A RESEARCH ON DIATOM-FLORA IN HELAN MOUNTAINS,NINGXIA AUTONOMOUS REGION

Helan mountains which runs a little near from south to north is located in the middle part of Ningxia Autonomous region, Its length is more than 200km and its average height is over 2000m, The west part of Helan platen is plane, Its east with a fault looks over the Yinchan-Wuzhong plain. Because of its position in front of desert, the region is a typical forest ecosytem in arid region and a natral reserve with a multipurpose, therefore it has great value in science research. Water resources can only take the form of spring instead of long river under the condition of such a geographical position and climates features, So there are only a few types of aquatic species.