Spatial and seasonal variation of climate on steppe slopes of the northern Mongolian mountain taiga.

The local climate of two south-facing, steppe-covered slopes was studied in the Eroo River valley in the western Khentey Mountains, northern Mongolia, and compared to the climate of a floodplain meadow. The microclimate of these sites is of special interest because: (i) the climate-dependent forest–steppe border runs through northern Mongolia; and (ii) the area encountered late 20th century warming far above the global average. The overall climate of the study area is characterized by highly variable, low annual precipitation (<300 mm), an annual average of air temperature around the freezing point and a high seasonal amplitude of temperature of 80°C. South-facing slopes were warmer and drier than the floodplain. High soil temperatures with maxima of nearly 60°C at 1 cm depth and low soil moisture are capable of inhibiting tree growth on the south-facing slopes. Soils on the open slope are warmer than at the treeline between taiga forests and grasslands and, thus, less suited for tree growth. On the open slopes, soil temperatures primarily depend on the inclination and the vegetation cover suggesting an interrelationship between the present vegetation, microclimate and the potential for the establishment of trees. Because climate in Mongolia is predicted to become warmer and drier at many places, hot and dry soil conditions inhibiting the establishment of trees may be expected to be more common in future. An expansion of such unfavorable conditions could cause the spread of grasslands to slopes in western and eastern aspects, which are presently occupied by forest. [ABSTRACT FROM AUTHOR]