Effects of Simulated Grazing in Ungrazed Wet Sedge Tundra in the High Arctic

Elliott, Tammy L.; Henry, Gregory H.R.

doi:10.1657/1938-4246-43.2.198

Cited by 12 publications

(13 citation statements)

References 106 publications

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“…However, in many studies conducted in the Arctic have reported the same trends as found in this study, with a decrease in NEE with grazing (Cahoon et al 2012;Elliott and Henry 2011;Sjögersten et al 2008Sjögersten et al , 2011Van der Wal et al 2007). Over the 3 years we found a 35 % reduction in mean seasonal NEE in clipped plots compared to control plots (Fig.…”

Section: Grazing Effects On Co 2 Fluxessupporting

confidence: 88%

“…6). It might be speculated that the short arctic summer may also be too short for plants to fully recover from the loss of above ground tissue (Elliott and Henry 2011), which makes these ecosystems more sensitive towards grazing than others. The vegetation survey in our study was, however, performed already 1 year after the start of simulated grazing experiment and it is not unlikely that the vegetation composition has continued to change in clipped plots.…”

Section: Grazing Effects On Plant Communitymentioning

confidence: 99%

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Effects of simulated increased grazing on carbon allocation patterns in a high arctic mire

2014

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Herbivory is an important part of most ecosystems, and grazing alone can have a considerable impact on the ecosystems carbon balance with both direct and indirect effects. Removal of above-ground biomass by consumption of herbivores will change the below-ground carbon stock; the reduction of litter that goes into the ground will influence the total ecosystem carbon content. Little is however known about how plant-herbivory interactions effect the carbon balance, in particular methane emissions, of high arctic mires. We hypothesized that increased grazing pressure will change carbon allocation patterns resulting in decreased net ecosystem uptake of carbon and subsequently in lower methane emissions. An in-situ field experiment was conducted over 3 years in a high arctic mire at Zackenberg in NE Greenland. The experiment consisted of three treatments, with five replicates of each (1) control, (2) vascular plants were removed (NV), (3) clipped twice each growing season in order to simulate increased muskox grazing. Immediately after the initiation of the experiment net ecosystem uptake of CO 2 decreased in clipped plots (mean total decrease for the three following years was 35 %). One year into the experiment a significantly lower CH 4 emission was observed in these plots, the total mean reduction for the following 2 years was 26 %. Three years into the experiment significantly lower substrate (acetic acid) availability for CH 4 production was observed (27 % reduction). NV plots had a mean decrease in CO 2 uptake of 113 %, a 62 % decrease in ecosystem respiration and an 84 % decrease in CH 4 emission (mean of all 3 years). Our study shows that increased grazing pressure in a high arctic mire can lead to significant changes in the carbon balance, with lower CO 2 uptake leading to lower production of substrate for CH 4 formation and in lower CH 4 emission.

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Section: Grazing Effects On Co 2 Fluxessupporting

confidence: 88%

Section: Grazing Effects On Plant Communitymentioning

confidence: 99%

Effects of simulated increased grazing on carbon allocation patterns in a high arctic mire

2014

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“…Vegetation structural parameters are effective tools for detection of stock effects on vegetation assemblages, to the extent that such measures have been used as proxies for grazing intensity or manipulated as independent variables to represent grazing (Hendricks et al 2005;Elliot and Henry 2011;Jones et al 2011). We measured percent bare ground, percent green, standing brown (senescent), and litter cover using a point-intercept transect centered and randomly oriented in each subsample location.…”

Section: Vegetation and Physical Datamentioning

confidence: 99%

Equine Grazing in Managed Subalpine Wetlands: Effects on Arthropods and Plant Structure as a Function of Habitat

Holmquist

Schmidt-Gengenbach

Haultain

2013

Environmental Management

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Grazing management necessarily emphasizes the most spatially extensive vegetation assemblages, but landscapes are mosaics, often with more mesic vegetation types embedded within a matrix of drier vegetation. Our primary objective was to contrast effects of equine grazing on both subalpine vegetation structure and associated arthropods in a drier reed grass (Calamagrostis muiriana) dominated habitat versus a wetter, more productive sedge habitat (Carex utriculata). A second objective was to compare reed grass and sedge as habitats for fauna, irrespective of grazing. All work was done in Sequoia National Park (California, USA), where detailed, long-term records of stock management were available. We sampled paired grazed and control wet meadows that contained both habitats. There were moderate negative effects of grazing on vegetation, and effects were greater in sedge than in reed grass.Conversely, negative grazing effects on arthropods, albeit limited, were greater in the drier reed grass, possibly due to microhabitat differences. The differing effects on plants and animals as a function of habitat emphasize the importance of considering both flora and fauna, as well as multiple habitat types, when making management decisions. Sedge supported twice the overall arthropod abundance of reed grass as well as greater diversity; hemipteran and dipteran taxa were particularly abundant in sedge. Given the greater grazing effects on sedge vegetation, greater habitat provision for terrestrial arthropods, and value as aquatic arthropod habitat, the wetter sedge assemblage is worthy of additional consideration by managers when planning for grazing and other aspects of land usage.

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“…A number of studies have reported some level of tolerance to both natural and artificial herbivory in arctic graminoids (e.g., Mattheis et al 1976;Chapin and Slack 1979;Chapin 1980;Archer and Tieszen 1983;Henry and Svoboda 1994;Bråthen and Junttila 2006;Elliot and Henry 2011). For example, Eriophorum vaginatum (L.) (hereafter Eriophorum) growing in Alaskan coastal tundra regrows well following moderate biomass removal (Chapin 1980;Archer and Tieszen 1983).…”

Section: Introductionmentioning

confidence: 99%

“…Clipped Eriophorum tillers also increased soil nutrient uptake into root tissue and shifted nutrient resources from roots to shoots (Chapin and Slack 1979). These traits (regrowth and nutrient uptake subsequent to defoliation) of Eriophorum and other graminoids in some tundra systems (e.g., Chapin and Slack 1979;Chapin 1980;Bråthen and Junttila 2006;Elliot and Henry 2011;Ravolainen et al 2011) may be mechanisms allowing herbivores to control transitions of communities from low productivity tundra towards alternative states such as more productive grasslands (Zimov et al 1996;van der Wal 2006;Blinnikov et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Two arctic tundra graminoids differ in tolerance to herbivory when grown with added soil nutrients

Johnson

Gough

2013

Botany

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Greater soil nutrients are thought to increase graminoid tolerance to herbivory (within-season regrowth following herbivore damage) by enabling new growth in response to defoliation, but these responses vary among graminoid species. We studied how two arctic graminoids, Eriophorum vaginatum (L.) in moist acidic tussock (MAT) tundra and Hierochloe alpina (Roem. & Schult.) in dry heath (DH) tundra, tolerate both experimental and natural herbivory when fertilized with nitrogen and phosphorus. Fertilization reduced the tolerance and recovery (regrowth in subsequent years) of defoliated Eriophorum relative to plants growing without fertilization. In contrast, fertilized Hierochloe plants regrew well following defoliation. These opposing results may be due to differential abilities of these two species to access other resources in MAT and DH when fertilized. Herbivory may be affecting access to light of Eriophorum in the more productive, closed canopy MAT, in spite of its ability to grow bigger when fertilized. Hierochloe may not face such a limitation in the more open DH community. Alternatively, the different responses between these two species could be caused by environmental differences between the two communities. Regardless, our results suggest that although high tolerance is thought to be a functional characteristic of graminoids, tolerance to herbivory varies within and between species with soil nutrient availability and thus caution must be exercised in predicting responses to herbivory within this plant growth form. Résumé :On croit qu'une meilleure teneur en nutriment du sol augmente la tolérance des plantes gramoinoïdes à l'herbivorie (repousse au cours de la saison suite au dommage par les herbivores) en permettant le rejet de nouvelles pousses en réaction à la défoliation, mais ces réactions varient selon les espèces graminoïdes. Les auteurs ont étudié deux graminoïdes arctiques, l'Eriophorum vaginatum (L.) venant en touffes humides acides (THA) en toundra et l'Hierochloe alpina (Roem. & Schult.) venant sur landes sèches (LS) en toundra, tolérant toutes les deux l'herbivorie naturelle et expérimentale lorsqu'on les fertilise avec de l'azote et du phosphore. La fertilisation réduit la tolérance et la repousse (années subséquentes) des Eriophorum défoliés comparativement aux plantes venant sans fertilisant. Au contraire, les plants de l'Hierochleum fertilisés repoussent bien suivant une défoliation. Ces résultats opposés peuvent être dus à des capacités différentes chez ces deux espèces à accéder à d'autres ressources dans les THA et LS lorsque fertilisées. L'herbivorie peut possiblement affecter l'accès à la lumière chez l'Eriophorum dans la canopée fermée des THA, en dépit de sa capacité à mieux se développer, lorsque fertilisée. L'Hierochloe peut ne pas rencontrer une telle limitation dans la communauté plus ouverte des LS. Alternativement, les réactions différentes entre ces deux espèces pourraient être causées par des différences environnementales entre les deux communautés. Quoi qu'il en soit, les r...

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Effects of Simulated Grazing in Ungrazed Wet Sedge Tundra in the High Arctic

Cited by 12 publications

References 106 publications

Effects of simulated increased grazing on carbon allocation patterns in a high arctic mire

Effects of simulated increased grazing on carbon allocation patterns in a high arctic mire

Equine Grazing in Managed Subalpine Wetlands: Effects on Arthropods and Plant Structure as a Function of Habitat

Two arctic tundra graminoids differ in tolerance to herbivory when grown with added soil nutrients

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