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Aims Plant species mixtures with different functional traits or microbial associations can more fully utilize soil nutrient pools. However, there is a gap in our understanding of the synergistic influences of arbuscular mycorrhizal (AM) fungi in nutrient capture and resource partitioning across different soil depths in mixed plant communities, as well as their possible effects on plant coexistence. To address these knowledge gaps, we assessed the effect of AM fungi on nutrient uptake and competition between shallow- and deep-rooted pairs of grass and legume species. Methods To quantify the mycorrhizal mediation of N uptake at different rooting depths, 15N tracer was injected into soil at 3- and 25-cm depths of monoculture or bi-species mixtures, with or without AM fungi. Results AM symbioses reduced plant competition by equalizing access to N and subsequently increasing shoot N and P concentrations of co-cultivated plant species. Niche differentiation, based on rooting depth, had minimal effects on grass and legume competitive interactions. Both deep-rooted plant species, i.e., Medicago sativa and Dactylis glomerata, and shallow-rooted species, i.e., Lolium perenne and Trifolium repens, primarily acquired nutrients from shallow soil layers. However, AM fungi significantly increased the rooting depth of both shallow- and deep-rooted plant species, enhancing nutrient uptake and N2 fixation from depths of both 3 and 25 cm. Conclusion Our results suggest a strong influence of AM fungi on host-plant competitiveness and vertical nutrient capture in mixed plant communities, underscoring that microbial mutualist-mediated nutrient acquisition is a key driver of gains in productivity of grass–legume mixtures.

Arbuscular mycorrhizal (AM) fungi and rhizobium are likely important drivers of plant coexistence and grassland productivity due to complementary roles in supplying limiting nutrients. However, the interactive effects of mycorrhizal and rhizobial associations on plant community productivity and competitive dynamics remain unclear. To address this, we conducted a greenhouse experiment to determine the influences of these key microbial functional groups on communities comprising three plant species by comparing plant communities grown with or without each symbiont. We also utilized N-fertilization and clipping treatments to explore potential shifts in mycorrhizal and rhizobial benefits across abiotic and biotic conditions. Our research suggests AM fungi and rhizobium co-inoculation was strongly facilitative for plant community productivity and legume (Medicago sativa) growth and nodulation. Plant competitiveness shifted in the presence of AM fungi and rhizobium, favoring M. sativa over a neighboring C

Evaluating the responses of ecosystem respiration (Re) and its components to climate change is crucial for predicting terrestrial carbon cycling, particularly for the alpine grassland ecosystems. However, effects of climatic warming on ecosystem heterotrophic respiration (Rh) and autotrophic respiration (Ra) remain poorly understood in semi-arid alpine grasslands. A field manipulative experiment was conducted to investigate the effects of experimental warming on total Re, Rh and Ra in a Tibetan semi-arid alpine steppe during growing seasons of 2013 and 2014. Our results showed that warming decreased seasonal Re, Rh and Ra by 29%, 37% and 13%, respectively. However, warming tended to increase the contribution of Ra to Re (Ra/Re) but decrease that of Rh to Re (Rh/Re). Negative responses of Re was closely related to the changes in plant biomass and soil microbial biomass carbon. The apparent Q10 values of Ra were higher than those of Re and Rh, with the Q10 values ranked as Ra > Re > Rh. Warming decreased the apparent Q10 values of Re and the two components. Our results emphasize that Re and its components respond negatively to experimental warming, and soil carbon loss has the potential to be less under future climatic warming in the Tibetan semi-arid alpine steppe.

Grazing exclusion by fencing has been widely used for restoring degraded alpine grasslands, but rarely studies have considered the altitudinal difference of grazing exclusion effects on vegetation characteristics and soil properties. In this study, we focused our attention mainly on how alpine grasslands at different altitudes will response to long-term grazing exclusion. A 10-year altitudinal grazing exclusion experiment was conducted along a large altitudinal gradient (six altitudes, from 4400 to 5100 m) in alpine meadows on the central Tibetan Plateau. The vegetation characteristics and soil properties across grazing exclusion plots and free grazing plots were observed at each of six altitudes. Above-ground biomass (AGB), below-ground biomass (BGB), soil organic carbon (SOC), soil total nitrogen (STN), soil microbial biomass carbon (MBC), and soil microbial biomass nitrogen (MBN) showed a unimodal pattern along the altitudinal gradient from 4400 to 5100 m. A similar altitudinal pattern was found in sedges biomass but not in that of grasses, legumes, and herbs. Grazing exclusion practice increased vegetation cover, plant height, AGB, BGB, STN, SOC but has no significant effect on community diversity. Grazing did not alter the altitudinal patterns of AGB, BGB, SOC, and STN, but the stimulation impacts of grazing exclusion on these factors decreased with increasing altitude. The relative changes of MBC and MBN after grazing exclusion were significant related with that of BGB. Our study indicates that grazing exclusion by fencing is effective to restore vegetation and improve soil carbon and nitrogen properties in overgrazed alpine grasslands. However, the stimulation effects of grazing exclusion on alpine grasslands decreased with increasing altitudes. We suggest that in the high-altitude grassland ecosystems, especially where environment is harsh and stocking rate is relative low, grazing exclusion might not be efficient enough for restoring degraded grasslands.

We newly obtained the near complete mitochondrial genome of Oreolalax schmidti (18,481bp) by using polymerase chain reaction (PCR) in this study. It includes 13 protein-coding genes (PCG), two ribosomal RNA (rRNA) genes, and 23 transfer RNA (tRNA) genes. The phylogenetic tree indicates that the Oreolalax schmidti is closely related to the O. lichuanensis. This report will help the further studies of Oreolalax species classification and source protection.

The complete mitochondrial genome of the Oreolalax major (17,786 bp long) was obtained in this study. It includes 13 protein-coding genes (PCG), two ribosomal RNA (rRNA) genes, and 23 transfer RNA (tRNA) genes (GenBank accession number MN803320). The phylogenetic tree indicates that the O. major is closely related to the O. xiangchengensis.

Cynops cyanurus chuxiongensis is distributed in Yunnan plateau. In this paper, we sequenced and determined the complete mitochondrial genome of C. c. chuxiongensis. The assembled mitogenome is 16,4...