What was done
A warming experiment was carried out on species-rich Carex sempervirens (CS) and species-poor Carex firma (CF) calcareous grasslands in the Berchtesgaden National Park of Southeast Germany by installing several open-top chambers on them in each of three successive years just after snowmelt was complete in the spring and by removing them just before snowfall commenced in the autumn, which operation led to snow-free-season increases in mean daily air temperature 0.7°C in the CS grasslands and 1.4°C in the CF grasslands, along with corresponding mean daily soil temperature increases of 0.2 and 0.8°C.

What was learned
Kudernatsch et al. report that "growth and/or reproduction of 12 of the 14 studied species were significantly stimulated by warming," that "only two species showed no response," and that "none of the species experienced decreases in growth or reproduction." They also found that dwarf shrubs and graminoids showed stronger responses than herbaceous perennials, and that "a significant effect of warming on nutrient availability could not be detected," leading them to conclude that "the observed response of vegetation is therefore mainly caused by direct and not by indirect temperature effects."

What it means
The four researchers found what most other studies of warming effects on alpine plants have found -- "positive effects on growth and reproduction of the species" -- in support of which statement they cite eleven different scientific papers, additionally noting that "the non-appearance of an effect or even a negative response is rather an exception." Hence, they write that "obviously -- as in our study -- a large number of alpine plant species benefit from temperature enhancement," so much so, in fact, that they are able to report that increases in species richness in high-mountain ecosystems have been documented for the Alps as well as for Scandinavia, citing five additional scientific papers in support of this statement.