黑河下游荒漠植物黑果枸杞分布格局及盐碱适应性研究

Study on life characters and adaptive mechanisms in desert habitat is an international frontier research field. The protection and sustainable use of germplasm resource have also been one of the central subjects concerning human environment and development. The natural community with Lycium ruthenicum Murr. located in the desert region of Heihe River downstream will be chosen as the building and dominant species, which will be investigated by combining the fixed sample survey and regular observation under the natural environment, and combining manual simulations and sample tests in laboratory under governing conditions. The relations between the plant distribution and the community structure with salinization habitat will be studied, as well as the morphological characteristics, the ecological control mechanism, and the physiological response of Lycium ruthenicum Murr. under different salinity-alkalinity conditions. The goal of the present project is to realize the comprehensive adaptive characters of Lycium ruthenicum Murr. With respect to the environment, to clarify the survival threshold to saline-alkali soil of the plant, and to establish the quantitative relationship between the physiological indexes and environmental factors, and eventually to reveal the stability and succession rule of the Lycium ruthenicum Murr. community in the Heihe downstream by dynamically analyzing plants' adaptation to saline-alkali habitat based on the advanced theory and technology such as ecological stoichiometry. the present study will help to find special functions and mechanisms for Lycium ruthenicum Murr. to survive adversity, to put the physiological ecology fruit in practice, and to provide scientific theory basis for the effective protection and rational utilization of Lycium ruthenicum Murr, as well as the regional society, ecology, and sustainable economic development.

干旱荒漠生境下生命特征和适应机制研究是地球科学与生命科学交叉的一个国际前沿领域，干旱荒漠生境下种质资源生物保护和持续利用也已成为当今人类环境与发展领域的中心课题之一。选择黑河下游荒漠地区以黑果枸杞为主要建群种和优势种的自然群落，将自然环境下固定样地调查和定期观测监测，控制条件下人工模拟和室内测试分析相结合；进行植物分布格局和群落结构与盐碱化程度的关系研究；研究不同盐碱条件下黑果枸杞形态特征、生理响应及生态调控机制；认识黑果枸杞对于环境的综合适应性特征，明确其耐盐碱生存阈值，建立生理指标与环境因子的定量关系；运用生态化学计量学等先进理论和技术对于盐碱生境适应性进行动态分析，揭示黑河下游黑果枸杞群落的稳定性及演替过程。该项研究有助于寻找黑果枸杞适应逆境的特殊功能和机制，提高生理生态学成果的实用性，为荒漠植物黑果枸杞的有效保护和合理利用、以及该区域社会、生态、经济的可持续发展提供科学理论依据。

沿黑河下游主河道垂直方向由近到远布设了黑果枸杞(Lycium ruthenicum Murr.)种群及群落调查观测样带和样地；开展了植物组成、盖度、密度、冠幅、高度、生物量和结构特征以及土壤水盐、养分调查；采集了植物叶片、茎干、根系及样地土壤样品分析了植物功能性状、生态化学计量特征、稳定同位素比率、矿质元素组成、渗透调节物质、非结构性碳水化合物、土壤物理组成、总盐及主要盐分离子含量；模拟了不同单盐及混合盐碱梯度胁迫对黑果枸杞种子萌发与幼苗生长的阈值与影响实验；比较了黑果枸杞在不同水盐条件下的叶片和群体光合作用及蒸腾作用等生理生态特征指标；拓展研究了黑河流域山前、中游、下游荒漠植物群落组成与分布格局及其环境响应；进行了黑河流域植物功能性状特征及反映荒漠植物的典型关键性状研究；比较了不同区域荒漠植物生理需水量和耗水规律。.研究分析得出：黑河下游重度盐碱条件下黑果枸杞重要值最高，为84.43%，中度盐碱重要值最小，为34.59%，离河道最近处，种群高度、盖度均最高；黑果枸杞种群均呈聚集分布格局；重度盐碱条件下黑果枸杞群落优势度最高，为0.94，轻度盐碱丰富度最大，为0.11；土壤表层(0-20cm)盐分主要影响了群落α-多样性指数的分布。黑果枸杞比叶体积(SLV)与叶干物质含量(LDMC)之间呈极显著负相关，叶C与P含量之间呈显著的负相关，土壤表层盐分对LT、SLV、Suc、TWC、RWC、C、N、P格局关系也具有重要影响，荒漠植物SLV可以作为反映叶性状特征的重要指标，这一特征性状综合的反映出荒漠植物的生态策略和适应途径。模拟盐碱胁迫实验表明，适量NaCl(150mM)处理可通过改善黑果枸杞幼苗根和叶水分状况促进植株的生长；盐处理可改善幼苗中Na+、K+积累和选择性运输能力特征；黑果枸杞种子萌发的NaCl、Na2CO3浓度的临界值分别是50mM和2.5mM，极限值分别是300mM和100mM；黑果枸杞是盐生植物，低浓度的盐促进萌发，高浓度的抑制萌发，综合表现出荒漠植物黑果枸杞更适于碱性盐生长；添加外源CaCl2能够有效地缓解盐胁迫对黑果枸杞种子及幼苗产生的伤害，提高种子及幼苗的抗盐能力。本研究为内陆河流域荒漠植被保育和生态恢复提供重要理论依据和应用指导。