Exclude or remove livestock from historically grazed brackish/saline swamps
Overall effectiveness category Awaiting assessment
Number of studies: 1
Background information and definitions
This action involves completely excluding or completely removing livestock from marshes or swamps that have been negatively impacted by livestock grazing – whether deliberate or accidental. This may be implemented at a large scale (e.g. removing livestock from an entire farm) or at a small scale (e.g. tethering cattle to keep them off sensitive vegetation patches).
Domestic livestock can directly consume vegetation, destroy vegetation by trampling, create bare patches of ground (e.g. repeatedly used tracks), affect water infiltration and flows by compacting soils, affect nutrient balance through excretion of waste products, and import seeds of undesirable plants (Morris & Reich 2013). Removing livestock can allow grazing-sensitive species to recover. The effects might depend on site conditions such as productivity (determined by soil moisture and nutrient levels; Berney et al. 2014).
Related actions: Use barriers to keep livestock off ungrazed brackish/saline swamps; Reduce intensity of livestock grazing, without completely removing livestock; Use grazing to maintain or restore disturbance; Use grazing to control problematic plants; Exclude wild vertebrates; Modify livestock farming practices in watershed; Use fences or barriers to protect planted areas.
Berney P.J., Wilson G.G., Ryder D.S., Whalley R.D.B., Duggin J. & McCosker R. (2014) Divergent responses to long-term grazing exclusion among three plant communities in a flood pulsing wetland in eastern Australia. Pacific Conservation Biology, 20, 237–251.
Morris K. & Reich P. (2013) Understanding the Relationship Between Livestock Grazing and Wetland Condition. Arthur Rylah Institute for Environmental Research, Technical Report Series No. 252.
Supporting evidence from individual studies
A replicated, paired, controlled study in 2010–2012 in an estuary in South Africa (Hoppe-Speer & Adams 2015) reported that excluding cattle increased the height and growth rate of grey mangrove Avicennia marina. After two years, grey mangroves were 91 cm tall in plots that had been fenced to exclude cattle (vs 77 cm in plots left open to cattle; statistical significance not assessed). Over the two years, trees in exclusion plots grew more than trees in open plots in three of four metrics: plant height (exclusion: 5.4; open: −0.2 cm/year), plant diameter (exclusion: 7.1; open: 2.0 cm/year) and crown volume (exclusion: 0.5; open: 0.1 m3/year). Circumference growth did not significantly differ between treatments (exclusion: 26; open: 15 cm). In the second year, a total of 75 grey mangrove seedlings appeared in exclusion plots (vs 35 in open plots). Methods: In 2010, five pairs of 25-m2 plots were established within stunted, shrubby, estuarine mangroves. In each pair, one plot was fenced to exclude cattle whilst the other remained open to cattle (3–11 cows/ha). Grey mangrove trees were measured and seedlings were counted three times after setting up the experiment, in July 2010, 2011 and 2012.Study and other actions tested