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Colonization by Robinia pseudoacacia of various soil and habitat types outside woodlands in a traditional Central-European agricultural landscape

Ivajnsic D., Cousins S., Kaligaric M.

Polish Journal of Ecology

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2012

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Vol. 60, nr 2

301-309

EN

The invasiveness of Robinia pseudoacacia, one of the most invasive alien tree species in the agricultural landscapes of Central Europe, was studied in relation to its colonization of various soil and habitat types. The study area was a traditional agricultural landscape in Goricko Landscape Park (Slovenia), a hilly region, where half the territory is covered by forests and where R. pseudoacacia is also common. Habitat mapping in the field with a resolution of two meters was applied and further elaborated in GIS. It revealed 1307 patches colonized by R. pseudoacacia and belonging to 11 habitat types, covering 0.6% of the total study area. The most widespread were pure R. pseudoacacia stands, representing 69% of the total patch area. R. pseudoacacia is also abundantly present in small woodlots (19%) and in lowland and collinar riverine willow scrub (6%). The patches vary little in fractal dimension; the elongation index is highest in lowland and collinar riverine willow scrub, stream ash-alder woods and mixed stands. The most frequently invaded soil is pseudogley, with more than 38% of the total surface, followed by 21% for fluvisol and 17% for eutric cambisol. We confirmed that distance from nearest woodland is important, since almost 32% of the invaded patches are found at a distance of 1-100 meters from closed woodland.

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Weed diversity in cottage building material used in 19th century : past and present of the plant occurence

Pausic I., Skornik S., Culiberg M., Kaligaric M.

Polish Journal of Ecology

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2010

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Vol. 58, nr 3

577-583

EN

Desiccated seeds were used in order to evaluate qualitatively and quantitatively the weed vegetation present in traditional Central-European agricultural landscape of the second half of the 19th century. More than seven thousand seeds were excavated from 100 kg of loam, chaff and straw that had been used as building material of cob cottages in NE Slovenia. About 7100 of these were wild plants, while only 126 belonged to cultivated/escaped species (cereals excluded). The diaspores belonged to 89 taxa and most of them were attributed to plant species from disturbed habitats (weeds and ruderals). A comparison with current conservation status of species found in the region showed that some of the weeds, such as Agrostemma githago, Anthemis cotula, Centaurea cyanus, Kickxia elatine, Papaver dubium and Ranunculus arvensis, are nowadays rare and threatened species. On the other hand, some weeds or ruderals that are very common nowadays were not found in the material. One species, Paronychia cephalotes, was found, which has not been recorded before on Slovenian territory. The plant material stored in the construction material of the cottage, gives us insight into the vegetation assemblages of arable land before the development of more intensive tillage and cultivation in the second half of the 20th century, which dramatically changed the Central-European agricultural landscape.

3

Semi-natural grasslands : the effects of cutting frequency on long-term changes of floristic Composition

Kramberger B., Kaligaric M.

Polish Journal of Ecology

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2008

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Vol. 56, nr 1

33-43

EN

The objective of the experiment was to study the effects of different frequencies of cutting on long-term changes in the floristic composition of grassland, with an emphasis on the effects of very late cutting. Cutting at 2, 4, 6, 8, 10 and 12-weekly intervals was applied from 1995 to 2006 in a randomized block experiment on semi-natural grassland fertilized with 170 kg N, 40 kg P and 150 kg K ha[^-1]. The floristic composition of treatments was determined in May 1995, 1999, 2002 and 2006. In the final year (2006) the proportion of grasses in the dry matter of harvest was highest (77%) in the treatment with the least frequent cuts, and it was the highest obtained during the whole experiment. Under very frequent cuts, the proportion of grasses ranged only from 45 to 57%. Among legumes, only Trifolium repens L. was represented in high proportions in the dry matter of the harvest (from 19 to 25%) in 2006, but only in the treatments involving high cutting frequencies. The proportion of non-legume forbs in treatments involving low cutting frequency did not exceed other treatments; moreover, their proportion in the dry matter of the harvest in the treatment with the lowest cutting frequency decreased significantly to the lowest value (19%). The increased proportion of grasses in treatments with low cutting frequency indicates that a very late cut does not necessarily mean that forbs increase in the floristic composition, but can help grasses to retain their dominant and stable proportion in the semi-natural sward. Consequently when farmers are being provided with financial incentives with the aim of protecting diversity and the natural environment, it is worth recommending also a very late cutting, which includes natural reseeding to a greater extent. This can help to find a compromise between farmers' expectations of stable yield and quality forage, and the public interest in having grasslands of high biodiversity.