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临泽县平川公社三大队林场、一九六七年建场。到一九八一年,造林保存面积达到5480亩,其中成林3200亩,幼林1880亩沙丘灌木400亩。对防风固沙调节小气候,解决本大队生产、生活用材、烧柴等方面,起到了显著作用。但在成林中,“小老树”面积达1400亩,占成林面积的43%,“小老树”的形成同二白杨具有适应性强,干形通直高大,生长迅速等特性和造林目的,是很不相称的,为了逐步摸清形成“小老树”的主导因子,以及在改造利用,促进生长发育,尽快成林成材,用于生产建设和群众生活用材等方面积累经验,提供科学依据。从一九七九年起,在三一大队林场选择立地条件一样,具有代表性的二白杨“小老树”标准地三块,采取综合措施,进行了改造试验。现将三年来的改造试验结果简述如下:一、试验区自然概况。三一大队林场位于临泽县黑河北岸,合黎山前山的干旱沙滩上。这里属于大陆性气候。年平均气温7.7℃一月平均气温-8.9℃七月平均气温21.8℃,极端最高气温39.1℃,极端最低气温-25.7℃,大于10℃以上的年积温3113度。年平均降水124.3毫米,变动在210.5—82.9毫米之间。年蒸发量2362毫米,相对湿度46%,年平均风速3.2米/秒,最大风速21米/秒。无霜期168天。试验区土壤为青沙土,PH 值8.69—9.2.全盐量0.001—0.028%。有机质和养分含量极少(表一),天然植被有生长稀疏
Linze County Hirakawa Commune three brigade forest farm, built in 1967. By 1981, the area for afforestation has reached 5,480 mu, including 3,200 mu of forest and 1,880 mu of young trees and 400 mu of dune shrubs. It has played a significant role in regulating the microclimate for windbreak and sand fixation and solving the problem of production, living timber and firewood for this brigade. However, in the forest, the “small tree” covers an area of 1400 acres, accounting for 43% of the area of forest, the formation of “little old tree” with two Poplar has strong adaptability, stem straight tall and rapid growth and other characteristics and In order to gradually find out the leading factor in forming the “small old tree”, as well as accumulating experience in transformation and utilization, promotion of growth and development, improvement of timber resources as soon as possible, production and construction and use of timber for the masses, Provide a scientific basis. Since 1979, on the site of the Sangtangtang Forest Farm, three representative standards of Populus euphratica have been chosen as site conditions. Comprehensive measures were taken to reform the experiment. Now the transformation test results over the past three years are summarized as follows: First, the natural overview of the pilot area. Trinity Battalion Forest Farm is located in the north bank of Heihe Linze County, in conjunction with arid beach in front of Mount Li. Here belongs to the continental climate. The annual average temperature of 7.7 ℃ January average temperature of -8.9 ℃ July average temperature of 21.8 ℃, extreme maximum temperature of 39.1 ℃, extreme minimum temperature of -25.7 ℃, greater than 10 ℃ above the annual accumulated temperature of 3113 degrees. The average annual rainfall of 124.3 mm, the change between 210.5-82.9 mm. The annual evaporation of 2362 mm, relative humidity 46%, the average annual wind speed of 3.2 m / s, the maximum wind speed of 21 m / s. Frost-free period of 168 days. The soil in the test area is sandy soil with a PH value of 8.69-9.2 and a total salt content of 0.001-0.028%. Organic matter and nutrient content is very small (Table 1), natural vegetation sparse growth