水保所知识产出(1956---)知识库

Moss-biocrusts (BCs) play an essential role in soil stabilization, but it reduces soil hydraulic conductivity, hin-
dering precipitation convert to soil water. Freeze-thaw cycles (FTCs) is a natural phenomenon, which can alter
soil properties, causing widespread concern. However, few studies have focused on the effects of FTCs on hy-
draulic conductivity in BCs, which may alter the negative effects of BCs on hydraulic conductivity. We conducted
an in-situ FTCs simulated experiment in BCs and bare sand (BS), to analyze the response of particle-size
composition, water-stable aggregates and water repellency (WR) to FTCs, and their effects on saturated hy-
draulic conductivity (K s ). The results showed that the existence of BCs had affected water-stable aggregates,
particle-size composition, WR and K s . Compared with BS, the percentage of clay-size particle content increased
by 44% and 60% in BCs layer and its underlying soil, respectively. The stability of water-stable aggregates was
19% higher in BCs than the measured stability in BS. K s of BS was 2.4 times higher than that of BCs, and the
increasing percentage of water-stable aggregates larger than 5 mm would reduce K s in sandy land. FTCs had the
significant effects on water-stable aggregates, WR and K s . WR and K s of BCs were decreased 57% and 25% after
FTCs, respectively. Moreover, after FTCs, the percentage of soil water-stable aggregates > 5 mm reduced 19%,
while 1–5 mm increased 18%. WR and sand content were significantly and negatively correlated with K s , while
clay content and the percentage of soil water-stable aggregates > 5 mm were significantly and positively
correlated with K s in BCs. Our results indicated that BCs and FTCs had a significant and negative effects on K s .
FTCs further decreased the hydraulic conductivity, which was not conductive to the supply of meltwater to soil
water reservoir in the period of winter and early spring.