喀喇昆仑山—西昆仑山地区属于青藏高原西北部寒冷干旱的荒漠、半荒漠地带,是连结高山荒漠和山地荒漠的关键区域。根据垂直自然带谱的基带及各分带的组合配置形式,可区分出干旱、极干旱、高寒干旱及高寒半干旱四种结构类型组。垂直自然带的区域变化明显,喀喇昆仑山与西昆仑山育显著不同,不仅南北翼有别,东西方向的递变也很突出,反映出大尺度的地域分异规律。全新世以来,干旱化的趋势十分明显,人类活动引起的环境问题突出,建议对雪岭云杉和昆仑圆柏等采取保护措施,并在羌塘高原腹地建立高原自然景观及野生动植物自然保护区。

The Karakoram and West Kunlun Mountains in the northwestern part of the Qinghai-Xizang Plateau are a transitional area between the alpine desert and the montane desert.On the bases of recent observations and investigations the structure type of the altitudinal belts, the regional differentiation, and environmental problems in the study area are dealt with in this paper.Characterized by the continental arid type of climate, the altitudinal belts of the Karakoram and West Kunlun Mts. consist chiefly of varions desert and steppe belts. According to the combination pattern of the altitudinal belts, the following four structure-type groups and seven structure types of the altitudinal belts may be identified in the study area:Ⅰ. The arid structure-type group. This structure-type group inclludes three structure types as follows: (1) the xero-mesophilic pattern consisting of the montane forest-steppe belt and the alpine meadow belt; (2) the meso-xerophilic pattern consisting of the montane steppe belt and the alpine meadow belt and (3) the xerophilic pattern possessing the montane steppe belt only.Ⅱ. The extremely arid structure-type group. It includes one structure type. That is the super-xerophilic pattern consisting of the following altitudinal belts: the montane desert belt, the alpine desert belt, the subnival pelt and the nival belt.Ⅲ. The alpine arid structure-type group. It includes two structure types as follows: (1) the super f rigo-xerophilic pattern consisting of the alpine desert belt, the subnival belt, and the nival belt; and (2) the frigo-xerophilic pattern consisting of the alpine desert steppe belt and the alpine desert belt.Ⅳ. The alpine semi-arid structure-type group. It includes one structure type. That is the frigo-meso-xerophilic pattern consisting of the following altitudinal belts: the alpine steppe belt the alpine meadow belt, the subnival belt, and the nival belt.Corresponding to the areal differentiation of the physical geography of the region, the above mentioned four structure-type groups and seven combination patterns of the altitudinal belts vary obviously with the flanks of the Karakoram and West Kunlun Mts. Tte combination of the altitudinal belts and the elevation of each altitudinal belt on the western section are different to a considerable degree from those on the eastern section. The moisture-bearing air masses coming from the west play a significant role in the regional differentiation of the altitudinal belts. They make the desiccation of the southeast more severe than that of the northwest. The broad valleys, basins and plateaus between the Karakorum and the Kunlun Mts. are climatically extremely arid. In these areas the montane desert and the alpine desert are dominant.Owing to the important function of the montane forests in water retention and soil conservation in the arid region, the overlogging and misuse of the forests should be replaced by rational utilization and regeneration. It is suggested that the local government should select proper areas where growing the montane coniferoue forests occur in the West Kunlun Wts. as nature reserves so as to protect a number of endemic and rare species of plants. It is also necessary to establish nature reserves for the conservation of the natural landscape and the wildlife of the Qiangtang Plateau.