fwww.conservationevidence.com%2Factions%2F3279https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3279Sat, 10 Apr 2021 17:07:46 +0100Collected Evidence: Collected Evidence: Expose seeds to light before sowingWe found no studies that evaluated the effects – on emergent wetland plants – of exposing their seeds to light before sowing. ‘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%2F3375https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3375Mon, 12 Apr 2021 08:22:11 +0100