Karlovské bučiny NNR (The Karlov Beechwoods) was declared in 1972 on the northern slopes of the Ještědský hřbet ridge (in the area of the Kryštofovy hřbety ridges). The NNR lies close to the city of Liberec between the villages of Karlov pod Ještědem and Kryštofovo údolí in the Liberecký kraj – Liberec Region. The reserve covers an area of 43.78 ha and stretches in an E-W direction. The 50 metre wide buffer zone covers an area of 24.61 ha. The steep slopes are at elevations between 360 – 580 metres above sea level and are oriented to the south-west in the eastern section and to the west and north-west in the western section. The NNR lies about 0.5 km from the Karlov railway line on the Liberec – Česká Lípa line and is bordered by forest tracks with a marked forest footpath running through the centre of the reserve. The railway line runs through a tunnel under the NNR. The subject of the protection is the ecosystem of herb-rich beechwoods on the crystalline limestone basement with preserved calciphilous vegetation, which is not found anywhere else in the region.
The protected area lies on the windward NW side of the Ještědský hřbet ridge. The climatic conditions are affected by the exposition and also by the proximity to the Ještěd mountain group which rises up to more than 1000 metres above sea level. The annual precipitation total is around 850 mm and mean annual temperatures are approximately 6.5 ºC.
The geological basement is built of crystalline limestones to dolomites and phyllitic greywackes to phyllites. The age of these rocks is uncertain but they are probably of Early Palaeozoic age. In places on the very steep slopes we can find rocky outcrops and Quaternary talus and the cover in some places is of Tertiary fluvial sediments. The soils are predominantly Cambisols with Podzols in places.
The NNR is a fragment of near-natural deciduous forest in the modified forest complexes of the Ještědský hřbet ridge, which are dominated by spruces in all other areas and at all vegetation levels. On the territory of the reserve we can find calciphilous beechwoods passing into herb-rich beechwoods, with smaller areas of acidophilous beechwoods and talus and ravine forest. The tree layer is dominated by beech (Fagus sylvatica) but we can also find sycamore (Acer pseudoplatanus), ash (Fraxinus excelsior), small-leaved lime (Tilia cordata) and Norway spruce (Picea abies) here. The herb layer is very rich and 230 vascular plant species have been identified here so far. In addition to common forest herbs we can find a whole range of very valuable species here. These include perennial honesty (Lunaria rediviva), martagon lily (Lilium martagon), lords and ladies (Arum maculatum), red and white helleborines (Cephalanthera rubra and Cephalanthera damasonium), coralroot orchid (Corallorhiza trifida) and the unique helleborine Epipactis microphylla.
The fauna in the Karlovské beechwoods is not exceptional and includes the common species for these biotopes. The old deciduous trees are a suitable habitat for birds which nest in hollow trees such as the black woodpecker (Dryocopus martius) and the greater spotted woodpecker (Dendrocopos major). The territory belongs to a hunting beat but inadequate game management has led to overpopulations of red and roe deer in the area and the introduction of non-native mouflon. The deer populations restrict the possibility of the forests rejuvenating naturally and also have a strong negative influence on the herb layer.
The crystalline limestones and dolomites are suitable for the formation of karst phenomena here. On the nearby Velký Vápenný vrch hill we can find the Západní jeskyně cave which is 350 metres in length and has a rich stalactite decoration (excentric stalagmites, helictites). Next to the NNR in the Rokytka stream valley we can find a number of underground spaces, some of which are also richly decorated (e.g. Nedobytná jeskyně cave). Old mine shafts can be found on the edge of the NNR, which were left behind by silver-ore miners. The Ještěd karst caves and the old mine shafts are favourite hibernating sites for several bat species, especially the lesser horseshoe bat (Rhinolophus hipposideros). A section of the Rokytka stream is proposed as a Site of Community Importance under the Natura 2000 system to protect the bullhead (Cottus gobio).