Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland.
Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Poznań, Poland.
Glob Chang Biol. 2022 May;28(9):3145-3160. doi: 10.1111/gcb.16122. Epub 2022 Feb 21.
Summer droughts strongly affect soil organic carbon (SOC) cycling, but net effects on SOC storage are unclear as drought affects both C inputs and outputs from soils. Here, we explored the overlooked role of soil fauna on SOC storage in forests, hypothesizing that soil faunal activity is particularly drought-sensitive, thereby reducing litter incorporation into the mineral soil and, eventually, long-term SOC storage. In a drought-prone pine forest (Switzerland), we performed a large-scale irrigation experiment for 17 years and assessed its impact on vertical SOC distribution and composition. We also examined litter mass loss of dominant tree species using different mesh-size litterbags and determined soil fauna abundance and community composition. The 17-year-long irrigation resulted in a C loss in the organic layers (-1.0 kg C m ) and a comparable C gain in the mineral soil (+0.8 kg C m ) and thus did not affect total SOC stocks. Irrigation increased the mass loss of Quercus pubescens and Viburnum lantana leaf litter, with greater effect sizes when meso- and macrofauna were included (+215%) than when excluded (+44%). The enhanced faunal-mediated litter mass loss was paralleled by a many-fold increase in the abundance of meso- and macrofauna during irrigation. Moreover, Acari and Collembola community composition shifted, with a higher presence of drought-sensitive species in irrigated soils. In comparison, microbial SOC mineralization was less sensitive to soil moisture. Our results suggest that the vertical redistribution of SOC with irrigation was mainly driven by faunal-mediated litter incorporation, together with increased root C inputs. Our study shows that soil fauna is highly sensitive to natural drought, which leads to a reduced C transfer from organic layers to the mineral soil. In the longer term, this potentially affects SOC storage and, therefore, soil fauna plays a key but so far largely overlooked role in shaping SOC responses to drought.
夏季干旱强烈影响土壤有机碳（SOC）循环，但由于干旱会影响土壤的 C 输入和输出，因此对 SOC 储存的净影响尚不清楚。在这里，我们探索了土壤动物在森林中对 SOC 储存的被忽视的作用，假设土壤动物活动对干旱特别敏感，从而减少凋落物向矿物质土壤的掺入，最终减少长期 SOC 储存。在一个易受干旱影响的松林（瑞士）中，我们进行了一项为期 17 年的大规模灌溉实验，评估了其对垂直 SOC 分布和组成的影响。我们还使用不同网眼尺寸的凋落物袋来测量主要树种的凋落物质量损失，并确定土壤动物的丰度和群落组成。17 年的灌溉导致有机层中的 C 损失（-1.0 kg C m ）和矿物质土壤中可比的 C 增益（+0.8 kg C m ），因此对总 SOC 储量没有影响。灌溉增加了 Quercus pubescens 和 Viburnum lantana 叶凋落物的质量损失，当包括中型和大型动物时，效应大小更大（+215%），而不包括时则更小（+44%）。在灌溉期间，土壤动物介导的凋落物质量损失的增加与中型和大型动物的丰度呈多倍增加平行。此外，节肢动物和弹尾目动物的群落组成发生了变化，在灌溉土壤中，干旱敏感物种的存在增加。相比之下，微生物 SOC 矿化对土壤水分的敏感性较低。我们的结果表明，灌溉引起的 SOC 垂直再分配主要是由土壤动物介导的凋落物掺入引起的，同时增加了根系 C 的输入。我们的研究表明，土壤动物对自然干旱非常敏感，这导致从有机层到矿物质土壤的 C 转移减少。从长远来看，这可能会影响 SOC 储存，因此土壤动物在塑造 SOC 对干旱的响应方面起着关键但迄今为止被严重忽视的作用。
Zotero 插件
