中国科学院新疆生态与地理研究所机构知识库

梭梭和白梭梭作为古尔班通古特沙漠建种群， 在维持荒漠生态系统稳定和减缓荒漠化进程方面有着重要的作用。研究其同化枝微生物群落结构组成及树干茎流特征有助于我们进一步认识荒漠植物生态水文及养分循环。本研究通过茎流槽收集树干茎流研究梭梭和白梭梭树干茎流特征及养分特征，并采用 IlluminaMiseq 高通量测序技术研究了不同季节（春季和秋季） 梭梭和白梭梭同化枝微生物群落组成， 揭示了梭梭和白梭梭同化枝微生物群落组成，并证实非豆科植物固氮微生物的存在。研究结果对于进一步揭示荒漠植物梭梭和白梭梭养分来源和抗旱性具有重要的研究意义。 主要研究结果如下：（1） 不同径级下，梭梭和白梭梭树干茎流均随降雨量的增加显著性增加。其临界降雨量值随着径级的增加先增加后减小最后趋于稳定。梭梭和白梭梭的临界降雨量值均为 1.6 mm，能够有效的将小量级降雨汇集到植物根部。 其集流率均随径级的增大而减小，梭梭高于白梭梭， 其值大致在 10-130 之间。无论梭梭还是白梭梭，降雨经过冠层以后均出现了一定程度的酸化和养分富集，其 pH 值表现为，树干茎流< 穿透雨< 降雨； EC 和 TN 表现为，树干茎流> 穿透雨> 降雨。（2） 梭梭和白梭梭同化枝微生物主要分布于变形菌门（Proteobacteria）、拟杆菌门（Bacteroidetes）、放线菌门（Actinobacteria）、厚壁菌门（Firmicutes）、酸杆菌门（Acidobacteria）、疣微菌门（Verrucomicrobia）。主要分布于 15 个属，分别是：假黄色单胞菌属（Pseudoxanthomonas）、链霉菌属（Streptomyces）、甲烷氧化菌属（Methylosinus）、根瘤菌属（Rhizobium）、 Sediminibacterium、类芽孢杆菌属（Paenibacillus）、雷尔氏菌属（Ralstonia）、噬几丁质属（Chitinophaga）、金黄杆菌属（Chryseobacterium）、土壤杆菌属（Agrobacterium）、红长命菌属（Rubrivivax ）、 嗜 麦 芽 窄 食 单 胞 菌 属 （Stenotrophomonas ）、 生 丝 微 菌 属（Hyphomicrobium）、嗜甲基菌属（Methylotenera）、 Candidatus Koribacter，其中嗜甲基菌属（Methylotenera）仅出现在其同化枝表面，而 Candidatus Koribacter仅出现在其同化枝内部。（3） 梭梭和白梭梭同化枝拥有丰富的固氮微生物，其中表面固氮微生物有 35 个属，内部固氮微生物有 33 个属，表面多于内部。无论梭梭还是白梭梭，其表面固氮微生物总丰度均高于内部。由春季到秋季，梭梭外生固氮菌和白梭梭内生固氮菌总丰度基本保持不变但稍有下降，而梭梭内生固氮菌和白梭梭外生固氮菌总丰度呈增加的趋势。

As the main population of Gurbantonggut Desert， Haloxylon ammodendron andHaloxylon persicum play an important role in maintaining the stability of the desertecosystem and slowing the progress of desertification. Studying their assimilatingbranch microbial community composition and stemflow characteristics will help usbetter to understand their ecological hydrology and nutrient cycle. Therefore, in thisstudy, we collected stemflow through stem chute to study their characteristics ofstemflow.And we also used Illumina Miseq high throughput sequencing technology tostudy the assimilating branches’ microbial community composition of Haloxylonammodendron and Haloxylon persicum in spring and autumn.We revealed themicrobial community composition of Haloxylon ammodendron and Haloxylonpersicum ， and confirmed the nitrogen-fixing microorganisms in non-legumeplants.The results will help us better to know the nutrient cycle and drought resistanceof desert plants from microbial perspective. The main findings of this study are asfollows:（1） Under different diameters， the stemflow was significantly increasinglinearly with the increasing precipitation amount.And the critical rainfall increasedfirst， then decreased and finally stablized with the increasing diameter.What’s more，the minimum critical rainfall of Haloxylon ammodendron and Haloxylon persicumwere 1.6 mm， which could effectively collect small rainfall to plant roots.Theirfunneling ratio decreased with the increasing diameter.And the funneling ratio valuewere 10-130， and Haloxylon ammodendron was higher than Haloxylon persicum.Nomatter Haloxylon ammodendron and Haloxylon persicum， the pH of throughfall andstemflow was lower than rain， and the EC and TN of throughfall and stemflow werehigher than rainfall.（2） The assimilating branches’ microorganisms of Haloxylon ammodendronand Haloxylon persicum were distributed in Proteobacteria, Bacteroidetes,Actinobacteria, Firmicutes, Acidobacteria, Verrucomicrobia in phylum. And mainlydistributed in Pseudoxanthomonas, Streptomyces, Methylosinus, Rhizobium,Sediminibacterium, Paenibacillus, Ralstonia, Chitinophaga, Chryseobacterium,Agrobacterium, Rubrivivax, Stenotrophomonas, Hyphomicrobium, Methylotenera,Candidatus Koribacter.Methylotenera only appeared on the surface of theassimilating branch, but Candidatus Koribacter only appeared in the interior of theassimilating branch.（3） The assimilating branches of Haloxylon ammodendron and Haloxylonpersicum have two many nitrogen-fixing microbes， among which there are 35 generanitrogen-fixing microorganisms on the surface, 33 genera in the interior, and more onthe surface than in the interior. No matter Haloxylon ammodendron and Haloxylonpersicum， the total abundance of nitrogen-fixing microorganisms on the surface washigher than that in the interior. From spring to autumn, the total abundance ofnitrogen-fixing microorganisms on the surface of Haloxylon ammodendron and in theinterior of Haloxylon persicum remained the same but a slight declined, and the totalabundance of nitrogen-fixing microorganisms in the interior of Haloxylonammodendron and on the surface of Haloxylon persicum increased.