Wildlife triangle

Riistakolmioaineisto, talvilaskennat Laji- ja vuosittaiset lumijälkien lukumäärät, sekä keskimääräiset lumijälkiin perustuvat runsausindeksit 50 × 50 km ruudukossa. Lumijälki-indeksi riistakolmiolle (eli noin 12 km pituiselle laskentalinjalle) lasketaan seuraavasti: N / (km_laskettu × lumipäiviä). Tässä N on laskentalinjan ylittävien lumijälkien lukumäärä. Nimittäjässä suluissa on laskentapanostus, joka saadaan lasketun kilometrimäärän (km_laskettu) ja jälkien kertymäpäivien (lumipäiviä) tulona. Lumipäivät lasketaan edellisestä lumisateesta tai ns. esikierrosta, jolloin laskija on kartoittanut vahat lumijäljet, jotta ei laskisi niitä uudestaan varsinaisessa laskennassa. Tässä esitetty laji-, vuosi- ja ruutukohtainen indeksi on aritmeettinen keskiarvo lumijälki-indekseistä niistä riistakolmioista, joiden painopiste osuu kyseiseen ruutuun. Lajikohtaisten indeksien lisäksi, myös jälkien yhteenlaskettu lukumäärä sekä riistakolmioiden lukumäärä on raportoitu. Ruudukko on muodostettu ETRS-TM35FIN -koordinaattijärjestelmän mukaan ja ruutujen sijainnit on ilmaistu vasemman alakulman koordinaatteina (”lon” ja ”lat”).

Wildlife triangle data, winter census Species-specific annual snow-track counts and average snow-track abundance indices in 50 × 50 km grid cells. The snow-track abundance index for a wildlife triangle (a ~12 km line transect) is calculated as N / (km_counted × snow_days). Here N is the number of snow-tracks crossing the transect line. The denominator stands for counting effort, consisting of the kilometers counted (km_counted) multiplied with the number of days during which tracks have accumulated (snow_days). The snow days are counted from last snowfall, or from the timing of a pre-mapping of snow-tracks, which prevents from recounting the tracks during the actual survey. The presented index for a given species, year and grid cell is calculated as the arithmetic mean index over all triangles, whose point of gravity are within the focal grid cell. In addition to the species-specific average abundance indices, also the number of snow tracks recorded, and the number of triangles counted are reported. The grid is constructed according to the ETRS-TM35FIN -coordinate system and the grid cell locations are given using the lower left corner coordinates (“lon” and “lat”).

Data and Resources

Additional Info

Field Value
Source https://www.riistakolmiot.fi/
Author Andreas Lindén
Maintainer Andreas Lindén
Last Updated February 15, 2022, 14:54 (EET)
Created February 15, 2022, 14:53 (EET)
% digitized 100
Coverage basis threatened and invasive mammal species in the winter track counts, excluding the large carnivores.
Data embargo period (years) 3
Data quality Professional / professionally curated
Data quality description Monitoring scheme
Geographical coverage Finland; boreal zone forests
Language (of the data) Finnish
Methods Line-transect census of snow tracks. The transect is ca 12 km long, shaped as an equilateral triangle and located in boreal forest landscape. The survey is done during one day by volunteers, mainly local hunters, skiing or walking along the transect. The survey period starts the 15th January and ends on the 28th February in the southern and central parts of Finland. In the northern parts of Finland (Oulu region and Lapland) the period continues until 15th March.
Size ~500 kB
Taxonomic coverage Siberian flying squirrel (Pteromys volans); http://tun.fi/MX.48243 Muskrat (Ondatra zibethicus); http://tun.fi/MX.48537 Raccoon dog (Nyctereutes procyonoides); http://tun.fi/MX.46564 American mink (Neovison vison); http://tun.fi/MX.47243 European polecat (Mustela putorius); http://tun.fi/MX.47240 White-tailed deer (Odocoileus virginianus); http://tun.fi/MX.47629
Temporal coverage 1989–2018