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

Abstract

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.

Impact of changed cropping practices on weed occurrence in spring cereals in Finland – a comparison of surveys in 1997–1999 and 2007–2009

“…, 2011). However, increased total biomass of weeds in organic cropping was mainly explained by the success of E. repens , as reported also by Riesinger and Hyvönen (2006).…”

Ecological impacts of early 21st century agricultural change in Europe – A review

“…Most recent studies from northern Europe confirmed the local value of organic farming for arable flora (Riesinger and Hyvö nen, 2006;Hyvö nen, 2007), pollinators (e.g. Ekroos et al, 2008), and some bird species (Piha et al, 2007;.…”

Assessing the effect of the time since transition to organic farming on plants and butterflies

“…(2000) showed that the response of farmland birds to agricultural intensification had a time‐lag of about 8–10 years over England and Wales. However, as far as we are aware, evaluations of a time since transition effect on authentic farms in replicated landscapes have only been made by Riesinger & Hyvönen (2006), studying weed species composition (but see also Kleijn & van Zuijlen 2004).…”