Study

An experimental assessment of slag as a substrate for mangrove rehabilitation

  • Published source details Day S., Streever W.J. & Watts J.J. (1999) An experimental assessment of slag as a substrate for mangrove rehabilitation. Restoration Ecology, 7, 139-144.

Actions

This study is summarised as evidence for the following.

Action Category

Disturb soil/sediment surface before planting trees/shrubs: brackish/saline wetlands

Action Link
Marsh and Swamp Conservation

Introduce tree/shrub seeds or propagules: brackish/saline wetlands

Action Link
Marsh and Swamp Conservation
  1. Disturb soil/sediment surface before planting trees/shrubs: brackish/saline wetlands

    A replicated, controlled study in 1995–1997 on an estuarine mudflat in New South Wales, Australia (Day et al. 1999) found that ploughing substrate before planting grey mangrove Avicennia marina propagules had no significant effect on their survival or seedling height after two growing seasons. At this time, ploughed and unploughed plots, initially planted with 16 propagules, contained a statistically similar number of seedlings (ploughed: 5.9; not ploughed: 6.7 seedlings/plot) and contained seedlings of statistically similar average height (ploughed: 45 cm; not ploughed: 49 cm). Initial survival rates (after two weeks) were also statistically similar in both treatments (ploughed: 4.7; not ploughed: 5.9 seedlings/plot). Methods: In December 1995, some 1-m2 plots (number not reported) were established in three areas on a tidal mudflat in the Hunter River estuary. The plots were excavated to 20 cm depth then refilled with the local natural substrate (sand/silt/clay). Some of the plots were then ploughed (10–15 cm depth) whilst the others were not ploughed. Sixteen locally collected grey mangrove propagules were planted into each plot. Seedlings were counted in each area after approximately two weeks, then counted and measured in two of the three areas (where some propagules survived) after 15 months.

    (Summarised by: Nigel Taylor)

  2. Introduce tree/shrub seeds or propagules: brackish/saline wetlands

    A replicated study in 1995–1997 on a tidal mudflat in New South Wales, Australia (Day et al. 1999) reported 0–53% survival of planted grey mangrove Avicennia marina propagules after two growing seasons, but that survivors grew. In one of three planted areas, there were no mangrove seedlings present after two weeks. In the other two areas, there were 3.5–8.4 mangrove seedlings/plot present after two growing seasons (vs 16 planted propagules/plot). Seedlings were 30–49 cm tall, on average. There were more surviving seedlings in sand or natural substrate (6.7–8.4 seedlings/plot) than in slag (3.5 seedlings/plot), but the average height of seedlings was lower in sand (30 cm) than in all other substrates (45–49 cm). Methods: In December 1995, sixty 1-m2 plots were established (in three sets of 20) on a tidal mudflat in the Hunter River estuary. The plots were excavated to 20 cm depth and refilled with sand, the local natural substrate (sand/silt/clay; ploughed or unploughed) or slag (a waste product from iron production). Sixteen locally collected grey mangrove propagules were planted into each plot. Seedlings were counted in each set after approximately two weeks, then counted and measured in two of the sets after 15 months.

    (Summarised by: Nigel Taylor)

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