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雪被斑块厚度对川西岷江冷杉林土壤有机层可培养细菌关键生理类群的影响

Effects of snow cover thickness on soil key physiological groups of cultivable bacteria in the organic layer of Abies faxoniana forest

  • 摘要: 全球气候变化正在影响高寒地区雪被格局,不同厚度雪被斑块可能通过影响土壤温度和湿度强烈作用于土壤微生物群落结构,进而影响微生物驱动的土壤生态过程,但缺乏必要关注。采用稀释平板法和最大或然数法,分析了川西高山典型岷江冷杉(Abies faxoniana)原始林季节性冻融末期林内天然形成的不同厚度雪被斑块下土壤有机层可培养细菌及其关键生理类群数量特征。结果表明:高山森林季节性冻融末期雪被厚度显著影响土壤有机层可培养细菌及其生理类群的结构和数量特征,而且不同土壤层次可培养细菌及其生理类群对雪被厚度的响应存在明显的差异。总体而言,氨化细菌、硝化细菌和嫌气性纤维素分解菌数量在厚型雪被下数量相对较高,反硝化细菌数量随雪被厚度增加而降低,而好气性纤维素分解菌数量受雪被厚度影响较小。季节性冻融末期,高山森林有机层细菌生理类群在不同雪被斑块下总体上数量变化趋势均表现为:氨化细菌>反硝化细菌>硝化细菌>好气纤维素分解菌>嫌气纤维素分解菌。为深入认识气候变化背景下高山森林土壤生态过程的季节转化提供了重要的理论和科学依据。

     

    Abstract: Global climate change is affecting the alpine snow cover pattern. In this context, different snow cover patches with different thickness may strongly affect soil microbial community structure by affecting soil temperature and humidity, and then influence the microbial-driven soil ecological process, but it lacks necessary attention. The effects of snow thickness on the characteristics of cultivable bacteria and physiological bacteria groups in the soil organic layer of Abies faxoniana forest were analyzed by using the plate culture method and the most probable number method, which have been used widely in measuring numbers of specific microbial physiological groups. The results showed that, at the end of seasonal freezing and thawing in alpine forest, snow cover thickness significantly influenced the numbers of bacteria and its physiological groups in the organic layer, and the response of culturable bacteria and their physiological groups in different soil layers were obviously different. In general, the number of ammonifying bacteria, nitrifying bacteria and anaerobic cellulose decomposing bacteria was relatively high under the thickest snow patch than under the other patches, and the number of denitrifying bacteria decreased with the increase of snow cover thickness, while the number of aerobic cellulose decomposing bacteria was less affected by snow cover thickness. At the end of seasonal freeze-thaw, the overall quantitative change trend of bacterial physiological groups in the organic layer of alpine forest under different snow patches was ammonifying bacteria > denitrifying bacteria > nitrifying bacteria > aerobic cellulose decomposing bacteria > anaerobic cellulose decomposing bacteria. The study provides important theoretical and scientific basis for understanding the seasonal transformation of soil ecological process in the alpine forests under the background of climate change.

     

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