Effect of reindeer grazing on snowmelt, albedo and energy balance based on satellite data analyses

Cohen, Juval; Pulliainen, Jouni; Ménard, Cécile B.; Johansen, Bernt; Oksanen, Lauri; Luojus, Kari; Ikonen, Jaakko

doi:10.1016/j.rse.2013.03.029

Cited by 59 publications

(55 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This study suggests surface albedo would be 6% greater if lemmings were absent from this landscape, which contrasts with Cohen et al . () reporting the opposite response for reindeer absence. This difference in albedo may quite significant across scales, as it has been hypothesized, for example, that the transition of all arctic graminoid tundra to shrub tundra may decrease albedo by 12% (Chapin et al .…”

Section: Discussionmentioning

confidence: 93%

Peak season carbon exchange shifts from a sink to a source following 50+ years of herbivore exclusion in an Arctic tundra ecosystem

et al. 2016

View full text Add to dashboard Cite

Summary 1.To date, the majority of our knowledge regarding the impacts of herbivory on arctic ecosystem function has been restricted to short-term (<5 years) exclusion or manipulation experiments. Our understanding of long-term responses of sustained herbivory and/or herbivore exclusion on arctic tundra ecosystem function is severely limited. 2. Recent evidence suggests lemming population outbreaks, which have historically been common in tundra regions, have become less frequent and in some cases disappeared. Here, we evaluate how 50+ years of lemming absence have impacted ecosystem carbon and energy exchange in an Arctic tundra region near Barrow, Alaska, using some of the oldest herbivore exclosures in the Arctic. 3. We show that sustained lemming absence dramatically altered peak growing season ecosystem function (i.e. thaw depth, water-table, NDVI, albedo and land atmosphere CO 2 and CH 4 exchange) in all land cover types (i.e. wet, moist and dry) investigated but was most profound in wet tundra, where the long-term absence of lemmings altered the largest carbon sink during peak growing season into a source to the atmosphere. Landscape-level analysis suggests the long-term absence of lemmings may increase peak growing season albedo by +6% and decrease net ecosystem exchange, CH 4 flux and the combined radiative forcing potential by À96, À79 and À104%, respectively. 4. Identified long-term functional responses to herbivory differed from many short-term exclusion studies, as we found higher rates of carbon uptake where herbivores are present, associated with a shift in plant community composition (i.e. graminoid to moss), while short-term studies typically report a reduction in carbon uptake where herbivores are present, associated with defoliation events that decrease above-ground biomass/photosynthesis. 5. Synthesis. This work highlights the long-term impact of herbivory on ecosystem function, which suggests (i) the measured response of arctic tundra to herbivory may be dependent on the duration of experimental observation, and (ii) if negative trends in lemming populations persist in arctic tundra regions, the historically strong carbon sink capacity may be severely reduced.

show abstract

Section: Discussionmentioning

confidence: 93%

Peak season carbon exchange shifts from a sink to a source following 50+ years of herbivore exclusion in an Arctic tundra ecosystem

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Shrub growth and responses to climate warming are critical for both the local ecosystem and also for the climate system as a whole, due to the ability of shrubs to alter albedo and trap windblown snow (Myers‐Smith et al ., ). Comparisons of vegetation (NDVI), snow melt (change in snow cover area), albedo (reflectivity of solar radiation), and energy balance between areas used for year‐round pasture in Finland and nonsummer pasture in Norway indicate that areas used for year‐round (include summer) grazing have lower NDVI, because summer reindeer herding reduces woody vegetation cover (Cohen et al ., ). In semimanaged reindeer pastures, incorporation of management policies may be crucial for the prediction of vegetation dynamics.…”

Section: Discussionmentioning

confidence: 97%

Circumpolar arctic tundra biomass and productivity dynamics in response to projected climate change and herbivory

Qin

Epstein

Engstrom

et al. 2017

Global Change Biology

View full text Add to dashboard Cite

Satellite remote sensing data have indicated a general 'greening' trend in the arctic tundra biome. However, the observed changes based on remote sensing are the result of multiple environmental drivers, and the effects of individual controls such as warming, herbivory, and other disturbances on changes in vegetation biomass, community structure, and ecosystem function remain unclear. We apply ArcVeg, an arctic tundra vegetation dynamics model, to estimate potential changes in vegetation biomass and net primary production (NPP) at the plant community and functional type levels. ArcVeg is driven by soil nitrogen output from the Terrestrial Ecosystem Model, existing densities of Rangifer populations, and projected summer temperature changes by the NCAR CCSM4.0 general circulation model across the Arctic. We quantified the changes in aboveground biomass and NPP resulting from (i) observed herbivory only; (ii) projected climate change only; and (iii) coupled effects of projected climate change and herbivory. We evaluated model outputs of the absolute and relative differences in biomass and NPP by country, bioclimate subzone, and floristic province. Estimated potential biomass increases resulting from temperature increase only are approximately 5% greater than the biomass modeled due to coupled warming and herbivory. Such potential increases are greater in areas currently occupied by large or dense Rangifer herds such as the Nenets-occupied regions in Russia (27% greater vegetation increase without herbivores). In addition, herbivory modulates shifts in plant community structure caused by warming. Plant functional types such as shrubs and mosses were affected to a greater degree than other functional types by either warming or herbivory or coupled effects of the two.

show abstract

“…Unfortunately, however, this novel community appears to be characterized by intense plant–plant competition, resulting in reduced species diversity (as predicted by Grime, , ) and conditions hostile for many arctic species. Measures which prevent the invasion of trees and tall shrubs can thus preserve the tundra as an open environment with high surface albedo (Cohen et al., ) but for the arctic flora, the only dependable cure is to stop the global warming.…”

Section: Discussionmentioning

confidence: 99%

“…With its total extent of 9.8 million square kilometres (Virtanen et al., ), the arctic tundra, including its altitudinal extensions, is among the world's largest biomes. The high surface albedo of these vast, open expanses plays a major role in cooling down the global climate (Chapin et al., ; Cohen et al., ). Changes in the arctic also influence climate patterns at lower latitudes (Sellevold, Sobolowski, & Li, ).…”

Section: Introductionmentioning

confidence: 99%

Open tundra persist, but arctic features decline—Vegetation changes in the warming Fennoscandian tundra

Vuorinen

Oksanen

et al. 2017

Global Change Biology

Self Cite

View full text Add to dashboard Cite

In the forest-tundra ecotone of the North Fennoscandian inland, summer and winter temperatures have increased by two to three centigrades since 1965, which is expected to result in major vegetation changes. To document the expected expansion of woodlands and scrublands and its impact on the arctic vegetation, we repeated a vegetation transect study conducted in 1976 in the Darju, spanning from woodland to a summit, 200 m above the tree line. Contrary to our expectations, tree line movement was not detected, and there was no increase in willows or shrubby mountain birches, either. Nevertheless, the stability of tundra was apparent. Small-sized, poorly competing arctic species had declined, lichen cover had decreased, and vascular plants, especially evergreen ericoid dwarf shrubs, had gained ground. The novel climate seems to favour competitive clonal species and species thriving in closed vegetation, creating a community hostile for seedling establishment, but equally hostile for many arctic species, too. Preventing trees and shrubs from invading the tundra is thus not sufficient for conserving arctic biota in the changing climate. The only dependable cure is to stop the global warming.

show abstract

Effect of reindeer grazing on snowmelt, albedo and energy balance based on satellite data analyses

Cited by 59 publications

References 47 publications

Peak season carbon exchange shifts from a sink to a source following 50+ years of herbivore exclusion in an Arctic tundra ecosystem

Peak season carbon exchange shifts from a sink to a source following 50+ years of herbivore exclusion in an Arctic tundra ecosystem

Circumpolar arctic tundra biomass and productivity dynamics in response to projected climate change and herbivory

Open tundra persist, but arctic features decline—Vegetation changes in the warming Fennoscandian tundra

Contact Info

Product

Resources

About