Study

How waterlogged microsites help an annual plant persist among salt marsh perennials

  • Published source details Varty A.K. & Zedler J.B. (2008) How waterlogged microsites help an annual plant persist among salt marsh perennials. Estuaries and Coasts, 31, 300-312

Actions

This study is summarised as evidence for the following.

Action Category

Create mounds or hollows before planting non-woody plants: brackish/saline wetlands

Action Link
Marsh and Swamp Conservation

Remove vegetation that could compete with planted non-woody plants: brackish/saline wetlands

Action Link
Marsh and Swamp Conservation

Introduce seeds of non-woody plants: brackish/saline wetlands

Action Link
Marsh and Swamp Conservation

Directly plant non-woody plants: brackish/saline wetlands

Action Link
Marsh and Swamp Conservation
  1. Create mounds or hollows before planting non-woody plants: brackish/saline wetlands

    A replicated, randomized, paired, controlled study in 2006 in an estuarine salt marsh in California, USA (Varty & Zedler 2008) found that excavating depressions before sowing/planting dwarf saltwort Salicornia bigelovii did not increase saltwort seedling density or transplant survival, but did reduce density of the initially dominant succulent. Two months after sowing/planting, there were fewer dwarf saltwort seedlings in 10-cm depressions (3 seedlings/0.25 m2) than on level plots (10–14 seedlings/0.25 m2), with no significant difference between 5-cm depressions (9 seedlings/0.25 m2) and level plots. The same was true for survival of dwarf saltwort transplants after six months (10-cm depressions: <40%; 5-cm depressions: 70%; level plots: 70%). However, depressions had lower cover of pickleweed Salicornia virginica in 12 of 12 comparisons over the whole growing season (10-cm depressions: 41–59%; 5-cm depressions: 49–65%; level plots: 58–78%). Methods: In March 2006, dwarf saltwort was planted and sown into seventy-two 0.25-m2 plots (three sets of 24) on a pickleweed-dominated salt marsh. Four seedlings and 1.25 ml of seed were added to each plot. Thirty-six plots (12 random plots/set) had been lowered by 5 cm or 10 cm before planting, by removing subsurface sediment. The other plots remained at ground level. Some pickleweed was cut and removed from half of the plots. Vegetation was surveyed between May and September 2006.

    (Summarised by: Nigel Taylor)

  2. Remove vegetation that could compete with planted non-woody plants: brackish/saline wetlands

    A replicated, randomized, paired, controlled study in 2006 in an estuarine salt marsh in California, USA (Varty & Zedler 2008) found that thinning dominant pickleweed Salicornia virginica before sowing/planting dwarf saltwort Salicornia bigelovii did not significantly affect the density of saltwort seedlings, but did increase survival of planted saltwort. Two months after sowing/planting, the total density of saltwort seedlings did not significantly differ between thinned and unthinned plots (data not reported). However, after six months, the survival rate of planted saltwort seedlings was 2.4 times greater in thinned than unthinned plots (further data not reported). Methods: In March 2006, dwarf saltwort was planted and sown into seventy-two 0.25-m2 plots (three sets of 24) on a pickleweed-dominated salt marsh. Four seedlings and 1.25 ml of seed were added to each plot. In 36 plots (12 random plots/set), pickleweed had been thinned (stems cut and removed) to leave roughly 50% cover. The other plots were left unthinned (>75% pickleweed cover). Pickleweed cover remained lower in thinned than unthinned plots throughout the growing season. Half of the plots had also been lowered slightly (5–10 cm). Vegetation was surveyed between May and September 2006.

    (Summarised by: Nigel Taylor)

  3. Introduce seeds of non-woody plants: brackish/saline wetlands

    A replicated study in 2006 in an estuarine salt marsh in California, USA (Varty & Zedler 2008) reported that plots sown with dwarf saltwort Salicornia bigelovii seeds contained dwarf saltwort seedlings two months later. A total of 650 seedlings were counted across seventy-two 0.25-m2 plots. There were 3–14 seedlings/0.25 m2 depending on plot elevation and location in the marsh (see Action: Create mounds or hollows before planting). Thinning the dominant pickleweed Salicornia virginica had no significant effect on seedling density. The study notes that there were probably lots of dwarf saltwort seeds already in the soil, and many of the seedlings probably germinated from these seeds. Methods: In March 2006, dwarf saltwort seeds were sown onto seventy-two 0.25-m2 plots in a pickleweed-dominated salt marsh (approximately 68 seeds/plot). Four dwarf saltwort seedlings were also planted in each plot. In some of the plots, the surface was lowered by 5–10 cm and/or pickleweed stems were cut and removed before planting. Seedlings were counted in May 2006.

    (Summarised by: Nigel Taylor)

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

    A replicated study in 2006 in an estuarine salt marsh in California, USA (Varty & Zedler 2008) reported that survival of transplanted dwarf saltwort Salicornia bigelovii seedlings depended on plot elevation and thinning of the dominant competitor. After one growing season, <40% of seedlings transplanted into 10-cm depressions were still alive. In contrast, 70% of seedlings transplanted into 5-cm depressions or level plots were still alive. The survival rate of transplants was 2.4 times greater in plots where dominant pickleweed Salicornia virginica had been thinned (to 50% cover) than where it had not been thinned (>75% cover). Methods: In March 2006, four dwarf saltwort seedlings were planted in each of seventy-two 0.25-m2 plots on a pickleweed-dominated salt marsh. Dwarf saltwort was also sown onto each plot (1.25 ml seed/plot). In some of the plots, the surface was lowered by 5–10 cm and/or pickleweed stems were cut and removed before planting. Survival was monitored in September 2006. This study was in the same area as (16b) and (19), but used different plots.

    (Summarised by: Nigel Taylor)

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