Whether grazing response of species abundance can be predicted by plant functional trait remains a challenge untested in a specific ecosystem. We measured species abundance and relevant functional traits for 30 common component species in a moderately grazed and a control community over 3 years (2005, 2006 and 2007) in a Kobresia capillifolia dominated alpine meadow on the Tibetan Plateau. Our objective was to examine species response to grazing and to test the relationship between the response of species abundance and functional traits in grazed and control habitats. Our results showed: i) in terms of species relative abundance and saturated height (the maximum height of an adult individual), most component species significantly decrease in response to moderate grazing and the effect differed among species and between functional groups.ii) The response of species abundance was significantly negatively correlated with saturated height, but not correlated with specific leaf area or seed size. We concluded that the response direction of species abundance to grazing can be predicted by functional traits, whereas it is a weak predictor of the extent of grazing response in species abundance.

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The relative importance of intraspecific trait variation (rITV) for functional diversity (FD) in plant communities is increasingly apparent, but the influence of abiotic factors on the balance between intraspecific and interspecific effects in contrasting environments is uncertain. Drawing on a novel conceptual and analytic framework, we quantified rITV as the ratio of FD associated with between‐population ITV (Intra_FD) and the interspecific variation (Inter_FD) due to species turnover across sites. We predicted that rITV would increase with environmental harshness as a result of decreasing interspecific variation and concomitant increases in between‐population ITV. We empirically tested this prediction in a comparison of rITV for five traits (mature plant height, SLA, leaf dry matter content and the foliar concentrations of nitrogen and phosphorus (P)) characterizing species in Tibetan alpine meadow communities from contrasting environmental regimes. We found that across sites: (a) rITV for all five traits increased with environmental harshness not only through decreasing Inter_FD but also through increasing Intra_FD; (b) increases in rITV were mostly attributable to declines in soil resources, especially soil P, with lower soil P significantly associated with lower Inter_FD but higher Intra_FD for most traits; and (c) although neither Intra_FD nor Inter_FD was significantly impacted by species richness for any traits, a higher rITV for SLA was significantly associated with low species richness. Taken together, these results support our hypothesis that the functional significance of ITV in plant communities increases with environmental harshness. Moreover, in the Tibetan alpine meadows we studied, the opposing intraspecific and interspecific responses along a gradient of P availability appear to act as a buffering mechanism stabilizing the functional structure of communities on P deficient soils. Our novel conceptual and analytical framework provides a template for evaluating the generality of this favourable mismatch between intraspecific and interspecific responses in FD along environmental gradients. A free Plain Language Summary can be found within the Supporting Information of this article.

Question Do the three chosen species ( Caltha palustris, Veratrum nigrum and Stellera chamaejasme) in humid alpine meadows take up water from different depths? Do these species differ in their responsiveness to rainfall? Location Mt. Balang, China. Methods Rainwater, soil water and plant water were collected from three plots over a 15‐day period during June–July 2006, and water isotopes analysed. The linear mixed models procedure was used to compare δD and δ 18O values across soil depths, while three‐factor ANOVA was performed to compare δD and δ 18O values among the three species. The contributions of different soil depths to plant water sources were analysed using MixSir. A classic two‐endmember linear mixed model was used to calculate the proportion of rainwater in plant stem water. Results Soil water showed substantial temporal shifts in isotopic profile from day to day, as influenced by rainwater input. The three plant species, C. palustris (CP), V. nigrum (VN) and S. chamaejasme (SC), acquired water from different soil depths, with their reliance on deeper soil water increasing in the order of CP < VN < SC. Moreover, CP, VN and SC absorbed 69.18%, 35.50% and 13.46% of their stem water, respectively, from the 4 July rainwater, suggesting that their responsiveness to rain pulses significantly differed in the order of CP > VN > SC. Conclusions The isotopic profiles of soil water shifted dramatically in response to rainfall, suggesting rapid movement of soil water. There was separation of the plant water uptake depths among the three species, with SC depending less on surface soil and being associated with drier soil habitats compared with CP and VN. Moreover, CP absorbed rainwater before it percolated below the root zone, while VN and SC did not; the differential responsiveness to water pulses may be related to their different water requirements as a result of adaptation to different soil water conditions. Our study demonstrates inter‐specific differentiation in plant water uptake in humid alpine meadows. Such information is important for species co‐existence and plant community composition.

Biogenesis of plant microRNAs (miRNAs) takes place in nuclear dicing bodies (D-bodies), where the ribonulease III-type enzyme Dicer-like 1 (DCL1) processes primary transcripts of miRNAs (pri-miRNAs) into miRNA/miRNA* (*, passenger strand) duplexes from either base-to-loop or loop-to-base directions. Hyponastic Leaves 1 (HYL1), a double-stranded RNA-binding protein, is crucial for efficient and accurate processing. However, whether HYL1 has additional function remains unknown. Here, we report that HYL1 plays a noncanonical role in protecting pri-miRNAs from nuclear exosome attack in addition to ensuring processing. Loss of functions in SOP1 or HEN2, two cofactors of the nucleoplasmic exosome, significantly suppressed the morphological phenotypes of hyl1-2. Remarkably, mature miRNAs generated from loop-to-base processing were partially but preferentially restored in the hyl1 sop1 and hyl1 hen2 double mutants. Accordingly, loop-to-base–processed pri-miRNAs accumulated to higher levels in double mutants. In addition, dysfunction of HEN2, but not of SOP1, in hyl1-2 resulted in overaccumulation of many base-to-loop–processed pri-miRNAs, with most of their respective miRNAs unaffected. In summary, our findings reveal an antagonistic action of exosome in pri-miRNA biogenesis and uncover dual roles of HYL1 in stabilizing and processing of pri-miRNAs.