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Background and aims <p>Precipitation is the primary driver of aboveground biomass in alpine desert steppes. However, the direct effects of precipitation on aboveground biomass and its indirect effects via interactions with phenology and leaf functional traits are little known.</p> Methods <p>Here, we report on a 2-year manipulative experiment in which we increased precipitation at each rainfall event (ambient, + 100%, + 200%, + 300% and + 400%) in an alpine desert steppe on the Tibetan Plateau. We measured plant cover, height, aboveground biomass (AGB), green-up date (GUD), senescence date (SD), growing season length (GSL), specific leaf area (SLA), leaf nitrogen concentration (N<sub>mass</sub> and N<sub>area</sub>) and leaf δ<sup>13</sup>C of the dominant tussock grass species, <i>Stipa glareosa</i>, in each treatment.</p> Results <p>Our data showed that increased precipitation significantly increased cover, height, and AGB of <i>S. glareosa</i>, while significantly decreased SLA, N<sub>mass</sub>, N<sub>area</sub> and δ<sup>13</sup>C. Increased precipitation led to earlier GUD and later SD, thus significantly extending GSL. In all pooled data, <i>S. glareosa</i> AGB positively correlated with GSL, but showed a negative correlation with N<sub>mass</sub> and δ<sup>13</sup>C. Structural equation models revealed that increased precipitation affected AGB mainly by extending GSL, but leaf functional traits played a minor role on AGB.</p> Conclusions <p>These findings clarify the regulatory mechanisms through which precipitation variations impact aboveground biomass in the alpine desert steppe, highlighting the critical role of phenology in cold and dry grasslands. Our findings advance our understanding of vegetation greening in response to the recent warming and wetting climate trends observed on the Tibetan Plateau.</p>

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Increased precipitation promotes aboveground biomass primarily by extending the growing season rather than by affecting leaf traits in alpine desert grasslands

  • 期刊论文

  • 发表日期：

    2026年2月17日

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  • Pengfei Ma,
  • Haoze Zhang,
  • Haijuan Wei,
  • Guangshuai Cui,
  • Liu Yang,
  • Haixia Wei,
  • Ying Guo,
  • Xinru Zhang,
  • Francisco I. Pugnaire,
  • Lin Zhang

摘要

Background and aims

Precipitation is the primary driver of aboveground biomass in alpine desert steppes. However, the direct effects of precipitation on aboveground biomass and its indirect effects via interactions with phenology and leaf functional traits are little known.

Methods

Here, we report on a 2-year manipulative experiment in which we increased precipitation at each rainfall event (ambient, + 100%, + 200%, + 300% and + 400%) in an alpine desert steppe on the Tibetan Plateau. We measured plant cover, height, aboveground biomass (AGB), green-up date (GUD), senescence date (SD), growing season length (GSL), specific leaf area (SLA), leaf nitrogen concentration (Nmass and Narea) and leaf δ13C of the dominant tussock grass species, Stipa glareosa, in each treatment.

Results

Our data showed that increased precipitation significantly increased cover, height, and AGB of S. glareosa, while significantly decreased SLA, Nmass, Narea and δ13C. Increased precipitation led to earlier GUD and later SD, thus significantly extending GSL. In all pooled data, S. glareosa AGB positively correlated with GSL, but showed a negative correlation with Nmass and δ13C. Structural equation models revealed that increased precipitation affected AGB mainly by extending GSL, but leaf functional traits played a minor role on AGB.

Conclusions

These findings clarify the regulatory mechanisms through which precipitation variations impact aboveground biomass in the alpine desert steppe, highlighting the critical role of phenology in cold and dry grasslands. Our findings advance our understanding of vegetation greening in response to the recent warming and wetting climate trends observed on the Tibetan Plateau.