Disturb soil/sediment surface: brackish/salt marshes
Overall effectiveness category Awaiting assessment
Number of studies: 1
Background information and definitions
This action involves shallow disturbance of the top few centimetres of soil/sediment in degraded marshes (e.g. by tilling, ploughing, disking or scarifying) without permanently removing any material. Such disturbance may encourage the growth of desirable plants. It can break up any hard soil crust, or create bare patches clear of competing vegetation or litter in which new plants can grow. Marsh plants may colonize from nearby habitat patches, or germinate from propagules (e.g. seeds, spores or root/rhizome fragments) already in the soil. The first colonizing plants will typically be fast-growing, weedy species – but these may also be desirable members of target plant communities, or act as nurse plants for later desirable communities.
Supporting evidence from individual studies
A replicated, paired, site comparison study in 2007–2009 of eight brackish/salt marshes in Texas, USA (Fitzsimmons et al. 2012) found that managed marshes (disked every spring, along with a spring/autumn drawdown) and unmanaged marshes (subjected to neither of these interventions) had few plant species in common, but had similar overall plant species richness and diversity. Only 24–34% of plant species were found in both managed and unmanaged marshes (reported as a similarity index). However, both marsh types had statistically similar plant species richness (six of six comparisons; managed: 12–21 species/marsh; unmanaged: 8–18 species/marsh) and plant diversity (six of six comparisons; data reported as a diversity index). Methods: In autumn, winter and spring 2007/2008 and 2008/2009, vegetation was surveyed in four pairs of managed and unmanaged marshes (fifty-six 1-m2 quadrats/marsh, placed along transects). In the managed marshes, the soil surface was disked every spring for 6–9 years. The managed marshes had also been impounded to control water levels and salinity (drawdown each spring-autumn). The study does not distinguish between the effects of three interventions. All marshes were grazed each summer and burned every three years. The marshes were brackish in 2007/2008 (managed: <2 ppt; unmanaged: <10 ppt) but saline in 2008/2009 following a hurricane and storm surge (e.g. average salinity in managed marshes: 20 ppt).Study and other actions tested