386 MR. M. P. PRICE ON THE VEGETATION OF 
the Siberian town of Minnusinsk. The Sayansk mountains, which form the 
nominal frontier between Siberia and Mongolia, are not a true range in the 
strict sense of the word, but rather a series of disjointed uplifts, of which 
the highest peaks reach 8000 and 9000 feet in places, and are connected by 
numerous passes of from 4000 to 5000 feet in altitude. The trend of the 
range is indefinite, and many spurs jut out far into the Siberian forests on 
the north and into the plateau basin of the Bei Kem on the south. The 
average height of the floor of the basin is roughly between 2000 and 3000 
feet, and it is thus everywhere surrounded, except at the point where the 
Ulu Kem bursts through the Sayansk mountains in a series of gorges and 
rapids, by a complete range of encircling mountains. To the south lie the 
Tannu-ola range, a complete barrier between the Yenisei basin and the 
North-West Mongolian plateau. 
The plains of the Siberian lowlands at Minnusinsk average about 900 feet 
in altitude, and going southwards from here the traveller rises on to the first 
step of the Central Asiatie plateau, which is formed by the northern spurs of 
the Sayansk mountain system. This first step of the plateau is clothed on its 
northern slopes with dense forests, which in their floral type show affinity to 
the sub-arctie forest of Siberia some 400 miles to the north. The latter lies 
between the latitudes of 56? and 72°, and nowhere rises above 600 feet above 
the level of the sea. Similar conditions, however, are found on the Sayansk 
mountains between latitudes 52° and 54° at heights varying from 3000 to 
5000 feet. Thus the same vegetations are found in northern latitudes at low 
altitudes, as in southern latitudes at higher altitudes. In other words altitude 
compensates for latitude. Between the sub-aretie forest belt of Central 
Siberia and the forests of the Sayansk mountains lie tlie steps of Minnusinsk 
and Abakansk in the Minnusinsk Government of Siberia. Here the dry 
steppe-like vegetation of Central Asia seems to have pushed its way in as a 
wedge between what may at one time have been a continuous zone of sub- 
arctic forest, As the glaciers retreated northwards a steppe-like vegetation 
crept evidently into the Siberian lowlands, which le in southern latitudes, 
and have thus effectively isolated the floral system of the Sayansk. 
In the Upper Yenisei plateau, besides the sub-arctie forest and a flora 
characteristic of northern Siberia, there isalso the Siberian Larch forest with 
an accompanying floral association. The former prevails in a long strip 
along the north or Siberian side of the Sayansk system and in all the higher 
parts of the plateau where the winter is long and severe. The Larch forest, 
on the other hand, prevails in the lower altitudes and is indicative of a drier 
climatie condition. For in winter snow lies less deeply in the more southern 
latitudes and on the lower altitudes of the Upper Yenisei plateau, than on 
the northern slopes of the Sayansk. In the former places the summer rain- 
fall is only assured by numerous sharp thunder-storms. 
