水保所知识产出(1956---)知识库

为评价黄土高塬沟壑区坡面植被自然恢复对土壤抵抗径流侵蚀性能的影响，以农地为对照，通过野外原位冲刷
试验研究了不同植被恢复年限（0~28 a）的坡面土壤抗冲性变化及其与土壤性质和根系密度的关系。结果表明，1）土壤
各项性质均随恢复年限的增加不断改善，其中土壤容重和崩解速率随恢复年限呈递减的指数函数关系（P<0.01），而饱和
导水率、有机质含量、水稳性团聚体、MWD 及各直径根系密度则随年限以线性或指数方式递增（P<0.01）。2）植被恢复
3 a 的坡面土壤抗冲性较农地增加不显著（P>0.05），恢复 3a 后土壤抗冲性显著增加 1.98～9.82 倍（P<0.05），且土壤抗冲
性与恢复年限呈极显著线性关系（R 2 =0.98，P<0.01）。3）土壤抗冲性与容重和崩解速率呈显著的负相关关系，与饱和导
水率、有机质含量、水稳性团聚体及MWD则呈极显著正相关关系；抗冲性与根系密度的关系可采用Hill曲线模拟，<0.5 mm
是提高抗冲性的最有效根系直径。4）土壤抗冲性的提高与土壤性质的改善和根系密度的增加密切相关，土壤容重、团聚
体稳定性（MWD）及<0.5 mm 根系密度是影响土壤抗冲性的关键因子。

Some water and soil conservation projects were continuously conducted on the Loess Plateau since 1970s.
Especially, in the gully region, some targeted measures were implemented in different geomorphic positions (gully heads, hill
slopes and gully channel) to control soil and water loss. To investigate the effect of vegetation restoration age on soil
anti-scourability, an in-situ runoff scouring experiment was carried out in grasslands of five natural vegetation restoration ages
with the slope farmland as CK. This study explored the variations in soil anti-scourability (ANS) with vegetation restoration
years and its relationships with soil properties and root characteristics. In this study, soil properties of soil bulk density (SBD),
saturated hydraulic conductivity (SHC), soil organic matter content (OMC), soil disintegration rate (SDR), soil particle size
distribution and water-stable aggregate (WSA) and root mass densities (RD) of different root diameters (<0.5, 0.5-1.0, 1.0-2.0,
>2.0 mm) were sampled and measured in each site. Each soil property and root index was repeated three times for each
sampling site. The scouring experimental plot size was set as 2.0 m×0.25 m to test soil anti-scourability, which included flow
transition section (0.5 m length) and soil test section (1.5 m length). The flow discharge was determined as 10 L/min. The
results indicated that 1) Vegetation restoration could significantly improve soil properties. The SBD generally decreased after 3
years restoration, and the SDR decreased 28.85%~88.22% compared with the CK (slope farmland). The SBD and SDR
exponentially decreased with the increase of restoration time (P<0.01). The SHC, OMC, WSA and MWD were 0.85-4.25
times, 1.12-5.61 times, 13.36%-91.82% and 10.18%-145.16% greater than those of the CK, respectively, and the four
indicators linearly increased with the restoration time increasing (P<0.01). Moreover, the RD of different root diameters (<0.5,
0.5-1.0, 1.0-2.0, >2.0 mm) also exponentially increased with the increase of restoration time (P<0.01). 2) Vegetation
restoration could create more stable soil structure by improving the effect of root physical consolidation and the biochemical
effect of root exudate matters, and thus improves the soil resistance to flow scouring. Soil anti-scourability after 3 years
restoration was greater than that of the CK, but had no significant difference with the CK. While the ANS significantly
increased by 1.98-9.82 times when the restoration time was higher than 3 years. Regression analysis showed that the ANS
increased linearly with the increase of restoration time (R 2 =0.98, P<0.01). 3) Partial correlation analysis showed that the ANS
had a negative related with SBD and SDR (P<0.05), but positive related with SHC, OMC, WSA and MWD (P<0.01). The
degree of correlation between ANS and OMC and MWD was higher than other soil property parameters. The Hill curve
function could simulate well the relationships between ANS and RD of different root diameters (R 2 =0.913-0.978, P<0.01). The
root diameter level of <0.5 mm was the optimal root diameter in improving ANS. 4) The enhancement of soil anti-scourability
was closely related with the improvement of soil properties and the increase of root mass density. The SBD, MWD and RD of
<0.5 mm were the key factors influencing ANS. The results could improve scientific reference for the assessment of soil and
water conservation benefits and the optimization of vegetation measures.