The ecological and biodiversity conservation values of farm dams: A systematic review

3.3 Which taxonomic groups are studied and which biodiversity metrics are used to quantify these groups at farm dams? Of the three target groups that we investigated (fauna, vegetation, and water quality), fauna was the most examined (n = 64) followed by vegetation (n = 32), and water quality (n = 22). Most articles focused on only one of the three categories, while eight described both vegetation and fauna, five described water quality and fauna, two described both vegetation and water quality, and another two described all three of the categories. Macroinvertebrates were the most commonly (n = 28) studied taxonomic group, followed by macrophytes (n = 26) and amphibians (n = 18). Many of the studies used different metrics as proxies to measure biodi- versity, with the most common measure being species richness (n = 35) followed by species abundance (n = 18). Species richness was most commonly measured as a response to the phys- ical characteristics of dams (n = 72) and the physical characteristics of the landscape surround- ing the dams (n = 43). Of the studies measuring species richness, 18 focused on macroinvertebrates and 13 focused on macrophytes (Fig 4). 3.4 What are the ecological variables used to predict the biodiversity values of farm dams (e.g., vegetation cover, and water quality)? In many of the selected studies, authors considered physical characteristics of dams, such as surface area and vegetation cover, as response variables. Out of those investigations, 48 looked at dam size while 30 explored dam depth, and 26 examined vegetation cover. Further, 24 of the

aforementioned studies focused on macroinvertebrates, 18 on macrophytes, and 16 on amphibians (Fig 5). Vegetation, of great importance in regard to habitat provision and sediment filtration, con- tributed to the biodiversity value in 14 studies, with the presence and cover of vegetation at Fig 4. Heatmap showing the taxon studied in each article and the response variable used. The darker colours represent a higher number of articles. Each paper may be represented in more than one category. Category definitions can be found in S1 Appendix. https://doi.org/10.1371/journal.pone.0303504.g004 PLOS ONE The ecological and biodiversity conservation values of farm dams PLOS ONE | https://doi.org/10.1371/journal.pone.0303504 May 13, 2024 9 / 18