【作者】 张德魁；

【导师】 牛俊义； 王继和；

【作者基本信息】 甘肃农业大学 ， 作物， 2007， 硕士

【摘要】 油蒿与沙蒿均是菊科蒿属半灌木植物,是干旱沙区重要的固沙植物,也是荒漠植被中的主要建群种和优势种,在荒漠区的生态环境保护和农牧业生产中发挥着极其重要的作用。研究油蒿与沙蒿的生理生态学特征及其防风固沙效应,对于进一步利用荒漠植物资源进行区域荒漠化治理,发展农牧业生产具有实践指导意义。同时对于进一步研究荒漠区植被的恢复与重建具有重要的学术价值。本文从油蒿与沙蒿的沙埋深度对种子萌发出苗的影响、生长发育规律、光合和蒸腾特性、种群分布格局、种群生态位、枝系构件组成特征以及防风固沙效应等方面进行了研究,主要结果如下:1.油蒿与沙蒿种子千粒重分别为0.311g和0.547g。种子在沙埋深度为0～4mm时,萌发率和出苗率均大于60%,沙埋深度从6mm到8mm时,萌发率和出苗率迅速下降,在4～20mm之间,萌发率和出苗率随沙埋深度的增加而下降,并且萌发率与出苗率的值随沙埋深度的增加而差距加大,沙埋深度大于20mm时种子不能萌发出苗。2.油蒿与沙蒿在荒漠区的物候发生日期相近,从3月中旬开始萌动至11月上旬停止生长,生长期230d左右,在生长发育过程中,营养枝积累养分,越冬后不死亡,第二年继续生长发育,而生殖枝开花结果后,随着种子的成熟干枯死亡,生殖枝的生长只有1a。3.油蒿与沙蒿的光合速率日变化呈单峰曲线变化趋势,且光合速率日变化随光量子密度的增减呈直线上升或下降趋势,一天中油蒿的光合峰值要比沙蒿的光合峰值出现的迟,油蒿在11:00 h出现,峰值为21.2272μmol·m^-2·s^-1,沙蒿在9:00 h出现,峰值为20.8348μmol·m^-2·s^-1,两种植物的净光合速率均在达到峰值之后迅速下降。一天中随光量子密度的增加或减少,油蒿的光合速率值上升或下降的时间要比沙蒿晚,光合速率值总体上油蒿高于沙蒿。4.油蒿的蒸腾速率日变化呈双峰曲线,两个峰值分别出现在9:00 h和13:00 h,蒸腾速率值分别为21.258 mol·m^-2·s^-1和24.404 mol·m^-2·s^-1;沙蒿呈单峰曲线,峰值出现在13:00 h,蒸腾速率值为16.444 mol·m^-2·s^-1。油蒿的蒸腾速率变化幅度比沙蒿大30.38%。5.由种群点格局分布分析和方差/均值比率法分析的油蒿与沙蒿种群的分布格局结论一致,油蒿与沙蒿种群中个体在水平空间的分布类型均为集群分布。6.从流动沙地、半固定沙地到固定沙地,油蒿的生态位宽度值分别为0.051、0.194、0.224;沙蒿的生态位宽度值分别为0.499、0.206、0.035;不同演替阶段的生态位宽度差异大,它们与其它物种间的生态位重叠差异也大,油蒿在固定沙地上与其它物种间的生态位重叠值大,而沙蒿在流动沙地上与其它物种间的生态位重叠值大;同一物种对间的生态位重叠值随着植被演替阶段的发展变化有相应地变化。7.油蒿与沙蒿的一、二、三级分枝均为中等分枝角度类型（分枝角度介于50o～60o之间）,只有梢部枝条的分枝为弱分枝角度类型（分枝角度介于35o～50o之间）,枝条的生长能较充分地向资源空间扩展;油蒿与沙蒿枝条的伸展从三级枝到一级枝呈现为减弱的趋势,枝条长度从三级枝向一级枝是逐渐变短的,油蒿各级枝长大于沙蒿的对应枝长。8.油蒿与沙蒿各构件中,叶构件的含水率远大于其他构件;枝构件的干重/鲜重的比率比其它构件的大,主要功能是干物质积累,枝构件中老枝的比率最大,老枝对植株的支撑与伸展功能是最大的。9.油蒿与沙蒿个体在地上不同高度处的生物量分配差别较大,油蒿地上生物量主要集中在0～50cm的高度上,30～40cm高度处生物量达到最大;沙蒿的生物量分散在10～100cm的不同高度上,70～80cm高度处生物量达到最大,沙蒿的各层枝条之间的间距大于油蒿,但枝条的总数比油蒿少。10.油蒿与沙蒿的个体防风固沙效应明显,在它们个体后0～300cm的距离范围内20cm与50cm高度处风速均有显著降低,特别是20cm高度风速下降最明显,均在植株后50cm处降到最低,之后缓慢增加。它们在不同高度风速变化曲线相似,油蒿对风速的降低程度明显强于沙蒿。油蒿与沙蒿群落防风固沙效应明显,特别是对近地面风速的降低显著,在半固定沙地和固定沙地近地面20cm高度同流动沙地相比,风速分别降低76.5%和86.0%,在200cm高度风速分别降低58.7%和56.3%。在流动沙地200cm高度风速为6.5m·s^-1时,固定沙地没有风蚀发生,半固定沙地输沙量为1.83 g·cm^-1·h^-1,只占到流动沙地57.18g·cm^-1·h^-1的3.2%。更多还原

【Abstract】 Artemisia ordosica krasch. and A. arenaria D.C. are both sub-shrubs of Artemisia in Asteraceaer, the main sand-fixing plants in arid desert and have played an important role in desert eco-environment protection and agriculture production. The paper has researched on impact of seed germinating ratio at different sand depth, growth and developing regulation, photosynthesis and evaporation characteristics, population distribution patterns, population niche, branching module characteristics and wind-break and sand-fixation effects. The main results are as follows.The average weight of 1 thousand seeds of A. ordosica krasch. and A. arenaria D.C is 0.311g and 0.547g respectively. The germinating and seedling ratio is both more than 60% when seed depth in the sand is 0～4mm, it is reduced quickly when seed depth is 6～8mm, especially, reduced remarkably in 4～20mm, the ratio is both reduced and different with the seed depth increasing in the sand, the seed can not germinate when the depth in the sand reaches to more than 20 mm.A. ordosica krasch. and A. arenaria D.C. have similar Phenological phase in research area, the yearly growth period is about 230d from the middle of March to early November. The nutrition branches can grow continually in life, however, fertile branches have only one growth season.The tendency of diurnal change on photosynthesis rate of A. ordosica krasch. and A. arenaria D.C. indicates single peak curves and also shows linear rising and declining tendency respectively. With the increasing of light quantum density, photosynthesis peak of A. ordosica krasch. occurs latter than that of A. arenaria D.C. in a day, A. ordosica krasch. is 11:00 am and peak value is 21.2272μmol·m^-2·s^-1,however, A. arenaria D.C. is 9:00 am and peak value is 20.8348μmol·m^-2·s^-1. The pure photosynthesis rate of two species reaches the peak values firstly, and then decline quickly. The value of photosynthesis rate of A. ordosica krasch .rising or reducing is later than that of A. arenaria D.C. with the light quantum increasing and reducing in a day, and the value of A. ordosica krasch is higher than that of A. arenaria D.C. generally. Diurnal change of evaporating rate of A. ordosica krasch. indicates double peak curves which occur at 9:00 and 13:00 in a day, the values are 21.258 mol·m^-2·s^-1 and 24.404 mol·m^-2·s^-1. However, Diurnal change of evaporating rate of A. arenaria D.C. indicates single peak curve, it occurs 13:00 in a day and peak value is 16.444 mol·m^-2·s^-1. The change range of evaporating rate of A. ordosica krasch. is 30.38% more than that of A. arenaria D.C.Population distribution patterns of the species are much similar under analysis methods by point distribution of population and space distribution index, the individual distribution patterns on horizontal space are hierachical clump.The breadth values on ecological-niche of A. ordosica krasch. are 0.051, 0.194, 0.224 from shifting sandy land, semi-fixed sandy land to fixed sandy land respectively, and the values of A. arenaria D.C. are 0.499, 0.206, 0.035, individually. And breadth value on ecological-niche in different succession stage has bigger difference, the difference of eco-niche overlaps between two species and other species is obvious, eco-niche overlap value of A. ordosica krasch. with other species at fixed sandy land is big, however, A. arenaria D.C. is big at shifting sandy land. And their eco-niche overlap is developing and changing with vegetation succession stages.The first, second and third grade branches of the two species belong to the medium branching angle patterns （the branch angle is 50o～60o, and the plant top is 35o～50o generally）. Branch growth can use resources fully in space and time through adaptability of long history succession.On branching module of the species, water content of leaf module is much more than that of other modules, the ratio of dry weight/fresh one in branch module is more than other modules in plant and its main function is to accumulate dry matter, old branch ratio in plant modules is the biggest and its function is also the biggest for supporting and developing plant growth in space and time.The plant biomass distribution at different high positions above ground is very different, the biomass of A. ordosica krasch. above ground is mainly concentrated at 0～50 cm high and is biggest value at 30～40 cm high, the biomass of A. arenaria D.C. is located at 10～100 cm high and is biggest value at 70～80 cm high. The distance between two branch layer of A. arenaria D.C. is bigger than that of A. ordosica krasch., the total branch number of A. arenaria D.C.is less than A. ordosica krasch..The wind-break and sand-fixing effect of two species is obvious, the wind speed at 20～50 cm above ground and distance of 0～300 cm from plants to the measuring points is reduced remarkably, especially, wind speed reduction at 20 cm high is the most remarkable and is the lowest wind speed at the distance of 50 cm to plants, and after that the wind speed is recovered gradually.The wind speed profile of two species are similar, the degree of wind speed reduction of A. ordosica krasch. is more obvious than that of A. arenaria D.C.. The wind-break and sand-fixing effect of the communities is obvious, especially to the ground surface. The wind speed at 20 cm high above ground in semi-fixed and fixed sandy lands comparison to the shifting sandy land is reduced 76.5% and 86.0% individually, and reduced 58.7% and 56.3% at 200 cm high above ground. When the wind speed at 200 cm high above ground in moving sandy land is 6.5m·s^-1, no wind erosion happens in fixed sandy land, transported sand quantity at semi-fixed sandy land is 1.83 g·cm^-1·h^-1, it is 3.2% of 57.18g·cm^-1·h^-1 at shifting sandy land.更多还原