Geomorphometric Features of the Alluvial Fans around the Chaka-Qinghai Lake in the Northeastern Tibetan Plateau

This article aims to study the geomorpometric features of alluvial fans since they act as a small-scale geomorphic unit response to tectonics and climate changes around the Chaka-Qinghai Lake area in the northeastern Tibetan Plateau. We quantitatively extracted geomorphic parameters, such as the surface area and slope of alluvial fans adjacent to the Qinghai Nan Shan and Ela Shan. Alluvial fans in the Chaka Lake partition area, south of the Qinghai Nan Shan, are featured by a small area and short length, but the largest slope. Geomorphic parameters of the alluvial fans in Ela Shan area are in- termediate in size, and the alluvial fans in the Qinghai Lake partition area north of Qinghai Nan Shan have the gentlest slope. Together with the regional faulting activity analysis, we suggest that the alluvial fans with the high slopes in the south of Qinghai Nan Shan are mainly controlled by the reverse faulting along the Qinghai Nan Shan faults, and the strike-slip movement of the Eia Shan fault zone plays a weak role. In contrast, due to the lack of active faults, the alluvial fans near the Qinghai Lake area north of the Qinghai Nan Shan only respond to regional erosion, transportation, and deposition proc- esses, thereby forming relatively gentle geomorphic units.

青海湖东北岸天然草地CO_2通量变化特征

采用涡度相关法对青海湖东北岸地区草甸化草原生态系统的CO_2通量进行了观测,结果表明:在生长季节(5—9月),就日变化,08:00—19:00为CO_2净吸收,20:00—07:00为CO_2净排放,CO_2通量净吸收峰值一般出现在12:00时,7月份12:00时CO_2净吸收峰值为1.41 g·(m^2·h)^(-1);就月变化,7月是生长季CO_2净吸收最高月份,月CO_2净吸收量达到162.70 g·m^(-2),整个生长季CO_2净吸收的总量达468.07 g·m^(-2)。非生长季节(1—4月及10—12月),CO_2通量日变化振幅极小,最大CO_2净排放通量出现在3月,为0.29 g·(m2·h)^(-1),除12月和1月各时段CO_2通量接近于零,其余月份各时段CO_2净排放在0.02~0.29g·(m^2·h)^(-1);3月是全年CO_2净排放的最高月份,全月CO_2净排放量为72.33 g·m^(-2),整个非生长季CO_2净排放为319.78 g·m^(-2)。结果表明,无放牧条件下青海湖东北岸地区草甸化草原,全年CO_2净吸收量达148.30 g·m^(-2),是显著的CO_2汇。

对青海湖北岸部分地区嵩草的调查研究

通过对青海湖北岸海拔 30 0 0～ 35 0 0m部分地区不同类型嵩草属植物的调查分析表明 :在沼泽草甸上西藏嵩草 (Kobresiatibetica)、矮生嵩草 (K humilis)及其它莎草科牧草生长良好 ,但由于沼泽草甸潮湿 ,绵羊对这些牧草利用差 ,牛、马利用较好 ;山地干草原草场不适宜嵩草属植物生长 ,仅分散着少量大花嵩草 (K macrantha) ,经济价值不大 ;在大片的撂荒地中几乎完全没有嵩草属牧草 ;在山地草原化草甸草场上 ,以矮生嵩草、短轴嵩草(K prattii)、线叶嵩草 (K capillifolia)及禾本科牧草为优势种 ,豆科牧草相应增加、杂类草相应减少 ,为最佳放牧场 ,各类牲畜均能很好地采食 ;在高寒草甸草场上 ,高山嵩草 (K pygmaea)为绝对的优势种 ,因植株矮小 ,牛、马利用差 ,绵、山羊则能很好地利用。盲目开垦。