Swiss Federal Institute for Forest, Snow and Landscape ResearchWSL, Zürcherstrasse 111, 8903 Birmensdorf, Zürich, Switzerland.
Department of Geosciences and Natural Resource Management, University of Copenhagen, Rolighedsvej 23, 1958 Frederiksberg, Denmark.
Sci Total Environ. 2018 Jul 1;628-629:1369-1394. doi: 10.1016/j.scitotenv.2018.01.012. Epub 2018 Feb 22.
Through litter decomposition enormous amounts of carbon is emitted to the atmosphere. Numerous large-scale decomposition experiments have been conducted focusing on this fundamental soil process in order to understand the controls on the terrestrial carbon transfer to the atmosphere. However, previous studies were mostly based on site-specific litter and methodologies, adding major uncertainty to syntheses, comparisons and meta-analyses across different experiments and sites. In the TeaComposition initiative, the potential litter decomposition is investigated by using standardized substrates (Rooibos and Green tea) for comparison of litter mass loss at 336 sites (ranging from -9 to +26 °C MAT and from 60 to 3113 mm MAP) across different ecosystems. In this study we tested the effect of climate (temperature and moisture), litter type and land-use on early stage decomposition (3 months) across nine biomes. We show that litter quality was the predominant controlling factor in early stage litter decomposition, which explained about 65% of the variability in litter decomposition at a global scale. The effect of climate, on the other hand, was not litter specific and explained <0.5% of the variation for Green tea and 5% for Rooibos tea, and was of significance only under unfavorable decomposition conditions (i.e. xeric versus mesic environments). When the data were aggregated at the biome scale, climate played a significant role on decomposition of both litter types (explaining 64% of the variation for Green tea and 72% for Rooibos tea). No significant effect of land-use on early stage litter decomposition was noted within the temperate biome. Our results indicate that multiple drivers are affecting early stage litter mass loss with litter quality being dominant. In order to be able to quantify the relative importance of the different drivers over time, long-term studies combined with experimental trials are needed.
通过凋落物分解，大量的碳被排放到大气中。为了了解控制陆地碳向大气转移的因素，已经进行了许多大规模的分解实验，这些实验主要集中在这个基本的土壤过程上。然而，以前的研究大多基于特定地点的凋落物和方法，这给不同实验和地点之间的综合、比较和荟萃分析增加了重大不确定性。在 TeaComposition 计划中，通过使用标准化的基质（Rooibos 和绿茶）来研究潜在的凋落物分解，在 336 个地点（范围从 -9 到 +26°C MAT 和从 60 到 3113mm MAP）比较凋落物质量损失，这些地点跨越了不同的生态系统。在这项研究中，我们测试了气候（温度和湿度）、凋落物类型和土地利用对九个生物群落早期分解（3 个月）的影响。我们表明，凋落物质量是早期凋落物分解的主要控制因素，它解释了全球范围内凋落物分解变异性的约 65%。另一方面，气候的影响不是特定于凋落物的，对绿茶的解释不到 0.5%，对 Rooibos 茶的解释不到 5%，而且只有在不利的分解条件下（即干旱与湿润环境）才具有重要意义。当数据在生物群落尺度上进行汇总时，气候对两种凋落物类型的分解都起着重要作用（对绿茶解释了 64%的变异，对 Rooibos 茶解释了 72%的变异）。在温带生物群落中，没有发现土地利用对早期凋落物分解有显著影响。我们的结果表明，多种驱动因素影响着早期凋落物质量损失，而凋落物质量是主要因素。为了能够随着时间的推移量化不同驱动因素的相对重要性，需要进行长期研究和实验。
