Natural Resources Institute Finland, P.O. Box 16, FI-96301 Rovaniemi, Finland.
Arctic Centre, University of Lapland, P.O. Box 122, FI-96101 Rovaniemi, Finland.
FEMS Microbiol Ecol. 2018 Sep 1;94(9). doi: 10.1093/femsec/fiy123.
The northern regions are experiencing considerable changes in winter climate leading to more frequent warm periods, rain-on-snow events and reduced snow pack diminishing the insulation properties of snow cover and increasing soil frost and freeze-thaw cycles. In this study, we investigated how the lack of snow cover, formation of ice encasement and snow compaction affect the size, structure and activities of soil bacterial and fungal communities. Contrary to our hypotheses, snow manipulation treatments over one winter had limited influence on microbial community structure, bacterial or fungal copy numbers or enzyme activities. However, microbial community structure and activities shifted seasonally among soils sampled before snow melt, in early and late growing season and seemed driven by substrate availability. Bacterial and fungal communities were dominated by stress-resistant taxa such as the orders Acidobacteriales, Chaetothyriales and Helotiales that are likely adapted to adverse winter conditions. This study indicated that microbial communities in acidic northern boreal forest soil may be insensitive to direct effects of changing snow cover. However, in long term, the detrimental effects of increased ice and frost to plant roots may alter plant derived carbon and nutrient pools to the soil likely leading to stronger microbial responses.
北方地区的冬季气候发生了巨大变化，导致温暖期更加频繁、雨夹雪事件增多、积雪减少，降低了雪盖的隔热性能，增加了土壤的冻融循环。在这项研究中，我们研究了缺乏雪盖、冰壳形成和积雪压实如何影响土壤细菌和真菌群落的大小、结构和活性。与我们的假设相反，一个冬季的雪处理对微生物群落结构、细菌或真菌拷贝数或酶活性的影响有限。然而，在融雪前、生长季早期和晚期采集的土壤中，微生物群落结构和活性会随季节发生变化，这似乎是由基质的可利用性驱动的。细菌和真菌群落主要由耐胁迫的类群主导，如 Acidobacteriales、Chaetothyriales 和 Helotiales 目，这些类群可能适应了不利的冬季条件。本研究表明，酸性北方北方森林土壤中的微生物群落可能对不断变化的雪盖的直接影响不敏感。然而，从长远来看，增加的冰和霜对植物根系的不利影响可能会改变植物来源的碳和养分库，从而导致更强的微生物响应。
