Fig. 1.
Location of the study area.
Explanations: 1 – lakes, 2 – scope of the study area, 3 – country border.
Table 1.
Numerical and areal variation of islands (according to Choiński 2007).
| Size class | Number of islands | Total area of islands | ||
|---|---|---|---|---|
| [ha] | [–] | [%] | [ha] | [%] |
| <1 | 783 | 70.22 | 314.3 | 13.12 |
| 1–5 | 253 | 22.69 | 560.4 | 23.40 |
| 5–10 | 38 | 3.41 | 251.8 | 10.51 |
| 10–20 | 18 | 1.61 | 265.0 | 11.06 |
| 20–50 | 15 | 1.35 | 393.4 | 16.42 |
| >50 | 8 | 0.72 | 610.7 | 25.49 |
| Total | 1115 | 100.00 | 2395.8 | 100.00 |
Fig. 2.
Examples of lakes (presented in different scales) with the highest island index (%) (Choiński 2007, changed).
Table 2.
Number of lakes and their surface areas on individual lakes based on the orthophotomaps.
| Lake district | Number of lakes | Total area of lakes | Number of lakes with islands | Number of islands | Total area of islands |
|---|---|---|---|---|---|
| [-] | [ha] | [-] | [-] | [ha] | |
| Pomeranian | 3214 | 106,622.6 | 234 | 407 | 714.60 |
| Masurian | 2019 | 135,138.0 | 236 | 572 | 1231.77 |
| Great Poland-Kuyavian | 1298 | 45,375.7 | 80 | 136 | 215.20 |
| Total | 6531 | 286,136.3 | 550 | 1115 | 2161.57 |
Table 3.
Share of islands in area ranges.
| Area range | Number of islands | Share |
|---|---|---|
| [ha] | [–] | [%] |
| 20–100 | 24 | 2.2 |
| 10–20 | 14 | 1.3 |
| 5–10 | 35 | 3.1 |
| 1–5 | 223 | 20.0 |
| Below 1 | 819 | 73.4 |
| Total | 1115 | 100.0 |
Table 4.
Surface areas of the largest islands on Polish lakes.
| Name of island | Name of lake | Area of islands based on orthophotomap [ha] |
|---|---|---|
| Wielimska | Wielimie | 94.6 |
| Ostrów Wielki | Wdzydze | 92.5 |
| Ostrów | Jeziorak | 85.1 |
| Duży Ostrów | Mamry | 79.8 |
| Bielawa | Drawsko | 75.0 |
| Upałty | Mamry | 68.3 |
| Róż | Orzysz | 56.4 |
Table 5.
Lakes with the highest number of islands (based on the orthophotomap).
| Lake | Number of lakes in the catalogue of Poland (Choiński 2006) | Area of the islands | Number of islands | Altitude |
|---|---|---|---|---|
| [ha] | [–] | [m a.s.l.] | ||
| Mamry | II-16-2 | 302.8 | 32 | 115.8 |
| Narie | II-23-32 | 26.99 | 17 | 104.6 |
| Jeziorak | II-32-41 | 192.2 | 16 | 99.2 |
| Dadaj | II-25-16 | 22.71 | 16 | 122.5 |
| Wigry | II-19-01 | 63.49 | 13 | 131.9 |
| Drawsko | I-44-36 | 86.57 | 12 | 128.3 |
| Kisajno | II-16-02 | 156.55 | 11 | 115.8 |
| Wielimie | I-45-53 | 124.32 | 11 | 132.6 |
| Wdzydze (whole) | I-28-47 | 140.96 | 9 | 134.1 |
| Orzysz | II-37-18 | 72.76 | 9 | 119.7–120.0 |
| Wulpińskie | II-34-32 | 22.76 | 7 | 105.8 |
| Bytyńskie | III-19-10 | 26.67 | 6 | 84.8 |
| Gopło | III-23-01 | 26.49 | 5 | 76.8–77.2 |
Table 6.
Lakes with the highest island index (more than 10%) (based on the orthophotomap).
| Lake | Number of lakes in the catalogue of Poland (Choiński 2006) | Area of the lake | Area of the islands | Number of islands | Island index |
|---|---|---|---|---|---|
| [ha] | [ha] | [–] | [%] | ||
| No name | I-28-51 | 2.0 | 0.36 | 1 | 180.0 |
| No name | I-76-01 | 1.2 | 0.20 | 1 | 16.8 |
| No name | I-19-92 | 1.5 | 0.22 | 1 | 14.9 |
| No name | I-27-98 | 3.4 | 0.51 | 9 | 14.8 |
| Szczurkowskie | II-53-06 | 31.2 | 4.37 | 1 | 14.0 |
| No name | II-05-05 | 16.2 | 2.21 | 1 | 13.6 |
| Lubicko Wielkie | I-45-07 | 195.0 | 25.98 | 2 | 13.3 |
| Wdzydze (whole) | I-28-47 | 1 078.6 | 140.96 | 9 | 13.1 |
| Przemęckie I | III-49-17 | 233.8 | 27.31 | 2 | 11.7 |
| Gordyjskie | II-17-48 | 30.0 | 3.40 | 1 | 11.3 |
| Ostrowieckie | I-83-20 | 123.8 | 13.79 | 2 | 11.1 |
| Ostrowite | I-18-104 | 10.5 | 1.15 | 1 | 11.0 |
Table 7.
Lake islands in Poland and their protection.
| Lake district | Number of lakes with islands based on the topographic map | Total number of islands based on the topographic map | Total area of islands | Number of islands under legal protection | Area of islands under protection | Share of islands under protection in total number of islands | Share of area of islands under protection in total area of islands |
|---|---|---|---|---|---|---|---|
| [–] | [–] | [ha] | [–] | [ha] | [%] | [%] | |
| Pomeranian | 239 | 410 | 822.0 | 343 | 796.00 | 83.7 | 96.8 |
| Masurian | 215 | 541 | 1342.5 | 506 | 1316.85 | 93.5 | 98.1 |
| Great Poland-Kuyavian | 102 | 164 | 231.3 | 114 | 196.40 | 69.5 | 84.9 |
| Total | 556 | 1115 | 2395.8 | 963 | 2309.25 | 86.9 | 96.4 |
Table 8.
Lake islands in national parks.
| Lake district | Number of lakes with islands in national parks based on topographic maps | Total number of islands in national parks | Total area of protected islands in national parks | Share of islands under protection in national parks in total number of islands | Share of area of islands under protection in national parks in total area of islands |
|---|---|---|---|---|---|
| [ha] | [%] | [%] | |||
| Pomeranian | 7 | 12 | 17.5 | 2.9 | 2.1 |
| Masurian | 3 | 16 | 88.5 | 3.0 | 6.6 |
| Great Poland-Kuyavian | 1 | 2 | 2.1 | 1.2 | 0.9 |
| Total | 11 | 30 | 108.1 | 2.7 | 4.5 |
Table 9.
Lake islands in nature reserves.
| Lake district | Number of lakes with islands in nature reserves based on topographic maps | Total number of islands in nature reserves | Total area of islands in nature reserves | Share of islands under protection in nature reserves in total number of islands | Share of area of islands under protection in nature reserves in total area of islands |
|---|---|---|---|---|---|
| [–] | [–] | [ha] | [%] | [%] | |
| Pomeranian | 10 | 12 | 54.25 | 2.9 | 6.6 |
| Masurian | 23 | 106 | 384.0 | 19.6 | 28.6 |
| Great Poland-Kuyavian | 6 | 15 | 72.4 | 9.1 | 31.3 |
| Total | 39 | 133 | 510.65 | 11.9 | 21.3 |
Table 10.
Lake islands in landscape parks.
| Lake district | Number of lakes with islands in landscape parks based on topographic maps | The total number of islands in the landscape parks | Total area of islands in the landscape parks | Share of islands under protection in the landscape parks in the total number of islands | Share of the area of islands under protection in the landscape parks in the total area of islands |
|---|---|---|---|---|---|
| [–] | [–] | [ha] | [%] | [%] | |
| Pomeranian | 43 | 98 | 408.65 | 24.2 | 49.7 |
| Masurian | 23 | 60 | 278.30 | 11.1 | 20.7 |
| Great Poland-Kuyavian | 16 | 36 | 84.45 | 22.0 | 36.5 |
| Total | 82 | 194 | 771.40 | 17.4 | 32.2 |
Table 11.
Lake islands in Natura 2000 areas.
| Lake district | Number of lakes with islands in Natura 2000 areas | Total number of islands in Natura 2000 areas | Total area of islands in Natura 2000 areas | Share of islands under protection in Natura 2000 areas in the total number of islands | Share of the area of islands under protection in Natura 2000 areas in the total area of islands |
|---|---|---|---|---|---|
| [–] | [–] | [ha] | [%] | [%] | |
| Pomeranian | 131 | 241 | 608.60 | 59.5 | 74.8 |
| Masurian | 90 | 246 | 860.15 | 45.5 | 64.1 |
| Great Poland-Kuyavian | 38 | 71 | 118.90 | 43.3 | 51.4 |
| Total | 259 | 558 | 1587.65 | 50.3 | 66.5 |
Table 12.
Lake islands in protected landscape areas.
| Lake district | Number of lakes with islands in protected landscape areas | Total number of islands in protected landscape areas | Total area of islands in protected landscape areas | Share of islands under protection in protected landscape areas in the total number of islands | Share of the area of islands under protection in protected landscape areas in the total area of islands |
|---|---|---|---|---|---|
| [-] | [-] | [ha] | [%] | [%] | |
| Pomeranian | 108 | 202 | 473.90 | 49.3 | 57.7 |
| Masurian | 163 | 405 | 937.75 | 74.9 | 69.9 |
| Great Poland-Kuyavian | 46 | 74 | 97.90 | 45.1 | 32.0 |
| Total | 317 | 681 | 1509.55 | 61.1 | 63.0 |
Table 13.
Lake islands are protected individually in the form of ecological sites, nature and landscape complexes and natural monuments.
| Lake district | Number of lakes with islands in the form of individual nature protection | The total number of islands in the form of individual nature protection | Total area of islands in the form of individual nature protection | Share of islands in the form of individual nature protection in the total number of islands | Share of the area of islands in the form of individual nature protection in the total area of islands |
|---|---|---|---|---|---|
| [–] | [–] | [ha] | [%] | [%] | |
| Pomeranian | 21 | 43 | 36.30 | 10.5 | 4.4 |
| Masurian | 15 | 55 | 312.40 | 10.2 | 23.3 |
| Great Poland-Kuyavian | 12 | 23 | 52.45 | 14.0 | 22.7 |
| Total | 48 | 121 | 401.15 | 10.9 | 16.7 |