The role of spatio‐temporal heterogeneity in the establishment and maintenance of Suaeda maritima in salt marshes

Tessier, Marc; Gloaguen, J. C.; Bouchard, Virginie

doi:10.1658/1100-9233(2002)013[0115:trosth]2.0.co;2

Cited by 17 publications

(19 citation statements)

References 28 publications

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“…Disturbances such as high tides, strong wave, strong wind, flooding, winter ice (high-latitude salt marsh), and human activities are ubiquitous in salt marshes (Ewanchuk and Bertness 2003;Tessier et al 2002). One consequence of disturbance is litter removal.…”

Section: Introductionmentioning

confidence: 99%

Intraspecific interactions shift from competitive to facilitative across a low to high disturbance gradient in a salt marsh

Zhang

Wang

2016

Plant Ecol

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Disturbances are ubiquitous among salt marshes, and disturbances such as litter removal may form stressful environmental conditions. The stressgradient hypothesis (SGH) predicts that the relative importance of facilitation and competition between species will vary inversely to each other across abiotic stress gradients. However, how intraspecific interactions vary across disturbance levels, and whether they follow the SGH has not been investigated. To test the SGH with intraspecific interactions within Suaeda salsa individuals, we assessed individual survival in established fully mapped salt marsh plots with two treatments, disturbed, litter removal and control, undisturbed plots. Recently developed spatial statistics were applied to distinguish between random processes, intraspecific facilitation, scramble competition, and contest competition underlying the spatial patterns at different spatial scales, growth stages, and disturbance levels. We found evidence that intraspecific interactions among S. salsa individuals across disturbance levels tended to support the SGH, but this support depended on time and space. Intraspecific interactions were more likely to show positive density dependence in disturbed plots, particularly at the seedling period and when individuals were separated by\9 cm. However, positive density dependence was not detected in undisturbed plots. The protective effects of litter on seedlings, which were lost in undisturbed sites, may have been at least partly simulated at high seedling densities. Mortality in disturbed sites was not random, and facilitation had a more important influence than competition on population dynamics in high disturbance sites. However, the influence of competition on population dynamics, specifically scramble competition was also clearly important.

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Section: Introductionmentioning

confidence: 99%

Intraspecific interactions shift from competitive to facilitative across a low to high disturbance gradient in a salt marsh

Zhang

Wang

2016

Plant Ecol

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“…Areas with greater topographical heterogeneity have greater surface space and environmental variability, which are predicted to increase niche space and species diversity and to impact community structure and ecosystem functioning (Larkin et al 2006). Small-scale heterogeneity can promote species coexistence by creating more varied sites for seedling establishment, refuges for subordinate species, and greater habitat surface area (Minchinton 2001, Tessier et al 2002, Werner and Zedler 2002, Peach and Zedler 2006, Varty and Zedler 2008. Microtopographic heterogeneity can influence many ecosystem functions, including net primary productivity (NPP) and carbon (C) and nitrogen (N) stocks in tundra systems (Campioli et al 2009), C balance in boreal bogs (Benscoter and Vitt 2008), and overland water flow in tropical rain forests (Godsey et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Formation of tussocks by sedges: effects of hydroperiod and nutrients

Lawrence¹,

Zedler²

2011

Ecological Applications

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Abstract. Tussock formation is a global phenomenon that enhances microtopography and increases biodiversity by adding structure to ecological communities, but little is known about tussock development in relation to environmental factors. To further efforts to restore wetland microtopography and associated functions, we investigated Carex stricta tussock size in relation to elevation (a proxy for water depth) at a range of sites in southern Wisconsin, USA, and tested the effect of five hydroperiods and N þ P addition (15 g N/m 2 þ 0.37 g P/m 2 ) on tussock formation during a three-year mesocosm experiment. Wet meadows dominated by C. stricta averaged 4.9 tussocks/m 2 , with a mean volume of 1160 cm 3 and height of 15 cm. Within sites, taller tussocks occurred at lower elevations, suggesting a structural adaptation to anoxic conditions. In our mesocosm experiment, C. stricta accelerated tussock formation when inundated, and it increased overall productivity with N þ P addition. Within two growing seasons, continuous inundation (þ18 cm) in the mesocosms led to tussocks that were nearly as tall as in our field survey (mean height in mesocosms, 10 6 1.3 cm; maximum, 17 cm). Plants grown with constant low water (À18 cm) only formed short mounds (mean height ¼ 2 6 0.4 cm). After three growing seasons, the volume of the largest tussocks (3274 6 376 cm 3 , grown with þ18 cm water depth and N þ P addition) was 12 times that of the smallest (275 6 38 cm 3 , grown with À18 cm water depth and no N þ P). Though tussock composition varied among hydroperiods, tussocks were predominantly organic (74-94% of dry mass) and composed of leaf bases (46-59%), fine roots (10-31%), and duff (5-13%). Only the plants subjected to high water levels produced the vertically oriented rhizomes and ascending shoot bases that were prevalent in field-collected tussocks. Under continuous or periodic inundation, tussocks achieved similar heights and accumulated similar levels of organic matter (range: 163-394 g C/m 2 ), and we conclude that these hydroperiods can accelerate tussock formation. Thus, C. stricta has high utility for restoring wetland microtopography and associated functions, including carbon accumulation.

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“…One means of persistence relies on disturbance (Grime 1977), and in salt marshes, canopy gaps develop where wrack smothers perennials (Neuenschwander et al 1979;Hartman 1988). Later, however, gap-colonizing salt marsh annuals are typically replaced by perennials (Valiela et al 1985;Bertness and Ellison 1987;Brewer et al 1997;Tessier et al 2002), such that their persistence depends on continual disturbance, like a fugitive species (sensu Hutchinson 1951). Another strategy of salt marsh annuals is to persist in habitats that are stressful for the dominant perennials, e.g., soils with high sulfide (Ingold and Havill 1984) or salt content (Thibodeau et al 1998).…”

Section: Introductionmentioning

confidence: 99%

How Waterlogged Microsites Help an Annual Plant Persist Among Salt Marsh Perennials

Varty

Zedler

2008

Estuaries and Coasts: J CERF

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Annual plants that coexist among perennial dominants might persist in microsites that are stressful to their competitors. In Californian salt marshes, where cover of annual and perennial Salicornia species are negatively correlated, we hypothesized that waterlogged depressions support the annual (Salicornia bigelovii) but not the region's dominant perennial (Salicornia virginica). In a large restoration site, S. virginica cover was low in naturally formed pools, and our 10-cm depressions decreased its cover by approximately 30% compared to the controls. S. bigelovii grew taller and produced more flowers in waterlogged sites with low soil redox potential, and it completed its life cycle in the 5-cm-deep depressions that we created. Experimentally reducing S. virginica canopy cover in shallow depressions also increased the survival of the annual. In the greenhouse, rhizosphere oxidation was indicated as a mechanism for tolerating waterlogging, as S. bigelovii elevated the soil redox potential by 50 mV more than S. virginica did. Also, in the greenhouse, S. bigelovii seedlings actually suppressed the growth of S. virginica seedlings under increased flooding. We conclude that waterlogged microsites help sustain S. bigelovii in Californian salt marshes and that this increasingly rare plant could be managed by adding shallow depressions to restoration sites.

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The role of spatio‐temporal heterogeneity in the establishment and maintenance of Suaeda maritima in salt marshes

Cited by 17 publications

References 28 publications

Intraspecific interactions shift from competitive to facilitative across a low to high disturbance gradient in a salt marsh

Intraspecific interactions shift from competitive to facilitative across a low to high disturbance gradient in a salt marsh

Formation of tussocks by sedges: effects of hydroperiod and nutrients

How Waterlogged Microsites Help an Annual Plant Persist Among Salt Marsh Perennials

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