仿真固沙灌木构型及配置的防风固沙效应

The activity of wind and sand is common and serious disaster in the arid area of China, while it is a still main method to set up the straw barrier and defend the disaster of wind and sand. Because of less water resource, so it is becoming very worthy and urgent to invent and develop new materials and techniques on combining with the function of plants and sand barrier for controlling damage of wind and sand. The simulated shrub is not only a new material, but also it can provide a convenience for simulation studying on the theory of controlling harm action from wind and sand, and design engineering of protecting oasis. The contents of the project, for which is applied, will be achieved by the field investigation and experiment of wind tunnel. The measurement and analysis indexes including the architecture of natural and simulation shrub, sand flux, the effectiveness of the simulated shrub caused by the action of wind and sand, the efficiency of structure and arrangement of shrub forest with 25-30 percent vegetation affected by the wind-sand action. The mechanism of controlling wind and sand damaged by shrub, special characteristics of the sand cloud will be measured in field and wind tunnel. The structural parameters of 22 shrubs, such as the ratio of branch and twig, branch dimension, box cutting dimension, upwind projected area, roughness concentration porosity, will be measured. The simulation experiment concerning the effectiveness of wind-sand of shrub forest with homogeneous and heterogeneous arrangement will be carried out in the field and wind tunnel. The indexes of wind-sand action, such as aerodynamic roughness, roughness, zero horizontal displacement, wind-sand structure, threshold wind velocity, wind velocity profile, sediment transport rate, and quantity of aeolation and sediment sand, will be calculated and explained. The effectiveness of wind and sand action will be evaluated by shrub structure and arrangement. The expectations of the project are as follows: mentioned by the above investigation and experiment. The architecture parameters of 22 eremophytes and simulated shrub will be ensured by compared and screened to defend wind-sand shrub. It will be explained that the structure and arrangement of shrub forest to affect wind-sand flux, the aeolation and sediment of sand. The influence of simulated shrub forest on wind-sand action will be discussed. It will be an expected result to find and explain that different arrangements of shrub forest influencing the efficiency on controlling wind-sand action, the mechanism of defending wind-sand harm by shrub in a special site condition and relation between threshold wind erosion velocity and vegetation coverage.

在干旱区，风沙活动常引发灾害，威胁区域生产和生活；但因水资源缺乏，植物治沙受到限制，而工程治沙多以设置柴草沙障为主，研发新型治沙材料与技术具有重要现实意义。结合了灌木空间结构和化学固沙优势的仿真灌木不仅增添了治沙新材料，也为灌木林防风固沙机理仿真研究提供了方便。本项目将结合野外观测与风洞实验，测定22种灌木构型，比较被测对象的结构参数，分析灌木构型对风沙流影响，筛选较优仿真固沙灌木构型及其标准化生产参数；在特定立地条件，配置确定覆盖度的不同结构仿真灌木林，观测其风速、输沙量、地表蚀积动态；分析粗糙元密集度、起沙风速、空气动力粗糙度、零平面位移、风沙流结构、输沙率、输沙通量比率和防风固沙效能及其关系，探讨灌木林结构与风沙流结构、输沙率、临界起沙风速、沙尘释放与沉降和地表蚀积关系；分析粗糙元密集度影响、灌木林配置与防风固沙效能关系；探求低覆盖度灌木林防风固沙效能最大化的配置和区域临界侵蚀风速。

项目通过观测分析沙旱生灌木，提出并仿制仿真灌木4种，其中2种应用到野外实验，比较了它们的防风固沙效能，提出了仿真固沙灌木构型参数，探讨了防风固沙林配置。全面完成了项目计划成果内容，项目取得主要结果可归纳如下：.①提出了优良仿真固沙灌木构型参数：通过对防风固沙灌木构型观测和仿真灌木的防风固沙效能比较，提出仿真固沙灌木标准化生产指标。仿照沙旱生灌木构型仿制了4种仿真固沙灌木：有主干松叶仿真灌木、有主干柏叶仿真灌木、无主干无叶和无主干有叶两种仿真固沙灌木。在野外观测其对风沙效应，仿真固沙灌木总高度小于1m，冠形为半球状，构型为内疏外密，分枝数自树体冠层内向冠层外逐级增加，侧影面的枝密度为25%-50%，冠幅覆盖面积为0.50-0.78m2。仿真固沙灌木总枝序为3~4级，分枝角介于25º~50º之间，自树冠层内向冠层外，分枝角逐级增大；枝长介于5~50cm之间，最高级枝全部集中凝结形成独根。仿真固沙灌木以钢丝为骨架，具有柔韧性。.②阐明了仿真灌木+梭梭林的风沙流特征及其防风固沙效能：仿真灌木+梭梭林增加地表粗糙度，削减风速率随风速的增大而增加，降低了林内输沙量。其风沙流的输沙通量随高度变化呈指数递减。仿真灌木+梭梭林不仅降低了输沙量，而且改变了风沙流的沙粒级空间结构，降低了20 cm高度以上粘粒的空气含量，具有防尘作用。.③提出低覆盖度灌木林配置模式：在低覆盖度25-30%的灌木林，配置模式为株距等于株高，行距等于株高5-6倍的防风固沙林防护效能相对较大。仿真固沙灌木林的粗糙度是流沙的2-5倍。无叶仿真固沙灌木最大降低风速达75.08%，有叶仿真固沙灌木最大降低风速达50.23%。相同配置的防风固沙林，调节灌丛结构可以提高其防风固沙效能。.项目共撰写论文10篇。项目将植物空间结构优势与工程治沙技术结合，形成新型防风固沙材料。项目部分成果在《中国科技成果》报道，得到中央财政林业科技推广示范项目（项目编号：[2015]ZYTG5号）”资助推广应用。