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一、沼泽土形成的自然条件 (一)水热条件 本区属于青藏高原寒冷气候区,主要特征是:寒冷而潮湿,冬长而无夏,气温较低,霜冻期长,阴雨日多,自然蒸发弱。年均温只有0.6—1.2℃,最热月(七月)的均温为10.9℃,最冷月(一月)为-10℃左右,年较差不大。全年≥10℃的积温只有600—900℃,生长季仅有百天左右。降水量一般在560—860毫米,年际变化不大,降雨主要集中在6、7、8月,约占全年降水量一半,降水频率大、年内雨日150天左右,使地表经常过湿,积雪长达五个月,雪深14—24厘米,翌年融雪水很丰富。这样,由于气温低、降水多、日照时数少,年平均实际蒸发量只有450毫米,而且第四纪沉积物质地粘重,水分不易下渗而积聚地表,极大地限制了微生物的活动,使有机物质不断积累,有利于沼泽土的形成。
First, the natural conditions of swamp soil formation (A) hydrothermal conditions The area belongs to the Qinghai-Tibet Plateau climate zone, the main features are: cold and humid, long winter without summer, low temperature, long frost, rainy days, natural Weak evaporation. The average annual temperature is only 0.6-1.2 ℃, the hottest month (July) average temperature of 10.9 ℃, the coldest month (January) -10 ℃, the annual difference is not large. The annual accumulated temperature ≥10 ℃ only 600-900 ℃, growth season only about one hundred days. Precipitation is generally 560-860 mm, little change in the interannual, rainfall is mainly concentrated in June, July and August, accounting for about half of the annual precipitation, precipitation frequency, the year around 150 days of rain, the surface often over-wet , Up to five months of snow, snow 14-24 cm deep, melting snow is very rich the following year. In this way, due to low temperature, more precipitation, less sunshine hours, the annual average actual evaporation is only 450 mm, and Quaternary sediment material sticky, water infiltration is not easy to infiltrate and accumulate surface, greatly limiting the microbial activity, so that Accumulation of organic matter is conducive to the formation of swamp soil.