沙坡头地区人工固沙植物水分利用及其生态位适宜度过程数值模拟分析

本文以干旱区植物为研究对象，探讨了自然降水资源的时空分布规律以及降水与固沙植物耗水之间的制约关系。通过扩展经典生态位理论的内涵，用数学抽象的方法定义植物水分生态位适宜度为其水分最适生态位点与现实生态位的贴近度，建立相应的数学模型，对固沙植物生态位适宜度进行了定量分析，并建立了生态位适宜度过程模拟方法。依据实验结果进行了有关计算与数值模拟，所做模拟结果与实际观测结果相吻合。结果表明，柠条与油嵩混播为实验条件下的最佳种植方式，密度为5000株／hm^2时其水分生态位适宜度最高，林木覆盖率也最大。文中进一步讨论了有限降水限制和沙地土壤水分亏缺胁迫下油篙和柠条对水分的竞争行为，混播下的生态位适宜度变化及稳定共存格局形成的机理。该结果为干旱区人工林的营建提供了定量依据。

Analysis on water utility of artificial sand fixing plants and its numerical simulation of the procedure of niche fitness in Shapotou Area

Focused on plants in arid region,the distribution regularity of the limited precipitation in spatial-temporal and the constraining relationship between precipitation and water consumption of sand fixing plants were discussed.We expended the definition of classical niche theory as that we defined the niche-fitness degree of plant moisture as the closeness between the optimal niche and the real niche by using abstract mathematics.Furthermore,we established the mathematical model.The niche fitness degree of sand fixing plants was quantitatively analyzed and the simulating method of niche-fitness degree procedure was established.The relative computation analysis and numerical simulation were completed on the basis of experimental data,and the result of simulation is agreement with the practical observation result.It indicated that the niche-fitness degree and the percentage of coverage of vegetation could gets the maximum value when interplanting Caragana korshinskii (C.K.) and Artemisia ordosica (A.O.) with 5 000 plants per hectare in the experiment,and this provides quantitative basis for artificial planting in arid regions.Otherwise,the competition between Caragana korshinskii (C.K.) and Artemisia ordosica (A.O.) for moisture in constraining of limited precipitation and coercing of soil diflicit in sand land and the variation of niche-fitness degree in mixed planting and the mechanism of generating the stable co-exist pattern were argued.