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一、调查区的概况蒸腾作用是树木生长的重要生理现象,尤其在干旱瘠薄的山区,更是反应林木水分生理特点和生长发育的主要指标之一。辽西地区地势起伏、植被稀少、冬季漫长、夏季炎热,年温差可达70℃以上。年降水量一般在400—600mm之间,分布极不均匀,多集中于7—8月份,为全年降水量的65—70％,冬春雨雪稀少而干旱,年蒸发量在1,700—1,900mm以上,年平均相对湿度为55％,春季平均为44％,最少月份可在20％以下。由于1980—83年的连续大旱,油松纯林曾发生枯
First, the survey area profile Transpiration is an important physiological phenomenon of tree growth, especially in barren mountainous areas, it is one of the main indicators of response to water stress physiological characteristics and growth and development. In western Liaoning, the terrain is undulating, the vegetation is sparse, the winter is long, the summer is hot, and the annual temperature difference is up to 70 ℃. Annual precipitation is generally between 400-600mm, the distribution is extremely uneven, mostly concentrated in July-August, for the annual rainfall of 65-70%, winter and spring rain scarce and droughts, the annual evaporation in the 1,700-1,900 mm above average annual relative humidity of 55%, the spring average of 44%, at least the month can be less than 20%. Owing to the successive drought in 1980-83, the pure pine forest had withered