Environmental-friendly farming in Switzerland is not hornwort-friendly

Leave overwinter stubbles

A replicated before-and-after study in 1989-2005 on 28 selected arable fields in the western Swiss Plateau (Bisang et al. 2009) found that populations of two hornwort species (Anthoceros agrestis and Phaeoceros carolinianus, the latter rare) declined between surveys carried out before and after introduction of the Swiss agri-environment scheme in 1999. An index of hornwort abundance was greater during an initial survey in 1989-1995 than in a repeat survey of the same sites in 2005-2007. Hornwort abundance was strongly affected by the availability of stubble fields. The proportion of stubble fields left unmanaged after harvest was found to decrease between the survey periods. The scheme appeared suboptimal for conserving hornwort taxa because it did not support the maintenance of autumn or winter stubble fields (which, in turn, declined as a result of soil conservation measures introduced in 2005). Selected fields (on average 1-2 ha) were surveyed every September-October, and observations of hornwort occurrences (of A. agrestis and P. carolinianus gametophytes, based on 20 minutes search by two people) were used to calculate an abundance index. Crop type and management were also recorded.