| 其他摘要 | Vegetation restoration is the most effective measures which increase soil organic carbon
content and improve soil structure on the Loess Plateau in China. This study selected the soil of
the Loess Plateau, Robinia pseudoacacia and Caragana Korshinskii Plantation as the research
object. The objective of this paper is to analyze characteristics of soil aggregates in the Loess
Plateau by using Le Bissonnais method and Yoder method, to understand vegetation restoration
process of Robinia pseudoacacia forest and Caragana Korshinskii forest on aggregate structure
and its stability and anti erosion ability (k) effects, to reveal the environmental factors and nutrient
factors affecting the relationship between soil aggregate stability, to provide a scientific basis for
the selection and practice of evaluation to determine the Loess Plateau Vegetation Restoration
Measures. The main conclusions are as follows:
(1) In the northern deciduous broad-leaved forest, forest steppe, typical steppe vegetation
zone from east to west, the mass fraction of soil aggregates and woodland increased gradually.
The results of Yoder method showed soil aggregate size >0.25mm of Caragana Korshinskii forest
and Robinia pseudoacacia forest overall average value of each particle size of soil aggregates:
Southern deciduous broad-leaved forest > Northern deciduous broad-leaved forest > forest steppe
zone > typical steppe zone.
(2) In the LB method, fast wetting treatment (FW) was the maximum extent of damage to
the soil aggregate structure, and soil water stable aggregates were <0.2 mm; Slow wetting
treatment (SW) was minimal damage to the aggregate, and soil water stable aggregates mainly
were >2 mm aggregates; And pre wet after perturbation treatment (WS) was between the damage
degree of aggregates between FW and SW. (3) Eastern R0.25, MWD and GMD values are higher than the Western, and K value was on
the contrary.With longitude reducing, R0.25, MWD and GMD values gradually increased in the
same latitude, and soil erodibility K value was on the contrary.
(4) To inhuanxian county (107 degrees longitude) as the dividing line, the average annual
rainfall (407mm) as the reference value, soil aggregate stability and anti erosion ability was better
in the east of black locust; And when the precipitation is less than 407mm, soil aggregate stability
and anti erosion ability was better after planting Caragana Korshinskii.
(5) The environmental factors effecting on the soil aggregate stability and corrosion
resistance is mainly the latitude, longitude, rainfall. The main soil nutrient factors effecting on the
soil aggregate stability and corrosion resistance is mainly the soil organic matter, soil total
nitrogen.
(6) The main failure mechanism of soil aggregates in Loess Plateau is the damage
dissipation and mechanical. And the heavy rain in the Loess Plateau with low coverage is
associated with heavy rain and vegetation in Loess Plateau. Therefor, in order to improve the
stability of soil aggregates, to prevent soil erosion, vegetation restoration can improve vegetation
coverage, invigorate the soil aggregate stability, and enhance the soil anti erosion ability and fast
wetting treatment. LB method can comprehensively measure soil aggregate node Structure.
Keywords: Loess Plateau, LB method, aggregate sdability, Robinia pseudoacacia plantations,
Caragana Korshinskii plantations |
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