Table 2. Tuber densities before and after the swan autumn stopover period.
Measured tuber densities (mean ± SE, (N)) in four patch types in the Lauwersmeer in four years. Samples were taken in autumn shortly before the arrival of swans (“Initial”) and after swan departure (“Final”). N is number of sampling points.
| Year | 2005 | 2006 | 2007 | 2008 | ||||
|---|---|---|---|---|---|---|---|---|
| Patch Type | Initial | Final | Initial | Final | Initial | Final | Initial | Final |
| Sandy—Shallow | 13.2 ± 2.2 (43) | 8.8 ± 1.4 (43) | 19.4 ± 2.2 (39) | 11.4 ± 1.2 (39) | 13.3 ± 2.0 (28) | 8.5 ± 0.7 (28) | 14.7 ± 2.1 (28) | 11.6 ± 1.4 (28) |
| Sandy—Deep | 16.4 ± 3.5 (5) | 20.6 ± 1.6 (5) | 13.9 ± 1.6 (6) | 7.5 ± 1.5 (6) | 7.9 ± 1.9 (12) | 7.0 ± 1.6 (12) | 17.5 ± 4.9 (11) | 15.4 ± 3.1 (11) |
| Clayey—Shallow | 9.9 ± 2.6 (31) | 9.2 ± 1.4 (31) | 14.2 ± 2.2 (35) | 14.2 ± 2.3 (35) | 14.9 ± 2.0 (30) | 10.0 ± 1.6 (30) | 19.3 ± 3.5 (33) | 14.8 ± 2.6 (33) |
| Clayey–Deep | 22.2 ± 4.9 (11) | 18.1 ± 5.9 (11) | 27.0 ± 4.9 (10) | 24.4 ± 4.1 (10) | 12.4 ± 1.4 (15) | 12.5 ± 1.7 (15) | 30.7 ± 6.0 (13) | 22.6 ± 4.0 (13) |
| Weighted Mean | 14.5 | 13.2 | 17.7 | 12.3 | 12.0 | 8.8 | 18.2 | 14.5 |