Study

Limited response of cordgrass (Spartina foliosa) to soil amendments in a constructed marsh

  • Published source details Gibson K.D., Zedler J.B. & Langis R. (1994) Limited response of cordgrass (Spartina foliosa) to soil amendments in a constructed marsh. Ecological Applications, 4, 757-767.

Actions

This study is summarised as evidence for the following.

Action Category

Disturb soil/sediment surface before planting non-woody plants: brackish/saline wetlands

Action Link
Marsh and Swamp Conservation

Add below-ground organic matter before/after planting non-woody plants: brackish/saline wetlands

Action Link
Marsh and Swamp Conservation

Add inorganic fertilizer before/after planting non-woody plants: brackish/saline wetlands

Action Link
Marsh and Swamp Conservation

Reprofile/relandscape: brackish/salt marshes

Action Link
Marsh and Swamp Conservation

Directly plant non-woody plants: brackish/saline wetlands

Action Link
Marsh and Swamp Conservation
  1. Disturb soil/sediment surface before planting non-woody plants: brackish/saline wetlands

    A replicated, randomized, paired, controlled study in 1990–1991 in a recently excavated estuarine salt marsh in California, USA (Gibson et al. 1994) found that tilling plots before planting California cordgrass Spartina foliosa had no significant effect on cordgrass biomass, stem density or plant height after two growing seasons. At this time, there was no significant difference between treatments in above-ground cordgrass biomass (tilled: 100 g/m2; untilled: 220 g/m2), cordgrass density (tilled: 30 stems/m2; untilled: 50 stems/m2) or average cordgrass height (data not reported). The same was true for density and height after one growing season, whilst cordgrass biomass was significantly lower in tilled plots (30 g/m2) than untilled plots (60 g/m2). Methods: In February 1990, four pairs of 5-m2 plots were prepared alongside a tidal creek in a recently excavated salt marsh. In each pair, one random plot was tilled to 15 cm depth. The other plots were left undisturbed. In March 1990, each plot was planted with cordgrass plants from ten 4-L pots. California cordgrass stems were counted and measured until October 1991. Dry biomass was estimated from heights.

    (Summarised by: Nigel Taylor)

  2. Add below-ground organic matter before/after planting non-woody plants: brackish/saline wetlands

    A replicated, randomized, paired, controlled study in 1990–1991 in a recently excavated estuarine marsh in California, USA (Gibson et al. 1994) found that tilling organic matter into plots before planting California cordgrass Spartina foliosa typically had no significant effect on cordgrass biomass, stem density or plant height. This was true after both one and two growing seasons. For example, after two growing seasons, plots amended with organic matter contained a similar cordgrass biomass to unamended plots in five of six comparisons (for which amended: 100–220 g/m2; unamended: 290–500 g/m2), a similar cordgrass density to unamended plots in five of six comparisons (for which amended: 70–100 stems/m2; unamended: 30–50 stems/m2), and cordgrass of a similar height to unamended plots in six of six comparisons (data not reported). Methods: In February 1990, twenty-eight 5-m2 plots were established, in four sets of seven, alongside a tidal creek in a recently excavated salt marsh. In 16 plots (four random plots/set), organic matter was tilled into the surface (3 kg/m2 straw or alfalfa). Eight plots (two random plots/set) were tilled but did not receive organic matter. The final four plots (one random plot/set) were not even tilled. Inorganic fertilizer was also added to some plots. In March 1990, each plot was planted with cordgrass plants from ten 4-L pots. California cordgrass stems were counted and measured until October 1991. Dry biomass was estimated from heights.

    (Summarised by: Nigel Taylor)

  3. Add inorganic fertilizer before/after planting non-woody plants: brackish/saline wetlands

    A replicated, randomized, paired, controlled study in 1990–1991 in a recently excavated estuarine marsh in California, USA (Gibson et al. 1994) found that adding inorganic fertilizer to plots planted with California cordgrass Spartina foliosa had no significant effect on cordgrass biomass, stem density or plant height after two growing seasons. In four of four comparisons per metric, there was no significant difference between treatments in above-ground cordgrass biomass (fertilized: 180–420 g/m2; unfertilized: 100–500 g/m2), cordgrass density (fertilized: 40–90 stems/m2; unfertilized: 30–100 stems/m2) or average cordgrass height (data not reported). Results were similar after one growing season, with no significant difference between fertilized and unfertilized plots in at least three of four comparisons per metric (see original paper for data). Methods: In February 1990, twenty-eight 5-m2 plots were established, in four sets of seven, alongside a tidal creek in a recently excavated salt marsh. In 12 plots (three random plots/set), ammonium nitrate fertilizer was tilled into the surface (105 g/m2). Twelve plots (three random plots/set) were tilled but not fertilized. The final four plots (one random plot/set) were not even tilled. Some plots were also amended with organic matter. In March 1990, each plot was planted with cordgrass plants from ten 4-L pots. California cordgrass stems were counted and measured until October 1991. Dry biomass was estimated from heights.

    (Summarised by: Nigel Taylor)

  4. Reprofile/relandscape: brackish/salt marshes

    A replicated study in 1989–1991 in an estuary in California, USA (Gibson et al. 1994) reported that after excavating a salt marsh and planting California cordgrass Spartina foliosa, there were increases in California cordgrass density and biomass. Statistical significance was not assessed. After one growing season, there were 25 cordgrass stems/m2 and 60 g/m2 dry above-ground biomass. After two growing seasons, there were 50 cordgrass stems/m2 and 220 g/m2 dry above-ground biomass. Methods: Between 1989 and March 1990, dredge spoil that had been deposited in San Diego Bay was excavated to elevations suitable for California cordgrass. In March 1990, California cordgrass was planted into four 5-m2 plots in the marsh (ten 4-L pots of cordgrass/plot). None of these four plots received any additional treatment. California cordgrass stems were counted and measured until October 1991. Note that this study does not distinguish between the effects of excavation and planting on any non-planted cordgrass.

    (Summarised by: Nigel Taylor)

  5. Directly plant non-woody plants: brackish/saline wetlands

    A replicated study in 1989–1991 in an estuary in California, USA (Gibson et al. 1994) reported that in an excavated salt marsh planted with California cordgrass Spartina foliosa, there were increases in California cordgrass density and biomass. Statistical significance was not assessed. After one growing season, there were 25 cordgrass stems/m2 and 60 g/m2 dry above-ground biomass. After two growing seasons, there were 50 cordgrass stems/m2 and 220 g/m2 dry above-ground biomass. Methods: In March 1990, California cordgrass plants were planted into four 5-m2 plots in a salt marsh that had been excavated in 1989 (ten 4-L pots of cordgrass/plot). None of these four plots received any additional treatment. California cordgrass stems were counted and measured until October 1991. Note that this study does not distinguish between the effects of planting and excavation on any non-planted cordgrass.

    (Summarised by: Nigel Taylor)

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