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• Cold environment suppressed the accumulation of microbial-derived C in the soil. • Warming increased microbial residues in the soil, but N addition decreased it. • Warming weakened the N-driven negative effect on soil C stability. Microbial-derived soil organic carbon has attracted increased attention as an important source of soil organic matter that may affect soil carbon persistence. Ecosystems at high elevation and latitude contain massive amounts of soil organic carbon that is potentially vulnerable to rapid climate change. However, little is known about the mechanisms that govern the production and accumulation of carbon derived from microbes in the context of global changes for these regions. Here, we investigate soil biomarkers from membrane lipids and microbial residues in an experiment with six-year warming and nitrogen (N) addition treatments in an alpine meadow of the Tibetan Plateau. The results showed low accumulation of amino sugars in soil (167.51 to 297.36 μg·g−1) for this alpine meadow. After the six-year manipulative experiment, warming promoted accumulation of microbial-derived carbon in soil with both increased bacterial (increased by 53.56%) and fungal carbon (increased by 25.60%). Nitrogen addition inhibited microbial-derived carbon accumulation (decreased by 25.37%) and significantly decreased the fungal carbon content relative to bacterial carbon content. Climate warming tended to weaken this N-driven negative effect. As microbial residues relate closely with soil organic matter stability, these results highlight the potential of global change factors (warming and N addition) to alter the structure and persistence of soil organic matter, with important implications in refining carbon cycle-climate models. [ABSTRACT FROM AUTHOR]

• Precipitation mainly drives biomass allocation (R/S) in temperate grasslands. • Both precipitation and temperature drive R/S in alpine grasslands. • Plant functional group compositions affect R/S more than soil nutrition. • Effects of forbs on R/S is larger than those other dominant plant groups. Elucidating biomass partitioning between above- and belowground parts in plant communities is vital to better assessing the ecological services of terrestrial ecosystems. However, the knowledge of biomass allocation in grasslands is scant, especially for the divergent mechanisms under both contrasting conditions. On two large geographic transects, Tibetan Plateau and Inner Mongolian Plateau, we analyzed the general and differential mechanisms of biomass allocation (plant biomass ratio of root to shoot, R/S) in temperate vs. alpine grasslands. We found that the R/S exhibited large variations, ranging from 3.89 to 45.10 in temperate grasslands and from 4.74 to 80.72 in alpine grasslands. The R/S decreased with increasing precipitation in both grasslands, whereas it weakly related to temperature. Plant functional group had highest importance on R/S than mean annual precipitation, mean annual temperature, soil nitrogen and phosphorus availabilities, and plant richness and diversity index. Climate factors indirectly but strongly drove R/S by mainly changing plant functional group compositions. Particularly, forbs affected R/S more than other dominant plant functional types. This information can provide a profound insight into the biomass allocation dynamics in grasslands at regional level under climate change scenarios. [ABSTRACT FROM AUTHOR]