Satellite‐based evidence for shrub and graminoid tundra expansion in northern <scp>Q</scp>uebec from 1986 to 2010

McManus, Kelly; Morton, Douglas C.; Masek, Jeffrey G.; Wang, Dongdong; Sexton, Joseph O.; Nagol, Jyoteshwar; Ropars, Pascale; Boudreau, Stéphane

doi:10.1111/j.1365-2486.2012.02708.x

Cited by 130 publications

(107 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The buffer layer: effects of shrubs on the snowpack Shrub distribution in the tundra is patchy at multiple spatial scales but is increasing as climate warms up (Sturm et al 2001;McManus et al 2012;Fraser et al 2014). Shrub abundance has far-reaching effects on the formation and properties of the snowpack.…”

Section: Snow and Ice In The Arctic Tundramentioning

confidence: 99%

Effects of changing permafrost and snow conditions on tundra wildlife: critical places and times

et al. 2017

View full text Add to dashboard Cite

The change of water phase around 0°C has considerable impacts on wildlife ecology because liquid and solid water strongly differ in their insulating capability, mechanical resistance, and light reflectance. Freeze and melt events thus have strong ecological relevance, particularly in the Arctic where snow and ice are omnipresent and their conditions are changing due to climate warming. We first review the mechanisms linking water phase transitions to wildlife ecology, with emphasis on seven key processes. These processes are illustrated with examples or detailed case studies, such as snowmelt and icing events affecting herbivore populations, thaw-induced collapse of structures used by wildlife for reproduction, and thermal erosion of ice wedges reducing waterfowl habitat. We infer that water phase transitions generate some critical places and critical times that play a disproportionate role in the ecology of tundra wildlife. We map these critical places and times to help structure future research on the effects of climate change on tundra wildlife in a context where changing permafrost and snow conditions might trigger abrupt ecological responses in the Arctic tundra.Key words: ice, permafrost, snow, tundra, wildlife.Résumé : Le changement de phase de l'eau autour de 0°C a des impacts considérables sur l'écologie de la faune parce que l'eau liquide et l'eau solide diffèrent fortement dans leur capacité d'isolation, leur résistance mécanique et leur réflectance à la lumière. Les évé-nements de gel et de dégel ont ainsi une grande pertinence écologique, particulièrement dans l'Arctique où la neige et la glace sont omniprésentes et leurs conditions changent en raison du réchauffement climatique. Nous passons d'abord en revue les mécanismes liant les transitions de phase de l'eau à l'écologie de la faune, l'accent étant mis sur sept processus clés. Ces processus sont illustrés par des exemples ou des études de cas détaillées, tels que des événements de fonte des neiges et de gel ayant un effet sur les populations herbivores, l'écroulement provoqué par le dégel des structures utilisées par la faune pour la reproduction et l'érosion thermique des fentes de glace réduisant l'habitat du gibier d'eau. Nous déduisons For personal use only. SYNTHESIS PAPERque ces transitions de phase de l'eau produisent quelques endroits critiques et temps critiques qui jouent un rôle disproportionné dans l'écologie de la faune de la toundra. Nous dressons la carte de ces endroits et temps critiques afin d'aider à structurer la recherche future sur les effets du changement climatique sur la faune de la toundra, dans un contexte où les conditions changeantes du pergélisol et de la neige pourraient déclencher des réponses écologiques brusques dans la toundra arctique.

show abstract

Section: Snow and Ice In The Arctic Tundramentioning

confidence: 99%

Effects of changing permafrost and snow conditions on tundra wildlife: critical places and times

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Recent climate warming in the Arctic (Stocker et al, 2013) is associated with increasing shrub abundance, cover, and biomass in many regions (Tape et al, 2006;Myers-Smith et al, 2011;Sturm et al, 2001b;McManus et al, 2012;Lantz et al, 2013;Frost and Epstein, 2014). However, vegetation can change in multiple directions and at larger scales the dominance of shrub tundra or wet sedge tundra is controlled by soil moisture and surface hydrology.…”

Section: Introductionmentioning

confidence: 99%

Contrasting radiation and soil heat fluxes in Arctic shrub and wet sedge tundra

et al. 2016

View full text Add to dashboard Cite

Abstract. Vegetation changes, such as shrub encroachment and wetland expansion, have been observed in many Arctic tundra regions. These changes feed back to permafrost and climate. Permafrost can be protected by soil shading through vegetation as it reduces the amount of solar energy available for thawing. Regional climate can be affected by a reduction in surface albedo as more energy is available for atmospheric and soil heating. Here, we compared the shortwave radiation budget of two common Arctic tundra vegetation types dominated by dwarf shrubs (Betula nana) and wet sedges (Eriophorum angustifolium) in North-East Siberia. We measured time series of the shortwave and longwave radiation budget above the canopy and transmitted radiation below the canopy. Additionally, we quantified soil temperature and heat flux as well as active layer thickness. The mean growing season albedo of dwarf shrubs was 0.15 ± 0.01, for sedges it was higher (0.17±0.02). Dwarf shrub transmittance was 0.36 ± 0.07 on average, and sedge transmittance was 0.28 ± 0.08. The standing dead leaves contributed strongly to the soil shading of wet sedges. Despite a lower albedo and less soil shading, the soil below dwarf shrubs conducted less heat resulting in a 17 cm shallower active layer as compared to sedges. This result was supported by additional, spatially distributed measurements of both vegetation types. Clouds were a major influencing factor for albedo and transmittance, particularly in sedge vegetation. Cloud cover reduced the albedo by 0.01 in dwarf shrubs and by 0.03 in sedges, while transmittance was increased by 0.08 and 0.10 in dwarf shrubs and sedges, respectively. Our results suggest that the observed deeper active layer below wet sedges is not primarily a result of the summer canopy radiation budget. Soil properties, such as soil albedo, moisture, and thermal conductivity, may be more influential, at least in our comparison between dwarf shrub vegetation on relatively dry patches and sedge vegetation with higher soil moisture.

show abstract

“…The monitoring of shrub vegetation is therefore important for the understanding of the ongoing changes in northern environments. Current methods rely either on field sampling or aerial and satellite imagery in the visible and infrared spectrum to assess changes in shrub coverage or growth [6,8,[16][17][18][19][20]. However, these methods have certain limitations as the field sampling methods can be very costly and do not provide a high spatial coverage, while satellite imagery in the visible and infrared spectrum is affected by the presence of clouds, which can be persistent in northern regions [16,21].…”

Section: Introductionmentioning

confidence: 99%

Land Cover Classification in SubArctic Regions Using Fully Polarimetric RADARSAT-2 Data

et al. 2016

View full text Add to dashboard Cite

Abstract:The expansion of shrub vegetation in Arctic and sub-Arctic environments observed in the past decades can have significant effects on northern ecosystems. There is a need for efficient tools to monitor those changes, not only in terms of the spatial coverage of shrubs, but also their vertical growth. The objective of the current paper is to evaluate the performance of polarimetric C-band SAR datasets for land cover classification in sub-Arctic environments. A series of RADARSAT-2 quad-pol images were acquired between October 2011 and April 2012. The Support Vector Machine (SVM) classification scheme was used on three sets of features: the elements of the polarimetric coherency matrix [T], the parameters extracted from a polarimetric decomposition based on the eigenvalues and eigenvectors of [T] and the parameters extracted from a model-based decomposition. Using a single image, the results show that the best classification accuracies (≈ 75%) are obtained using the [T] matrix with the October images. When adding a second image to the feature set, either from two different dates or two incidence angles, the classification accuracy is improved and reaches 90.1% with two images from October 2011 and April 2012 at 27 • incidence. The results show that C-band polarimetric SAR imagery is an adequate tool to map shrub vegetation in sub-Arctic environments.

show abstract

Satellite‐based evidence for shrub and graminoid tundra expansion in northern Quebec from 1986 to 2010

Cited by 130 publications

References 49 publications

Effects of changing permafrost and snow conditions on tundra wildlife: critical places and times

Effects of changing permafrost and snow conditions on tundra wildlife: critical places and times

Contrasting radiation and soil heat fluxes in Arctic shrub and wet sedge tundra

Land Cover Classification in SubArctic Regions Using Fully Polarimetric RADARSAT-2 Data

Contact Info

Product

Resources

About