Key Laboratory of Mountain Environment Evolution and Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China; Xainza Alpine Steppe and Wetland Ecosystem Observation Station, Xainza 853100, China; University of Chinese Academy of Sciences, Beijing 100049, China.
College of Geographical Science, Shanxi Normal University, Taiyuan 030031, China.
Sci Total Environ. 2022 Jul 15;830:154635. doi: 10.1016/j.scitotenv.2022.154635. Epub 2022 Mar 18.
As an important coarse inorganic fraction of soil, gravel may regulate the effects of the interaction between above- and belowground communities and affect the relationship between microorganisms and plants in alpine ecosystems. However, comparatively little is known about the effects of gravel on the acquisition pattern of nitrogen (N) by microorganisms and plants in alpine ecosystems. In this study, a N-labelling experiment was conducted to investigate the acquisition pattern of organic (N-glycine) and inorganic N (N-NO and N-NH) by microorganisms and plants under three particle sizes of gravel mulch (fine: 2-10 mm, medium: 10-20 mm, coarse: 20-40 mm) on a semiarid Tibetan grassland. Gravel mulch significantly improved the N recovery of Stipa purpurea, but had no significant impacts on A. nanschanica. Therefore, gravel mulch decreased the ratio of microbial biomass N recovery to plant biomass N recovery for S. purpurea, but caused little effect on the state of N competition between plants and soil microbes for A. nanschanica. The N absorption preference of plants from both species shifted from an individual preference for N-NO in the natural (i.e., control) microplots to a common preference for N-NOand N-NH in the fine- and medium-sized gravel mulch microplots, while there were no significant differences in microbial N recovery between N-NO and N-NH across all treatments. The results helped to improve the understanding of the acquisition pattern of N by microorganisms and plants under the influence of gravel mulch in alpine ecosystems, and provide theoretical support for revegetation in alpine ecosystems in the future.
作为土壤的重要粗无机部分，砾石可能会调节地上和地下群落之间相互作用的影响，并影响高山生态系统中微生物和植物之间的关系。然而，对于砾石对高山生态系统中微生物和植物获取氮（N）模式的影响，人们知之甚少。本研究通过氮标记实验，研究了在三种砾石覆盖粒径（细：2-10mm，中：10-20mm，粗：20-40mm）下，微生物和植物对有机（N-甘氨酸）和无机 N（N-NO 和 N-NH）的获取模式在半干旱西藏草原上。砾石覆盖显著提高了紫花针茅的氮回收，但对 A. nanschanica 没有显著影响。因此，砾石覆盖降低了紫花针茅的微生物生物量氮回收与植物生物量氮回收的比值，但对 A. nanschanica 植物和土壤微生物之间氮竞争状态影响不大。两种植物的氮吸收偏好均从自然（即对照）微区中对 N-NO 的个体偏好转变为细和中砾石覆盖微区中对 N-NO 和 N-NH 的共同偏好，而在所有处理中，微生物对 N-NO 和 N-NH 的氮回收均无显著差异。这些结果有助于提高对砾石覆盖影响下高山生态系统中微生物和植物获取氮模式的理解，并为未来高山生态系统的植被恢复提供理论支持。
