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Scientia Silvae Sinicae ›› 2013, Vol. 49 ›› Issue (8): 21-28.doi: 10.11707/j.1001-7488.20130804

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Fine Root Decomposition Dynamics during Freeze-Thaw Season in the Subalpine/Alpine Forests

Wei Yuanyun1,2, Wu Zhichao1,3, Yang Wanqin1, Wu Fuzhong1   

  1. 1. Institute of Ecological Forestry, Sichuan Agricultural University Chengdu 611130;
    2. Institute of Wetland Research, CAF Beijing 100091;
    3. Beijing Products Quality Supervision and Inspection Institute Beijing 101300
  • Received:2012-12-11 Revised:2013-02-25 Online:2013-08-25 Published:2013-08-17

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Abstract:

The ongoing winter warming inevitably alters the process of fine root decomposition in high-altitude area by changing the pattern of seasonal soil freezing and thawing. As yet, the dynamics of fine root decomposition at different stages in the freeze-thaw season remain uncertainty. In order to characterize the dynamics of fine root decomposition at different stages of a freeze-thaw season in cold biomes under climate change scenarios, litterbags with 10 g fine roots of Picea asperata, Betula albo-sinensis and Abies faxoniana were buried in the forest soil at the 3 582, 3 298 and 3 023 m altitudes in western Sichuan, China. These litterbags were recovered at onset of freezing (OF), deep frozen stage (DF), early thawing stage (ETS), middle thawing stage (MTS), and later thawing stage (LTS) from December 10, 2009 to April 28, 2010. The residual rate of fine roots was 88%-92% after a freeze-thaw season, and varied significantly with altitudes and tree species. The fine root decomposition occurred at all stages of the freeze-thaw season, among which OF had the highest rate of fine root decomposition. However, the rate of the fine root decomposition declined as decomposing, especially in the lower altitude. The decay rate constant of fine roots varied from 0.177 6 to 0.242 4, and the relative mass loss was correlated closely with soil temperature at the different stages, but the rate of the fine root decomposition was not significantly correlated with the indices of the measured initial qualities of fine roots. The regression model based on average soil temperature, fluctuated soil temperature, calcium concentration of fine roots and the ratio of lignin to nitrogen in fine roots during the freeze-thaw season, interpreted 95% of the reason of differences in the fine root decay rate. It is concluded that the soil freeze-thaw process caused by temperature fluctuations was an important factor in influencing the rate of the fine root decomposition during the freeze-thaw season in the high-frigid forest ecosystem, and the fine root quality also had minor impact on the fine root decomposition.

Key words: fine root decomposition, subalpine/alpine forest, seasonal freeze-thaw, relative mass loss

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