Tab. 2. Utilization of soil water in seabuckthorn woodland
Soil water content (%)
Soil layer
Depth of soil
layer (cm)
Range
Average
Percentage of
field capacity
Available water
storage (mm)
Soil water weak use layer
0-20
2.8-22.4
10.4
50.6
9.6
Soil water use layer
20-300
5.7-9.4
7.5
36.5
47
Soil water regulative and
supplemental layer
300-400
8.8-11.9
10.5
50.9
57.2
Soil water faint use layer
400-500
11.1-13.7
12.6
50.9
85.5
Note: 6-year-old seabuckthorn in Guyuan experimental area.
3.5 Woodland's management measures to improve WUE of seabuckthorn
To improve the WUE and productivity of seabuckthorn, emphasis needs to be put not only on the
use of available soil water, but also on the use of rainfall. Suitable site conditions for seabuckthorn
include shade, semi-shade and gully slopes. WUE and water productivity can be improved by
adopting measures such as land preparation (level ditch, short-band terrace and opposite slope
terrace), fertilization (organic fertilizer, chemical fertilizer and tiny spraying manure), chopping at
suitable times (6-7 years old), thinning, pruning or sowing between herbs and shrubs. For example,
the water content in upper soil layers of seabuckthorn woodland at Guyuan has been obviously
increased by means of loosening the soil. Fertilizer (manure and minerals) should be applied when
the leaves are being shed. Experimental results showed that either fertilization or spraying of manure
on the leaves could increase the productivity of seabuckthorn woodland by 33%-133% as compared
to the control. The sequence of spraying manure with best results is Mn>Zn>Mo>B, the effect of
spraying mixed N and P fertilizers is obvious. In the mountainous experimental field, the productivity
of seabuckthorn fruit is 125 kg /mu with N and P fertilizer, which is 191% higher as compared to the
control. An experiment of intercropping between seabuckthorn and Astragalus adsurgeas, with the
width of strips being 2-3 m, showed that water productivity is 1-2 times higher than that of seabuck-
thorn woodlands according to investigations in Wuqi and Guyuan.
4. Conclusions and Discussion
According to the results of studies on water use efficiency of seabuckthorn woodland in semi-arid
loess region in Wuqi, Ansai and Guyuan counties, WUE of seabuckthorn is 1.12-1.53g/m
2
.mm, which
is 3.1-6.4 times that of the vegetation in wasteland. Therefore, seabuckthorn has the physiological
characteristic of stable transpiration intensity, great water consumption of transpiration, strong water-
absorbing capability, more bound and less free water, and lower water potential. Morphological
anatomy shows that seabuckthorn has flourishing epidermis hair, thicker cuticle and developed
palisade tissue, and larger crevice of cells around the cortex parenchyma of the root. These charac-
teristics are a predominant reason why seabuckthorn can resist cold and wet habitat, withstand high
temperature and air drought, and adapt to the environmental conditions of semi-arid Loess Plateau.
Soil water used by seabuckthorn can be classified into four layers: weak use layer of root system,
use layer of root system, soil water regulated and supplied layer and faint regulative lager. The deficit
of soil moisture will be more serious with increasing age of seabuckthorn woodland, but the moisture
above 1-1.5m soil layer recovered very well, in which water content may excess or approach that in
natural grassland of barren hill.
The WUE of seabuckthorn can be improved by means of selecting suitable sites for afforestation,
regulating the density of woodland, strengthening management in the process of seabuckthorn
woodland closing and especially managing water and manure.
References
Li Daiqiong et al. 1986 Research on the Characteristics and Benefits of Hippophae rhamnoides Stands
Established by Air Seeding. Forest Science and Technology (6).
