What are the alpine meadows

 

Land ecosystems absorb a quarter of the carbon dioxide released by humans, primarily through fossil fuels. They cushion the greenhouse effect. Forests in particular have so far been analyzed in this context. “Unforested grassy areas, however, cover a quarter of the earth. This also includes the alpine meadows that have so far been little investigated and that are now being released from the snow, ”says Wohlfahrt. What happens to subalpine grasslands and their role in the carbon cycle when the thickness of the winter blanket decreases and so does the length of the snow season - both of which are predicted consequences of climate change - the scientist from the Institute of Ecology at the University of Innsbruck is investigating together with Italian colleagues in the Aosta Valley, among others, at 2,200 meters. The researchers recently published their first results in the “Environmental Research Letters”.
While there is currently around half a meter of snow on the test area in the Aosta Valley, it had already melted in mid-April in 2011. This was a consequence of the shortest winter since there are climate records there. Two years ago, the snowmelt in the Aosta Valley not only started 30 days earlier, the cold season also began 30 days later in autumn. This amounted to an extension of the growing season by two months. According to Wohlfahrt, if winter lasts less long, alpine meadows would actually have more time to absorb and bind carbon dioxide during the snow-free period. “Viewed over the whole year, this was also the case in the Aosta Valley. However, this was mainly due to lower carbon dioxide losses over the winter, since exactly the same amount of carbon dioxide was absorbed during the two-month longer vegetation period as in normal years.
We were therefore surprised that this so-called "carbon sink", which counteracts the greenhouse effect, was not as strong as assumed. The reasons for this are still in the dark. We suspect, however, that temporal shifts in the availability of nutrients and the need for vegetation in the period after the snow melts could play a role. It can already be assumed, however, that several such short winters in a row can have an impact on the carbon balance and thus on the earth's atmosphere and our climate. After all, the mountain ecosystems in our Alps react extremely sensitively to increases in temperature, changes in the distribution of precipitation and increasing extreme weather events, ”emphasizes the ecologist.

Field research as micrometeorological precision work

In their pioneering work, the team uses the most modern technology. Computerized micrometeorological special devices measure the speed and composition of the smallest air parcels over the respective alpine meadow 20 times per second. With this so-called "eddy covariance method", carbon dioxide flows between the underlying ecosystem and the atmosphere can be precisely quantified. This also enables a balance sheet of how much carbon dioxide a meadow absorbs or gives off.
In addition to the research in the Aosta Valley, the Innsbruck ecologists are on the trail of alpine meadows as sensors for our climate, together with experts from the Institute for Ion Physics at the University of Innsbruck in the Tyrolean Stubai Valley and in teamwork with Italian researchers in Trentino. This research is funded by the Austrian Science Fund FWF, the Tyrolean Science Fund, the Autonomous Province of Bolzano, and the European Union. "We hope to be able to systemically use the data obtained in an altitude transect between 1,000 meters in the Tyrolean Stubai Valley, 1,500 meters in Trentino and 2,200 meters in the Aosta Valley in the long term in a new model to improve understanding of the exchange processes between grassland ecosystems and the atmosphere", declares welfare. The ecologist had already developed new, regionalized climate scenarios for managed grassland as part of the Sparkling Science project "GrassClim", which was financed by the Austrian Federal Ministry of Science and Research, simulated possible climate changes and thus taught agricultural school students practical strategies for the future.

More knowledge about our meadows

The growing season of the alpine meadows begins with the melting of the snow. Depending on the biodiversity or altitude, sweet grass, sour grass and bristle grass, arnica, mountain carnation, goldfinch, alpine clover and dandelion filter the greenhouse gas carbon dioxide from the atmosphere during photosynthesis and bind carbon in their biomass. Science calls this a "carbon sink". In autumn, when these plants stop growing and the winter snowpack sets in, they become sources of carbon, because then they release carbon dioxide back into the atmosphere. The subpolar tundra, tropical savannahs and our native alpine meadows - all these grassland ecosystems can therefore act as both sinks and sources of carbon and thus slow down or accelerate climate change. Overall, in this new field of research, ecological long-term studies are indispensable for the further assessment of the carbon balance, and thus ultimately the impact of climate changes on our quality of life.