Journal of Plant Ecology ›› 2022, Vol. 15 ›› Issue (6): 1273-1284.DOI: 10.1093/jpe/rtac027

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  • 收稿日期:2021-09-05 修回日期:2021-10-09 接受日期:2021-12-09 出版日期:2022-12-01 发布日期:2022-12-08

Additive effects of warming and grazing on fine-root decomposition and loss of nutrients in an alpine meadow

Yang Zhou1,2,†, Wang-Wang Lv1,2,†, Shi-Ping Wang1,3,†, Li-Rong Zhang4, Jian-Ping Sun1,2, Li-Li Jiang1,2, Pei-Pei Liu1,2, Qi Wang1, Bo-Wen Li1,2, A. Wang1,2, Huan Hong1,2, Su-Ren Zhang1,2, Lu Xia5, Nan Ji1,2, Zheng-Xin Xie5, Cai-Yun Luo6, Zhen-Hua Zhang6, Chang-Hui Wang7, Jin-Zhi Wang8, Ci Yang9 and Tsechoe Dorji1,2,*    

  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 CAS Center for Excellence in Tibetan Plateau Earth Science of the Chinese Academy of Sciences, Beijing 100101, China, 4 Department of Resources and Environment, Hebei Normal University for Nationalities, Chengde 067600, China, 5 Science College, Tibet University, Lhasa 850001, China, 6 Northwestern Institute of Plateau Biology, Chinese Academy of Sciences; Qinghai Provincial Key Laboratory of Restoration Ecology of Cold Area, Xining 810008, China, 7 Grassland College, Shanxi Agriculture University, Taigu 030801, China, 8 Wetland Institute, Chinese Academy of Forestry, Beijing 100093, China, 9 Center for Meteorology, Meteorological Bureau of Tibet Autonomous Region, Lhasa 850000, China

    * Corresponding author. E-mail: tsechoedorji@itpcas.ac.cn
    † These authors contributed equally to this work.
  • Received:2021-09-05 Revised:2021-10-09 Accepted:2021-12-09 Online:2022-12-01 Published:2022-12-08

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摘要： 增温和放牧对高寒草甸植物细根的分解和养分丧失具有叠加效应

细根的分解是调控生态系统碳循环，影响养分循环以及土壤肥力的关键过程。然而，在自然生态系统中关于增温和放牧影响细根分解的研究十分匮乏。本研究利用非对称增温(即：昼夜和季节性不对称)和适度放牧(约50%饲草利用率)的两因素野外控制试验，探讨增温和放牧对青藏高原高寒草甸为期两年的细根分解和养分丧失的影响。增温和放牧通过提高细根分解促进了碳的循环，并影响了元素循环，但各元素的循环特征各自不同。增温和放牧对细根分解和养分丧失的影响是叠加的。试验两年期间，增温和放牧显著提高了细根累积生物量和总有机碳的丧失量。仅增温并放牧处理显著降低了氮元素百分率丧失量，而无论放牧与否，增温显著降低了磷元素苞粉率丧失量。与对照比较，仅增温或放牧提高了钾、钠、钙、镁的百分率丧失量。增温和放牧对细根分解和养分丧失未呈现交互影响。降低磷丧失较减低氮丧失对温度更加敏感。在未来变暖情景下，细根分解产生的不同养分百分率丧失对温度的敏感性差异可能调整不同养分在土壤中的有效率，进而影响生态系统的结构和功能。

关键词: 根系分解, 有机碳丧失, 养分丧失, 增温和放牧, 高寒草甸, 青藏高原

Abstract:

Fine-root decomposition is a critical process regulating ecosystem carbon cycles and affecting nutrient cycling and soil fertility. However, whether interaction between warming and grazing affects fine-root decomposition is still under-researched in natural grasslands. A two-factorial experiment with asymmetric warming (i.e. daytime vs. nighttime and growing season vs. nongrowing season) and moderate grazing (i.e. about average 50% forage utilization rate) was conducted to explore whether warming and grazing affect fine-root decomposition and loss of nutrients during a 2-year decomposition period in an alpine meadow on the Tibetan Plateau. Both warming and grazing facilitated carbon cycling through increase in fine-root decomposition, and influenced element cycling which varies among elements. The effects of warming and grazing on fine-root decomposition and loss of nutrients were additive. Both warming and grazing significantly increased cumulative percentage mass loss and total organic carbon loss of fine roots during the 2-year experiment. Only warming with grazing treatment reduced percentage nitrogen loss, whereas warming, regardless of grazing, decreased percentage phosphorus loss. Warming and grazing alone increased percentage loss of potassium, sodium, calcium and magnesium compared with control. There were no interactions between warming and grazing on fine-root decomposition and loss of nutrients. There was greater temperature sensitivity of decreased phosphorus loss than that of decreased nitrogen loss. Different temperature sensitivities of percentage loss of nutrients from fine-root decomposition would alter ratios of the available nutrients in soils, and may further affect ecosystem structure and functions in future warming.

Key words: root decomposition, organic carbon loss, loss of nutrients, warming and grazing, alpine meadow, Tibetan Plateau

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