Three decades of environmental change studies at alpine Finse, Norway: climate trends and responses across ecological scales

Roos, Ruben E.; Asplund, Johan; Birkemoe, Tone; Halbritter, Aud H.; Olsen, Siri Lie; Vassvik, Linn; Zuijlen, Kristel van; Klanderud, Kari

doi:10.1139/as-2020-0051

Cited by 5 publications

(3 citation statements)

References 156 publications

(196 reference statements)

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“…Scharnagl et al (2019) documented the expansion of shrubs in alpine ecosystems over a 40-year period, but argue that plant community composition remained mostly intact, demonstrating a surprising resilience of alpine tundra plant communities to ongoing global climate change. Similarly, Roos et al (2022) show that experimental warming with ITEX chambers over a 30-year period in alpine Norway only had a modest effect on the community composition, while nutrient additions caused strong responses in vegetation dynamics.…”

Section: Introductionmentioning

confidence: 78%

Snow-vegetation-atmosphere interactions in alpine tundra

Pirk

Aalstad

Yılmaz

et al. 2023

Preprint

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Abstract. The interannual variability of snow cover in alpine areas is increasing, which may affect the tightly coupled cycles of carbon and water through snow-vegetation-atmosphere interactions across a range of spatio-temporal scales. To explore the role of snow cover for the land-atmosphere exchange of CO2 and water vapor in alpine tundra ecosystems, we combined three years (2019–2021) of continuous eddy covariance flux measurements of net ecosystem exchange of CO2 (NEE) and evapotranspiration (ET) from the Finse site in alpine Norway (1210 m a.s.l.) with a ground-based ecosystem-type classification and satellite imagery from Sentinel-2, Landsat 8, and MODIS. While the snow conditions in 2019 and 2021 can be described as site-typical, 2020 features an extreme snow accumulation associated with a strong negative phase of the Scandinavian Pattern of the synoptic atmospheric circulation during spring. This extreme snow accumulation caused a one-month delay in melt-out date, which falls on the 92nd-percentile in the distribution of yearly melt-out dates in the period 2001–2021. The melt-out dates follow a consistent fine-scale spatial relationship with ecosystem types across years. Mountain and lichen heathlands melt out more heterogeneously than fens and flood plains, while late snowbeds melt out up to one month later than the other ecosystem types. While the summertime average Normalized Difference Vegetation Index (NDVI) was reduced considerably during the extreme snow year 2020, it reached the same maximum as in the other years for all but one the ecosystem type (late snowbeds), indicating that the delayed onset of vegetation growth is compensated to the same maximum productivity. Eddy covariance estimates of NEE and ET are gap-filled separately for two wind sectors using a random forest regression model to account for complex and nonlinear ecohydrological interactions. While the two wind sectors differ markedly in vegetation composition and flux magnitudes, their flux response is controlled by the same drivers as estimated by the predictor importance of the random forest model as well as the high correlation of flux magnitudes (correlation coefficient r = 0.92 for NEE and r = 0.89 for ET) between both areas. The one-month delay of the start of the snow-free season in 2020 reduced the total annual ET by 50 % compared to 2019 and 2021, and reduced the growing season carbon assimilation to turn the ecosystem from a moderate annual carbon sink (−31 to −6 gC m−2 yr−1) to a source (34 to 20 gC m−2 yr−1). These results underpin the strong dependence of ecosystem structure and functioning on snow dynamics, whose anomalies can result in important ecological extreme events for alpine ecosystems.

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Section: Introductionmentioning

confidence: 78%

Snow-vegetation-atmosphere interactions in alpine tundra

Pirk

Aalstad

Yılmaz

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…Scharnagl et al (2019) documented the expansion of shrubs in alpine ecosystems over a 40-year period but argue that plant community composition remained mostly intact, demonstrating a surprising resilience of alpine tundra plant communities to ongoing global climate change. Similarly, Roos et al (2022) show that experimental warming with International Tundra Experiment (ITEX) chambers over a 30-year period in alpine Norway only had a modest effect on the community composition, while nutrient additions caused strong responses in vegetation dynamics.…”

Section: Introductionmentioning

confidence: 96%

Snow–vegetation–atmosphere interactions in alpine tundra

et al. 2023

View full text Add to dashboard Cite

Abstract. The interannual variability of snow cover in alpine areas is increasing, which may affect the tightly coupled cycles of carbon and water through snow–vegetation–atmosphere interactions across a range of spatio-temporal scales. To explore the role of snow cover for the land–atmosphere exchange of CO2 and water vapor in alpine tundra ecosystems, we combined 3 years (2019–2021) of continuous eddy covariance flux measurements of the net ecosystem exchange of CO2 (NEE) and evapotranspiration (ET) from the Finse site in alpine Norway (1210 m a.s.l.) with a ground-based ecosystem-type classification and satellite imagery from Sentinel-2, Landsat 8, and MODIS. While the snow conditions in 2019 and 2021 can be described as site typical, 2020 features an extreme snow accumulation associated with a strong negative phase of the Scandinavian pattern of the synoptic atmospheric circulation during spring. This extreme snow accumulation caused a 1-month delay in melt-out date, which falls in the 92nd percentile in the distribution of yearly melt-out dates in the period 2001–2021. The melt-out dates follow a consistent fine-scale spatial relationship with ecosystem types across years. Mountain and lichen heathlands melt out more heterogeneously than fens and flood plains, while late snowbeds melt out up to 1 month later than the other ecosystem types. While the summertime average normalized difference vegetation index (NDVI) was reduced considerably during the extreme-snow year 2020, it reached the same maximum as in the other years for all but one of the ecosystem types (late snowbeds), indicating that the delayed onset of vegetation growth is compensated to the same maximum productivity. Eddy covariance estimates of NEE and ET are gap-filled separately for two wind sectors using a random forest regression model to account for complex and nonlinear ecohydrological interactions. While the two wind sectors differ markedly in vegetation composition and flux magnitudes, their flux response is controlled by the same drivers as estimated by the predictor importance of the random forest model, as well as by the high correlation of flux magnitudes (correlation coefficient r=0.92 for NEE and r=0.89 for ET) between both areas. The 1-month delay of the start of the snow-free season in 2020 reduced the total annual ET by 50 % compared to 2019 and 2021 and reduced the growing-season carbon assimilation to turn the ecosystem from a moderate annual carbon sink (−31 to −6 gC m−2 yr−1) to a source (34 to 20 gC m−2 yr−1). These results underpin the strong dependence of ecosystem structure and functioning on snow dynamics, whose anomalies can result in important ecological extreme events for alpine ecosystems.

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“…Alpine plants are well adapted to reproduce under harsh conditions (Körner, 2003), however with ongoing and expected climate change (IPCC, 2023), abiotic and biotic conditions are changing and the challenges put on plants' sexual reproduction are increasing. An understanding of the most important factors in uencing reproductive output in alpine plants are therefore essential (Roos et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Variations in reproductive output in alpine populations of Ranunculus acris

Vassvik,

Nielsen,

Östman

et al. 2024

Preprint

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Plant reproduction is affected both directly by small-scale abiotic heterogeneity in the alpine topography (abiotic), and indirectly through flower density and plant-pollinator interactions (biotic). In this study we investigated how different abiotic and biotic factors influence reproductive output in alpine populations of Ranunculus acris over a two-year period. We used ten snowmelt gradients in an alpine area at Finse, southern Norway, where each gradient contained three stages representing three different times of snowmelt. Reproductive output, measured as both seed mass and number of seeds, in alpine R. acris was affected by different factors, varying between years and timing of snowmelt. Higher temperatures during seed maturation resulted in higher reproductive output in both years, with a lower output later in the growing season. We also found a negative correlation between seed mass and R. acris density in the surrounding vegetation in the second year, when flower density was substantially higher than in the first year. We found no signs of pollen limitation, suggesting that pollinators did not limit reproductive output. Our study shows that reproductive output in R. acris is affected by both abiotic and biotic factors, and since timing and length of the flowering period in alpine environments are expected to change due to climate change, this could have further implications for plants in this study system.

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Three decades of environmental change studies at alpine Finse, Norway: climate trends and responses across ecological scales

Cited by 5 publications

References 156 publications

Snow-vegetation-atmosphere interactions in alpine tundra

Snow-vegetation-atmosphere interactions in alpine tundra

Snow–vegetation–atmosphere interactions in alpine tundra

Variations in reproductive output in alpine populations of Ranunculus acris

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