【作者】 刘虎俊；

【导师】 王继和； 李毅；

【作者基本信息】 甘肃农业大学 ， 水土保持与荒漠化防治， 2012， 博士

【摘要】 我国干旱区面积约占陆地面积的32.8%，而风沙则是引发区域灾害的重要因素之一。控制风沙危害对于干旱区工农业生产和人居环境意义深远。由于水资源限制，沙障成为干旱区治沙的主要措施。选用替代材料，对于区域风沙危害防治具有现实意义。沙旱生灌木构型和防风固沙特性研究将对植物治沙理论完善、干旱区的植物治沙工程设计、风沙灾害防治和植物防风固沙工程评价提供参考。通过野外观测和风洞模拟实验，观测了民勤治沙综合实验站周围的7种灌木，分析了其构型与枝系格局；测定了仿真固沙灌木构型及其对风沙流作用，并对其构成的灌木林的水平和垂直梯度风速、输沙量、风蚀量或风积量进行了观测，分析了空气动力粗糙度、风沙流结构和输沙率等。初步确定了防风固沙灌木结构参数，比较了仿真固沙灌木的防风固沙效能。仿真固沙灌木以优良的固沙灌木为原型，结合多种植物构件优势组合而成，是化学固沙的立体化，也是植物固沙的工程应用。应用仿真固沙灌木建立防风固沙林随时可以栽植，基本不受立地条件约束，可以补充和优化防风固沙林，也为灌木林防风固沙机理的野外模拟研究提供了材料。通过观测分析7种沙旱生灌木以及仿真固沙灌木及其灌木林，获得如下结论。1）梭梭、花棒、沙拐枣、白刺、红砂、沙篙和油篙的构型可归为两类，而枝系格局也属于两种类型，灌木个体的空间结构影响其防风固沙能力。（1）从生物形态学特征分析，以叶的多少和相对大小，将白刺定为有叶型灌木，梭梭、沙拐枣、红砂、花棒、沙篙和油篙都归入叶特化类型。以枝的密度可分为密生型和疏生型灌木，红砂、白刺、油篙和花棒可归为密生型灌木，梭梭、沙拐枣和沙篙则可定为疏生型灌木。（2）从枝系格局分析，叶特化灌木的各级枝分枝角变化较小，有65.0%的分枝角为25o~50o，有叶灌木的冠层的一级枝的分枝角度大于叶特化灌木。7种灌木分枝角度平均值趋势是自冠层内向外分枝角度逐渐变大，枝序都可分为四级。油篙、花棒、沙拐枣、白刺和红砂为外层枝较短而内层枝较长，梭梭和沙篙则为外层枝较长，而中间枝较短的逐级增长型灌木，所有观测灌木枝长主要是5~30cm；分枝分维数都小于1，也就是说随着枝长的增加，分枝数增加的趋势变小，即枝长达到一定值时就不再产生分枝。除梭梭外，6种灌木的总体分枝率都小于1，说明6种灌木的枝条分布都是外密内疏。所观测灌木的积沙量与枝条分布的高度和密度均匀度相关，迎风面枝条的密度约在20%～30%积沙量相对较大。（3）白刺和红砂的树冠近似成坛状，白刺和红砂的侧影面积在高度10cm内最大，而红砂的侧影面积随高度变化幅度较白刺为小。花棒、梭梭和沙篙的侧影面积最宽处则为高度20-40cm范围，略成梭形。沙拐枣的侧影面积则随高度变化幅度与其他几种灌木相反，在最高处宽度最大，近乎扫帚形态。2）仿真固沙灌木采用高分子聚合材料加工而成，仿照固沙灌木结构制作，参考天然灌木的构型与枝系，制作了有叶仿真固沙灌木和无叶仿真固沙灌木两种。仿真固沙灌木可以单独应用建立防护林，也可与其它机械沙障、雨养植被配置，形成工程治沙为主的防护体系，也可形成以植物为主、仿真植物补充的植物治沙体系。（1）仿真固沙灌木总枝序为3~4级，分枝数自树体冠层内向冠层外逐级增加；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；有叶仿真固沙灌木高度为50cm；叶披针形长4-7cm，无主干，主枝上不再分枝，直接在枝上连接叶，叶充当一级枝，形成二级枝序的独根仿真固沙灌木。无叶仿真固沙灌木高40cm，分为三级枝序，第三级枝全部集中凝结形成独根。两种仿真固沙灌木皆以钢丝为骨架，具有柔韧性，为无主干的丛枝灌木。（2）仿真固沙灌木的冠形为半球状，构型为内疏外密，侧影面的枝密度为25%-50%。仿真固沙灌木的冠幅覆盖面积为0.50-0.78m~2，侧影面积等于冠幅覆盖面积50%。可以设置成不同覆盖度纯林，也可以与其他植物或沙障等搭配组合，形成防风固沙体系。3）通过野外和风洞仿真固沙灌木个体对风速影响和积沙形态比较，仿真固沙灌木增大了地表粗糙度，降低了风速，减弱了风力，拦截运动沙粒形成积沙，仿真固沙灌木纯林及与梭梭混交林防风防风固沙效应显著。（1）在野外对照观测无叶仿真固沙灌木、有叶仿真固沙灌木和沙篙周围风速，仿真固沙灌木风速削减率随风速增大而增加；不同风速等级，仿真固沙灌木风速削减率不同。在20cm高度，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风速削减率达50.23%。当风速大于5m/s时，有叶仿真固沙灌木风速削减率相对较大。有叶和无叶仿真固沙灌木的平均透风系数大于50%，最大可达92.23%，但小于对照观测的沙篙透风系数。（2）无叶仿真固沙灌木的积沙范围可达0.50m2，每株无叶仿真固沙灌木积沙体积约为其冠幅体积的3倍，无叶仿真固沙灌木的积沙以其为中心呈饼状。有叶仿真固沙灌木形成漏斗形积沙形态，每株有叶仿真固沙灌木积沙体积约为其冠幅体积的1.04倍。（3）无叶仿真固沙灌木纯林的防风效能低于有叶仿真固沙灌木林，但二者都随风速增加而增大。当风速为8.0-10.7m/s，有叶仿真固沙灌木林降低风速率约是无叶仿真固沙灌木林的1.5倍。不同风速和不同高度，两种仿真固沙灌木平均削弱风速差异显著。两种仿真固沙灌木纯林风速与高度变化关系都呈指数函数关系，仿真固沙灌木林粗糙度是流沙地2.01倍。（4）仿真固沙灌木+梭梭林平均降低风速率小于塑料方格沙障，但随着风速等级的增加，仿真固沙灌木与塑料方格沙障降低风速的差值缩小。在风速为8.1-8.9m/s时，仿真固沙灌木降低风速率达塑料方格沙障的80%。在20cm高度，梭梭+仿真固沙灌木林输沙率随高度变化为指数递减相关；裸沙地平均输沙率是梭梭+仿真固沙灌木林输沙率的4.13倍。在流沙地仿真固沙灌木林内，观测50cm高度输沙率，仿真灌木林密度越大，输沙率越小。裸沙地输沙率最小输沙率是仿真固沙灌木林输沙率的1355.70倍，仿真固沙灌木林具有显著的阻沙和固沙作用。（5）在7m/s、9m/s、12m/s、15m/s实验室控制风速下，有叶仿真固沙灌木在风洞内形成6个减速区和4个加速区。仿真固沙灌木的主枝条数量为16-20根，疏透度为30%-40%之间的防风阻沙效能相对较大，在不同风速下输沙率的变异系数较小，是相对较优的仿真固沙灌木构型。更多还原

【Abstract】 The32.8percent of total territory of China is located arid region with a common and strong harm from wind and sand. It is important to control wind-sand disaster for developing region economy and improve resident quality in arid area of China. As less water resource, it was still a main method in arid region to set up the sand barrier for controlling wind-sand harm. It would be worth to research and develop a new material and techniques on integration and experiment at harm area of arid region for the implement on enhanced function of control desertification damage, and a urgently task on wind-sand action, control wind and sand harm, especially the connection between structure of shrub and wind-sand flux. It would boost the study and give an actuality improve to support control theory of plant, design and management of combating project on wind-sand, disaster prevention and control and evaluation of engineering of combating wind and sand harm. The control efficiency of simulation shrub forest was effected relatively the wind-sand action and combating damage of wind and sand by an investigation in simulated plant of field and reference simulated experiment in wind tunnel. The architecture of seven shrubs and simulation shrub was measured in field and wind tunnel at Gansu Minqin National Studies Station for Desert Steppe Ecosystem with the Minqin Desert Botanical Garden and Sha Potou Desert Study Station. It was discussed that the architecture index of simulation shrub and the efficiency of simulation shrub forest to defend wind and sand damage. The architecture and ordination of branchs the relation between architecture of simulated shrub and wind-sand action, vertical and horizontal wind velocity, transporting sand, aeolian and traped sand were measured and aerodynamic roughness, structure of sand cloud and ratio of sand dischange were calculated. The simulated shrub, which modeled the shrub, combined goodness of constructions of psammophyteses with adaption architecture at wind-sand environment, and the techniques of control wind-sand disaster by simulated shrub that was a chemistry control wind-sand, as well as control wind-sand by biological method. It was not limited to establish windbreak for denfending wind-sand by forest that would be supplied by simulated shrub and gived a material for study on mechanism of desert control by shrub. The results were as follows to be taken by the study in field and wind tunnel on simulation shrub.1) The architectures of Haloxylon ammodendron, Hedysarum scoparium, Calligomtm mongolicum, Nitraria tangutorum, Reaumuria kaschgarica, Artemisia ordosica and A. arenaria were divided into two categories, as well as the branch ordination, which affected the ability to control wind-sand by shrub.(1) According to the biological characteristics such as leaf, Nitraria tangutorum was category with relative big leaf, and the others were classified into a type with especial leaf. Reaumuria kaschgarica, Nitraria tangutorum, Artemisia ordosica, Hedysarum scoparium, would be classified into a shrub with dense branching architature, as well as the spacing architecture of Haloxylon ammodendron, Calligonum mongolicum, Artemisia arenaria.(2) On the basis analysis of branche ordination,65.0%of branching angle was25°～50°. The changes of different grade branch’s branching angle of shrub with leaf, were bigger than that of shrub with especial leaf. The mean of branching angle of seven shrubs was gradually bigger from inside to outer position of canopy. The branch ordination of all of seven shrubs was divided into four degrees, according to proportion of branching by degrees rate. The branch length of all observated shrubs was mainly5-30cm. The outer branches of canopy of Artemisia ordosica, Hedysarum scoparium, Calligonium mongolicum, Nitratia tangutorm and hololachne soongarica were shorter than that of ins id banches. It was shrub, such as Haloxylon ammodendron and Artemisia arenaria, that outer branches were gradually longer than that of middle branch and inside. The count of branching fractal dimension of shrubs observed all of was decimal, which showed that increased degree of length of branch decrease with that of branch length increase, and would not devided secondary branch as branch length achieved a certain value, but it had one branch at least. Except Haloxylon ammodendron, all of branching rate of six shrubs were smaller than one, which showed that branching distribution of the six shrubs was dense outside whereas thinned inside of canopy. The collection quantity of sand related with percent of windward density of branch distribution as20%-30%, and relatively collected larger number of sand.(3) The outline of Nitraria tangutorum and Reaumuria songarica was like a bomb one with the widest at the height of10cm, while the grade of change upwind projected area with height of Reaumuria songarica is smaller than that of Nitraria tangutorum. The canopy of Hedysarum scoparium, Haloxylon ammodendron and Artermisia sphaerocephala was like spindle with the widest at the height of20-40cm. It was opposite with measured other shrubs that wide of upwind projected area of Calligonum mongolicunl increase with height of canopy which showed the widest at the top and almost a shape like a broom.2) The simulation sand-fixed shrub was maded from polymer materials, and simulating architecture of sand-fixed shrub. The two kinds of simulation sand-fixed shrub modeled natural shrub were produced which one was simulation shrub with leaf, and another leafless simulation shrub, according to configuration and branching architecture. The simulation shrub had advantage of sand barrier and sand-fixed shrub. It could be a method to establish shelterbelt alone or collocate with other sand barrier or rain-fed vegetation by simulation shrub.The biological sand-control system and sand barrier was complemented by simulation shrub.(1) The branch ordination of simulation shrub should progressively reduce from the inside to outside of canopy, and the grade of general branch ordination was3-4levels. The branch angle of simulation shrubs should be better between25°to50°. The branch angle progressively became bigger from grade to grade at the inside to outside of canopy. The simulation shrub with leaf would be composed with lanceolate leaves at length of4-7cm, without trunck at height of5-50cm, and tall of50cm. The leaves connect directly the primary branch without secondary branch, which formed simulattion shrub with alone roots without the secondary branch ordination. The height of simulated shrubs without leaves is40cm, it can be divided into three-level branch ordination, the third-level branch all concentrate on the roots; the two kinds of simulated shrubs take the steel wire as its body, it has flexibility, is arbuscular without trunk.(2) The shape of simulation shrub was hemispherical canopy whith architecture of sparse inside and dense outside. The branch density of upwind projected area would be not less than0.25-0.50, and it was half that upwind projected area equal the canopy area of0.50-0.78m2. The simulation sand-fixed shrubs could be established windbreak by themself and combined sand-fixed forestry system with shrubs.3) Compared the impact on the wind velocity and the magnitude of transported and accumulated sand in experiment in the field and wind tunnel, it determined that the simulation shrubs increased the surface roughness, reduced the wind velocity, weakened wind power, and intercepted movement sand, and had evident function to control wind and fix shifting sands.(1) The wind velocity, surround the simulation no-leaf-shrub and the leaf simulation in the field, as well as Artemisia arenaria, decreased relatively with wind velocity increased. Under the different wind velocity grade, the ratio of weakened wind velocity of the simulation shrubs was different. At height of20cm, it was biggest ratio of75.08%to decrease wind velocity by no-simulation leaf-shrubs, as well as50.23%of the simulation leaf-shrubs. It was relatively large that simulation leaf-shrubs decraese ratio of wind velocity at the wind velocity more than5m/s. The average ventilation coefficient of the leaf and no-simulation leaf-shrubs was more than50%, and the largest was92.23%, while less than the ventilation coefficient of Artemisia arenaria.(2) The range of accumulating sand of simulation no-leaf-shrubs was up to0.5m2. The volume of accumulating sand of per simulation shrubs was about three times of its canopy volume, and shape accumulated sand of no-simulation leaf-shrubs with its center look like a discoid. The simulation leaf-shrubs formed a funnel-shaped accumulated sand shape, and the sand volume of per simulation leaf-shrubs was approximately1.04times of its canopy volume.(3) Windbreak efficiency of simulation no-leaf-shrubs forests was lower than the simulation leaf-shrubs forests, while efficiency of both increased with the wind velocity. At the wind velocity was8.0-10.7m/s, the rate of reducing the wind velocity of the simulation leaf-shrubs forest was about1.5times that of the simulation no-leaf-shrubs forest. At different wind speeds and at different heights, the difference of weakening the average wind speed of two kinds of simulation shrubs was significant. The wind velocity of two simulation shrubs forests had exponent function relationship with a high degree of change, and the roughness of simulation shrubs forest was more two times of that shifting sand-land.(4) The average reducing ratio of wind velocity of simulation shrubs+Haloxylon ammodendron forest was less than that of the plastic checkerboard barrier. Nevertheless, the compared ratio decreasing the wind velocity between simulation shrubs and plastic checkerboard barriers was less with the wind speed increasing. At8.1-8.9m/s of wind velocity, the ratio of decreasing wind velocity of the simulation shrubs was80%of plastic checkerboard barriers. At height of20cm, the transporting rate of Haloxylon ammodendron+simulation shrub forest was exponential decline correlation coefficient with height changes. The average transporting rate of the pure sand-land was4.13times of the Haloxylon ammodendron+simulation shrub forests. At moving sandland, the transport ratio of sand was measured. The results shown the transporting rate of sand in simulation shrub forest increased with the dencity of forest was less. The average transporting rate of the pure sandland was1355.70times of the simulation shrub forests with1.5×2.0m of spacing in the rows and spacing between rows.(5) At the7m/s,9m/s, of12m/s, and15m/s of wind velocity of laboratory, six deceleration zone and four acceleration zone of wind velocity were formed around simulation leaf-shrubs. The number of main branches of simulation shrubs was16-20branchs. The performance ratio of wind and sand prevention was relatively large with transparence degrees30%-40%of simulation leaf-shrubs. At different wind velocity, sand transport ratio of sand was relatively less, which was compared with better simulation shrubs architecture.更多还原