Study

The challenge of restoring vegetation on tidal, hypersaline substrates

  • Published source details Zedler J.B., Morzaria-Luna H. & Ward K. (2003) The challenge of restoring vegetation on tidal, hypersaline substrates. Plant and Soil, 253, 259-273.

Actions

This study is summarised as evidence for the following.

Action Category

Introduce nurse plants to aid focal 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

Directly plant non-woody plants: brackish/saline wetlands

Action Link
Marsh and Swamp Conservation
  1. Introduce nurse plants to aid focal non-woody plants: brackish/saline wetlands

    A replicated, controlled study in 2001 in an estuary in California, USA (Zedler 2003) reported that planting nurse plants before sowing seeds of arrowgrass Triglochin concinna had no effect on its germination. In the growing season after sowing, no arrowgrass seedlings were found – whether seeds were sown under nurse plants or onto bare sediment. The study suggests that high temperatures, high salinities and thick mats of microorganisms may have limited germination across the site. Methods: In March 2001, sets of 25 arrowgrass seeds were sown onto an area of recently reprofiled intertidal sediment. Of these, 288 sets were sown under planted adult nurse plants (alkali heath Frankenia salina, salt marsh daisy Jaumea carnosa or California sea lavender Limonium californicum; single plants or single-species clusters). A further 144 sets were sown onto bare sediment. All seeds sets were covered with burlap fabric after sowing. Any nurse plants that died were replaced. Seedlings were counted over the 2001 growing season.

    (Summarised by: Nigel Taylor)

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

    A replicated study in 2001 in an estuary in California, USA (Zedler 2003) reported that after sowing 21,600 seeds of two salt marsh species, only 17 seedlings grew. These 17 seedlings were all dwarf saltwort Salicornia bigelovii. No seedlings of arrowgrass Triglochin concinna were found. Methods: In March 2001, a total of 10,800 seeds/species were sown onto an area of recently reprofiled intertidal sediment. Sets of 50 seeds (25 seeds/species) were sown under single adult herbs/succulents (144 sets), under clusters of adult herbs/succulents (144 sets) or onto bare sediment (144 sets). All seed sets were covered with burlap fabric after sowing. Seedlings were counted over the 2001 growing season.

    (Summarised by: Nigel Taylor)

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

    A replicated study in 1997–1998 in an estuary in California, USA (Zedler 2003) reported ≥81% survival of eight planted salt marsh species through their first growing season, and ≥58% survival through their first winter. Over the first growing season, the survival rate ranged from 81% for saltwort Batis maritima to 99% for alkali heath Frankenia salina (overall: 93%). Over the first winter, the survival rate ranged from 58% for arrowgrass Triglochin concinna to >99% for pickleweed Salicornia virginica (overall: 82%). The study suggests that winter mortality was related to smothering by algae and sediment, and feeding/trampling by waterbirds. Colonization by non-planted seedlings was also reported (see Study 13). Methods: In April 1997, greenhouse-reared herbs/succulents were planted into seventy-two 4-m2 plots, on an area of recently reprofiled intertidal sediment (90 seedlings/plot; 1–6 species/plot; eight species total). Plots were amended with fine sediment, tilled and levelled before planting. Seedlings were watered regularly after planting. Dead planted seedlings were replaced. Non-planted seedlings were removed. Survival was assessed in July 1997 and March 1998. This study was based on the same experimental set-up as (12), (13) and (15).

    (Summarised by: Nigel Taylor)

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

    A replicated study in 2000–2002 in an estuary in California, USA (Zedler 2003) reported <1–80% survival of six planted salt marsh species. Of 1,332 seedlings planted in April 2000, only 9% survived their first growing season (from <1% of salt marsh daisy Jaumea carnosa to 16% of alkali heath Frankenia salina). For 180 seedlings planted in December 2000, the survival rate over one year was 48% (from 30% for estuary seablite Suaeda esteroa to 80% for saltwort Batis maritima). For 504 seedlings planted in March 2001, the survival rate was 70% over the first growing season (68–90% per species) then 62% over the first winter (45–82% per species). The study identified high salinities, waterlogging, limited tidal flushing and sediment deposition as possible causes of mortality. Methods: Between April 2000 and March 2001, greenhouse-reared herbs/succulents were planted into an area of recently reprofiled intertidal sediment (36–48 plots/trial; 1–6 species/plot; 1–42 seedlings/plot, ≥5 cm apart). In two of three trials, dead planted seedlings were replaced. Survival was assessed in July 2000, December 2001, July 2001 and January 2002. One trial in this study used a subset of the plots in (20).

    (Summarised by: Nigel Taylor)

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