Dářko NNR covers a forest peatbog which lies 1 km south of the municipality of Radostín in the kraj Vysočina – Bohemian-Moravian Highlands Region, on an area of 64.91 ha at elevations between 619 and 623 metres above sea level. The protected area was declared here in 1933 and is the largest transitional raised peatbog in the Bohemian – Moravian Highlands region with unusually well-reserved peatbog communities and bog pine stands (Pinus rotundata) and numerous protected and endangered plant and animal species can be found here.
The basement of the Dářská brázda depression is built of glauconitic sandstones and marlstones of the Dlouhá mez spur of the Bohemian Cretaceous Basin, which are covered by sand and clay-dominated Quaternary sediments. The peatbog of the transitional raised bog type formed on top of the older fen layers, which in turn were formed when the shallow Preboreal period lake was filled with acidic raised bog peat containing sphagnum mosses, cotton-grasses and a mixture of tree species which had grown here during the cold, damp climate of the Atlantic period. The microrelief of the peatbog is formed of a mosaic of peat banks and hollows. Water from this flat watershed flows to the Sázava and also to the Doubrava rivers. The reserve includes the most valuable part of the Padrtina seam of peat, which covers an area of 154 ha, has an estimated volume of peat – 6,206 million m3 of peat and a peat layer up to 8.6 metres in depth.
The plant communities on the peatbog belong to the Sphagnion medii alliance and to the Pino rotundatae-Sphagnetum and Andromedo polifoliae-Sphagnetum magellanici associations. The forest stands are formed of bog pine stands on the deep peat with the significant occurrence of the bog pine (Pinus rotundata) as this is the only locality in the Bohemian-Moravian Highlands region where it grows. In the gappy stands the bog pines are found in a mosaic (depending on the moisture levels), mixed with Scots pine (Pinus sylvestris) along with a whole range of hybrid pines (Pinus × digenea). Scattered downy birch (Betula pubescens) and Norway spruce (Picea abies) can also be found In the tree composition. More Norway spruces are found towards the edge of the reserve where they form pine-spruce mire forests with bilberry of the Dicrano-Pinion alliance. Tufts of hare’s-tail cottongrass (Eriophorum vaginatum) rise above the sphagnum layer (Sphagnum magellanicum, Sphagnum rubellum, Sphagnum papillosum, Sphagnum recurvum) and moss layer (Hylocomium splendens, Bazzania trilobata, Aulacomnium palustre, Ptilidium ciliare et al). Here we can also find an abundant shrub vegetation with bilberry (Vaccinium myrtillus), cowberry (Vaccinium vitis-idaea), bog whortleberry (Vaccinium uliginosum), cranberry (Oxycoccus palustris), marsh andromeda (Andromeda polifolia) and heather (Calluna vulgaris). A number of sedges also grow here, including string sedge (Carex chordorrhiza), slender sedge (Carex lasiocarpa), lesser tussock sedge (Carex diandra) and Hartmann’s sedge (Carex hartmanii,) in addition to round-leaved sundew (Drosera rotundifolia), marsh cinquefoil (Comarum palustre), creeping willow (Salix rosmarinifolia), lesser bladderwort (Utricularia minor) and others. Fungi which grow in Dářko NNR include the boletes Suillus flavidus and Leccinum variicolor, yellow swamp brittlegill (Russula claroflava) and the puffball Bovista paludosa.
A wide range of invertebrate species are bound to the conserved peatbog communities. Butterflies which are found here include cranberry blue (Vacciniina optilete), large heath (Coenonympha tullia) and also moths such as golden-rod brindle (Lithomoia solidaginis), the cameo (Polymixis gemmea), the brindle Apamea rubrirena, large ear moth (Amphipoea lucens), light knot grass (Acronicta menyanthidis), scarce silver Y (Syngrapha interrogationis), the geometrid Arichanna melanaria and Devon carpet (Lampropteryx otregiata). The peatbog butterfly: moorland clouded yellow (Colias palaeno) lived here but has not been recorded since the mid-1980s. The preserved natural environment in Dářko NNR is demonstrated by the presence of the ground beetles Carabus linnei, Carabus nitens, Carabus auronitens, Carabus glabratus and Trechus pulchellus, the ants Formica picea and Formica lugubris and the spiders Aphileta misera, Notioscopus sarcinatus and the fishing spider (Dolomedes fimbriatus). Strong amphibian populations live here, including the Alpine newt (Triturus alpestris), common toad (Bufo bufo), common frog (Rana temporaria), edible frog (Rana esculenta) and moor frog (Rana arvalis). The surface of the peatbog is the home of the slowworm (Anguis fragilis), viviparous lizard (Zootoca vivipara) and the adder (Vipera berus). Nesting bird species in the reserve include tawny owl (Strix aluco), meadow pipit (Anthus pratensis), the woodcock (Scolopax rusticola), spotted flycatcher (Muscicapa striata), dunnock (Prunella modularis), crested tit (Parus cristatus) as well as the great grey shrike (Lanius excubitor) and hen harrier (Circus cyaneus) which have been seen here during the nesting season. A permanent population of black grouse (Tetrao tetrix) lived in the area until the 1980s. Mammals which live on and around the peatbog include common shrew (Sorex araneus), field vole (Microtus agrestis), pine marten (Martes martes), badger (Meles meles) and red deer (Cervus elaphus)
The forest stands in the reserve are included in the category of protection forest and are left without intervention (to natural processes). Old drainage channels which are now completely overgrown, were dug for a length of 700 – 800 metres across the peatbog in the early 19th century. In the early 1980s, during works to drain the Padrtiny forest soil complex, deep ditches were dug towards the western and south-western edges of the NNR. However, during repair works to the drainage network the recipients of water in the buffer zone did not renew these channels. Žďárské vrchy PLA Administration monitors the water regime in the NNR by way of 6 probes.
The surroundings of the reserve have been influenced by man since Medieval times with the founding of the Velké Dářsko fishpond in around 1480 A.D. and the brushwood path which ran along the current eastern edge of Dářko NNR. The edge of the protected area is accessible by way of the Dářko themed nature trail. Visitors from the nearby recreational area tend to ignore the protection regime of the reserve and enter the territory without authorisation to gather forest fruits. The reserve is a notable object of scientific study in a number of fields and is a part of the unique Biocentre of Supraregional Importance under the Territorial System of Ecological Stability.