Ruderals and Weeds in Godby, Åland Islands, SW Finland
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Memoranda Soc. Soc. Fauna Fauna Flora Flora Fennica Fennica 91, 91: 2015 21–32. • Hæggström 2015 & Hæggström 21 Ruderals and weeds in Godby, Åland Islands, SW Finland Carl-Adam Hæggström & Eeva Hæggström Carl-Adam Hæggström, Finnish Museum of Natural History, Botanical Museum, P. O. Box 7, FI- 00014 University of Helsinki, Finland. E-mail: [email protected] Eeva Hæggström, Tornfalksvägen 2/26, FI-02620 Esbo, Finland. E-mail: eeva.haeggstrom@ kolumbus.fi The Åland Islands in SW Finland are known for their luxuriant vegetation with numerous calci- philic vascular plants. Ruderal plants are rather few compared to the adjoining regions of Finland and Sweden. However, new ruderal plants are occasionally found in Åland. We came across a ruderal site in the centre of the village of Godby, municipality of Finström, in 2002. Most of the organic topsoil had been removed and several rare ruderal species grew then on the open ruderal site. The site became more closed, resembling a meadow rather than a ruderal ground already in 2006 and later the vegetation developed into a tall and rough grown meadow with some shrubs and young trees. The following ruderal plants are treated more in detail: Agrostemma githago, Anthemis tinctoria, Centaurea cyanus, Cichorium intybus, Dianthus deltoides (cultivar), Echium vulgare, Holcus lanatus, Leontodon hispidus, Lotus corniculatus var. sativus, Papaver dubium subsp. dubium, P. rhoeas, Phleum phleoides, Rumex thyrsiflorus, Senecio jacobaea, Thymus pule- gioides, Trifolium dubium and Vicia tenuifolia. Besides some trees and shrubs, 133 vascular plant taxa, most of them common in the Åland Islands, were observed growing in the ruderal site during the period 2002–2015. The origin of the ruderal flora is not known. It is suggested that at least some of the plants have originated from seeds in the former cultivated field. A deliberate sowing of flower seeds of foreign provenance cannot, however, be excluded, although we have not been able to prove it. Introduction the Baltic Area to a wood chipping plant in God- The Åland Islands in southwestern Finland are by, municipality of Finström in the early 1990’s known for a flora with numerous calciphilic vas- (Hæggström et al. 2003) and ruderals on a waste cular plants. The vegetation is in many parts lux- ground on the island of Dånö, municipality of uriant with species, which have a southwest- Geta, in 2014 (Carlsson et al. 2014). ern distribution in Finland. On the other hand, An area with exotic ruderals were found by weeds and ruderal plants are rather few compared us at the main road northwards in the central part to the adjoining regions of Finland (e.g. Hämet- of Godby village, municipality of Finström. We Ahti et al. 1998) and Sweden (e.g. Hultén 1971, studied it in 2002, 2003, 2006, 2007, 2009 and Jonsell 2010). However, new weeds and ruderal 2015. We visited the site also in 2004–2005, 2008 plants are occasionally found in Åland, e.g. spe- and 2010–2014, without making detailed studies cies probably introduced with logs imported from then. 22 Hæggström & Hæggström • Memoranda Soc. Fauna Flora Fennica 91, 2015 The vascular plant flora the grasses Alopecurus pratensis, Dactylis glome - rata, Festuca ovina, F. rubra, Phleum phleoides. The ruderal site is a former cultivated field (the P. pratense subsp. pratense and Poa pratensis. coordinates are, according to the Uniform Co- The bulk of the species were common her- ordinate System (UCS) Grid 27 °E, 670060– baceous meadow plants typical for the Åland Is- 670066:311197–311208). The size of the site is lands, such as Achillea millefolium, Alchemil- approx. 60 m × 110 m. Most of the organic top- la acutiloba, A. monticola, Anthriscus sylvestris, soil was removed from the field before 2002 and Centaurea jacea, C. scabiosa, Cerastium fonta- the vegetation was lax with spots of naked soil in num subsp. vulgare, Galium verum, Geranium that year. During the following years, the vege- sylvaticum, Knautia arvensis, Lathyrus praten- tation became more closed, and already in 2006, sis, Medicago lupulina, Plantago lanceolata, Po- the site resembled a meadow rather than a ruder- tentilla reptans, Primula veris, Ranunculus ac- al ground. Later, the vegetation developed into a ris, Rumex acetosa, Stellaria graminea, Trifolium tall and rough grown meadow with some shrubs medium, T. pratense, T. repens and Vicia crac- and young trees. During several years, the eastern ca. Common meadow grasses were Agrostis gi- part of the site has been managed as a park with a gantea, Alopecurus pratensis, Briza media, Cy- mown lawn with a few cultivated trees. nosurus cristatus, Festuca ovina, F. pratensis, The ruderal site is bordered to the north by a Phleum pratense subsp. pratense and Poa pra- hedge of trees and shrubs such as Alnus glutino- tensis. Some taxa typical of dry meadows and sa, Populus tremula, Salix caprea, S. cinerea, S. rock meadows were also found, such as Alche- phylicifolia, Rosa dumalis and cultivated R. ru- milla glaucescens, Arabidopsis thaliana, Arenar- gosa. A few cultivated poplar trees (Populus sp.) ia serpyllifolia, Hieracium umbellatum, Hyperi- grew in the hedge; the large poplar trees are dead cum perforatum, Lychnis viscaria, Rumex aceto- since a few years. One sapling of this poplar spe- sella subsp. acetosella, Silene nutans, Vicia hir- cies grows in the northern part of the site. An suta, Vicia tetrasperma and the annual grass Bro- Acer platanoides and a Fraxinus excelsior grows mus hordeaceus. at the southwestern corner of the site. A few trees The rest of the vascular plants were weeds and shrubs have been planted in the site. The fol- and ruderals, many of them quite common in the lowing were seen in 2015: two about 7-metre- Åland Islands, such as Aegopodium podagraria, high Betula pendula trees side by side, one about Artemisia vulgaris var. vulgaris, Capsella bur- 4-metre-high Quercus robur and two about 2-me- sa-pastoris, Carduus crispus, Chenopodium al- tre-high Corylus avellana shrubs. A few one to bum coll., Cirsium arvense var. arvense, C. ar- two metres high saplings and shrubs of Betula vense var. maritimum, C. vulgare, Lamium hybri- pendula, Fraxinus excelsior, Rosa dumalis, one dum, L. purpureum, Lapsana communis, Matri- shrub of R. rugosa and a couple of small Sorbus caria chamomilla, M. discoidea, Myosotis arven- aucupa ria grew in the site in 2015. A cultivated sis, Plantago major subsp. major, Rumex longi- bramble (Rubus corylifolius coll.) was seen at the folius, R. obtusifolius, Stellaria media, Taraxa- eastern margin of the site in 2007 but it disap- cum spp., Thlaspi arvense, Tripleurospermum in- peared later. odorum, Tussilago farfara, Viola arvensis and the In all, 133 vascular plant taxa were observed grass Lolium perenne. in the field layer of the ruderal site (Table 1). The number of taxa was fairly low in 2002 and in- creased to an observed maximum in 2007, where- Rare ruderals as it was lower in 2015. Abundant species dur- ing the latter years were, e.g. Achillea millefo- Several of the species in the ruderal site of Godby lium, Centaurea jacea (two different races, one are rare in the Åland Islands. The following are with capitulas with pale brown bract appendages, worth mentioning: and the other with dark brown bract appendages), C. scabiosa, Galium verum, Lathyrus pratensis, Agrostemma githago – Sixteen specimens of this Silene nutans, Trifolium medium, T. pratense and cereal field weed were seen in 2002 and more Memoranda Soc. Fauna Flora Fennica 91, 2015 • Hæggström & Hæggström 23 than 100 specimens in 2003. None was seen later, tybus are few in the Åland Islands before the 21st probably because the vegetation became too dense century. The first observation was in a rye field for the seeds of this annual species to germinate. in Mångstäkta (Mångsteckta on the label) in the Agrostemma githago was previously recorded in municipality of Sund in 1885 (Lampinen et al. all municipalities of the Åland Islands, with the 2015d). The following records are from the is- exception of Kumlinge and Kökar (Lampinen et land of Dånö in Geta in 1901, on a field margin al. 2015a). The earliest dated knowledge is found in Lumparland in 1901 and from the harbour of in the paper by Bergstrand (1852). The species Mariehamn in 1912. One record regards a culti- was collected during every decade from 1866 to vated plant in Hammarland in 1931. The next re- the mid 1950’s, and it was particularly frequently cord is from a roadside in Mariehamn in 1996. found during the 1930’s. The last collection was Between 2002 and 2015, it has been observed as from a rye field 300 m west of the church in the a weed in the municipalities of Finström, Ham- municipality of Jomala in 1962. A possible find marland, Jomala, Kumlinge, Saltvik and Sund. in a field in the municipality of Saltvik in the mid Most of the recent records are on roadsides. C. in- 1970’s was never confirmed (Hæggström et al. tybys has recently been sown in fields grazed by 1982). A. githago disappeared in Åland Islands cattle and sheep in Åland, e.g. in Jomala, Djur- during the latter part of the 20th century and it be- vik, Lemland Rörstorp and Mariehamn Strand- came simultaneously very rare in the rest of Fin- näs. Plants have spread from the fields to road- land, with one record only, in Turku, during the sides in all three places. 21st century (Lampinen et al. 2015a). Dianthus deltoides – Two specimens of a culti- Anthemis tinctoria – A few specimens grew in var with deep dark red flowers grew in the ruder- the ruderal site in 2003–2009. This species is of- al site in 2006. Such cultivars are seen in gardens ten cultivated in flowerbeds and it is occasionally and as garden escapes.