Vegetation Community, Foliar Nitrogen, and Temperature Effects on Tundra CO<sub>2</sub>Exchange across a Soil Moisture Gradient

Dagg, Jennifer; Lafleur, Peter M.

doi:10.1657/1938-4246-43.2.189

Cited by 27 publications

(28 citation statements)

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“…CB and SL appear to have a natural moisture gradient, at peak season, that generates three distinct moisture categories across the landscape; dry, mesic and wet [11,69,70]. Variations along this gradient may not simply be limited to vegetation composition and structure but extend to ecosystem function and processes; e.g., carbon flux (CO 2 ; CH 4 ) and nitrogen availability/mobilization [7].…”

Section: Figurementioning

confidence: 99%

“…Changes to the Arctic climate have been observed over the past century and are being manifested through shifts in vegetation phenology and species composition [4]. Arctic ecosystems have the potential to shift from a sink for carbon-based greenhouse gases to a source, possibly creating a positive feedback mechanism, intensifying global climate change [5][6][7]. Net ecosystem CO 2 exchange (NEE) is the product of opposing fluxes: gross carbon uptake through photosynthesis (gross ecosystem productivity: GEP) and carbon losses from plant and soil respiration (ecosystem respiration: ER).…”

Section: Introductionmentioning

confidence: 99%

“…Changes to ER are of serious concern when monitoring the sink to source status of an ecosystem. ER is related to many factors including: vegetation type, soil organic matter, soil moisture, N and/or P availability, macro and micro topography, temperature, and thaw depth [6,7] Vegetation cover is both an integrator and indicator of climate and ecosystem properties [12]. Hence, detailed community level knowledge along with high spatial resolution remote sensing data can provide us with the ability to understand fine-grain spatial variation and improve our ability to scale to synoptic predictions [6,13].…”

Section: Introductionmentioning

confidence: 99%

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Arctic Ecological Classifications Derived from Vegetation Community and Satellite Spectral Data

Atkinson

Treitz

2012

Remote Sensing

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Abstract:As a result of the warming observed at high latitudes, there is significant potential for the balance of ecosystem processes to change, i.e., the balance between carbon sequestration and respiration may be altered, giving rise to the release of soil carbon through elevated ecosystem respiration. Gross ecosystem productivity and ecosystem respiration vary in relation to the pattern of vegetation community type and associated biophysical traits (e.g., percent cover, biomass, chlorophyll concentration, etc.). In an arctic environment where vegetation is highly variable across the landscape, the use of high spatial resolution imagery can assist in discerning complex patterns of vegetation and biophysical variables. The research presented here examines the relationship between ecological and spectral variables in order to generate an ecologically meaningful vegetation classification from high spatial resolution remote sensing data. Our methodology integrates ordination and image classifications techniques for two non-overlapping Arctic sites across a 5° latitudinal gradient (approximately 70° to 75°N). Ordination techniques were applied to determine the arrangement of sample sites, in relation to environmental variables, followed by cluster analysis to create ecological classes. The derived classes were then used to classify high spatial resolution IKONOS multispectral data. The results demonstrate moderate levels of success. Classifications had overall accuracies between 69%-79% and Kappa values of 0.54-0.69. Vegetation classes were generally distinct at each site with the exception of sedge wetlands. Based on the results presented here, the combination of ecological and remote sensing techniques can produce classifications that have ecological meaning and are spectrally separable in an arctic environment. These

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Section: Figurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Arctic Ecological Classifications Derived from Vegetation Community and Satellite Spectral Data

Atkinson

Treitz

2012

Remote Sensing

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“…In our study, all types of polygons were recharged by snowfall and summer rainfall, yet disturbed habitats had lower soil moisture than wet polygons and a thorough examination of moisture evolution throughout an entire summer showed that soil moisture of breached polygons was significantly more variable than that of wet polygons at both intra-and inter-polygonal scales . Given that soil moisture is an important driver of plant community composition (Dagg and Lafleur, 2011), it is no surprise that we observed a shift in vegetation following changes in moisture regime. Decreasing soil moisture in the center of disturbed polygons came with decreasing thaw-front depth, which was expected given that active layer thickness is closely related to soil moisture (Nelson et al, 1999;Hinzman et al, 2005;Minke et al, 2009;Wright et al, 2009;Gangodagamage Table 4).…”

Section: Transient Environmental Conditionsmentioning

confidence: 74%

Thermo-erosion gullies boost the transition from wet to mesic tundra vegetation

et al. 2016

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Abstract. Continuous permafrost zones with well-developed polygonal ice-wedge networks are particularly vulnerable to climate change. Thermo-mechanical erosion can initiate the development of gullies that lead to substantial drainage of adjacent wet habitats. How vegetation responds to this particular disturbance is currently unknown but has the potential to significantly disrupt function and structure of Arctic ecosystems. Focusing on three major gullies of Bylot Island, Nunavut, we estimated the impacts of thermoerosion processes on plant community changes. We explored over 2 years the influence of environmental factors on plant species richness, abundance and biomass in 62 low-centered wet polygons, 87 low-centered disturbed polygons and 48 mesic environment sites. Gullying decreased soil moisture by 40 % and thaw-front depth by 10 cm in the center of breached polygons within less than 5 years after the inception of ice wedge degradation, entailing a gradual yet marked vegetation shift from wet to mesic plant communities within 5 to 10 years. This transition was accompanied by a five times decrease in graminoid above-ground biomass. Soil moisture and thaw-front depth changed almost immediately following gullying initiation as they were of similar magnitude between older (> 5 years) and recently (< 5 years) disturbed polygons. In contrast, there was a lag-time in vegetation response to the altered physical environment with plant species richness and biomass differing between the two types of disturbed polygons. To date (10 years after disturbance), the stable state of the mesic environment cover has not been fully reached yet. Our results illustrate that wetlands are highly vulnerable to thermo-erosion processes, which drive landscape transformation on a relative short period of time for High Arctic perennial plant communities (5 to 10 years). Such succession towards mesic plant communities can have substantial consequences on the food availability for herbivores and carbon emissions of Arctic ecosystems.

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“…Soil respiration, nitrogen mineralization, plant productivity, and biomass all vary along soil moisture gradients from wet to dry tundra (Dagg and Lafleur 2011). For example, CO 2 uptake in response to warming may be greatest in wet tundra due to the combination of increased plant productivity and limited soil respiration (Oberbauer et al 2007; Dagg and Lafleur 2011).…”

Section: Introductionmentioning

confidence: 99%

Contrasting changes in surface waters and barrens over the past 60 years for a subarctic forest–tundra site in northern Manitoba based on remote sensing imagery

et al. 2013

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Intensified warming in the Arctic and Subarctic is resulting in a wide range of changes in the extent, productivity, and composition of aquatic and terrestrial ecosystems. Analysis of remote sensing imagery has documented regional changes in the number and area of ponds and lakes as well as expanding cover of shrubs and small trees in uplands. To better understand long-term changes across the edaphic gradient, we compared the number and area of water bodies and dry barrens (>100 m 2 ) between 1956 (aerial photographs) and 2008-2011 (high-resolution satellite images) for eight ϳ25 km 2 sites near Nejanilini Lake, Manitoba (59.559°N, 97.715°W). In the modern landscape, the number of water bodies and barrens were similar (1162 versus 1297, respectively), but water bodies were larger (mean 3.1 × 10 4 versus 681 m 2 , respectively) and represented 17% of surface area compared with 0.4% for barrens. Over the past 60 years, total surface area of water did not change significantly (16.7%-17.1%) despite a ϳ30% decrease in numbers of small (<1000 m 2 ) water bodies. However, the number and area of barrens decreased (55% and 67%, respectively) across all size classes. These changes are consistent with Arctic greening in response to increasing temperature and precipitation. Loss of small water bodies suggests that wet tundra areas may be drying, which, if true, may have important implications for carbon balance. Our observations may be the result of changes in winter conditions in combination with low permafrost ice content in the region, in part explaining regional variations in responses to climate change.Résumé : L'intensification du réchauffement dans l'Arctique et les régions subarctiques cause de nombreux changements dans l'étendue, la productivité et la composition des écosystèmes aquatiques et terrestres. Une analyse de l'imagerie par télédétection a révélé des changements régionaux dans le nombre et l'étendue des étangs et des lacs ainsi que dans l'agrandissement de la couverture des arbustes et des petits arbres dans les terres hautes. Afin de mieux comprendre les changements à long terme à travers le gradient édaphique, nous avons comparé le nombre et l'étendue des plans d'eau et de la toundra sèche (>100 m 2 ) entre 1956 (photographies aériennes) et 2008-2011 (images satellite à haute résolution) pour huit sites d'environ 25 km 2 à proximité du lac Nejanilini, Manitoba (59,559°N, 97,715°O). Dans le paysage moderne, le nombre de plans d'eau et de parcelles de toundra était semblable (respectivement 1162 et 1297) mais la superficie des plans d'eau était supérieure à celle des parcelles de toundra (moyennes respectives de 3,1 × 10 4 et de 681 m 2 ) et représentait 17 % de la surface par rapport à 0,4 % pour la toundra. Au cours des 60 dernières années, la surface totale des plans d'eau n'a pas changée de manière significative (16,7 à 17,1 %) malgré une diminution d'environ 30 % du nombre de petits (<1000 m 2 ) plans d'eau. Toutefois, le nombre et la superficie des parcelles de toundra ont diminué (respectivement de ...

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Vegetation Community, Foliar Nitrogen, and Temperature Effects on Tundra CO₂Exchange across a Soil Moisture Gradient

Cited by 27 publications

References 97 publications

Arctic Ecological Classifications Derived from Vegetation Community and Satellite Spectral Data

Arctic Ecological Classifications Derived from Vegetation Community and Satellite Spectral Data

Thermo-erosion gullies boost the transition from wet to mesic tundra vegetation

Contrasting changes in surface waters and barrens over the past 60 years for a subarctic forest–tundra site in northern Manitoba based on remote sensing imagery

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Vegetation Community, Foliar Nitrogen, and Temperature Effects on Tundra CO2Exchange across a Soil Moisture Gradient

Cited by 27 publications

References 97 publications

Arctic Ecological Classifications Derived from Vegetation Community and Satellite Spectral Data

Arctic Ecological Classifications Derived from Vegetation Community and Satellite Spectral Data

Thermo-erosion gullies boost the transition from wet to mesic tundra vegetation

Contrasting changes in surface waters and barrens over the past 60 years for a subarctic forest–tundra site in northern Manitoba based on remote sensing imagery

Contact Info

Product

Resources

About

Vegetation Community, Foliar Nitrogen, and Temperature Effects on Tundra CO₂Exchange across a Soil Moisture Gradient