Disturb soil/sediment surface before planting trees/shrubs: brackish/saline wetlands
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
This action involves shallow disturbance of the top few centimetres of soil/sediment (and any vegetation on it), without permanently removing any soil/sediment. Mechanical disturbance could be carried out by tilling, ploughing, disking or scarifying. It may improve survival or growth of planted vegetation. It can clear potentially competing vegetation, and loosen up the soil to allow roots to penetrate more easily.
Supporting evidence from individual studies
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.Study and other actions tested