Consequences of warming on tundra carbon balance determined by reindeer grazing history

Väisänen, Maria; Ylänne, Henni; Kaarlejärvi, Elina; Sjögersten, Sofie; Olofsson, Johan; Crout, N.M.J.; Stark, Sari

doi:10.1038/nclimate2147

Cited by 82 publications

(106 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…), reinforcing the potential impact herbivory can have on arctic greening (Olofsson, Tommervik & Callaghan ) and growing season carbon uptake potential (Vaisanen et al . ). Although exclusion had no effect on R E , similar to Cahoon et al .…”

Section: Discussionmentioning

confidence: 97%

See 1 more Smart Citation

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: 97%

“…However, notable uncertainty pertains to how shifts in grazer species and herbivory intensity may impact carbon balance in tundra landscapes (Tanentzap & Coomes ; Vaisanen et al . ; Metcalfe & Olofsson ). Some studies suggest that herbivory can facilitate ecosystem carbon uptake (Sjogersten et al .…”

Section: Introductionmentioning

confidence: 99%

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

“…The response of root biomass and Rs to grazing varied with grazing time; in summer grazed pasture root biomass and Rs were reduced at high stocking rates while grazing had no influence in winter grazed pasture. The effect of grazing on soil CO 2 flux depends on grazing intensity and history (Owensby et al 2006;Väisänen et al 2014).…”

Section: Discussionmentioning

confidence: 99%

Stocking Rate and Grazing Season Modify Soil Respiration on the Loess Plateau, China

Chen

Hou

Chen

et al. 2015

Rangeland Ecology & Management

View full text Add to dashboard Cite

“…, Metcalfe and Olofsson ) or in the longer term by inducing a vegetation transition to a state that maintains higher ecosystem respiration (Väisänen et al. ). This influence of grazing may determine how the ecosystem responds to global changes and how ecosystems’ carbon storage develops with time.…”

Section: Introductionmentioning

confidence: 99%

Removal of grazers alters the response of tundra soil carbon to warming and enhanced nitrogen availability

Ylänne

Kaarlejärvi

Väisänen

et al. 2019

Ecological Monographs

Self Cite

View full text Add to dashboard Cite

The circumpolar Arctic is currently facing multiple global changes that have the potential to alter the capacity of tundra soils to store carbon. Yet, predicting changes in soil carbon is hindered by the fact that multiple factors simultaneously control processes sustaining carbon storage and we do not understand how they act in concert. Here, we investigated the effects of warmer temperatures, enhanced soil nitrogen availability, and the combination of these on tundra carbon stocks at three different grazing regimes: on areas with over 50‐yr history of either light or heavy reindeer grazing and in 5‐yr‐old exlosures in the heavily grazed area. In line with earlier reports, warming generally decreased soil carbon stocks. However, our results suggest that the mechanisms by which warming decreases carbon storage depend on grazing intensity: under long‐term light grazing soil carbon losses were linked to higher shrub abundance and higher enzymatic activities, whereas under long‐term heavy grazing, carbon losses were linked to drier soils and higher enzymatic activities. Importantly, under enhanced soil nitrogen availability, warming did not induce soil carbon losses under either of the long‐term grazing regimes, whereas inside exclosures in the heavily grazed area, also the combination of warming and enhanced nutrient availability induced soil carbon loss. Grazing on its own did not influence the soil carbon stocks. These results reveal that accounting for the effect of warming or grazing alone is not sufficient to reliably predict future soil carbon storage in the tundra. Instead, the joint effects of multiple global changes need to be accounted for, with a special focus given to abrupt changes in grazing currently taking place in several parts of the Arctic.

show abstract

Consequences of warming on tundra carbon balance determined by reindeer grazing history

Cited by 82 publications

References 30 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

Stocking Rate and Grazing Season Modify Soil Respiration on the Loess Plateau, China

Removal of grazers alters the response of tundra soil carbon to warming and enhanced nitrogen availability

Contact Info

Product

Resources

About