East European forest steppe
The East European forest steppe ecoregion (WWF ID: PA0419) is a patchwork of broadleaf forest stands and grasslands (steppe) that stretches 2,100 km across eastern Europe from the Ural Mountains in Ural, through Povolzhye, Central Russia to the middle of Ukraine.There are also isolated areas of similar character off the western end in eastern Romania, Moldova, and Bulgaria. The region forms a transition zone between the temperate forests to the north, and the steppe to the south. The forest-steppe is an area of Russia in which precipitation and evaporation are approximately equal. The ecoregion  is in the Palearctic realm, with a Humid Continental climate. It covers . Location and description. The ecoregion forms a long band, about 2,100 km long and 600 km wide, from western edge of Siberia at the Ural Mountains in Ural in the east, through Povolzhye, to Central Russia and Ukraine. Most of the terrain is rolling hills and some plains. Average elevations range from 150 meters (above sea level) in the lowlands to 250 meters in the hills, with some isolated ranges of low mountains on the edges of the area. The ecoregion can be divided into sub-provinces from  west to east: Dnieper Upland, Dnieper Lowland, Central Russian Upland, Oka–Don Plain, Volga Upland, and the Trans-Volga. Moisture diminishes as the ecoregion stretches to the east, as does the forest fragmentation. Climate. The climate in most of the ecoregion is "Humid continental climate, warm summer" (Köppen climate classification (Dfb)). This climate is characterized by large seasonal temperature differentials and a warm summer (at least four months averaging over , but no month averaging over . Seasonal temperature extremities increase eastward across the ecoregion, due to the nature of continental climate towards the center of the continent. Flora. The natural vegetation  of the forest steppe is a mosaic of woodlands and open shrublands and grasslands. Shrublands typically include the shrubs "Caragana frutex, Prunus fruticosa", and "Prunus stepposa". "Stipa ucrainica" and "Bromus riparius" are common grasses. Typical trees of the woodlands and forests include "Quercus robur, Tilia cordata, Acer platanoides", and "Corylus avellana". For centuries, scientists have speculated on the causes of variations in stands of trees. It is currently understood that on the macro level, steppes are more arid and that trees thin out in the transition zones. Because the terrain of the ecoregion is relatively flat or low hills, with  no physical barriers between the biomes to the north and south, the plant communities tend to be shaped by local variations in water flow. Differences in drainage, variations in soil type (pine trees on sandy soil, deciduous trees on loamy soil, etc.) and salinity, the effects of blowing wind (which drives snow off the hills into depressions, affecting soil quality), and the historic activities of humans all combine to create the mosaic character of the region. Open landscapes show that steppe plant communities can compete with forest. Sedges are characteristic in the steppe areas, resisting low-moisture conditions with much  of their biomass underground. Fauna. Characteristic mammals include the bobak marmot ("Marmota bobak") and European ground squirrel ("Spermophilus citellus"). The European bison ("Bison bonasus") and Saiga antelope ("Saiga tatarica tartarica") formerly lived in the forest-steppe, but are now locally extinct. Protected areas. The East European forest steppe has been affected heavily by human pressure: over half is arable land, and the natural forest stands have mostly been cleared. Little of the territory is legally protected as nature reserves, and such reserves that exist tend to be small tracts set aside for study. Representative protected areas in the ecoregion include