Highway is a national fundamental infrastructure. The highway construction generates
large numbers of excavation and filling slope which result in loose deposit soil and aggravate
soil and water loss. The vegetation restoration in slag yards becomes a hot issue in the
research of man-made soil and water loss. In this paper, with the study approach of combining
field investigation and laboratory analysis, we chose 13 sampling spots in the slag yards of
Qinba Mountains with different vegetation restoration periods (0, 2, 5, 7, 15a) as our study
area, and analyzed the measured data using analysis idea of substituting ‘space’ for ‘time’. For
each sampling spot, we surveyed soil physical and chemical properties, including soil enzyme
activity, vegetation growth status, soil seed bank types and quantity etc. Meanwhile, we
clarified the soil and vegetation response pattern during vegetation restoration in the slag
yards of Qinba Mountain, and discussed the similarity correlation between soil seed bank
condition and ground vegetation so as to provide soil and water conservation management
with scientific reference. The results obtained were presented as follows:
(1) Soil organic matter and total nitrogen in slag yards are low in the early stage of
vegetation restoration. Both increase as recover age increases, and the increase magnitude
reduce gradually with the increase of recover age. For different recover ages in 0-5cm soil
layers of the slag yards, both soil available P and K content (P<0.01) show very significant
difference, and nitrate nitrogen had significant difference (P<0.05). For different recover ages
in 5-10cm soil layers, nitrate nitrogen, ammonium nitrate nitrogen and available K content
have very significant difference. The activity of phosphatase and catalase do not changed
significantly in vegetation recover process, and phosphatase has a stable increasing trend with
the increase of vegetation recover age.
(2) Organic matter and total nitrogen content have very significant positive correlation
for all restoring ages (p<0.01). In 0-5cm soil layers, soil total nitrogen content has very
significant positive correlation with phosphatase and urease activity respectively, and has significant positive correlation with available K content; organic matter has very significant
positive correlation with available K content and urease activity respectively, and organic
matter had significant positive correlation with catalase activity.
Soil enzyme activity and soil nutrient content have significant correlation (P<0.05). The
relativity closeness is in the order of urease>phosphatase>catalase. Urease activity has very
significant positive correlation with soil organic matter and total nitrogen content respectively.
It is shown that urease activity takes an important role in C and N conversion process.
(3) Cover process can improve soil conditions in slag yard, and is conductive to
vegetation recovery. In the comparison between the results based on cover-process and that
based on un-cover-process, both soil organic matter and total nitrogen content show obvious
difference (soil organic matter and total nitrogen content based on cover-process are about 1.5
time of those based on un-cover-process respectively), and available nutrient content shows
less difference. The cover-process can increase the organic matter in slag yards, but it can’t
improve the soil enzyme activity in the short time. After about 5 years, phosphatase and
urease activity in slag yards with cover-process are significantly higher than that with
(4) In early stage of recovery, vegetation growth status is relatively poor, coverage rate
and diversity index are also low, and the vegetation mainly composes of annual herb.
However, artificial vegetation has a good growth status. Soil nutrient based on artificial
vegetation restoration is less than that based on natural vegetation restoration. With the
increasing of recover age, the soil improvement based on artificial vegetation gradually shows
effect and soil nutrient content is improved faster, because artificial recovery can increase soil
biomass. At the same time, with the increase of recovery age, perennial plant species
gradually invades and increases their proportion in vegetation community. Thus, diversity
index increases as a result.
(5) Seed bank and ground vegetation have a certain degree of similarity. However, the
similarity shows different degrees for different restoration age and cover-process strategy (i.e.
cover-process and un-cover-process). Cover-process restoration provides slag yards with the
highest similarity coefficient (up to 0.45) after 2 years, while un-cover-process restoration
leads to relatively bad similarity coefficient (0.05) after 15 years.
Key Words：Soil chemical property; Soil enzyme activity; Vegetation recovery; Soil seed
bank; Slag yard; Highway