Lokalmeteorologiska förhållanden i Västra Ängby, Knivsta : förstudie /

<p>Variation of pollen beetle abundance along within-field (A) and between-field (B) transects as a function of distance (km) to woodland edges. (A) Number of pollen beetles per sampling point within two different OSR fields (fields in complex site, C). (B) Mean number of pollen beetles per field in three transects (in zones S, for simple landscape, and HC, for highly complex landscape). Abundance were measured on 10 OSR plants at each sampling point during three (A) or four (B) consecutive weeks (dates 1 to 4). Trans: Transect.</p

Image_1_How farmers perceive perennial weeds in Northern France and Eastern Germany.tif

European farmers are required to follow the transition towards sustainable agriculture and food systems. Perennial weed management without chemical herbicides and inversion tillage is challenging farmers. Questions arise to cope with these spreading weeds. Our study focuses on farmers’ perceptions and experiences of perennial weeds and their control in Northern France and Eastern Germany. A survey was developed to explore the situation regarding present concerns and future problems for perennial weed control. The survey conducted from winter 2020/21 to spring 2021 targeted conventional, conservation and organic farms. We found a high level of awareness for perennial weeds. On average, 80.0% of Northern French farmers and 65.9% of Eastern German farmers revealed present concerns about perennial weeds. Both, Northern French and Eastern German farmers perceived perennial weeds are more damaging to crop production than other pests. In both regions, the farmers considered Cirsium arvense (L.) Scop. as the most important perennial weed. While the majority of the Eastern German farmers observed field infestations of Elymus repens (L.) Gould, Northern French farmers more often reported Sonchus arvensis L. infestations. More than 50% of the farmers stated Rumex spp. infestations in Northern France and Eastern Germany. Interestingly, Eastern German farmers are more concerned about future perennial weed problems than Northern French farmers. The reasons for farmer’s future concerns are probably connected to the farming system. In both regions, conservation and conventional farmers heavily rely on herbicides for perennial weed control, however, more farms used the active ingredient glyphosate in Eastern Germany. Nonetheless, perennial weed control is a major concern for organic farmers in both regions. We conclude that optimizing and integrating non-chemical alternatives is promising in all farming systems. Research activities are required to provide farmers and extension services with novel and profitable perennial weed management practices.</p

Observed pollen beetles mean abundance [±SE] (number for ten plants) by site and date.

<p>Observed pollen beetles mean abundance [±SE] (number for ten plants) by site and date.</p

Value of fitted dispersal distance global (D_mean) at each date (D_mean (t_n)) and impact of time on the dispersal (β_dt) for the best model (N°1) and for the best model without field effect (N°7).

<p>Value of fitted dispersal distance global (D_mean) at each date (D_mean (t_n)) and impact of time on the dispersal (β_dt) for the best model (N°1) and for the best model without field effect (N°7).</p

Map of the four studied sites (Normandy region, France), describing land uses within two kilometers radius buffer around the barycenter of the sampled OSR fields in 2015.Green: woodlands.

<p>Blue: grasslands. Yellow: OSR crops. Diamond: sampled OSR fields. Red lines: between fields transect lines. Red circles single out fields where we followed within-field transects from woodlands over 200 m. We distinguish four sites with differing complexities: Highly Simple: HS (7 fields), Simple: S (4 fields), Complex: C (7 fields), Highly Complex: HC (5 fields). Complexity here is a gradient of woodland surfaces in each sites, simple is a site with few woodlands.</p

Landscape characteristics of the four study sites in 2009 (within two kilometers of sampled fields).

<p>Woodland edges are the first 100 m within the woodlands from its edge.</p

Best models obtained out of the 161 models estimating pollen beetles dispersal from woodlands to OSR, constraining in turn each modality (categorical factor type, origin, Field point structure, kernel and site dependant dispersal) leaving other modalities and parameters free, with or without a field effect.

<p>Bold: parameter constrained, allowing a field effect. Underlined: parameter constrained, not allowing a field effect.</p

Parameters and modalities used to test the 161 models.

<p>Parameters and modalities used to test the 161 models.</p