Journal of Plant Ecology ›› 2022, Vol. 15 ›› Issue (5): 977-990.DOI: 10.1093/jpe/rtac009

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  • 收稿日期:2021-07-12 修回日期:2021-09-30 接受日期:2021-11-22 出版日期:2022-09-01 发布日期:2022-09-30

Warming and grazing enhance litter decomposition and nutrient release independent of litter quality in an alpine meadow

Bowen Li1,2,†, Wangwang Lv1,2,†, Jianping Sun1,2, Lirong Zhang1, Lili Jiang1, *, Yang Zhou1,2, Peipei Liu1,2, Huan Hong1,2, Qi Wang1, Wang A1,2, Suren Zhang1,2, Lu Xia3, Zongsong Wang2, Tsechoe Dorji1,4, Ailing Su5, Caiyun Luo5, Zhenhua Zhang5 and Shiping Wang1,4, *   

  1. 1 Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China, 2 University of the Chinese Academy of Sciences, Beijing 100049, China, 3 College of Science, Tibet University, Lhasa 850000, China, 4 CAS Center for Excellence in Tibetan Plateau Earth Science of the Chinese Academy of Sciences, Beijing 100101, China, 5 Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwestern Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China

    *Corresponding author. E-mail: lljiang@itpcas.ac.cn (L.J.); wangsp@itpcas.ac.cn (S.W.)
    † These authors contributed equally to this work.
  • Received:2021-07-12 Revised:2021-09-30 Accepted:2021-11-22 Online:2022-09-01 Published:2022-09-30

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摘要： 增温和放牧对高寒草甸凋落物分解及其养分释放的影响不依赖于凋落物品质
在放牧生态系统中，增温、放牧和凋落物品质共同决定着凋落物分解和养分释放。然而，在以往的研究中这些因子的效应通常被单独地研究。在本研究中，我们在青藏高原高寒草甸开展了一个昼夜非对称增温和中度放牧两因子的凋落物分解试验。从每个处理中收集了凋落物样品，这些凋落物一部分放在它们的来源处理小区，另一部分放在其他处理小区以此来探究增温、放牧以及凋落物品质对凋落物分解和养分释放的影响。研究结果表明，增温而不是放牧显著增加了凋落物质量的损失、单位面积全碳、全氮以及全磷含量的损失，这主要是因为增温增加了凋落物生物量和分解速率。然而，尽管同时增温放牧处理也加快了凋落物分解速率，但由于降低了凋落物生物量，所以增温放牧处理并没有显著影响单位面积的凋落物碳和养分释放量。相比木质素含量和碳氮比而言，季节性土壤平均温度能够更好地预测凋落物分解速率。增温和放牧对凋落物分解存在交互作用，但它们和凋落物品质对凋落物的影响均不存在交互作用。单位面积的总氮释放的温度敏感性要高于总磷。因此，我们的结果表明，增温对凋落物分解以及养分释放的影响要显著大于凋落物品质变化对其分解的影响。在高寒草甸，氮释放的增加可能会间接导致土壤磷有效性的缺乏。

关键词: 不对称增温, 高寒草甸, 分解速率, 凋落物生物量和品质, 中度放牧, 养分释放

Abstract:

Warming and grazing, and litter quality jointly determine litter decomposition and nutrient releases in grazing ecosystems. However, their effects have previously been studied in isolation. We conducted a two factorial experiment with asymmetric warming using infrared heaters and moderate grazing in an alpine meadow. Litter samples were collected from all plots in each treatment, among which some subsamples were placed in their original plots and other samples were translocated to other treatment plots to test the relative effects of each treatment on litter decomposition and nutrient releases. We found that warming rather than grazing alone significantly increased total losses of litter mass, total organic carbon, total nitrogen (TN) and total phosphorus (TP) per unit area due to increases in both mass loss rates and litter biomass. However, grazing with warming did not affect their total mass losses because increased mass loss was offset by decreased litter biomass compared with the control. Seasonal mean soil temperature better predicted litter decomposition than litter lignin content or carbon to nitrogen ratio. There were interactions between warming and grazing, but there were no interactions between them and litter quality on litter decomposition. The temperature sensitivity of TN loss was higher than that of TP loss per unit area. Our results suggest that increased temperature has a greater effect on litter decomposition and nutrient release than change in litter quality, and that more N release from litter could result in greater P deficiency in the alpine meadow.

Key words: asymmetric warming, alpine meadow, decomposition rate, litter biomass and quality, moderate grazing, nutrient release

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