Peng Yan, Yang Wanqin, Li Jun, Wang Bin, Zhang Chuan, Yue Kai, Wu Fuzhong
Long-term Research Station of Alpine Forest Ecosystem, Key Laboratory of Ecological Forestry Engineering, Institute of Ecology & Forestry, Sichuan Agricultural University, Chengdu 611130, Sichuan, PR China.
PLoS One. 2015 Apr 22;10(4):e0124605. doi: 10.1371/journal.pone.0124605. eCollection 2015.
Litter decomposition during winter can provide essential nutrients for plant growth in the subsequent growing season, which plays important role in preventing the expansion of dry areas and maintaining the stability of ecotone ecosystems. However, limited information is currently available on the contributions of soil fauna to litter decomposition during winter in such ecosystems. Therefore, a field experiment that included litterbags with two different mesh sizes (0.04 mm and 3 mm) was conducted to investigate the contribution of soil fauna to the loss of foliar litter mass in winter from November 2013 to April 2014 along the upper reaches of the Minjiang River. Two litter types of the dominant species were selected in each ecosystem: cypress (Cupressus chengiana) and oak (Quercus baronii) in ecotone; cypress (Cupressus chengiana) and clovershrub (Campylotropis macrocarpa) in dry valley; and fir (Abies faxoniana) and birch (Betula albosinensis) in montane forest. Over one winter incubation, foliar litter lost 6.0%-16.1%, 11.4%-26.0%, and 6.4%-8.5% of initial mass in the ecotone, dry valley and montane forest, respectively. Soil fauna showed obvious contributions to the loss of foliar litter mass in all of the ecosystems. The highest contribution (48.5%-56.8%) was observed in the ecotone, and the lowest contribution (0.4%-25.8%) was observed in the montane forest. Compared with other winter periods, thawing period exhibited higher soil fauna contributions to litter mass loss in ecotone and dry valley, but both thawing period and freezing period displayed higher soil fauna contributions in montane forest. Statistical analysis demonstrated that the contribution of soil fauna was significantly correlated with temperature and soil moisture during the winter-long incubation. These results suggest that temperature might be the primary control factor in foliar litter decomposition, but more active soil fauna in the ecotone could contribute more in litter decomposition and its related ecological processes in this region.
冬季凋落物分解可为后续生长季节的植物生长提供必需养分，这对于防止干旱地区扩张和维持生态交错带生态系统的稳定性起着重要作用。然而，目前关于此类生态系统中土壤动物对冬季凋落物分解的贡献的信息有限。因此，于2013年11月至2014年4月在岷江上游开展了一项田间试验，该试验使用了两种不同网孔尺寸（0.04毫米和3毫米）的凋落物袋，以研究土壤动物对冬季叶片凋落物质量损失的贡献。在每个生态系统中选择了两种优势物种的凋落物类型：生态交错带中的岷江柏木（Cupressus chengiana）和巴郎山栎（Quercus baronii）；干旱河谷中的岷江柏木（Cupressus chengiana）和大叶羊蹄甲（Campylotropis macrocarpa）；以及山地森林中的岷江冷杉（Abies faxoniana）和红桦（Betula albosinensis）。经过一个冬季的培养，生态交错带、干旱河谷和山地森林中的叶片凋落物分别损失了初始质量的6.0% - 16.1%、11.4% - 26.0%和6.4% - 8.5%。土壤动物对所有生态系统中叶片凋落物质量的损失均表现出明显贡献。在生态交错带观察到最高贡献（48.5% - 56.8%），而在山地森林中观察到最低贡献（0.4% - 25.8%）。与其他冬季时期相比，解冻期土壤动物对生态交错带和干旱河谷凋落物质量损失的贡献更高，但在山地森林中，解冻期和冻结期土壤动物的贡献均更高。统计分析表明，在整个冬季培养期间，土壤动物的贡献与温度和土壤湿度显著相关。这些结果表明，温度可能是叶片凋落物分解的主要控制因素，但生态交错带中更活跃的土壤动物可能对该地区凋落物分解及其相关生态过程贡献更大。
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