Experimental studies have well illustrated that plant and microbe interactions play an important role in the absorption of nitrogen (N) under different environmental conditions. However, it remains to be seen what role plant–microbe interactions play in regulating plant N accumulation rates (NAR) over broad climatic and geographic scales. Here, a transect survey was conducted in alpine grassland on the Tibetan Plateau to measure aboveground net primary production and plant N concentration corresponding with phenology indexes, the NAR patterns were measured by “changepoint” analysis. Meanwhile, matrix correlation analysis and variation partitioning analysis were performed to explore the dynamic of NAR in response to environment factors. Finally, structural equation model was employed to express the path coefficients of environmental factors on NAR. A significantly (P＜0.05) lower NAR (8.9 mg/m²/day) in cold-dry climates than that in warm-wet climates (31.1 mg/m²/day) were detected. Our results further demonstrated a cooperative interaction between microbes and plants stimulated NAR in weakly resource-limited environments but a competitive effect of microbes on plants-constrained NAR in strongly resource-limited environments. The NAR was strongly governed by coupled water-heat availability and microbial biomass via their effects on plant diversity. Our findings highlighted that plant–microbe interactions offered an important framework to better understand the generalizable mechanisms of plant N accumulation in different environmental conditions. The knowledge of ecological N accumulation mechanisms obtained here not only emphasized the importance of incorporating plant phenology and dynamics of plant N into the ecological N cycle model but also promoted our understanding of resource utilization between plants and soil microbes under ongoing global climate change.

实验研究已经很好地说明了植物和微生物之间的相互作用在不同环境条件下对氮（N）的吸收起着重要作用。然而，在广泛的气候和地理范围内，植物与微生物之间的相互作用在调节植物氮素积累率（NAR）中起什么作用还有待观察。在这里，在青藏高原的高寒草地上进行了横断面调查，以测量地上净初级生产力和与物候指标相对应的植物氮含量，通过“变化点”分析来测量NAR模式。同时，进行了矩阵相关分析和变异划分分析，以探索NAR响应环境因素的动态。最后，利用结构方程模型表达环境因子在NAR上的路径系数。P＜0.05），冷干气候下的NAR（8.9 mg / m ² / day）比温湿气候下的NAR （31.1 mg / m ^2）低/天）。我们的结果进一步表明，在资源有限的环境中，微生物与植物之间的协同相互作用会刺激NAR，但是在资源有限的环境中，微生物对植物限制的NAR具有竞争作用。NAR受水热可用性和微生物生物量对植物多样性的影响而受到强烈控制。我们的发现强调，植物与微生物的相互作用提供了一个重要的框架，可以更好地理解不同环境条件下植物氮素积累的普遍机制。