Conservation Evidence: Evidence Data

Collected 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%2Fconservationevidencejournal.com%2Factions%2F3132https%3A%2F%2Fconservationevidencejournal.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%2Fconservationevidencejournal.com%2Factions%2F3133https%3A%2F%2Fconservationevidencejournal.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%2Fconservationevidencejournal.com%2Factions%2F3134https%3A%2F%2Fconservationevidencejournal.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%2Fconservationevidencejournal.com%2Factions%2F3135https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3135Mon, 05 Apr 2021 12:16:39 +0100Collected Evidence: Collected Evidence: Control populations of wild vertebrates: freshwater marshes Two studies evaluated the effects, on vegetation, of controlling populations of wild vertebrates in freshwater marshes. Both studies were in the USA. In one study, the problematic animals were mammals and in the other study they were birds. VEGETATION COMMUNITY VEGETATION ABUNDANCE Overall abundance (1 study): One before-and-after study of marshy vegetation in the USA reported that over two years of trapping and shooting feral swine Sus scrofa, overall vegetation cover increased. Characteristic plant abundance (1 study): One before-and-after study in the USA reported that over two years of trapping and shooting feral swine Sus scrofa, cover of two plant species characteristic of target seepage slope vegetation increased. Herb abundance (1 study): One before-and-after study of marshy vegetation in the USA reported that over two years of trapping and shooting feral swine Sus scrofa, total forb cover increased. Individual species abundance (2 studies): One paired, controlled, before-and-after study in freshwater marshes in the USA reported that killing and scaring Canada geese Branta canadensis reduced their impacts on the density of wild rice Zizania aquatica: its density became similar in plots open to geese and plots fenced to exclude geese. One before-and-after study of marshy vegetation in the USA reported mixed responses of individual plant species to two years of trapping and shooting feral swine Sus scrofa. VEGETATION STRUCTURE Height (1 study): One paired, controlled, before-and-after study in freshwater marshes in the USA reported that killing and scaring Canada geese Branta canadensis reduced their impacts on the height of wild rice Zizania aquatica: its height became similar in plots open to geese and plots fenced to exclude geese. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3136https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3136Mon, 05 Apr 2021 14:09:16 +0100Collected Evidence: Collected Evidence: Control populations of wild vertebrates: brackish/salt marshesWe found no studies that evaluated the effects, on vegetation, of controlling populations of wild vertebrates in brackish/salt marshes. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3137https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3137Mon, 05 Apr 2021 14:10:04 +0100Collected Evidence: Collected Evidence: Control populations of wild vertebrates: freshwater swampsWe found no studies that evaluated the effects, on vegetation, of controlling populations of wild vertebrates in freshwater swamps. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3138https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3138Mon, 05 Apr 2021 14:10:15 +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%2Fconservationevidencejournal.com%2Factions%2F3140https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3140Mon, 05 Apr 2021 14:24:23 +0100Collected Evidence: Collected Evidence: Control populations of wild invertebratesWe found no studies that evaluated the effects, on vegetation, of controlling populations of wild invertebrates in marshes or swamps. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3141https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3141Mon, 05 Apr 2021 14:25:23 +0100