气候变化背景下陇东塬区麦田土壤水分变化及生产特征研究

Ecological Response of Soil Moisture in Wheat Fields to Climate Change in Eastern Gansu Province

董志塬20世纪90年代以来增温最为显著,年增温线性趋势0.099 5℃/a,其中春季、冬季、夏季、秋季增温幅度和显著性依次减弱。年降水量以V抛物线形式变化,90年代中后期为明显的枯水期,以春季和秋季降水减少最为显著,1998年以来春季降水量以准2 a为周期,丰水年和枯水年交替出现。由于增温和降水量减少的共同影响,冬小麦春季重要生长阶段麦田土壤水分含量呈现出逐年减少,春旱逐年加重的趋势。早春耕作层土壤水分逐年减少的一致性比较好,春末夏初2 m土层含水量逐年减少的一致性比较好,其余时段土壤水分年际变化和降水量年际变化基本一致。尽管麦田不同时段土壤水分年际变化不同,但不同年型麦田土壤水分年内变化形式则基本一致,即以V抛物线形式显著变化,冬小麦成熟期的6月份土壤含水量降至最低,伏秋收墒期含水量又逐步回升,其中1998和1999年为特殊年型,土壤水分年内变化线性趋势明显。气候变化特征影响土壤水分盈亏,土壤水分盈亏又决定农业生产年景。分析显示,土壤水分盈亏基本与产量水平一致,水分年型基本与农业生产年景一致。

Temperature in the Dongzhiyuan region has increased remarkably since 1990s, with the linear trend being 0. 099 5 ℃/a. In terms of warming amplitudes and significance decreased, spring, winter, summer, and autumn were ranked in descending order. Annual precipitation varied like a V-type parabola. The middle and late 1990s was a dry period, especially in spring and autumn. The wet year and dry year changed with a cycle of about two years from 1998. Due to the increase in temperature and decrease in precipitation, soil moisture in winter wheat fields was reduced year by year during the growing season in spring. Soil moisture in tillage layer was reduced consistently year by year in early spring and soil moisture within 30 cm soil layer, in the period of late spring and early summer. Besides, soil moisture changed .with precipitation amount in other periods. Although the inter-annual variation of soil moisture was different in different time, soil mois- ture in winter wheat fields varied like V-type parabola in each year. Soil water content was decreased to the lowest in June, which is the mature period of winter wheat, and then it was gradually increased in autumn. However, soil moisture changed as a linear trend in 1998 and 1999. Agricultural production is affected by soil water conditions （surplus or deficit） which are affected by climate change again. Results from the study also show that agricultural production changes with soil moisture conditions.