Can we see the effects of social change or glob­al warm­ing since 1900 in the flo­ra of Graubün­den? Flo­ra Raet­i­ca is inves­ti­gat­ing this ques­tion through com­pre­hen­sive map­ping and com­par­ing his­tor­i­cal records of plant sight­ings with cur­rent occur­rences. Thomas Wohlge­muth, co-pres­i­dent of Flo­ra Raet­i­ca, pro­vid­ed answers to these ques­tions on Sep­tem­ber 16 dur­ing the “Ren­dez-vous am Mit­tag” event host­ed by the Graubün­den Nat­ur­al His­to­ry Muse­um. About 60 inter­est­ed atten­dees lis­tened to his pre­sen­ta­tion.

Few­er farm fields, more urban areas and forests

Using his­tor­i­cal pho­tos, Wohlge­muth vivid­ly illus­trat­ed how our ances­tors prac­ticed agri­cul­ture on a small scale and with a great deal of man­u­al labor through­out Graubün­den.

Over the past hun­dred years, the fields sur­round­ing the vil­lages have large­ly disappeared—and with them, tra­di­tion­al crops such as flax, hemp, and rye.

In many val­ley areas, wet mead­ows and nat­ur­al riv­er land­scapes have dis­ap­peared, and mead­ows that were once nutri­ent-poor are now fer­til­ized even at high ele­va­tions. There has been an increase in built-up areas, roads, farm access roads, and also forest­ed areas.

Over fifty new species in forests

Changes in habi­tats are also reflect­ed in the plant com­mu­ni­ty. In the cur­rent map­ping efforts, new species are emerging—particularly along trans­porta­tion routes, rivers, and oth­er rud­er­al sites—including many neo­phytes. Some are spread­ing rapid­ly and are there­fore being specif­i­cal­ly con­trolled, such as the glan­du­lar impa­tiens and Japan­ese knotweed.

Among the species found in rich fens—which are much more com­mon today than in the past—only a hand­ful of new species have been added, such as the thread-leaved speed­well. More than 50 new species now grow in the forests, includ­ing sev­er­al tree species such as Dou­glas fir and red oak, which were inten­tion­al­ly plant­ed, as well as shade-tol­er­ant neo­phytes such as the autumn cher­ry.

At the same time, many species of for­mer agri­cul­tur­al crops have dis­ap­peared or become less com­mon, includ­ing, for exam­ple, corn cock­le and sev­er­al species that grow in flax fields: flax cock­le, flax silk, and flax rag­wort.

Sur­pris­ing­ly, sev­er­al dozen of the numer­ous neo­phytes already known around 1900 have dis­ap­peared. They were appar­ent­ly unable to become estab­lished.

Blue­ber­ries are par­tic­u­lar­ly wide­spread

The map­ping also reveals sig­nif­i­cant dif­fer­ences in the dis­tri­b­u­tion of the approx­i­mate­ly 3,000 plant species. Accord­ing to Wohlge­muth, about 400 species have so far been record­ed in only a sin­gle 5 × 5‑km square and are there­fore among the species that are par­tic­u­lar­ly rarely record­ed, such as the moor gen­tian at Hei­d­see or the dyer’s woodruff at Ell­horn.

At the oth­er end of the spec­trum are the blue­ber­ry and the crest­ed water-crow­foot: both have been found in 84 per­cent of the sur­veyed areas so far and are the most wide­spread species.

Map­ping will con­tin­ue through 2028

The more thor­ough­ly today’s plant pop­u­la­tions are doc­u­ment­ed, the more accu­rate­ly we can track how the flo­ra of Graubün­den is chang­ing. Flo­ra Raet­i­ca will there­fore con­tin­ue its map­ping efforts through 2028. New vol­un­teers are always wel­come!