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以沙坡头地区人工固沙植物为研究对象 ,扩展了 Hutchinson提出的 n维超体积生态位概念 ,定义固沙植物种的水分生态位适宜度是该种的最适水分生态位与现实水分资源位之间的贴近度 .水分生态位适宜度的大小表示植物对土壤水分的利用程度 .根据几何平行度方法建立了新的数学模型 .实例计算结果表明 ,利用新模型计算结果比常用的百分比相似性公式计算的结果有较合理的数值分布 ;实验条件下的合理营林密度为 5 0 0 0株 /hm2 ,营林方式为柠条与油蒿均匀混播 ,此种情况下水分生态位适宜度最高 ,相应林木覆盖率最大 .在试验条件下 ,油蒿和柠条纯林的水分生态位适宜度平均值低于混播下的值 .关于不同种植密度下水分生态位适宜度的变化规律 ,呈现随密度增加先上升后下降的趋势 .由于油蒿是浅根系植物 ,利用土壤上层水分 ;柠条是深根系植物 ,利用土壤下层水分 ;二者适当混播后可使土壤水分合理分配和充分利用 ,因此混播下具有较高的水分适宜度值 ,而且实验条件下能够实现稳定共存 ,达到较好的防风固沙效果
The concept of n-dimensional hypersonic niche proposed by Hutchinson was extended to artificial sand-fixing plants in Shapotou region. The definition of water-niche fitness of sand-fixing plants is the most suitable water niche and water resource of this species The closeness between the water niche.The degree of water niche suitability indicates the degree of plant water use.A new mathematical model is established according to the geometric parallelism method.Example calculation results show that the new model is more efficient than the commonly used percent similarity formula The results showed that the distribution of water niche was reasonable. Under the experimental conditions, the reasonable planting density was 500 trees / hm2, and the mixed forests were planted with Caragana korshinskii and Artemisia ordosica. In this case, the water niche fitness was the highest, And the corresponding forest coverage was the highest.Under the experimental conditions, the average values of water niche fitness of Artemisia ordosica and pure stands were lower than those under mixed sowing.As for the variation of water niche fitness under different planting densities, Increase first and then decline.As Artemisia ordosica is shallow root plants, the use of the upper soil moisture; Caragana is a deep root system plants, the use of soil Water; Mixed After both appropriate and reasonable distribution of soil moisture can make full use of, thus having a higher water fitness value Mixture under the experimental conditions and can be stably coexist, achieve better results sand-fixing