Radiating Benefit of Windbreak and Sand Fixation in the Baijitan Nature Reserve of Lingwu, Ningxia, China

Abstract

Many important ecosystem services show spatial flow characteristics, which are crucial for the study of environmental processes, such as the transformation, correlation, coordination, and management of ecosystem services at different scales. As a result, flow characteristics should be taken into account when it comes to the evaluation of ecosystem services. The study area was the Baijitan Nature Reserve, used to assess the radiating benefits of the windbreak and sand fixation from 2000 to 2019, based on wind erosion loss and sand spatial erosion models. The main results are as follows: Firstly, the fractional vegetation coverage (FVC) clearly increased over the last 20 years and the medium coverage, which accounted for 66.13%, became the main vegetation cover. The wind speed in the reserve dropped gradually as well. Secondly, sand only affected the nature reserve and the surrounding communities. When the wind speed was above a strong breeze (10.8–13.8 m/s), coarse silt could affect 26 downwind administrative regions, with an affected area of 2.13 × 106 km2. Thirdly, the benefits of windbreak and sand fixation varied with the beneficial range, including distance from the Baijitan Nature Reserve and the beneficial area. Dust deposition decreased as the beneficial distance increased. For instance, Shaanxi Province saw the greatest benefit of windbreak and sand fixation, with a dust deposition reduction of 6.87 × 107 t (1 t = 103 kg), followed by Hubei and Henan Provinces, with reductions of 5.31 × 107 t and 5.59 × 107 t, respectively. Fourthly, the periodical deposition in administrative regions decreased gradually, as did the different influence ranges. The dust depositions in the five phases of Shaanxi Province were 2.04 × 107, 1.83 × 107, 6.63 × 106, 4.65 × 106, and 3.48 × 106 t. Fifthly, medium silt, fine silt, and clay silt could easily drift long distances under the influence of sand-driving wind, thus affecting the air quality in downwind administrative regions. Sixthly, the sand source in Baijitan Nature Reserve was an important factor that caused sand–dust weather in downwind areas. The frequency of sand–dust weather was significantly higher in cities near the sand source than in other regions in downwind areas, and the correlations between particle concentrations less than 10 microns in diameter (PM10) and the time sequences of sand-driving wind reached significant levels in certain cities. We found that the windbreak and sand fixation in Baijitan Nature Reserve could offer great benefits to the downwind area. Establishing a desert nature reserve could be a great way to promote environmentally sustainable development since it could effectively reduce dust deposition and the frequency of sand–dust weather in downwind areas.