The area is part of the northern boreal vegetation zone, and its nature has plenty of eastern characteristics. According to the statistics of the Finnish Meteorological Institute, the mean annual air temperature is -0.5 °C. The mean temperature in January is -11.4 °C and in July 13.1 °C. The mean annual precipitation is 601 mm. The area is a watershed, where rivers flow towards three seas: river Yli-Nuortti flows to the Arctic Sea, river Hirvasjoki to the White Sea and river Värriöjoki to the Baltic Sea. The topography in the area varies: the landscape is a mosaic of old-growth forests on mineral and paludified soils, open mire patches, small rivers, steep gorges, sparse mountain birch forests, and open fell heaths and fragmented rock areas. The highest fell is round stony fell Sauoiva, 615 m a.s.l. The hilltop of Kotovaara, where the SMEAR I station is located, lies at about 370 m a.s.l.
The dominating tree species are Scots pine (Pinus sylvestris), Norway spruce (Picea abies), and pubescent birch (Betula pubescens). European aspens (Populus tremula), rowans (Sorbus aucuparia) and European bird cherries (Prunus padus) grow in places. The forest floor is covered with bilberry (Vaccinium myrtillus), crowberry (Empetrum nigrum) and mosses such as red-stemmed feather moss (Pleurozium schreberi). On the open fell heaths, for example black bearberry (Arctostaphylos alpina) and mountain everlasting (Antennaria dioica) form low patches.
The area is a part of reindeer herding area. Moose (Alces alces) are common, and all the Finnish large predators (lynx, brown bear, wolf, and wolverine) occur in the area. Capercaillies (Tetrao urogallus), black grouses (Lyrurus tetrix) and willow grouses (Lagopus lagopus) live in the forests. On the highest fells, one may observe ptarmigans (Lagopus mutus) and Eurasian dotterels (Eudromias morinellus). Both peregine (Falco peregrinus) and gyr falcon (Falco rusticolus) as well as golden eagle (Aquila chrysaetos) are found from the area. Northern hawk-owl (Surnia ulula) is common.
The station is surrounded by a strict nature reserve of 125 km2. The area was protected for nature conservation and scientific purposes on the 14th October 1981. Thanks to the multiple biotopes, the area is an important bird area (IBA) where e.g. dotterel (Eudormia morinellus) and red-flanked bluetail (Tarsiger cyanurus) nest.