再论青藏高原苔原:地球第三极地理极性之确认

Study Again on Qinghai-Tibet Plateau Tundra:Determination of Geography Polarity for the Third Pole of Earth

青藏高原是否存在苔原,关系到地球是否有地理意义的第三极——高极,因此其是全球地理科学的一个基本问题。在给出苔原定义的基础上,拟定了由5个要素组成的苔原环境指标组合。这5个要素分别是7月平均气温为0℃～10℃;位于冰盖或冰川外围的冰缘区,寒冻强烈;存在多年冻土;土壤为寒冻土;植被无林。青藏高原7月平均气温介于0℃～10℃的范围约占高原面积的50.4%,为129.64×104 km2;在此范围内,山谷冰川广泛分布,现代冰缘环境典型,寒冻过程强烈;连续多年冻土占高原多年冻土面积的72.5%,土壤为寒冻土,且冰沼土发育;植被因海拔高度突破森林线而无林,仅有小灌丛、草类及苔藓等;因此,判定青藏高原存在苔原。青藏高原沼泽湿地植物多特有种,冻胀泥炭丘普遍,与多边形土等形成冻胀组合,构成沼泽苔原。高原外围山地发育山地苔原,中部发育高原苔原。青藏高原具有山原性质,因此有世界唯一的山原苔原,表现出苔原的多样性。中国除长白山、阿尔泰山和天山以外不存在苔原的传统观点是不正确的,青藏高原苔原才是中国苔原的南缘。高原苔原的发现将从地理环境上确认青藏高原全球第三极的地理极性,这对深化高原环境认识具有重要意义。

Whether if there is tundra in Qinghai-Tibet Plateau, is very important for the problem that whether or not the third pole of earth （high pole） is geographic, so that it is a basic problem for global geographical science. The definition of tundra was proposed, and the index assembly of tundra environment composed by five factors was put forward. The five factors include that the mean temperature in July is 0 ℃-10℃ ; there is periglaeial environment located in ice cover or glaciers periphery, and frost is strong; there is permafrost; soil is frost; it is treeless. The region with average temperature of 0 ℃-10 ℃ in July is about 50.4% （129.64× 10^4 km2） of Qinghai-Tibet Plateau; distribution of valley glacier is wide, and modern periglacial environment is typical in the region; the area of permafrost in the region is 72.05% of that in Qinghai-Tibet Plateau, soil is frost and tundra soil develops; it is treeless because altitude is high than forest line, but there are small brush, grass, moss and so on; therefore, there is tundra in Qinghai-Tibet Plateau. A lot of plants in marsh are special, frost peat mound is wide and is combined with cellular soil, so that marsh tundra develops. Hill tundra develops in the mountain around Qinghai-Tibet Plateau, and plateau tundra develops in the middle. The characteristic of Qinghai- Tibet Plateau is highland, so that there is highland tundra only in the plateau, showing the diversity of tundra. It is incorrect that there is no tundra in China except Changbai, Altai and Tianshan Mountains, but Qinghai-Tibet Plateau is the southern edge for tundra in China. The discovery of tundra in Qinghai-Tibet Plateau can confirm the geography polarity of the third pole in earth, and has important significance for understanding plateau environment deeply.