衰败梭梭林下土壤结皮发育对黄花补血草种子萌发和种群发育的影响研究

Limonium aureum (L.) Hill, is a typical perennial herb which belonging to Plumbaginaceae Family, Limonium Genus, and a fine plant resource of landscape vegetation which widely distributes in the desert and Gobi in the arid desert regions. With the developing of soil crust under the decayed Haloxylon ammodendron forest in Minqin desert areas, its population has showed a dispersing tendency and has important ecological value in the restoration of landscape vegetation and the function of wind-break and sand-fixation. However, it is not clear that how its seeds germination and population development adapts to the environment change controlled by the soil crust development in the arid desert regions. In this subject, investigations on the L. aureum population in the key stages of the soil crust development, such as shifting sandy, physical soil crust sandy and biological soil crust sandy will be performed to illustrate the soil seed germination , population development, the ability of soil crust trap seed, the characteristic of soil seed bank, the ecological and physiological characteristics by the field investigation, located observation and control experiment, and reveal adaptability of seed germination and population development to specific desert environment factors(such as soil moisture and nutrient) in the development of the soil crust, and explore the artificial promotion technology of Limonium aureum population and the mode of wind-break and sand-fixation with combination of shrub and herb(Haloxylon ammodendron and Limonium aureum) , thus provide scientific basis and technical support for restoration of landscape vegetation and function of wind-break and sand-fixation under decayed Haloxylon ammodendron forest in arid desert regions.

黄花补血草是蓝雪科补血草属多年生草本，是优良的地被植物资源，分布于干旱荒漠区的沙漠、戈壁等生境。黄花补血草种群在民勤荒漠区衰败梭梭林下土壤结皮发育区域呈现扩散势态，对林下地被植被恢复和防风固沙具有重要的生态价值，但土壤结皮发育过程中环境演变对其土壤种子萌发和种群发育的影响尚不清楚。本项目以衰败梭梭林下土壤结皮发育的关键阶段（流动沙地、物理结皮沙地、生物结皮沙地）的黄花补血草种群为研究对象，通过野外调查、定位实验观测和控制实验，研究在土壤结皮发育关键阶段其土壤种子萌发、种群发育、生理生态特征、土壤结皮捕获种子能力以及土壤种子库特征，揭示土壤结皮发育的特定环境因子（土壤水分和养分）演变对其种子萌发和种群发育的影响，探索种群人工促进技术和灌草（梭梭+黄花补血草）结合的防风固沙模式，为干旱荒漠区衰败梭梭林地被植被恢复和防风固沙提供科学依据和技术支撑。

1.项目背景: “衰败梭梭林下土壤结皮发育对黄花补血草种子萌发和种群发育的影响研究（31660124）”国家地区基金项目，执行期限为2017年1月至2020年12月。在民勤荒漠区衰败梭梭林下土壤结皮发育过程中，黄花补血草种群具有较高的防沙治沙和荒漠草地生态修复的生态价值，土壤结皮发育与黄花补血草土壤种子萌发和种群发育的具有较高的相关性。2.主要研究内容: 梭梭林下土壤结皮发育对降水入渗和土壤水分动态、土壤种子萌发、种群发育格局、分布格局、资源配置的影响、土壤种子分布以及土壤结皮类型对种子捕获能力的影响。 3.重要结果: （1）梭梭林下土壤结皮发育对降水的截留作用逐渐增强（土壤结皮层最大含水率分别为2.3%，3.8%，7.8%），限制了降水的深层入渗，但在限制深层土壤蒸发方面具有积极的作用。（2）土壤结皮发育既增加了土壤结皮层水土环境的稳定性，又增加了土壤种子基数，有利于土壤种子萌发和种群的发育（萌发密度分别为0.28，3.66，6.91株/m2），而模拟降水可有效改善土壤水分条件，为土壤种子萌发和种群更新提供了有利条件（土壤种子萌发密度分别为（5.81，90.13，33.12株/m2）。（3）土壤结皮发育对种群密度具有显著的促进作用（分别为0.94，11.07，8.00株/m2），对植株发育具有显著的抑制作用，具有小型化发育的趋势，但对种群总体发育具有显著的促进作用（种群盖度分别为13.33%，23.26%，19.57%）。（4）在个体水平上有利于根系的发育，提高个体生存力（根系占总资源的17-20%）。而种群水平上利用群体效应增加种群的繁殖（花占总资源的25%）,其生殖枝既是营养组织，又是生殖组织，是一种高效的资源配置模式（生殖枝占总资源的50%），根系和花之间存在权衡关系。（5）土壤结皮发育过程中种群分布格局均为集群分布，但集群程度逐渐增强（分别为3.45，16.53，37.60）。4科学意义: 揭示了梭梭林下土壤结皮发育促进其土壤种子萌发和种群发育的机制，提出了种群人工促进技术和灌草（梭梭+黄花补血草）结合的防风固沙模式，为梭梭林下荒漠草地生态修复和防风固沙提供科学依据。