Combining strengths - PARTRIDGE flower mix plots perform best in comparison with other flower mix types!
Wildflower or wild bird seed mixes are a conservation measure, which are widely used within agri-environment schemes (AES). In the state of Lower-Saxony (Germany) there three different types of flower mixes are currently available under AES:
1) Annual flower mixes, which are sown each year. The vegetation from the previous year is removed in April and a mixture of annual plants are sown. This is repeated each year for five consecutive years.
2) Perennial flower mixes, which are sown in the first year with a seed mixture of perennial species and left for five years to allow natural succession.
3) Rotational flower mixes which are managed in a partridge-friendly way: One half of the sown plot is sown each year while last year’s vegetation on the other half is left untouched. In the advanced version of the PARTRIDGE flower mix, annual re-sowing of the annual part can be replaced by simple cultivation as the plants sown in the first year, reseed naturally (see Fig.1). The two parts are interchanged/rotated every year for five years. This creates a habitat with a diverse vegetation structure (Fig. 1). This method was developed in the Partridge Conservation Project in Göttingen and is now featured at the two PARTRIDGE Demonstration sites “Diemarden” and “Nesselröden”.
Fig. 1: Rotational flower mix plot at Diemarden demonstration site in mid-June – the annually cultivated area is on the right (after the second vegetation period re-sowing of this mix is not necessary and a simple cultivation in late winter is sufficient to create a suitable high-quality habitat).The area with second-year vegetation is on the left.
Andreas Wiedenmann’s masters thesis (2019) compared the Lower-Saxony’s three flower mix types with cereal fields growing in the same areas to assess differences in arthropod biomass as well as the possible preference of farmland songbirds for one of these four farmland habitat types. He sampled arthropod biomass using an insect vacuum (Fig. 2) and surveyed songbird abundance and species richness with point-counts once every month from April to July 2019.
Fig. 2: Sampling insect biomass with a vacuum.
The results best support the management method of the rotating flower mix plots. Levels of arthropod biomass in the part of the rotating flower mixes with last year’s vegetation are very similar to those in perennial flower fields and are substantially higher in April and May than in cereal fields. In June and July, however, arthropod biomass in the annually cultivated part of rotational flower mixes is higher than in the perennial part. The high availability of arthropod prey throughout the breeding season is reflected by the songbird abundance and species richness: only rotational flower mixes had significantly more visits by individuals and species than cereal fields (Fig. 3).
Figure 3: Bird abundance per hectare (ha) over four months in annual, rotational and perennial flower mix plots in comparison with cereal fields; the only significant difference occurs between cereal fields and rotational flower mix plots.
Bird abundance was also positively correlated with arthropod biomass: flower mix plots with a higher arthropod biomass attracted more birds!
Fig. 4: Example of arthropod biomass sample
Rotational flower mix plots offer arthropod prey throughout the whole breeding season and creates a structurally diverse habitat. Therefore, this measure benefits bird species with different habitat requirements.
Overall conclusion: Rotational flower mix plots combine the strengths of annual and perennial flower plots to maximize the effect of this conservation measure for farmland birds!
Written by Eckhard Gottschalk und Andreas Wiedenmann, University of Göttingen, PARTRIDGE project Germany, edited by Molly Crookshank and Francis Buner, PARTRIDGE project UK