Spatially structured population dynamics in feral oilseed rape

Abstract

We studied the population dynamics of feral oilseed rape (Brassica napus) for 10 years (1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002) in 3658 adjacent permanent 100 m quadrats in the verges of the M25 motorway around London, UK. The aim was to determine the relative importance of different factors affecting the observed temporal patterns of population dynamics and their spatial correlations. A wide range of population dynamics was observed (downward or upward trends, cycles, local extinctions and recolonizations), but overall the populations were not self-replacing (k < 1). Many quadrats remained unoccupied throughout the study period, but a few were occupied at high densities for all 10 years. Most quadrats showed transient oilseed rape populations, lasting 1-4 years.There were strong spatial patterns in mean population density, associated with soil conditions and the successional age of the plant community dominating the verge, and these large-scale spatial patterns were highly consistent from year to year. The importance of seed spilled from trucks in transit to the processing plant at Erith in Kent was confirmed: rape populations were significantly higher on the 'to Erith' verge than the 'from Erith' verge (overall mean 2.83-fold greater stem density). Quadrats in which k > 1 were much more frequent in the 'to Erith' verge, indicating that seed immigration can give the spurious impression of self-replacing population dynamics in time-series analysis.There was little evidence of a pervasive Moran effect, and climatic forcing did not produce widespread large-scale synchrony in population dynamics for the motorway as a whole; just 23% of quadrats had significant rank correlations with the mean time-series. There was, however, significant local spatial synchrony of population dynamics, apparently associated with soil disturbance and seed input. This study draws attention to the possibility that different processes may impose population synchrony at different scales. We hypothesize that synchrony in this system is driven by at least three processes: small-scale, local forcing caused by soil disturbance, intermediate-scale forcing as a result of seed input, and large-scale climatic forcing (e.g. winter rainfall) that affects the motorway as a whole.

Monitoring the occurrence of genetically modified oilseed rape growing along a Japanese roadside: 3-year observations

“…During our preliminary monitoring, however, oilseed rape plants along Route 51 were mainly found along the inbound lane (from Kashima to Narita). Such an asymmetrical distribution of oilseed rape plants between the two sides of the road was also reported by Crawley and Brown (2004) and von der Lippe and Kowarik (2007b). This evidence suggests that the oilseed rape plants found growing along Route 51 originated as seeds spilled from vehicles during transportation from the Port of Kashima into Keiyo District.…”

“…Depositions of seeds of these crops were associated with the direction of traffic flow. As in the report by Crawley and Brown (2004), seed spillage and dispersal by vehicles was the likely origin of these crops, since there were no potential seed sources near the tunnels.…”

“…Crawley and Brown (2004) found an asymmetrical distribution of oilseed rape (Brassica napus L.) along roads. Spontaneous oilseed rape populations were significantly more abundant in lanes leading to an oilseed processing factory than along the side of roads leading away from the factory.…”

The Biology of Canadian Weeds. 137. Brassica napus L. and B. rapa L.

“…Two further models developed in the United Kingdom describe the population dynamics of winter B. napus. The first examines the persistence of transgenic volunteer B. napus populations in fields (Begg et al 2006), while the second describes the spatial population dynamics of feral B. napus outside agricultural fields (Crawley and Brown 2004). A fifth model, developed in France, simulates the effect of cropping system on transgene escape through pollen flow in B. napus crops from volunteer and cropped plants (Colbach et al 2000) and a sixth model developed in Germany describes reproduction in volunteer winter B. napus (Gruber and Claupein 2007).…”

Spillage of Viable Seeds of Oilseed Rape along Transportation Routes: Ecological Risk Assessment and Perspectives on Management Efforts

“…Transport and handling have been identified as the main reasons for spillage of OSR (Crawley and Brown, 2004;Pivard et al, 2008) and are therefore the focus of the present work. In Central Europe, feral OSR plants are able to reproduce, and populations may persist for several years outside cultivation, especially along transportation routes such as railway lines or roads, as known for France (Pessel et al, 2001;Garnier et al, 2008;Pivard et al, 2008), Germany (Dietz-Pfeilstetter et al, 2006;Menzel, 2006;Elling et al, 2009;Middelhoff et al, 2009;Franzaring et al, 2016), the Netherlands (Tamis and de Jong, 2010), Great Britain (Crawley and Brown, 2004;Squire et al, 2010) and Austria (Pascher et al, 2000(Pascher et al, , 2006(Pascher et al, , 2010. In Switzerland, feral glyphosate resistant OSR (GT73) was identified on four of 79 sample sites (Schoenenberger and D'Andrea, 2012), although like in the European Union GT73 is not permitted for cultivation.…”