Is<i>Empodisma minus</i>the ecosystem engineer of the FBT (fen–bog transition zone) in New Zealand?

Hodges, TA; Rapson, Gillian L.

doi:10.1080/03036758.2010.503564

Cited by 16 publications

(13 citation statements)

References 180 publications

(130 reference statements)

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“…Northern New Zealand raised bogs have developed under warm annual temperatures and summer water deficits, climatic conditions that would generally be considered unfavorable for bog formation and persistence [McGlone, 2009]. However, even in periods of summer water deficit, water tables in these bogs are generally higher than in Northern Hemisphere bogs during summer [Hodges and Rapson, 2010]. These peatlands display similar morphology to Northern Hemisphere ombrotrophic raised bogs [Agnew et al, 1993;Hodges and Rapson, 2010], but water table range and mean depth more closely resemble those of fens [Turetsky et al, 2014] and blanket bogs [e.g., Sottocornola and Kiely, 2010].…”

Section: Introductionmentioning

confidence: 99%

Overriding control of methane flux temporal variability by water table dynamics in a Southern Hemisphere, raised bog

Goodrich

Campbell

Roulet

et al. 2015

J. Geophys. Res. Biogeosci.

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There are still large uncertainties in peatland methane flux dynamics and insufficient understanding of how biogeochemical processes scale to ecosystems. New Zealand bogs differ from Northern Hemisphere ombrotrophic systems in climatic setting, hydrology, and dominant vegetation, offering an opportunity to evaluate our knowledge of peatland methane biogeochemistry gained primarily from northern bogs and fens. We report eddy covariance methane fluxes from a raised bog in New Zealand over 2.5 years. Annual total methane flux in 2012 was 29.1 g CH 4 m À2 yr À1 , whereas during a year with a severe drought (2013) A correlation between daytime CO 2 uptake and methane fluxes emerged during times with shallow water tables, suggesting that controls on methane production were critical in determining fluxes, more so than oxidation. Water table recession through this shallow zone led to increasing methane fluxes, whereas changes in temperature during these periods were not correlated. Models of methane fluxes should consider drought-induced lags in seasonal flux recovery that depend on drought characteristics and location of the critical zone for methane production.

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Section: Introductionmentioning

confidence: 99%

Overriding control of methane flux temporal variability by water table dynamics in a Southern Hemisphere, raised bog

Goodrich

Campbell

Roulet

et al. 2015

J. Geophys. Res. Biogeosci.

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“…First, as a result of the changes mentioned above, an increasingly hummocky habitat develops. Hummock-forming species are considered ecosystem engineers in mires (Jones and others 1994;van Breemen 1995;Granath and others 2010;Hodges and Rapson 2010). With an increasing height and cover of hummocks, a mire becomes increasingly prone to peat mineralization, due to prolonged oxic conditions within hummocks.…”

Section: Discussionmentioning

confidence: 99%

Alleviation of Plant Stress Precedes Termination of Rich Fen Stages in Peat Profiles of Lowland Mires

et al. 2019

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Mesotrophic rich fens, that is, groundwater-fed mires, may be long-lasting, as well as transient ecosystems, displaced in time by poor fens, bogs, forests or eutrophic reeds. We hypothesized that fen stability is controlled by plant stress caused by waterlogging with calcium-rich and nutrient-poor groundwater, which limits expansion of hummock mosses, tussock sedges and trees. We analysed 32 European Holocene macrofossil profiles of rich fens using plant functional traits (PFTs) which indicate the level of plant stress in the environment: canopy height, clonal spread, diaspore mass, specific leaf area, leaf dry matter content, Ellenberg moisture value, hummock-forming ability, mycorrhizal status and plant functional groups. Six PFTs, which formed long-term significant trends during mire development, were compiled as rich fen stress indicator (RFSI). We found that RFSI values at the start of fen development were correlated with the thickness of subsequently accumulated rich fen peat. RFSI declined in fens approaching change into another mire type, regardless whether it was shifting into bog, forest or eutrophic reeds. RFSI remained comparatively high and stable in three rich fens, which have not terminated naturally until present times. By applying PFT analysis to macrofossil data, we demonstrated that fens may undergo a gradual autogenic process, which lowers the ecosystem's resistance and enhances shifts to other mire types. Long-lasting rich fens, documented by deep peat deposits, are rare. Because autogenic processes tend to alleviate stress in fens, high levels of stress are needed at initial stages of rich fen development to enable its long persistence and continuous peat accumulation.

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“…However, widespread drainage and development into pasture in the early to mid-1900s has confined the Sporadanthus – Empodisma robustum association to three sites in the Waikato: Torehape, Kopuatai, and Moanatuatua ( de Lange et al 1999 , Clarkson 2002 ). Elsewhere in the northern North Island, Empodisma robustum occurs in fens and young restiad bogs ( Johnson and Brooke 1989 , Johnson and Gerbeaux 2004 , Hodges and Rapson 2011 ), and gumland heaths ( Clarkson et al 2011 ). Apart from Sporadanthus ferrugineus , the species associated in these younger/shallower peat systems are similar to those listed above.…”

Section: Discussionmentioning

confidence: 99%

Systematics and ecology of the Australasian genus Empodisma (Restionaceae) and description of a new species from peatlands in northern New Zealand

Wagstaff¹,

Clarkson²

2012

PHYTOKEYS

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The genus Empodisma comprises two species that are ecologically important in wetland habitats. Empodisma gracillimum is restricted to south-western Australia, whereas Empodisma minus is found in Tasmania, eastern Australia and New Zealand. We sequenced three cpDNA genes for 15 individuals of Empodisma sampled from throughout the range of the species. The results support an Australian origin for Empodisma sometime during the late Oligocene to early Miocene with more recent dispersal, colonization and diversification in New Zealand. We recovered six genetically distinct maternal lineages: three Empodisma gracillimum haplotypes corresponding to the three accessions in our analysis, a wide-ranging Empodisma minus haplotype found in eastern Australia and Tasmania, an Empodisma minus haplotype found in New Zealand from Stewart Island to approximately 38° S latitude on the North Island, and a distinct haplotype restricted to the North Island of New Zealand north of 38° S latitude. The Eastern Australian and New Zealand haplotypes of Empodisma minus were supported by only one cpDNA gene, and we felt the relatively minor morphological differences and the small amount of genetic divergence did not warrant taxonomic recognition. However, we recommend that the northern New Zealand haplotype should be recognized as the new species Empodisma robustum and provide descriptions and a key to the species of Empodisma. Monophyly of Empodisma robustum is supported by all three cpDNA genes. Empodisma robustum can be distinguished from Empodisma gracillimum and Empodisma minus by its robust growth stature and distinct ecology. It is typically eliminated by fire and re-establishes by seed (seeder strategy), whereas Empodisma minus and Empodisma gracillimum regrow after fire (sprouter strategy).

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IsEmpodisma minusthe ecosystem engineer of the FBT (fen–bog transition zone) in New Zealand?

Cited by 16 publications

References 180 publications

Overriding control of methane flux temporal variability by water table dynamics in a Southern Hemisphere, raised bog

Overriding control of methane flux temporal variability by water table dynamics in a Southern Hemisphere, raised bog

Alleviation of Plant Stress Precedes Termination of Rich Fen Stages in Peat Profiles of Lowland Mires

Systematics and ecology of the Australasian genus Empodisma (Restionaceae) and description of a new species from peatlands in northern New Zealand

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