吐哈地区是亚洲中部荒漠地区的重要组成部分，由于其极端而独特的自然地理条件和暖温带干旱荒漠气候特点，生长在该地区的荒漠植被体现出不同的分布规律和群落特征。梭梭（Haloxylon ammodendron）是该地区荒漠主要建群种之一，通过第三次新疆科考，本研究对地区梭梭的分布情况和群落特征有了更全面的了解。同时结合生境信息，使用冗余分析（RDA）和偏最小二乘路径模型（pls–pm）明确该地区影响梭梭分布和群落结构的主导环境因素，在此基础上，使用梭梭基因组数据进行群体遗传分析，探究该地区梭梭种群的可能来源和扩散路径，得到的主要结论如下：

（1）在吐哈地区，梭梭主要分布范围为88.86°–95.70° E，41.98–44.72° N，海拔约700–1600 m，主要分布地形为山前冲洪积平原、山地中低山丘陵，以及噶顺戈壁平原，主要分布位置为哈密市伊州区东部和北部、巴里坤哈萨克自治县、吐鲁番市高昌区北部，主要分布特征为呈斑块状间断分布，在哈密市伊州区东部镜儿泉附近形成吐哈地区较连续、生长良好的疏林。

（2）吐哈地区梭梭自然群落划分为5个类型，分别为：类型I，梭梭+戈壁藜群落；类型II，包梭梭+泡果白刺群落；类型III，梭梭+膜果麻黄群落；类型IV，梭梭+白皮锦鸡儿+驼绒藜群落；类型V，梭梭+短叶假木贼群落。5种群落类型的分布与海拔有关，并在不同地区和地貌上呈现不同的规律。整体上，在海拔900 m左右的荒漠，梭梭与戈壁藜构成群落，在海拔1100 m左右为梭梭+泡果白刺群落，在海拔1200 m左右为梭梭+膜果麻黄群落，在海拔1300 m左右为梭梭+无叶假木贼群落，在海拔1400 m左右为梭梭+白皮锦鸡儿+驼绒藜群落，此时与草本层优势种沙生针茅构成荒漠草原。

（3）温度日较差和年平均降水量影响吐哈地区梭梭的地理分布。温度日较差和土壤有机组分含量影响吐哈地区梭梭的群落物种组成，与白皮锦鸡儿、驼绒藜等适应山地等海拔较高地区的物种为共优种，且草本层优势种是沙生针茅的群落倾向于分布在土壤有机物含量较高，温度日较差较低的区域，与胞果白刺为共优种的群落分布的区域较其他类型的温度日较差更大。在降水、温度、土壤三个影响物种多样性的潜在变量中，土壤因素对物种多样性起直接作用，与物种多样性呈正相关，降水、温度通过影响土壤因子间接影响物种多样性，从总体效果看，物种多样性与降水呈正相关，与温度呈负相关。

（4）使用SNPs数据，将13个梭梭种群分为4类，奇台、吐鲁番、镜儿泉、亚勒曼、敦煌种群的核苷酸多样性较高，位于吐哈地区的东西两侧。使用叶绿体基因组数据，将白梭梭作为外类群构建系统发育树和单倍型网络，将13个梭梭种群及39种单倍型分为4个进化枝，其中奇台种群拥有最古老的单倍型类型，检测到的单倍型分布在各个枝中，单倍型多样性最高，认为是最扩散源种群。推测吐哈地区大部分梭梭种群由奇台种群向东扩散形成，在至少两次扩散事件中，不同的单倍型分别传播到以巴里坤县、西山乡、沁城乡为代表的哈密市北部、中部和新甘边界处星星峡、镜儿泉、敦煌等地，在西山乡梭梭种群可能保留了部分特殊的遗传成分。

The Turpan-Hami region is an integral part of the inner Asia, because of its extreme and unique natural geographic conditions and a temperate desert climate. The desert vegetation in this region exhibits different distribution patterns and community characteristics. Haloxylon ammodendron is one of the main dominant species in the desert of this region. The successful implementation of the third Xinjiang scientific expedition has updated the baseline data on desert plants in the Turpan-Hami region, providing valuable opportunities to study the distribution patterns, community characteristics, and possible origins of H. ammodendron in this region. Combining habitat information, redundancy analysis (RDA), and partial least squares path modeling (pls-pm), the dominant environmental factors influencing H. ammodendron distribution and community structure in the region were identified. Based on this analysis, population genetic analysis using genomic data was conducted to explore the possible sources and dispersal paths of H. ammodendron populations in the region. The main conclusions drawn are as follows:

1. In the Turpan-Hami region, H. ammodendron is mainly distributed between 88.86°–95.70° E and 41.98–44.72° N, at an altitude of approximately 700–1600 m, mainly distributed in piedmont alluvial plains, hills, as well as in the Gaxun Gobi. Major distribution areas include the eastern and northern parts of Yizhou District in Hami City, Barkol Kazakh Autonomous County, and the northern part of Gaochang District in Turpan City. H. ammodendron exhibits a patchy and discontinuous distribution, with relatively continuous and well-growing sparse forests in the eastern Yizhou District of Hami City.

2. Based on community dominant species and indicator species, the H. ammodendron communities in the Turpan-Hami region were categorized into five types: Type I, Haloxylon ammodendron+ Iljinia regelii community; Type II, Haloxylon ammodendron+ Nitraria sphaerocarpa community; Type III, Haloxylon ammodendron+ Ephedra przewalskii community; Type IV, Haloxylon ammodendron+ Caragana leucophloea+ Krascheninnikovia ceratoides community; Type V, Haloxylon ammodendron+ Anabasis brevifolia community. The distribution of community types is associated with altitude and exhibits different patterns in different regions and landforms. Generally, in deserts at an altitude of 900 m, H. ammodendron and I. regelii forms communities. At around 1100 m, it forms communities with H. ammodendron and N. sphaerocarpa. At approximately 1200 m, it forms communities with H. ammodendron and E. przewalskii. At around 1300 m, it forms communities with H. ammodendron and A. brevifolia. At around 1400 m, it forms communities with H. ammodendron, C. leucophloea and K. ceratoides, where the dominant species in the herbaceous layer is Stipa caucasica, forming a desert steppe.

3. Mean diurnal range and annual precipitation influence the geographical distribution of H. ammodendron in the Turpan-Hami region. Mean diurnal range and soil organic matter affect the species composition of communities. Species adapted to mountainous and higher altitude regions, such as C. leucophloea and K. ceratoides, are co-dominant species, and the dominant species of the herbaceous layer was S. psammosa tend to occur in regions with higher soil organic matter and lower mean diurnal range. The areas where communities co-dominated by N. sphaerocarpa have greater mean diurnal range than other types. Among the three potential variables affecting species diversity (precipitation, temperature, and soil), soil directly affects species diversity positively, while precipitation and temperature indirectly affect species diversity through soil factors. Overall, species diversity is positively correlated with precipitation and negatively correlated with temperature.

4. Using SNP data obtained, thirteen populations were classified into four cluster. The nucleotide diversity of populations in Qitai, Turpan, Jingerquan, Yaleman, and Dunhuang is relatively high and located on both sides of the Turpan-Hami region. Using chloroplast genome, Haloxylon persicum was used as an outgroup to construct a phylogenetic tree and haplotype network. Thirteen populations and thirty-nine haplotypes were classified into four clades. Among them, Qitai population had the oldest haplotype, the detected haplotypes were distributed in each clade, and the haplotype diversity was the highest, which was considered to be the most diffuse source population. It is inferred that most H. ammodendron populations in the Turpan-Hami region originated from the Qitai population and dispersed eastward. In at least two dispersal events, different haplotypes spread to the northern and central parts of Hami city, represented by Barkol County, Xishan Township, Qincheng Township, and the Xinjiang-Gansu border areas, represented by Xingxingxia Town, Jingerquan, and Dunhuang. The population in Xishan Township may retain some special genetic components.