The occurrence of alien plant species in field margins in Finland

The results suggest that alien plant species comprise an important part of the biodiversity of Finnish field margins and semi-natural agricultural habitats. The role of field margins as dispersal corridors for invasive alien plants is limited for certain species

Weed occurrence in Finnish coastal regions: a survey of organically cropped spring cereals

Weed communities of organically cropped spring cereal stands in the southern and the northwestern coastal regions of Finland (= south and northwest, respectively) were compared with respect to number of species, frequency of occurrence, density and dry weight. Regional specialization of agricultural production along with differences in climate and soil properties were expected to generate differences in weed communities between south and northwest. Total and average numbers of species were higher in the south than in the northwest (33 vs. 26 and 15.6 vs. 10.0, respectively). Some rare species (e.g. Papaver dubium) were found in the south. Fumaria officinalis and Lamium spp. were found only in the south. The densities and dry weights of Lapsana communis, Myosotis arvensis, Polygonum aviculare, Tripleurospermum inodorum and Vicia spp. were higher in the south, while the densities and dry weights of Elymus repens, Persicaria spp. and Spergula arvensis were higher in the northwest. Total density of weeds did not differ between south and northwest (average = 565 vs. 570 shoots m-2, respectively). Total dry weight of weeds was higher in the northwest compared with the south (average = 1594 vs. 697 kg ha-1, respectively), mainly due to the high dry weight of E. repens. The only variable that was dependent on the duration of organic farming was weed density in the south. The abundance of nitrophilous in relation to non-nitrophilous weed species was higher while the abundance of perennial ruderal and grassland weed species was lower compared with previous weed surveys. This can be regarded as the result of increasing cropping intensity on organic farms in Finland. Different weed communities call for the application of specific target-oriented weed management in the respective coastal regions

Temporal and spatial variation in weed community composition of spring cereal fields

Academic Dissertation Helsinki, May 28th at 12 o'clock noon, 2004. KIRVA KSU/XII, N11.v2004okDiss. : Helsingin yliopisto, 200

Impact of temperature and germination time on the success of a C4 weed in a C3 crop: Amaranthus retroflexus and spring barley

Elevation in temperatures due to climate change could promote the invasion by C4 weed species of arable fields in the boreal region, which are dominated by C3 crops. The success of Amaranthus retroflexus L. (a C4 weed) in spring barley (a C3 crop) was studied at current and elevated temperatures (3°C difference) in a greenhouse experiment in southern Finland. The competition treatments included no competition and four levels of competition with barley, differing in terms of germination time. The success of A. retroflexus was measured as growth (height and biomass) and seed production (number and biomass). Elevation in temperature enhanced seed production of A. retroflexus, but the impact on growth was minor (only difference in plant height in one treatment). The growth and seed production of A. retroflexus in competition with barley was minimal although the growth of barley decreased with the rise in temperature. The results indicate that climate change could improve growth of a C4 weed such as A. retroflexus, but it is unlikely to succeed in spring barley

Weed mapping activities in Scandinavia and Finland

Weed mapping in Nordic countries; what has been done

The change in the distribution of arable weeds in Europe as a consequence of climate change

This study aimed at exploring the future distribution of 25 weeed species, representing different distribution patterns and taxa, at European scale. Using generalized additive models, and data on current climate and species distributions and two different climate scenarios for the period 2051-2080, we developed predictions of the currently suitable area and potential range size changes of 25 European weed species

Weed flora and weed management of field peas in Finland

The composition of the weed flora of dry pea (Pisum sativum L.) fields and cropping practices were investigated in southwestern Finland. Surveys were done in 2002–2003 in 119 conventionally cropped fields and 64 fields under organic cropping. Herbicides were applied to 92% of conventionally cropped fields where they provided relatively good control but were costly. Weeds were controlled mechanically only in five fields under organic production. A total of 76 weed species were recorded, of which 29 exceeded the 10% frequency level of occurrence. The average number of weed species per field was 10 under conventional cropping and 18 under organic cropping. The most frequent weed species in both cropping practices were Chenopodium album, Stellaria media and Viola arvensis. Elymus repens was the most frequent grass species. The difference in species composition under conventional and organic cropping was detected with Redundancy Analysis. Under conventional cropping, features of crop stand and weed control explained 38.7% and 37.6% of the variation respectively. Under organic cropping the age of crop stand and field location (y co-ordinate) respectively explained best the variation. Weeds could be efficiently managed with herbicides under conventional cropping, but they represented a significant problem for organic production. Mixed cultivation of pea with cereals is recommended, particularly for organic cropping, as it favours crop competition against weeds

Temporal and spatial variation in weed community composition of spring cereal fields

Academic Dissertation Helsinki, May 28th at 12 o'clock noon, 2004. KIRVA KSU/XII, N11.v2004okDiss. : Helsingin yliopisto, 200

Repeated surveys in Finland follow the changes of weed flora in spring cereal fields

Typically, as observed in 1997-1999, the average weed species number was about 25 in organically farmed field and some 10 species less in conventionally farmed field. In this respect, organic farming clearly promotes biodiversity at the farm scale but not so much at the national scale as the field area of organic cropping is only about 6 % of the total Finnish field area

Juolavehnä valtaa kevätviljapellot

Juolavehnä on yleistynyt ja runsastunut kevätviljapelloilla. Se tuottaa puolet tavanomaisesti viljeltyjen peltojen ja neljäsosan luomupeltojen rikkakasvimassasta. Juolavehnä menestyy karjatilojen nurmikierrossa.vo