Table 4.
Numbers of flowers supplied by selected agri‐environment options on arable farmland, based on densities per m2 of floral units, scaled × 10 000 to get per ha values
| Option and entry level stewardship code | Source | Mean density of floral units per ha per month* | Period of flowering time |
|---|---|---|---|
| Nectar flower mixture EF4 | Carvell et al. (2007)* | 215 342 (14 160) | May–August† |
| Nectar flower mixture EF4 | Carvell et al. (2011)‡ | 419 970 (42 606) | May–August |
| Wildflower mixture EE3/HE10 | Carvell et al. (2007) | 244 841 (20 533) | May–August |
| Tussocky grass mixture EE3 | Carvell et al. (2007) | 19 525 (2 642) | May–August |
| Uncropped natural regeneration EF11 | Carvell et al. (2007) | 73 124 (7 463) | May–August |
| Cropped cereal headland EF9 | Carvell et al. (2007) | 34 916 (5 575) | May–August |
Adapted from data on 6 m field margins, averaged over 3 years (2002–2004), 92–108 plots per year. Mean numbers of floral units of all species in flower at any sampling time.
Flower densities were much higher in July and August than May and June, particularly for pollen & nectar mix, but reported values under each option are averages per month (Carvell et al., 2007).
Adapted from data for nectar flower mix planted in blocks of between 0.25 and 1 ha, averaged over 3 years (2005–2007), 100–118 plots per year. Mean numbers of floral units of bumblebee‐visited plant species in flower at any sampling time are presented.
Standard errors (in brackets) represent variation between sites, months, and years.