Root dynamics of Carex stricta-dominated tussock meadows

Lawrence, Beth A.; Fahey, Timothy J.; Zedler, Joy B.

doi:10.1007/s11104-012-1360-y

Cited by 21 publications

(12 citation statements)

References 62 publications

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“…Our manipulations were meant to create variation in soil moisture like that created by natural tussocks. In two remnant tussock sedge meadows, Lawrence et al () recorded mean soil moistures of 0.30 and 0.32 m 3 /m 3 at tussock tops and 0.73 and 0.61 m 3 /m 3 between tussocks; across both of our experiments, we recorded mean soil moistures of 0.50 m 3 /m 3 at soil mound tops and 0.67 m 3 /m 3 between soil mounds (excluding data from FlatGround and Holes treatments). The drier tussock tops of Lawrence et al () were higher on average (approximately 20 cm) and composed of accumulated plant tissue rather than soil; accordingly, our driest mounds were tall (LargeMound) or had incorporated organic matter (WoodChip).…”

Section: Discussionsupporting

confidence: 63%

“…In experiments, plugs withstood drought, flooding, and alternation between the two (Kercher & Zedler ) or flooding at a depth of 18 cm for up to 22 weeks (Lawrence & Zedler ). Natural C. stricta tussocks increase variation in soil moisture and temperature as compared with flat ground (Lawrence et al ). Given its tolerance of a wide range of conditions and its potential to add variation by forming tussocks, we consider C. stricta ideal for planting in substrates that are expected to vary in moisture level.…”

Section: Introductionmentioning

confidence: 99%

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Increasing substrate heterogeneity as a bet‐hedging strategy for restoring wetland vegetation

Doherty

Zedler

2014

Restoration Ecology

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Mimicking the natural heterogeneity of wetland substrates, e.g. by roughening surface soil or constructing hummocks, has been shown to facilitate wetland plant establishment. We asked if incorporating substrate heterogeneity could also help plants withstand variation in moisture levels. In a wetland with Carex stricta (tussock sedge) as the main restoration target, we manipulated substrates to create different soil moisture environments for planted C. stricta plugs. Our artificial mounds mimicked tussocks formed by C. stricta in natural meadows (circa 10-40 cm in height); we also varied mound compositions and created shallow depressions. Monitoring demonstrated variation in soil moisture among our treatments and natural differences in soil moisture between experimental blocks. Additionally, rainfall varied from severe drought in year 1 to extreme rainfall in year 2. Plug survival, flowering, cover, biomass, leaf length, and growth rate all varied with treatment, block, and/or year. Interactions among those factors were common. Planting plugs in shallow depressions exacerbated stress in a wet block during a wet year, causing low survival. Planting plugs in moisture-retaining peat pots allowed them to survive and sustain growth even in a dry block during a dry year. We conclude that heterogeneous substrates can be used to hedge against environmental variability by widening the range of microsites available within a restoration site and thereby moderating stressful conditions in some areas.

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Section: Discussionsupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Increasing substrate heterogeneity as a bet‐hedging strategy for restoring wetland vegetation

Doherty

Zedler

2014

Restoration Ecology

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“…Since variability in k v is likely driven by differences in gas‐permeable root surface areas, the large within‐zone variability in field k v values reveals heterogeneities in root surface area over spatial scales of tens of cm that are not discernible from the surface. High spatial variability in wetland root densities has been observed elsewhere [ Lawrence et al ., ]. Injecting a larger tracer plume would integrate over a larger volume and could potentially reduce the within‐zone variability determined through our relatively low volume tracer injections.…”

Section: Discussionmentioning

confidence: 99%

Dissolved gas dynamics in wetland soils: Root-mediated gas transfer kinetics determined via push-pull tracer tests

2015

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Gas transfer processes are fundamental to the biogeochemical and water quality functions of wetlands, yet there is limited knowledge of the rates and pathways of soil‐atmosphere exchange for gases other than oxygen and methane (CH4). In this study, we use a novel push‐pull technique with sulfur hexafluoride (SF6) and helium (He) as dissolved gas tracers to quantify the kinetics of root‐mediated gas transfer, which is a critical efflux pathway for gases from wetland soils. This tracer approach disentangles the effects of physical transport from simultaneous reaction in saturated, vegetated wetland soils. We measured significant seasonal variation in first‐order gas exchange rate constants, with smaller spatial variations between different soil depths and vegetation zones in a New Jersey tidal marsh. Gas transfer rates for most biogeochemical trace gases are expected to be bracketed by the rate constants for SF6 and He, which ranged from ∼10−2 to 2 × 10−1 h−1 at our site. A modified Damköhler number analysis is used to evaluate the balance between biochemical reaction and root‐driven gas exchange in governing the fate of environmental trace gases in rooted, anaerobic soils. This approach confirmed the importance of plant gas transport for CH4, and showed that root‐driven transport may affect nitrous oxide (N2O) balances in settings where N2O reduction rates are slow.

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“…In June 2012, pots were placed randomly within an environmental growth chamber under a fluctuating light and temperature regime approximating June conditions in the GL region: 16-hr light at 22.5°C and eighthour dark at 12.5°C (Lawrence, Fahey, & Zedler, 2013). We randomly assigned pots to three different water-level treatments (relative to soil surface): high (+5 cm), moist (0 cm), or low (−5 cm).…”

Section: Seed Bank Experimentsmentioning

confidence: 99%

“…Four replicates of each zone × water-level treatment were tested (2 sites × 2 zones × 3 water levels × 4 replicates = 48 total). In June 2012, pots were placed randomly within an environmental growth chamber under a fluctuating light and temperature regime approximating June conditions in the GL region: 16-hr light at 22.5°C and eighthour dark at 12.5°C (Lawrence, Fahey, & Zedler, 2013). Throughout the 6-month study period, we maintained water levels twice per week.…”

Section: Seed Bank Experimentsmentioning

confidence: 99%

Invasive species removal increases species and phylogenetic diversity of wetland plant communities

Lishawa

Lawrence

Albert

et al. 2019

Ecology and Evolution

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Plant invasions result in biodiversity losses and altered ecological functions, though quantifying loss of multiple ecosystem functions presents a research challenge. Plant phylogenetic diversity correlates with a range of ecosystem functions and can be used as a proxy for ecosystem multifunctionality. Laurentian Great Lakes coastal wetlands are ideal systems for testing invasive species management effects because they support diverse biological communities, provide numerous ecosystem services, and are increasingly dominated by invasive macrophytes. Invasive cattails are among the most widespread and abundant of these taxa. We conducted a three‐year study in two Great Lakes wetlands, testing the effects of a gradient of cattail removal intensities (mowing, harvest, complete biomass removal) within two vegetation zones (emergent marsh and wet meadow) on plant taxonomic and phylogenetic diversity. To evaluate native plant recovery potential, we paired this with a seed bank emergence study that quantified diversity metrics in each zone under experimentally manipulated hydroperiods. Pretreatment, we found that wetland zones had distinct plant community composition. Wet meadow seed banks had greater taxonomic and phylogenetic diversity than emergent marsh seed banks, and high‐water treatments tended to inhibit diversity by reducing germination. Aboveground harvesting of cattails and their litter increased phylogenetic diversity and species richness in both zones, more than doubling richness compared to unmanipulated controls. In the wet meadow, harvesting shifted the community toward an early successional state, favoring seed bank germination from early seral species, whereas emergent marsh complete removal treatments shifted the community toward an aquatic condition, favoring floating‐leaved plants. Removing cattails and their litter increased taxonomic and phylogenetic diversity across water levels, a key environmental gradient, thereby potentially increasing the multifunctionality of these ecosystems. Killing invasive wetland macrophytes but leaving their biomass in situ does not address their underlying mechanism of dominance and is less effective than more intensive treatments that also remove their litter.

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Root dynamics of Carex stricta-dominated tussock meadows

Cited by 21 publications

References 62 publications

Increasing substrate heterogeneity as a bet‐hedging strategy for restoring wetland vegetation

Increasing substrate heterogeneity as a bet‐hedging strategy for restoring wetland vegetation

Dissolved gas dynamics in wetland soils: Root-mediated gas transfer kinetics determined via push-pull tracer tests

Invasive species removal increases species and phylogenetic diversity of wetland plant communities

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