| 其他摘要 | Soil, as a vital natural resource, performs key environmental, economic, and social functions. High
quality of soil not only produces better food and fiber, but also helps establish natural ecosystems and enhances air
and water quality. Soil quality improvement is important for sustaining a global biosphere. Understanding the
variability of soil quality is important in improving an ecological environment. Vegetation restoration played an
important role in the ecological environment construction, and it could reduce the soil erosion and improve the
soil quality. The hilly area of southern Ningxia, one of the soil erosion areas, was the key region of the conversionof cropland to forest and grassland and ecological construction. According to the complexity of the ecological
environment in the hilly area of southern Ningxia, lots of vegetation restoration patterns had developed from the
1990s. Medicago sativa and Caragana microphylla were the main plant species in the vegetation restoration of
this area. Some studies had also shown the variability of soil aggregate content and soil microorganisms under
different artificial vegetation restoration patterns in the hilly area of southern Ningxia. However, little attention
had been paid to the effects of vegetation restoration patterns on soil quality using a mathematical model. The
objective of this research is to explore the response of soil quality to artificial vegetation restoration patterns in the
hilly area of southern Ningxia. In this paper, soil samples were taken in 0-10 and ＞10-20 cm soil layers under
seven artificial patterns. Soil samples were air-dried, divided, and passed through a 2-mm nylon sieve for
measuring soil available phosphorus, available potassium, and soil pH value. Part of the air-dried and sieved
samples were grounded and passed through either a 1-mm or a 0.25-mm nylon sieve for determining soil total
nitrogen, total phosphorus, and organic matter. The soil organic matter and total nitrogen were determined using
the potassium dichromate hydrometer method and the semi-micro Kjeldahl method, respectively. Soil total
phosphorus was digested by H2SO4-HClO4 and followed by molybdate colorimetric measurement. Soil available
phosphorus and available potassium was attained by extracting soil with 0.5 mol/L sodium bicarbonate (NaCO3)
and 1 mol/L ammonium acetate (NH4Ac) then measured by molybdate colorimetric measurement and an atomic
absorption spectrometer, respectively. A pH meter determined soil pH after extraction from a soil water ratio of
1:1. Soil water content was measured using a drying method. Considering the natural conditions of the hilly area
of southern Ningxia, soil total nitrogen, total phosphorus, available phosphorus, available potassium, organic
matter, pH, and soil water content in 0-10 and ＞10-20 cm soil layers were selected as the index. Using the grey
correlation model and cluster analysis, seven artificial patterns were selected to study the effect of vegetation
restoration on the soil quality and determine the optimum pattern. The results showed that different artificial
vegetation restoration patterns had different effects on soil quality. Compared to farmland, both the Medicago
sativa pattern with 5, 10, 15, 20 years and Caragana microphylla pattern with 30 years could improve soil quality.
The best pattern was the Caragana microphylla pattern with 30 years. It indicated that with the development of
the Conversion of Cropland to Forest and Grassland Project, planting both Medicago sativa and Caragana
microphylla should be the optional choices to restore soil quality, since they could decrease the soil erosion and
improve soil condition, especially in the hilly area of Southern Ningxia. |
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