沙漠·戈壁·绿野

  塔里木盆地地处亚洲腹部，是地球上离海洋最远的地方，它的周围，几乎全是巍峨的群山，广大的高原，这些山地平均海拔高度都在4000至5000米以上。塔里木盆地深藏在大陆腹心的地理位置，构成了它特殊的地理地貌和生态环境。

  塔里木盆地气候极端干燥，降水稀少，蒸发大大超过降水量，气温的年较差和日较差也都极大。尤其是在夏季，辐射强盛，温差悬殊，使盆地边缘年平均降雨量只有30—50毫米，盆地腹部的沙漠地带少于20毫米甚至5毫米，而且蒸发量却在2500—3400毫米。由于千旱和炎热便形成了荒漠和半荒漠的地理景观。但在同一个干燥的环境下，因地形和人文悄况的不同，它大体上可以分为几个层次和几种景观带：最内为盐湖带，分布有大面积的盐碱土，仅生长些极耐盐碱的稀疏草类和灌木，成为盐湖景观；外为沙漠带，植物极少，成为沙丘起伏的荒漠景观；再外为沃野带，植被主要为耐干旱耐盐碱的灌木和乔木，上壤灌溉后多成为灰钙土，有利于灌溉农业的发展，成为沃野景观；再外为山麓砾石带，砾石暴露，草木稀少，水多潜伏地下，成为荒凉的戈壁景观，总的说来，塔里木盆地境内植被极为稀疏，主要生长旱生灌木和耐旱草类，代表土壤为含有不同盐度的漠钙土类，且多为未发育土壤。

  塔里木盆地砾石戈壁的形成主要是高山雪水冲刷了风化的山岩碎屑，把夹带的砂砾搬运到山麓地方，因水流速度骤减积成。

  塔里木盆地中沃野的面积大小不一，它们都是以10—2500平方公里等的绿洲出现在整个盆地。沃野总面积为14600平方公里，约占盆地面积的六十分之一。它与山的高度和雪源的多寡有极密切的关系。像疏勒沃野面积为2650平方公里，莎车沃野面积为2600平方公里，而在山势较低的柬部盆地，气候干燥，水源不足，因此沃野分布也较少。像若毛沃野面积仅30平方公里。

   从沃野带向内，不是沙丘累累，便是戈壁暴露，成为一片广大而荒凉的地方，这就是沙漠带，也是世界第二大流动性沙漠，33万多平方公里的塔克拉玛干。

   塔里木沙漠的形成是由地岩石受机械风化崩裂成碎屑和细沙形成的。盆地内的湖水干涸后的湖底砂泥也是流沙的一个主要来源。这一片沙海，形成许多平均高达90米左右的新月形沙丘、沙岗和沙脊。它们的分布很规律，大部分与从库鲁克山吹来的干热风以及来自干燥的蒙古，西伯利亚反气旋的分支，由东北部向塔里木盆地方向侵入有关。因此，这里所有荒漠上的新月型沙丘、沙岗和沙脊，它们的缓坡一律面向北偏东，陡坡一律面向西偏南。沙丘、沙岗和沙脊此起彼伏，正像大海波浪一样。  

   在沙漠中心，没有植物，也没有野兽，甚至连飞鸟虫类都很少，完全是一片荒凉寂静的地方。塔里木盆地的中部柬端为著名的罗布泊，那里地势较低，塔里木河水汇集成为盐湖，因此，这一带又称盐湖带。但是由于罗布泊的游移，现在这里的湖泊已干涸多年。只有那无边无际的“土丘林”，令人神秘莫测，那就是著名的“雅丹”地貌。它是干燥地区的一种特殊地貌，由一系列平行的“垄脊”和“沟槽”构成，顺盛行风方向伸展。雅丹地形以罗布泊北面最典型，分布也最广泛。这在世界上也属罕见。罗布泊盆地，历史上有盐湖和沼泽密布。据现在的沙漠考察人员讲，罗布泊盆底有大量的盐类品，成为塔里木盆地现代积盐中心。

  罗布泊的往返迁移，留下的古河床，是一个无人区，这里的地表凝结成一片盐壳，在长期东北风的影响下形成一种为东北风相垂直的坡状地形。所以在这里旅行十分艰难。      

此处还有更多图片欣赏 ...

   Desert ·Gobi·Verdant Plains

   The Tarim Basin is located in the hinterland of Asia, further removed from any outlet to the sea, almost completely surrounded by lofty mountains and vast plateaus. The average elevation of the mountains range alive 4,000 - 5, 000 meters sea level. Its geographical location accounts for its unique landtorm and ecological environment.
    The climate of the Tarim Basin is extremely arid with little precipitation, and often its evaporation exceeds its precipitation volume, with huge differences in its year- round and daily temperatures. Especially in the summer when there is strong radiation and huge differences in daily temperature. Its annual precipitation is only around 30 - 50 millemeters and less than 20 millimeters, or as little as 5 millimeters in the desert at the interior of the Basin, but its evaporation is at 2500 - 3400 millemeters. Its barren and semi-barren geographical features are the result of the drought and heat. However, the environment can be divided into several 'circles' and landscape belts according to the difference in terrain and human culture. The innermost circle is the salt lakelandscape where the vast area is saline-alkali soil on which only grass and shrubbery which are extremely resistant to salt and alkali are very sparsely grown, commonly known as the salt lake landscape belt; the circle outside it is covered with undulating sandhills, making it the desert landscape belt;the outer circle is the fertile plain where the vegetation is extremely drought and saline- alkali resistant shrubbery and trees, and the soil turns to dust or becomes calcified after irrigation which is conducive to the development of irrigated agriculture, making it the fertile plain landscape belt; the outermost ring is the mountain slope gravel circle where the ground is exposed and vegetation is sparse, and most of the water runs underground, making it the gobi landscape belt. In general, vegetation is sparse in the Tarim Basin, and whatever there is are mostly dry land shrubbery and drought resistant species of grass, and the typical soil is calcified with difLerent degrees of salinity, and most of it is immature soil.
   The gobi in the Tarim is formed by the snowmelt from towering mountains that can'y the weathered rock down to the slopes and accumulated there by the ebbing flow.
    The fertile plains in the Tarim Basin vary in range and they usually appear as oases measuring 10 - 2,500 square kilometers. The entire area of the fertile plains is 14,600 square kilometers, making up for one - sixtieth the total area of the Basin. The number and size of the oases are closely related to the altitude and quantity in precipitation of the nearby mountains. For instance, the Shule fertile plains measure 2, 650 square kilometers, and the Shache fertile plains measure 2, 600 square kilometers, whereas the east of the Basin where the mountains are of much lower altitude and the climate is more arid and there is a lack of water, the distribution of fertile plain as an example, it only measures about 30 square kilometers.
   Going inward from the fertile plains one sees little else but countless sand hills or endless stretches of gobi, barren and wasted, and that is the desert belt, also known as the world' s second largest shilling deser't, covering an area of over 330, 000 square kilometers -- the Taklimakan.
   The Tarim desert is formed by weathered fragments of rocks and fine sand. The main source of the shifting sand is from the lake bottoms of dried up lake beds of the Basin. This sea of sand formed many crescent-shaped sand hills, sand dunes and ridges reaching a height of around 90 meters. They are regularly distributed in the Tarim Basin according to the influx of the dry heat from the Kuruktag, from Mongolia, and the branches of reverse air currents from Siberia which blow from the northeast of the Basin which account [.or the gradual sloping of the sand hills, sand dunes, and ridges all facing the north -northeasterly direction, and their steeper slopes all facing the west-southwesterly direction. The undulating sand hills, dunes, and ridges of the desert resemble waves in the ocean.
   The heart of the desert is devoid of plants and beasts, and even birds and insects are rarely seen, and the land is a completely barren and wasted. At the eastern edge of the center of the Tarim Basin is the famous Lopnur, which is at a relatively low elevation, is a salt lake resulting from the convergence of waters from the Tarim River. So it is known as the salt lake belt. However, due to the constant change in course of the Lopnur, this lake has been dried for many years. The endless stretches of hills, which appear so mystical, is known as the 'Yardan' landform, which is a unique landform found in arid regions, made up of a series of parallel ridges and troughs which run in the direction of the wind. The most typical 'Yardan' landfoms are found north of the Lopnur, and their distribution is vast. A phenomena rarely found elsewhere in the world.
  Historically, the Lopnur Basin had densely distributed salt lakes and marshy swamps. According to present - day desert surveyors, there are great quantities of multiple varieties of salts at the bottom of the Lopnur Basin, and it has become the center of salt accumulation of the Tarim Basin.
  The constant change of the Lopnur has left behind an ancient riverbed which is a no-man' s land, covered by a crust of crystallized salt, and due to the permanent northeasterly winds, the land is a series of slope-like forms vertical to the northeasterly winds, hence traveling in the area is especially difficult.

See more photos...