Arable weeds and their seedbanks are an important source of biological diversity, and crucial to the functioning of arable systems. The weed flora in the UK has declined over the past 50 years, along with other indicators of diversity, primarily due to the increased use of herbicide and the competitive suppression of weeds by autumn-sown crops.
The seedbank is a valuable reference in studies of ecological impact and in the conservation and restoration of the commoner arable flora. In particular, the persistence of seeds in the seedbank make them far less sensitive than the emerged flora to immediate conditions of the field or weather and therefore confer a certain degree of resilience to the arable weed community.
At the CSC platform, 60 x 1 kg bulk soil samples are collected to 20 cm depth from each field in March (360 samples across the site per year).
Soil is sieved to 10 mm and seeds germinated in seed trays under standard glasshouse conditions (light intensity 300µmol.m2.sec-1; 12 hour day length; 18 deg C min day temp; 15 deg C min night temp; shade screens operative at 600µmol.m2.sec-1 set and 22 deg C).
Numbers of emerged seedlings per species are recorded until no further emergence is observed for 7 days. Soil is then re-sieved and the process repeated for a 2nd flush.
In the first six year rotation, the arable weed seedbank community composition showed significant differences between fields (coloured points in the figure above).
However there was no difference between conventional (filled symbols) or sustainable (open symbols) treatments. Each field appears to have a seedbank “finger print” that is resilient to change in management.