Research data of the article entitled "Recruitment of oligotrophic bacteria and stimulation of soil ammonium production co-alleviate microbial nitrogen limitation of shrublands in the Mu Us Desert"

In the present study, we anticipated that 1) microbial enzyme activities and microbial N limitation vary across shrublands, especially in the rhizosphere;2) the prevalence of oligotrophic bacteria and fungi alleviate microbial N limitation; 3) higher soil GMR and biological N fixation rates reduce microbial N limitation, while great GNR increase microbial N limitation. To test these hypotheses, we investigated three typical shrublands in the Mu Us Desert (dominated by Artemisia ordosica, Salix psammophila and Caragana korshinskii, respectively), to delineate their patterns of microbial resource utilization and underlying microbial mechanism. The microbial metabolic limitation in the rhizosphere and bulk soil, along with the relative abundances of oligotrophs and copiotrophs, GMR, GNR, and biological N fixation rates (nitrogenase activity) were investigated using an integrated approach combining vector model of EES and 15N isotope tracing.本研究提出以下预设假说：1）微生物酶活性与微生物氮限制在灌丛生态系统间存在显著异质性，尤以根际（rhizosphere）土壤为然；2）贫营养细菌与真菌的相对优势可缓解微生物氮限制；3）较高的土壤GMR与生物固氮速率可削弱微生物氮限制，而高GNR则会加剧微生物氮限制。为验证上述假说，本研究选取毛乌素沙漠（Mu Us Desert）内3处典型灌丛生态系统，其优势物种分别为油蒿（Artemisia ordosica）、沙柳（Salix psammophila）与柠条锦鸡儿（Caragana korshinskii），旨在阐明其微生物资源利用模式与潜在微生物调控机制。本研究采用整合EES向量模型与15N同位素示踪技术的综合研究方法，对根际与非根际（bulk soil）土壤的微生物代谢限制、贫营养型微生物（oligotroph）与富营养型微生物（copiotroph）的相对丰度、GMR、GNR以及生物固氮速率（即固氮酶活性）开展了测定分析。