Zhang Bei-Ying, Xu Xue-Xuan, Liu Wen-Zhao, Chen Tian-Lin
Institute of Soil and Water Conservation, Chinese Academy of Sciences & Ministry of Water Resources, Yangling 712100, Shaanxi, China.
Ying Yong Sheng Tai Xue Bao. 2008 Jun;19(6):1234-40.
Based on field determinations, the dynamic changes of soil moisture in dry farmland, Robinia pseudoacacia forestland, Hippophae shrubland and Bothriochloa ischaemum grassland in loess hilly and gully region under effects of different yearly precipitation patterns were analyzed. The results showed that yearly precipitation pattern had definite effects on the seasonal variation and profile distribution of soil moisture. In normal year, soil moisture in dry farmland had a gentle seasonal variation; in dry year, it decreased slowly before rainy season but increased markedly after rainy season; while in rainy year, it had an overall increase and the increment was remarkable after rainy season. The soil moisture in R. psendoacacia forestland, Hippophae shrubland, and B. ischaemun grassland decreased as a whole in normal year. In dry year, soil moisture in Hippophae shrubland decreased first and increased then, while that in R. psendoacacia forestland and B. ischaemun grassland varied in "W" type, with the minimum in June and August. In rainy year, the seasonal variation of soil moisture in R. psendoacacia forestland and Hippophae shrubland presented "V" type, and that in B. ischaemu grassland fluctuated markedly, with the minimum in August. In dry farmland, the active and sub-active layers of soil moisture were deeper in dry year than in normal year, and the sub-active layer disappeared in rainy year. In R. psendoacacia forestland and B. ischaemu grassland, the active layer of soil moisture was deeper in dry and rainy years than in normal year; while in Hippophae shrubland, this active layer was shallower in dry and rainy years than in normal year.
基于实地测定，分析了黄土丘陵沟壑区不同年降水模式影响下旱作农田、刺槐林地、沙棘灌丛地和白羊草草地土壤水分的动态变化。结果表明，年降水模式对土壤水分的季节变化和剖面分布有一定影响。正常年份，旱作农田土壤水分季节变化平缓；干旱年份，雨季前缓慢下降，雨季后显著增加；多雨年份，整体增加，雨季后增幅明显。正常年份，刺槐林地、沙棘灌丛地和白羊草草地土壤水分总体下降。干旱年份，沙棘灌丛地土壤水分先降后升，刺槐林地和白羊草草地土壤水分呈“W”型变化，6月和8月最低。多雨年份，刺槐林地和沙棘灌丛地土壤水分季节变化呈“V”型，白羊草草地波动明显，8月最低。旱作农田中，干旱年份土壤水分活跃层和次活跃层比正常年份深，多雨年份次活跃层消失。刺槐林地和白羊草草地中，干旱和多雨年份土壤水分活跃层比正常年份深；而沙棘灌丛地中，干旱和多雨年份该活跃层比正常年份浅。
