Significant anthropogenic and biophysical changes have caused fluctuations in the soil salinization area of the Keriya Oasis in China. The Driver-Pressure-State-Impact-Response (DPSIR) sustainability framework and Bayesian networks (BNs) were used to integrate information from anthropogenic and natural systems to model the trend of secondary soil salinization. The developed model predicted that light salinization (vegetation coverage of around 15-20%, soil salt 5-10 g/kg) of the ecotone will increase in the near term but decelerate slightly in the future, and that farmland salinization will decrease in the near term. This trend is expected to accelerate in the future. Both trends are attributed to decreased water logging, increased groundwater exploitation, and decreased ratio of evaporation/precipitation. In contrast, severe salinization (vegetation coverage of around 2%, soil salt ≥20 g/kg) of the ecotone will increase in the near term. This trend will accelerate in the future because decreased river flow will reduce the flushing of severely salinized soil crust. Anthropogenic factors have negative impacts and natural causes have positive impacts on light salinization of ecotones. In situations involving severe farmland salinization, anthropogenic factors have persistent negative impacts.
After analyzing and studying the existing sowing operation in forestry, a set of technological process of precision seeding based on optimal-control theory has been put forward and the prototype has also been designed and produced. This paper presents the general structure of the apparatus and analyses the working principle. An adjustable cell wheel feeding apparatus is designed to solve the problem of the uniformity of seeding. The theories of cooling mulching without adhesive on nutrition membrane and the process of membrane mulching are analyzed to set up the pressure model of the roll. After the experiments on the pressure of the roll and the analysis of the data, by the calculation of axial pressure transfer coefficient of the roll, has determined the best pressure of membrane mulching. At last, the test conditions of the prototype show that the frequency of failures is decreased, the damage rate of seeds is reduced, the seeding precision is improved, which satisfy the requirements of technical regulation on seeding in forestry and is beneficial to improve utilization ratio of good seeds.
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